PD-L1 and TROP-2 targeting conjugates comprising effector molecules and uses thereof

Abstract

The present application provides a multispecific targeting conjugate comprising a first targeting moiety that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule wherein the effector molecule is affixed to the second targeting moiety via a conjugation site. In some embodiments, the multispecific targeting conjugate further comprises a cleavage site between the first targeting moiety and the conjugation site, and wherein the second targeting moiety conjugated to the effector molecule is capable of being released from the multispecific targeting conjugate via cleavage at the cleavage site. The present application also provides a novel anti-PD-L1 antibody construct and a novel anti-Trop-2 antibody construct. Pharmaceutical compositions and methods of treatment using the multispecific targeting conjugates are also provided.

Description

[0001] Cross-reference of related applications

[0002] This application claims priority to International Patent Application No. PCT / CN2023 / 096036, filed on May 24, 2023, and International Patent Application No. PCT / CN2023 / 095850, filed on May 23, 2023, the contents of which are incorporated herein by reference in their entirety.

[0003] Reference to the electronic sequence list The contents of the electronic serial number (199872000542SEQLIST.xml; size: 246,381 bytes; and creation date: April 26, 2024) are incorporated herein by reference in their entirety. Technical Field

[0004] This application relates to targeted conjugates containing effector molecules and their uses. Background Technology

[0005] Antibody-drug conjugates (ADCs) are targeted therapeutic agents designed to preferentially deliver a drug (“payload”) to diseased tissues expressing a surface antigen recognized by the antibody. ADCs typically consist of an antibody linked to a therapeutic agent (e.g., a cytotoxic drug) via a chemical linker capable of releasing the therapeutic agent to treat the disease. Currently, more than 10 ADCs have been FDA-approved for therapeutic use, and more than 100 are in clinical trials. Most currently approved or clinically evaluated ADCs are small molecule drug-antibody conjugates. Current ADCs incorporate standard chemotherapeutic agents, including, for example, derivatives of orlistatine monomethyl orlistatine E (MMAE), chalcogenide, SN-38, Dxd (an ethatecan derivative), and maytansine 1 (DM1). See, for example, Polakis, Pharma Rev , 2016, 68(1)3-19.

[0006] Despite the conceptual advantages and promising clinical outcomes of ADCs, developing effective ADC therapeutics remains highly challenging. The overall design of the ADC, the choice of target tissue, the antibody, the chemical linker, the drug attachment site, and the nature of the drug payload all influence the efficacy and risks of the ADC (see, for example, Chau et al.). Lancet2019; 394:793-804). For example, early-stage ADCs in clinical trials are affected by the immunogenicity of the mouse antibodies used, and recent advances in ADC development rely on humanized antibodies. Other prominent challenges of ADCs include a) ineffective drug payload; b) premature drug release, leading to loss of efficacy and increased toxicity; c) target expression levels; d) suboptimal target selectivity; e) poor penetration into solid tumor tissues; f) as in KADCYLA ® and ADCETRIS ® Side effects observed in patients include thrombocytopenia and neuropathy.

[0007] ADC platforms, as highly specific in vivo payload delivery systems, are also suitable for applications beyond small molecule drug delivery. For example, siRNA can be fused with antibodies and developed into an effective in vivo mRNA knockdown method (see Böumer et al.). Nature Protocols (2016, 11:22-36). Antibody-mediated siRNA delivery of this type has shown promising results in the treatment of colorectal cancer (see Bӓumer et al., 2016, 11:22-36). Clin Cancer Res 2015 15;21(6):1383-94.). A wider range of designs, antibody types, and therapeutics are still needed in ADC platforms. Summary of the Invention

[0008] In one aspect, this application provides a multispecific targeting conjugate comprising a first targeting portion that specifically recognizes PD-L1, a second targeting portion that specifically recognizes Trop-2, and an effector molecule, wherein the effector molecule is conjugated to the second targeting portion via a conjugation site.

[0009] In some embodiments of the multispecific targeting conjugate described above, the multispecific targeting conjugate further includes a cleavage site between the first targeting portion and the conjugation site, wherein the second targeting portion conjugated with the effector molecule can be released from the multispecific targeting conjugate via cleavage at the cleavage site.

[0010] In some embodiments of any of the above-described multispecific targeting conjugates, the multispecific targeting conjugate comprises the structure of Formula 1: (Equation 1) Where: A1 is the first target part; A2 is the second target part; P is the cleavage site; C is the conjugation site; L is the linker; D is the effector molecule; x = 0 or 1; a = 1-20; and b = 1-20.

[0011] In some embodiments of any of the above-described multispecific targeting conjugates, the first and / or second targeting portion comprises one or more targeting peptides or antibodies or antigen-binding fragments thereof. In some embodiments, the antibody or antigen-binding fragment thereof is selected from the group consisting of: full-length antibodies, biantibodies, scFv, scFab, Fab, Fab', F(ab')2, single-domain antibodies (sdAb), dsFv, and combinations thereof.

[0012] In some embodiments of any of the above-described multispecific targeting conjugates, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor, for example, a solid tumor. In some embodiments, the conditions are the tumor microenvironment.

[0013] In some embodiments of any of the above-described multispecific targeting conjugates, cleavage is carried out by a protease. In some embodiments, the protease is selected from the group consisting of: urokinase plasminogen activator (uPA), podocyte oleoresin, plasmin, TMPRSS3, TMPRSS4, TMPRSS6, MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12, MMP-13, MMP-14, MT1-MMP, cathepsin D, cathepsin K, cathepsin S, ADAM10, ADAM 12. ADAMTS, caspase-1, caspase-2, caspase-3, caspase-4, caspase-5, caspase-6, caspase-7, caspase-8, caspase-9, caspase-10, caspase-11, caspase-12, caspase-13, caspase-14, TACE, human neutrophil elastase, β-secretase, fibroblast-associated protein, proteolytic enzyme, PSMA, and PSA. In some embodiments, the protease is MMP. In some embodiments, the cleavage site that can be cleaved by MMP comprises the amino acid sequence of any one of SEQ ID NO: 71 and 137-143. In some embodiments, the MMP is MMP-9. In some embodiments, the cleavage site that can be cleaved by MMP-9 comprises the amino acid sequence of SEQ ID NO: 71 or 142. In some embodiments, the protease is uPA. In some embodiments, the cleavage site that can be cleaved by uPA contains the amino acid sequence of SEQ ID NO: 214.

[0014] In some embodiments of any of the above-described multispecific targeting conjugates, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the effector molecule is a therapeutic agent such as those selected from the group consisting of: protein-based drugs, small molecule drugs, cytotoxic agents, toxins, immunomodulators, anti-inflammatory agents, anti-infective agents, and epigenetic regulators. In some embodiments, the therapeutic agent is ethanotecan.

[0015] In some embodiments of any of the above-described multispecific targeting conjugates, the multispecific targeting conjugate comprises two or more effector molecules.

[0016] In some embodiments of any of the above-described multispecific targeting conjugates, x is 0. In some embodiments, x is 1. In some embodiments, a is 1-10, such as 1. In some embodiments, b is 2-10, such as 4-6.

[0017] In some embodiments of any of the above-described multispecific targeting conjugates, the first targeting portion is located at the N-terminus of the second targeting portion.

[0018] In some embodiments of any of the above-described multispecific targeting conjugates, the conjugation site comprises a transglutaminase conjugation site. In some embodiments, the transglutaminase conjugation site comprises any one of SEQ ID NO: 145-196, such as the amino acid sequence of SEQ ID NO: 147 or 188.

[0019] In some embodiments of any of the above-described multispecific targeting conjugates, the conjugation site (e.g., a transglutaminase conjugation site) comprises two or more glutamine-containing tags fused in tandem with each other.

[0020] In some embodiments according to any of the above-described multispecific targeting conjugates (e.g., multispecific targeting conjugates of Formula 1), L is represented by the following formula: (Gly) n -(PEG) m -VC-PAB-(DMAE) k Where n, m, and k are integers, n≥1, m≥2, and k is 0 or 1. In some implementations, L is represented by the following formula: (Gly) n -(PEG) m -VA-PAB-(DMAE) k Where n, m, and k are integers, n≥1, m≥2, and k is 0 or 1. In some embodiments, L is (Gly)6-amido-PEG8-VA-PAB. In some embodiments, L is (Gly)6-amido-PEG8-VC-PAB.

[0021] In some embodiments of any of the above-described multispecific targeting conjugates, L-(D) a The structure of inclusion A:

[0022] Equation A, where the wavy line represents the site covalently connected to the ligation site C.

[0023] In some embodiments of any of the above-described multispecific targeting conjugates, the second targeting portion comprises one or more sdAbs (e.g., VHHs) that specifically recognize Trop-2 (anti-Trop-2 sdAb or anti-Trop-2 VHH). In some embodiments, one or more anti-Trop-2 sdAbs are anti-Trop-2 VHHs, each of which independently comprises: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37 or a variant thereof comprising up to 3 amino acid variations; a CDR2 comprising the amino acid sequence of SEQ ID NO: 42 or a variant thereof comprising up to 3 amino acid variations; and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47 or a variant thereof comprising up to 3 amino acid variations; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 35 or a variant thereof comprising up to 3 amino acid variations; a CDR2 comprising the amino acid sequence of SEQ ID NO: 40 or a variant thereof comprising up to 3 amino acid variations; and a CDR3 comprising the amino acid sequence of SEQ ID NO: 45 or a variant thereof comprising up to 3 amino acid variations; iii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 36 or a variant thereof comprising up to 3 amino acid variations; and a CDR3 comprising the amino acid sequence of SEQ ID NO: 36. CDR2 containing the amino acid sequence of SEQ ID NO: 41 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 46 or a variant thereof containing up to 3 amino acid variations; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 38 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 43 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 48 or a variant thereof containing up to 3 amino acid variations; v) CDR1 containing the amino acid sequence of SEQ ID NO: 39 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 44 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 49 or a variant thereof containing up to 3 amino acid variations; vi) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 54 or a variant thereof containing up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 58 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 63 or a variant thereof comprising up to 3 amino acid variations; vii) comprising the amino acid sequence of SEQ ID NO: 51 or a variant thereof comprising up to 3 amino acid variations;CDR2 comprising the amino acid sequence of SEQ ID NO: 56 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 61 or a variant thereof comprising up to 3 amino acid variations; viii) CDR1 comprising the amino acid sequence of SEQ ID NO: 52 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 57 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 62 or a variant thereof comprising up to 3 amino acid variations; ix) CDR1 comprising the amino acid sequence of SEQ ID NO: 54 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 59 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 64 or a variant thereof comprising up to 3 amino acid variations; x) CDR3 comprising the amino acid sequence of SEQ ID NO: 54 or a variant thereof comprising up to 3 amino acid variations; CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 60 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 65 or a variant thereof containing up to 3 amino acid variations; xi) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 205 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations; xii) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 206 or a variant thereof containing up to 3 amino acid variations; xiii) CDR3 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 60 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 243 or a variant thereof containing up to 3 amino acid variations; or xiiiv) CDR1 containing the amino acid sequence of SEQ ID NO: 216 or a variant thereof containing up to 3 amino acid variations; and CDR2 containing the amino acid sequence of SEQ ID NO: 217 or a variant thereof containing up to 3 amino acid variations.And a CDR3 comprising the amino acid sequence of SEQ ID NO: 218 or a variant thereof comprising up to 3 amino acid variations. In some embodiments, one or more anti-Trop-2 VHHs independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, the second targeting portion comprises a first anti-Trop-2 sdAb (e.g., VHH) and a second anti-Trop-2 sdAb (e.g., VHH) fused in tandem with each other. In some embodiments, the first anti-Trop-2 sdAb (e.g., VHH) and the second anti-Trop-2 sdAb (e.g., VHH) bind to different Trop-2 epitopes. In some embodiments, the first or second anti-Trop-2 sdAb is anti-Trop-2 VHH, which comprises: CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 42, and CDR3 containing the amino acid sequence of SEQ ID NO: 47. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 50, 124, and 126. In some embodiments, the first or second anti-Trop-2 sdAb is anti-Trop-2 VHH, which comprises: CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 66, 123, and 131. In some embodiments, the first or second anti-Trop-2 sdAb is an anti-Trop-2 VHH, said anti-Trop-2 VHH comprising: CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of SEQ ID NO: 203.

[0024] In some embodiments of any of the above-described multispecific targeting conjugates, the first targeting portion comprises one or more antibodies or antigen-binding fragments thereof that specifically recognize PD-L1 (anti-PD-L1 antibody or antigen-binding fragment thereof). In some embodiments, one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) a heavy chain CDR1 (“H-CDR1”) comprising the amino acid sequence of SEQ ID NO: 3 or a variant thereof comprising up to 3 amino acid variations; H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8 or a variant thereof comprising up to 3 amino acid variations; H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13 or a variant thereof comprising up to 3 amino acid variations; a light chain CDR1 (“L-CDR1”) comprising the amino acid sequence of SEQ ID NO: 20 or a variant thereof comprising up to 3 amino acid variations; L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25 or a variant thereof comprising up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30 or a variant thereof comprising up to 3 amino acid variations; ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 1 or a variant thereof comprising up to 3 amino acid variations; and H-CDR1 comprising the amino acid sequence of SEQ ID NO: 13 or a variant thereof comprising up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 11 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 18 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 23 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 28 or a variant thereof containing up to 3 amino acid variations; iii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 2 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 7 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 12 or a variant thereof containing up to 3 amino acid variations; and H-CDR3 containing the amino acid sequence of SEQ ID NO: 11 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 19 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 24 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 29 or a variant thereof containing up to 3 amino acid variations; iv) H-CDR1 containing the amino acid sequence of SEQ ID NO: 4 or a variant thereof containing up to 3 amino acid variations;H-CDR2 comprising the amino acid sequence of SEQ ID NO: 9 or a variant thereof comprising up to 3 amino acid variations; H-CDR3 comprising the amino acid sequence of SEQ ID NO: 14 or a variant thereof comprising up to 3 amino acid variations; L-CDR1 comprising the amino acid sequence of SEQ ID NO: 21 or a variant thereof comprising up to 3 amino acid variations; L-CDR2 comprising the amino acid sequence of SEQ ID NO: 26 or a variant thereof comprising up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 31 or a variant thereof comprising up to 3 amino acid variations; v) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 5 or a variant thereof comprising up to 3 amino acid variations; H-CDR2 comprising the amino acid sequence of SEQ ID NO: 10 or a variant thereof comprising up to 3 amino acid variations; H-CDR3 comprising the amino acid sequence of SEQ ID NO: 15 or a variant thereof comprising up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 9 or a variant thereof comprising up to 3 amino acid variations. L-CDR1 containing the amino acid sequence of SEQ ID NO: 22 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 27 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 32 or a variant thereof containing up to 3 amino acid variations; or vi) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 245 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 246 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 247 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 248 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 247 or a variant thereof containing up to 3 amino acid variations; and L-CDR2 ... The amino acid sequence of SEQ ID NO: 16 or a variant thereof containing at most 3 amino acid variations of L-CDR3. In some embodiments, one or more anti-PD-L1 antibodies or antigen-binding fragments thereof independently comprise: i) a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33;ii) A VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and a VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; iii) A VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VL comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; iv) A VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VL comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; v) A VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219. VH containing at least about 85% sequence identity of SEQ ID NO: 221, and VL containing the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; vi) VH containing the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; vii) VH containing the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL containing the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; viii) VH containing the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing the amino acid sequence of SEQ ID NO: 212; VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; ix) VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222;x) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; xi) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xiii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223; VH containing at least about 85% sequence identity of a variant thereof, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL containing the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xv) VH containing the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL containing the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224. 223 VH having at least about 85% sequence identity, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xvii) VH containing the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 227, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226;xviii) A VH comprising the amino acid sequence of SEQ ID NO: 228 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xix) A VH comprising the amino acid sequence of SEQ ID NO: 229 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 229, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xx) A VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xxi) A VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; VH comprising a variant of SEQ ID NO: 230 having at least about 85% sequence identity, and VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; xxii) VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; or xxiii) VH comprising the amino acid sequence of SEQ ID NO: 250 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 250, and VL comprising the amino acid sequence of SEQ ID NO: 251 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 251. In some embodiments, the first targeting portion comprises a full-length anti-PD-L1 antibody. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82;iv) A heavy chain containing the amino acid sequence of SEQ ID NO: 83 and a light chain containing the amino acid sequence of SEQ ID NO: 84; v) A heavy chain containing the amino acid sequence of SEQ ID NO: 85 and a light chain containing the amino acid sequence of SEQ ID NO: 86; vi) A heavy chain containing the amino acid sequence of SEQ ID NO: 87 and a light chain containing the amino acid sequence of SEQ ID NO: 88; vii) A heavy chain containing the amino acid sequence of SEQ ID NO: 91 and a light chain containing the amino acid sequence of SEQ ID NO: 92; viiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 93 and a light chain containing the amino acid sequence of SEQ ID NO: 94; ix) A heavy chain containing the amino acid sequence of SEQ ID NO: 95 and a light chain containing the amino acid sequence of SEQ ID NO: 96; x) A heavy chain containing the amino acid sequence of SEQ ID NO: 97 and a light chain containing the amino acid sequence of SEQ ID NO: 98; xi) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 94. The following are listed: a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) a heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) a heavy chain containing the amino acid sequence of SEQ ID NO: 103 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) a heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid sequence of SEQ ID NO: 106; xv) a heavy chain containing the amino acid sequence of SEQ ID NO: 107 and a light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) a heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) a heavy chain containing the amino acid sequence of SEQ ID NO: 100; xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) a heavy chain containing the amino acid sequence of SEQ ID NO: 100; xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 10 ... The heavy chain containing the amino acid sequence of SEQ ID NO: 113 and the light chain containing the amino acid sequence of SEQ ID NO: 114; xix) the heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116; xx) the heavy chain containing the amino acid sequence of SEQ ID NO: 117 and the light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) the heavy chain containing the amino acid sequence of SEQ ID NO: 119 and the light chain containing the amino acid sequence of SEQ ID NO: 120;xxii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 121 and a light chain comprising the amino acid sequence of SEQ ID NO: 122; xxiii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 17 and a light chain comprising the amino acid sequence of SEQ ID NO: 34; or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, the anti-PD-L1 antibody or its antigen-binding fragment comprises i) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 33; or ii) a VH comprising the amino acid sequence of SEQ ID NO: 250 and a VL comprising the amino acid sequence of SEQ ID NO: 251. In some embodiments, the full-length anti-PD-L1 antibody comprises (i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 17 and a light chain comprising the amino acid sequence of SEQ ID NO: 34; or (ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242.

[0025] In some embodiments of any of the above-described multispecific targeting conjugates, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) an anti-PD-L1 antibody or an antigen-binding fragment thereof – optional linker 1 – conjugation site – optional linker 2 – anti-Trop-2 sdAb (e.g., VHH); ii) an anti-PD-L1 antibody or an antigen-binding fragment thereof – optional linker 1 – cleavage site – optional linker 2 – conjugation site – optional linker 3 – anti-Trop-2 sdAb (e.g., VHH); iii) an anti-PD-L1 antibody or an antigen-binding fragment thereof – optional linker 1 – conjugation site – optional linker 2 – first anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – second anti-Trop-2 sdAb (e.g., VHH); or iv) an anti-PD-L1 antibody or an antigen-binding fragment thereof – optional linker 1 – cleavage site – optional linker 2 – conjugation site – optional linker 3 – first anti-Trop-2 sdAb (e.g., VHH) – Optional connector 4 – Second anti-Trop-2 sdAb (e.g., VHH).

[0026] In some embodiments of any of the above-described multispecific targeting conjugates, the multispecific targeting conjugate comprises a full-length anti-PD-L1 antibody; wherein the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus, a fusion polypeptide: the heavy chain of the full-length anti-PD-L1 antibody – optional linker 1 – optional cleavage site – optional linker 2 – conjugation site – optional linker 3 – one or more anti-Trop-2 sdAbs (e.g., VHH); i) wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 17, and the light chain comprises the amino acid sequence of SEQ ID NO: 34; and wherein the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 67, 69, 215, and 238-240; or ii) wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 241, and the light chain comprises the amino acid sequence of SEQ ID NO: 242; and wherein the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 231-237. In some embodiments, the fusion peptide comprises the amino acid sequence of any one of SEQ ID NO: 67, 69 and 215.

[0027] Also provided are isolated antibody constructs (anti-PD-L1 antibody constructs) comprising a targeting moiety that specifically recognizes PD-L1 (anti-PD-L1 targeting moiety), wherein the anti-PD-L1 targeting moiety comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3 or a variant thereof comprising up to 3 amino acid variations; H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8 or a variant thereof comprising up to 3 amino acid variations; H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13 or a variant thereof comprising up to 3 amino acid variations; L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20 or a variant thereof comprising up to 3 amino acid variations; L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25 or a variant thereof comprising up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30 or a variant thereof comprising up to 3 amino acid variations; ii) comprising SEQ ID NO: H-CDR1 containing the amino acid sequence of SEQ ID NO: 1 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 6 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 11 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 18 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 23 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 28 or a variant thereof containing up to 3 amino acid variations; iii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 2 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 7 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 6 ... H-CDR3 containing the amino acid sequence of SEQ ID NO: 12 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 19 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 24 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 29 or a variant thereof containing up to 3 amino acid variations; iv) H-CDR1 containing the amino acid sequence of SEQ ID NO: 4 or a variant thereof containing up to 3 amino acid variations; and H-CDR2 containing the amino acid sequence of SEQ ID NO: 9 or a variant thereof containing up to 3 amino acid variations.H-CDR3 comprising the amino acid sequence of SEQ ID NO: 14 or a variant thereof comprising up to 3 amino acid variations; L-CDR1 comprising the amino acid sequence of SEQ ID NO: 21 or a variant thereof comprising up to 3 amino acid variations; L-CDR2 comprising the amino acid sequence of SEQ ID NO: 26 or a variant thereof comprising up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 31 or a variant thereof comprising up to 3 amino acid variations; or v) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 5 or a variant thereof comprising up to 3 amino acid variations; H-CDR2 comprising the amino acid sequence of SEQ ID NO: 10 or a variant thereof comprising up to 3 amino acid variations; H-CDR3 comprising the amino acid sequence of SEQ ID NO: 15 or a variant thereof comprising up to 3 amino acid variations; L-CDR1 comprising the amino acid sequence of SEQ ID NO: 22 or a variant thereof comprising up to 3 amino acid variations; L-CDR2 comprising the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 32 or a variant thereof containing up to 3 amino acid variations.

[0028] In some embodiments of the anti-PD-L1 antibody construct isolated according to the above, the anti-PD-L1 targeting portion comprises: i) a VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; ii) a VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and a VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; iii) a VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VH comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VL ... VL containing at least about 85% sequence identity of SEQ ID NO: 213; iv) VH containing the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL containing the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; v) VH containing the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL containing the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; vi) VH containing the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; vii) VL containing SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; VH, comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL, comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222;viii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; ix) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; x) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; xi) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16. VH containing at least about 85% sequence identity of SEQ ID NO: 224, and VL containing the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xii) VH containing the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xiii) VH containing the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL containing the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL containing the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; VL containing the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; VH containing the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223; and VL containing the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224;xvi) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xvii) A VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 227, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xviii) A VH comprising the amino acid sequence of SEQ ID NO: 228 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xix) A VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228; xvii) A VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228; xviii) A VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228; xviiii) A VH comprising the amino acid sequence of SEQ ID NO: 228 ... VH containing the amino acid sequence of SEQ ID NO: 229 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 229, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL containing the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL containing the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; or xxii) VH containing the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 229; VH, a variant of SEQ ID NO: 229 having at least about 85% sequence identity, and VL, comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226.

[0029] In some embodiments of any of the anti-PD-L1 antibody constructs isolated according to the above, the anti-PD-L1 targeting portion is selected from the group consisting of: full-length antibody, biantibody, scFv, scFab, Fab, Fab', F(ab')2, sdAb, dsFv, and combinations thereof.

[0030] In some embodiments of any of the anti-PD-L1 antibody constructs isolated above, the anti-PD-L1 targeting portion is a full-length antibody (full-length anti-PD-L1 antibody). In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86; vi) a heavy chain comprising the amino acid sequence of SEQ ID NO: 87 and a light chain comprising the amino acid sequence of SEQ ID NO: 88; vii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 91 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; viii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) the heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: The heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) the heavy chain containing the amino acid sequence of SEQ ID NO: 109 and the light chain containing the amino acid sequence of SEQ ID NO: 110;xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) a heavy chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 114; xix) a heavy chain containing the amino acid sequence of SEQ ID NO: 115 and a light chain containing the amino acid sequence of SEQ ID NO: 116; xx) a heavy chain containing the amino acid sequence of SEQ ID NO: 117 and a light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) a heavy chain containing the amino acid sequence of SEQ ID NO: 119 and a light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) a heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; or xxiii) a heavy chain containing the amino acid sequence of SEQ ID NO: 17 and a light chain containing the amino acid sequence of SEQ ID NO: 34. ;

[0031] In some embodiments of any of the isolated anti-PD-L1 antibody constructs described above, the isolated anti-PD-L1 antibody construct is multispecific.

[0032] In some embodiments of any of the isolated anti-PD-L1 antibody constructs described above, the isolated anti-PD-L1 antibody construct is selected from the group consisting of: bispecific T cell connectors (BiTE), bispecific killer cell connectors (BiKE), trispecific killer cell connectors (TriKE), trifunctional hybrid antibodies (triomab), dual affinity targeted antibodies (DART), chimeric antigen receptors (CAR), engineered T cell receptors (TCR), antibody-drug conjugates (ADC), and combinations thereof.

[0033] In some embodiments of any of the isolated anti-PD-L1 antibody constructs described above, the isolated anti-PD-L1 antibody construct is a multispecific targeting conjugate comprising a first targeting moiety that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule, wherein the first targeting moiety is an anti-PD-L1 targeting moiety, and wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site. In some embodiments, the multispecific targeting conjugate further comprises a cleavage site between the first targeting moiety and the conjugation site, and wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site.

[0034] Also provided is an isolated antibody construct (anti-Trop-2 antibody construct) comprising a targeting moiety that specifically recognizes Trop-2 (anti-Trop-2 targeting moiety), wherein the anti-Trop-2 targeting moiety is VHH (anti-Trop-2 VHH), the VHH comprising: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37 or a variant thereof comprising up to 3 amino acid variations; a CDR2 comprising the amino acid sequence of SEQ ID NO: 42 or a variant thereof comprising up to 3 amino acid variations; and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47 or a variant thereof comprising up to 3 amino acid variations; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 35 or a variant thereof comprising up to 3 amino acid variations; a CDR2 comprising the amino acid sequence of SEQ ID NO: 40 or a variant thereof comprising up to 3 amino acid variations; and a CDR3 comprising the amino acid sequence of SEQ ID NO: 45 or a variant thereof comprising up to 3 amino acid variations; iii) a CDR3 comprising the amino acid sequence of SEQ ID NO: 45 or a variant thereof comprising up to 3 amino acid variations; CDR1 containing the amino acid sequence of SEQ ID NO: 36 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 41 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 46 or a variant thereof containing up to 3 amino acid variations; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 38 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 43 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 48 or a variant thereof containing up to 3 amino acid variations; v) CDR1 containing the amino acid sequence of SEQ ID NO: 39 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 44 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 49 or a variant thereof containing up to 3 amino acid variations; vi) CDR1 containing the amino acid sequence of SEQ ID NO: 49 or a variant thereof containing up to 3 amino acid variations; CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 63 or a variant thereof containing up to 3 amino acid variations; vii) CDR1 containing the amino acid sequence of SEQ ID NO: 51 or a variant thereof containing up to 3 amino acid variations; and CDR2 containing the amino acid sequence of SEQ ID NO: 56 or a variant thereof containing up to 3 amino acid variations;CDR3 containing the amino acid sequence of SEQ ID NO: 61 or a variant thereof containing up to 3 amino acid variations; viii) CDR1 containing the amino acid sequence of SEQ ID NO: 52 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 57 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 62 or a variant thereof containing up to 3 amino acid variations; ix) CDR1 containing the amino acid sequence of SEQ ID NO: 54 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 59 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 64 or a variant thereof containing up to 3 amino acid variations; x) CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 64 or a variant thereof containing up to 3 amino acid variations. CDR2 containing the amino acid sequence of SEQ ID NO: 60 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 65 or a variant thereof containing up to 3 amino acid variations; xi) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 205 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations; xii) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 206 or a variant thereof containing up to 3 amino acid variations; xiii) CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: CDR2 containing the amino acid sequence of SEQ ID NO: 243 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 243 or a variant thereof containing up to 3 amino acid variations; or xiiiv) CDR1 containing the amino acid sequence of SEQ ID NO: 216 or a variant thereof containing up to 3 amino acid variations; and CDR2 containing the amino acid sequence of SEQ ID NO: 217 or a variant thereof containing up to 3 amino acid variations.And CDR3 comprising the amino acid sequence of SEQ ID NO: 218 or a variant thereof comprising up to three amino acid variations. In some embodiments, anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203.

[0035] In some embodiments of the isolated anti-Trop-2 antibody construct described above, the isolated anti-Trop-2 antibody construct comprises two or more anti-Trop-2 VHHs fused in tandem with each other.

[0036] In some embodiments of any of the isolated anti-Trop-2 antibody constructs described above, the isolated anti-Trop-2 antibody construct is multispecific.

[0037] In some embodiments of any of the isolated anti-Trop-2 antibody constructs described above, the isolated anti-Trop-2 antibody construct comprises a first anti-Trop-2 VHH and a second anti-Trop-2 VHH. In some embodiments, the first anti-Trop-2 VHH and the second anti-Trop-2 VHH bind to different Trop-2 epitopes. In some embodiments, the first or second anti-Trop-2 VHH comprises: CDR1 comprising the amino acid sequence of SEQ ID NO: 37, CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and CDR3 comprising the amino acid sequence of SEQ ID NO: 47. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 50, 124, and 126. In some embodiments, the first or second anti-Trop-2 VHH comprises: CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 66, 123, and 131. In some embodiments, the first or second anti-Trop-2 VHH comprises: CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, the first or second anti-Trop-2 VHH comprises the amino acid sequence of SEQ ID NO: 203.

[0038] In some embodiments of any of the isolated anti-Trop-2 antibody constructs described above, the isolated anti-Trop-2 antibody construct is selected from the group consisting of: BiTE, BiKE, TriKE, DART, CAR, engineered TCR, ADC, and combinations thereof.

[0039] In some embodiments of any of the isolated anti-Trop-2 antibody constructs described above, the isolated anti-Trop-2 antibody construct is a multispecific targeting conjugate comprising a first targeting moiety that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule, wherein the second targeting moiety is an anti-Trop-2 targeting moiety, and wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site. In some embodiments, the multispecific targeting conjugate further comprises a cleavage site between the first targeting moiety and the conjugation site, and wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site.

[0040] Pharmaceutical compositions are also provided comprising any one of the isolated anti-PD-L1 antibody constructs described above and optionally a pharmaceutically acceptable carrier.

[0041] Pharmaceutical compositions are also provided comprising any one of the isolated anti-Trop-2 antibody constructs described above and optionally a pharmaceutically acceptable carrier.

[0042] Pharmaceutical compositions are also provided comprising any one of the above-described multispecific targeting conjugates and optionally a pharmaceutically acceptable carrier. In some embodiments, at least two of the multispecific targeting conjugates in the pharmaceutical composition comprise different numbers of effector molecules. In some embodiments, the average molar ratio of the effector molecules to the multispecific targeting moiety in the pharmaceutical composition is at least about 1:1.

[0043] A method for treating an individual with Trop-2 positive cancer (e.g., recurrent Trop-2 positive cancer) is also provided, the method comprising administering to the individual an effective amount of any of the above-described multispecific targeting conjugates or any of the above-described pharmaceutical compositions. In some embodiments, Trop-2 positive cancer is selected from the group consisting of: breast cancer, cervical cancer, colorectal cancer, esophageal cancer, gastric cancer, lung cancer, oral squamous cell carcinoma, ovarian cancer, pancreatic cancer, kidney cancer, prostate cancer, stomach cancer, thyroid cancer, head and neck cancer, bladder cancer, urothelial carcinoma, uterine cancer, leukemia, extranodal nasal lymphoma and non-Hodgkin's lymphoma (NHL), gallbladder cancer, bile duct cancer, endometrial cancer, and glioblastoma. In some embodiments, Trop-2 positive cancer is prostate cancer, lung cancer, cervical cancer, or colorectal cancer.

[0044] Also provided are isolated nucleic acids encoding one or more polypeptide chains of any one of the above-described multispecific targeting conjugates (e.g., multispecific targeting moieties), isolated anti-PD-L1 antibody constructs, or isolated anti-Trop-2 antibody constructs; vectors containing such isolated nucleic acids; and host cells containing such isolated nucleic acids or vectors. A method for preparing any one of the above-described multispecific targeting conjugates, isolated anti-PD-L1 antibody constructs, or isolated anti-Trop-2 antibody constructs is also provided, the method comprising (i) culturing host cells containing any one of the isolated nucleic acids or vectors described herein, or any of the host cells described herein, under conditions suitable for expressing polypeptide moieties of any one of the multispecific targeting conjugates (e.g., multispecific targeting moieties), isolated anti-PD-L1 antibody constructs, or isolated anti-Trop-2 antibody constructs described herein; and (ii) obtaining polypeptide moieties of any one of the multispecific targeting conjugates, isolated anti-PD-L1 antibody constructs, or isolated anti-Trop-2 antibody constructs described herein from said host cells.

[0045] This document also provides a method for preparing any of the above-described multispecific targeting conjugates, wherein the method includes conjugating an effector molecule to a second targeting moiety via a conjugation site. In some embodiments, the method includes the steps of: (a) reacting a multispecific targeting moiety comprising a first targeting moiety, optionally a cleavage site, a second targeting moiety, and a conjugation site with a linker reagent to form a multispecific targeting moiety-linker intermediate; and (b) reacting the multispecific targeting moiety-linker intermediate with a nucleophilic group of an effector molecule moiety; thereby forming a multispecific targeting conjugate; or the method includes the steps of: (c) reacting an effector molecule moiety with a linker reagent to form a linker-effector molecule intermediate; and (d) reacting the linker-effector molecule intermediate with a conjugation site of a multispecific targeting moiety comprising a first targeting moiety, optionally a cleavage site, a second targeting moiety, and a conjugation site; thereby forming a multispecific targeting conjugate; or the method includes the step of: (e) reacting a multispecific targeting moiety comprising a first targeting moiety, optionally a cleavage site, a second targeting moiety, and a conjugation site with a linker-effector molecule conjugate; thereby forming a multispecific targeting conjugate. In some embodiments, conjugation is performed via transglutaminase-mediated conjugation. In some embodiments, the method further includes expressing a multispecific targeting moiety prior to step (a), step (d), or step (e). In some embodiments, expressing a multispecific targeting moiety includes: (i) culturing host cells containing an isolated nucleic acid or vector encoding any of the multispecific targeting moieties described herein; and (ii) obtaining the expressed multispecific targeting moiety from the host cells. Attached Figure Description

[0046] Figure 1 The schematic structure of an exemplary multispecific targeting conjugate is depicted, comprising: a first targeting portion that specifically recognizes PD-L1, such as a full-length anti-PD-L1 antibody; a second targeting portion that specifically recognizes Trop-2, such as one or more anti-Trop-2 sdAbs (e.g., VHH) fused together in tandem; an effector molecule, such as a small molecule drug; an optional protease cleavage site; a conjugation site; and an effector molecule linker.

[0047] Figure 2 The serum titers of human PD-L1 (F19-R238)-Fc fusion protein in four PD-L1-immunized BALB / c mice are shown according to ELISA.

[0048] Figures 3-4The results of binding of an exemplary anti-PD-L1 antibody to Flp-In-CHO cells expressing full-length human PD-L1 are shown (fluorescence-activated cell sorting; FACS). PD-L1-BMK1 (atezolizumab biosimilar) is a positive control. Human IgG1 isotype antibody is a negative control.

[0049] Figures 5-6 The results of binding of an exemplary anti-PD-L1 antibody to Flp-In-CHO cells expressing full-length cynomolgus monkey PD-L1 are shown (FACS). PD-L1-BMK1 is a positive control. Human IgG1 isotype antibody is a negative control.

[0050] Figures 7-8 The following are FACS results of a competitive assay of an exemplary anti-PD-L1 antibody in blocking the binding of hPD-1(ECD)-Avitag-His tag-biotin to Flp-In-CHO cells expressing full-length human PD-L1. PD-L1-BMK1 is a positive control. Human IgG1 isotype antibody is a negative control.

[0051] Figures 9-10 The following are FACS results of a competitive assay of an exemplary anti-PD-L1 antibody in blocking the binding of hCD80(ECD)-Fc-Avitag-biotin to Flp-In-CHO cells expressing full-length human PD-L1. PD-L1-BMK1 is a positive control. Human IgG1 isotype antibody is a negative control.

[0052] Figure 11 The dose-response curves for the immune blockade reporter gene assay of humanized anti-PD-L1 antibody against Jurkat-NFAT-Luc2-PD-1 effector cells and 293T-OS8-PD-L1 cells are shown. Atezolizumab served as a positive control. Human IgG1 isotype served as a negative control.

[0053] Figure 12 The diagram illustrates the binding of exemplary anti-Trop-2 VHH-hIgG1 Fc protein to human Trop-2 according to an ELISA assay. Salcituzumab (ALGA106A) and datopromab (ALGA106B) serve as positive controls. Human IgG1 isotypes serve as negative controls.

[0054] Figure 13 This diagram illustrates the binding of exemplary anti-Trop-2 VHH-hIgG1 Fc protein to MDA-MB-468 (a human triple-negative breast cancer cell line expressing Trop-2), according to FACS. Salcituzumab (ALGA106A) and datopromab (ALGA106B) served as positive controls. Human IgG1 isotypes served as negative controls.

[0055] Figures 14-15 The diagram illustrates the internalization curve of exemplary anti-Trop-2 VHH-hIgG1 Fc protein over time in MDA-MB-468 cells. Salcituzumab served as a positive control.

[0056] Figure 16 The binding affinity of llama parental Trop-2-B-YC-82 and humanized anti-Trop-2 VHH-hIgG1 Fc protein to MDA-MB-468 is shown according to FACS. Salcituzumab (ALGA106A) served as a positive control. Human IgG1 isotype served as a negative control.

[0057] Figure 17 The graphs show the internalization of llama parent Trop-2-B-YC-82 and humanized anti-Trop-2 VHH-hIgG1 Fc protein over time in MDA-MB-468 cells. Salcituzumab (ALGA106A) served as a positive control.

[0058] Figure 18 The binding affinity of llama parental Trop-2-A-258 and humanized anti-Trop-2 VHH-hIgG1 Fc protein to MDA-MB-468 is shown according to FACS. Salcituzumab (ALGA106A) and datopromab (ALGA106B) served as positive controls. Human IgG1 isotype served as a negative control.

[0059] Figure 19 The curves show the internalization of llama parental Trop-2-A-258 and humanized anti-Trop-2 VHH-hIgG1 Fc protein over time in MDA-MB-468 cells. Salcituzumab (ALGA106A) and datopromab (ALGA106B) served as positive controls.

[0060] Figure 20 The stability of the multispecific Abs ALGA105S and ALGA105X in human plasma over time, as measured by ELISA, is shown.

[0061] Figures 21-23 The A431 cell line is shown. Figure 21 HCC827 cell line ( Figure 22 ) and HCT15-hPD-L1-hTrop-2 cell line ( Figure 23 The internalization efficiency of multispecific antibodies conjugated with pHAb dyes was measured. Salcituzumab (ALGA106A) and datopromab (ALGA106B) served as positive controls for anti-Trop-2.

[0062] Figures 24-25 The PC3-hPD-L1-hTrop-2 cell line is shown. Figure 24 ) and HCT15-hPD-L1-hTrop-2 cell line ( Figure 25 The dose-response curves for cytotoxicity in ALGA105S were used. Unconjugated sacitrus abamectin (ALGA106A), datopromab (ALGA106B), ALGA105S, and ALGA105X served as controls.

[0063] Figure 26 The mean body weight curves over time in the MC38-hPD-L1-hTrop-2 mouse syngeneic tumor model are shown after single-dose intravenous administration of the test ADC, unconjugated multispecific Ab, or combination therapy with durvalumab (anti-PD-L1 mAb).

[0064] Figures 27-29 The tumor growth curves over time in the MC38-hPD-L1-hTrop-2 mouse syngeneic tumor model are shown after single-dose intravenous administration of the test ADC, unconjugated multispecific Ab, or combination therapy with durvalumab (anti-PD-L1 mAb).

[0065] Figure 30 Depicting the stability of ADCs in human plasma as measured by ELISA. ALGA106B (datopromab)-ADC served as a control.

[0066] Figures 31-32 Depicting exemplary ADCs in Trop-2 positive A431 cell lines ( Figure 31 ) and HCC827 cell line ( Figure 32 The dose-response curves for cytotoxicity in ALGA106A (sacituzumab)-ADC and ALGA106B (datopromab)-ADC served as positive controls.

[0067] Figure 33 The tumor growth curves of the MC38-hPD-L1-hTrop-2 mouse syngeneic tumor model over time are shown after a single intravenous administration of ALGA105X-ADC and subsequent re-stimulation of MC38-hPD-L1-hTrop-2 cells by a second subcutaneous injection without further ALGA105X-ADC administration.

[0068] Figure 34 Shown in Figure 33 The average body weight of mice receiving ALGA105X-ADC in the re-excitation experiment. Detailed Implementation

[0069] This application provides compositions and methods for treatment using targeted conjugates comprising a targeting moiety and an effector molecule, wherein the targeting moiety specifically recognizes PD-L1 and / or Trop-2, wherein the effector molecule is conjugated to the targeting moiety via a conjugation site, and wherein the targeting moiety linked to the effector molecule is release from the targeted conjugate via cleavage. The targeting moiety recognizing PD-L1 and / or Trop-2 binds to cell surface PD-L1 and / or Trop-2 expressed on diseased tissue or diseased cells (e.g., tumor cells). Upon entry of the targeted conjugate into a target site (e.g., the tumor microenvironment), cleavage of the cleavage site in the targeted conjugate can be triggered, resulting in the release of the targeting moiety linked to the effector molecule at the target site. In some embodiments, the targeted conjugate is multispecific. In some embodiments, the targeted conjugate comprises a first targeting moiety and a second targeting moiety, wherein the first targeting moiety and the second targeting moiety are fused to each other via optional cleavage sites and conjugation sites, and one or more effector molecules are conjugated to the conjugation sites. For example, the targeting moiety can be designed by fusing one or more scFv, scFab, or single-domain antibodies (e.g., anti-Trop-2 VHH) with a monoclonal antibody (e.g., anti-PD-L1 mAb) that has proven clinical efficacy and safety to provide multispecificity of target recognition, thereby providing enhanced clinical benefit. The targeting conjugates described herein may possess one or more of the following properties: i) enhanced selective target recognition and efficacy compared to conventional ADCs; ii) enhanced safety by targeting the drug to the tumor site and optionally releasing the drug conjugated to the anti-Trop-2 targeting moiety (which is also limited to the tumor site); and iii) better tissue penetration upon release of the drug-conjugated anti-Trop-2 sdAb (e.g., VHH) moiety compared to conventional IgG-ADCs.

[0070] This invention addresses one or more unmet needs for effective and / or highly specific drug payload release, high penetration efficiency, payload delivery to tumor tissue, increased antibody-target selectivity, and reduced toxicity (e.g., against non-target cells) / increased safety profiles. Furthermore, the multispecific targeting conjugate of this invention employs an immunomodulator (anti-PD-L1 Ab) and an ADC in a single construct, achieving a dual antitumor mechanism: i) the ADC portion exhibits targeted tumor cell killing; and ii) the immunomodulator portion improves tumor cell immune checkpoint inhibition of effector T cells, thereby reducing effector T cell exhaustion and tumor cell evasion of the immune response. The PD-L1 / Trop-2 multispecific targeting conjugates described herein: i) are effective in vivo for treating Trop-2 positive cancers, exhibiting superior therapeutic efficacy compared to combinations of sacitrus-ADC + durvalumab or datopromab-ADC + durvalumab; ii) demonstrate enhanced therapeutic efficacy when a cleavage site is employed between the anti-PD-L1 targeting moiety and the anti-Trop-2 targeting moiety conjugated to the effector molecule; iii) exhibit excellent safety profiles, comparable to combinations of sacitrus-ADC + durvalumab or datopromab-ADC + durvalumab; iv) possess excellent PK characteristics, as reflected by stability in human plasma, compared to datopromab-ADC; and v) demonstrate surprisingly long-term immune memory and safety profiles against tumor cells in vivo, potentially offering promising therapeutic potential for recurrent tumors or prevention of cancer recurrence.

[0071] Therefore, one aspect of this application provides a multispecific targeting conjugate comprising a first targeting portion specifically recognizing PD-L1, a second targeting portion specifically recognizing Trop-2, and an effector molecule, wherein the effector molecule is conjugated to the second targeting portion via a conjugation site. In some embodiments, the multispecific targeting conjugate further comprises a cleavage site between the first targeting portion and the conjugation site, wherein the second targeting portion conjugated to the effector molecule can be released from the multispecific targeting conjugate via a cleavage at the cleavage site.

[0072] Another aspect of this application provides a novel anti-PD-L1 antibody construct comprising a targeting moiety that specifically recognizes PD-L1. Another aspect of this application provides a novel anti-Trop-2 antibody construct comprising a targeting moiety that specifically recognizes Trop-2.

[0073] Pharmaceutical compositions, kits, and articles comprising any one of the multispecific targeting conjugates, anti-PD-L1 antibody constructs, or anti-Trop-2 antibody constructs described herein are also provided. Methods for treating an individual with Trop-2 positive cancers using the multispecific targeting conjugates or anti-Trop-2 antibody constructs or pharmaceutical compositions thereof described herein are also provided. Methods for preparing any of the multispecific targeting conjugates described herein are also provided.

[0074] I. Definition Terms are used herein as they are commonly used in the art, unless otherwise defined below.

[0075] As used herein, the term "targeting moiety" refers to a peptide-based binding molecule, or a portion thereof, that specifically binds to a target molecule. Both antibody-based and non-antibody-based binding molecules or portions thereof are considered herein.

[0076] As used herein, the term "therapeutic agent" refers to a molecule that has a therapeutic effect. A therapeutic agent can be any suitable molecular entity, except for oligonucleotides.

[0077] As used herein, the term "effect molecule" refers to a molecule that can be used for therapeutic and / or diagnostic purposes. Exemplary effect molecules include, but are not limited to, therapeutic agents, diagnostic markers, and oligonucleotides.

[0078] The term "combination" refers to the chemical connection of two chemical groups or parts together by one or more covalent or non-covalent bonds. Combination can be a direct combination between two chemical groups or parts, or an indirect combination through a third chemical group or part (e.g., a connector) that bridges the two chemical groups or parts.

[0079] The term "connection site" refers to a site that directly connects two chemical parts.

[0080] The term "antibody" is used in its broadest sense and encompasses a wide variety of antibody structures. An "antibody" can refer to an immunoglobulin molecule or fragment thereof (including the basic 4-chain antibody unit) capable of specifically binding to a specific epitope of an antigen. Antibodies can be complete immunoglobulins derived from natural or recombinant sources, and can be the immunoreactive portion of a complete immunoglobulin. The antibodies in this invention can exist in various forms, including, for example, polyclonal antibodies, monoclonal antibodies, intracellular antibodies (“intramolecular antibodies”), antigen-binding fragments (such as Fv, Fab, Fab', F(ab)2, and F(ab')2), as well as single-chain antibodies (scFv), heavy-chain antibodies (such as camel antibodies), and humanized antibodies (Harlow et al., 1999, Using Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, NY; Harlow et al., 1989, Antibodies: A Laboratory Manual, Cold Spring Harbor, New York; Houston et al., 1988, Proc. Natl. Acad. Sci. USA 85:5879-5883; Bird et al., 1988, Science242:423-426).

[0081] Full-length antibodies consist of two heavy chains and two light chains. Variable regions of the light and heavy chains are responsible for antigen binding. These variable domains of the heavy and light chains may be referred to as “VH” and “VL”, respectively. The variable regions of the two chains typically contain three highly variable loops called complementarity-determining regions (CDRs): light chain (LC) CDRs, including LC-CDR1, LC-CDR2, and LC-CDR3; heavy chain (HC) CDRs, including HC-CDR1, HC-CDR2, and HC-CDR3. The CDR boundaries of the antibody and antigen-binding fragments disclosed herein can be defined or identified according to the Kabat, Chothia, or Al-Lazikani conventions (Al-Lazikani 1997; Chothia 1985; Chothia 1987; Chothia 1989; Kabat 1987; Kabat 1991). The three core-residue junctions (CDRs) of either the heavy or light chain are interspersed between flanking segments called framework regions (FRs), which are more conserved than the CDRs and form a scaffold supporting the hypervariable loop. The constant regions of the heavy and light chains do not participate in antigen binding but exhibit various effector functions. Antibodies are classified according to the amino acid sequence of their heavy chain constant regions. The five major classes or isotypes of antibodies are IgA, IgD, IgE, IgG, and IgM, characterized by the presence of α, δ, ε, γ, and μ heavy chains, respectively. Several major antibody classes are further subdivided into subclasses such as IgG1 (γ1 heavy chain), IgG2 (γ2 heavy chain), IgG3 (γ3 heavy chain), IgG4 (γ4 heavy chain), IgA1 (α1 heavy chain), or IgA2 (α2 heavy chain).

[0082] As used herein, the term "antigen-binding fragment" refers to an antibody fragment, including, for example, biantibodies, Fab, Fab', F(ab')2, Fv fragments, disulfide-stabilized Fv fragments (dsFv), (dsFv)2, bispecific dsFv (dsFv-dsFv'), disulfide-stabilized biantibodies (ds biantibodies), single-chain Fv (scFv), scFv dimers (bivalent biantibodies), multispecific antibodies formed from a portion of an antibody containing one or more CDRs, camelified single-domain antibodies, nanobodies, domain antibodies, bivalent domain antibodies, or any other antibody fragment that binds to an antigen but does not contain the complete antibody structure. An antigen-binding fragment is capable of binding to the same antigen bound to a parent antibody or a parent antibody fragment (e.g., a parental scFv). In some embodiments, the antigen-binding fragment may contain one or more CDRs from a specific human antibody that have been grafted into a frame region from one or more different human antibodies.

[0083] "Fv" is the smallest antibody fragment containing a complete antigen recognition and binding site. This fragment consists of a dimer of a heavy chain variable region domain and a light chain variable region domain in tight, non-covalent association. The folding of these two domains generates six hypervariable rings (three from each of the heavy and light chains), which contribute amino acid residues for antigen binding and confer antigen-binding specificity to the antibody. However, although the affinity is lower than the entire binding site, even a single variable domain (or half of the Fv containing only three antigen-specific CDRs) can recognize and bind to the antigen.

[0084] A "single-chain Fv," also abbreviated as "sFv" or "scFv," is an antibody fragment containing VH and VL antibody domains linked together as a single polypeptide chain. In some embodiments, the scFv polypeptide also includes a polypeptide linker between the VH and VL domains, which allows the scFv to form the structure required for antigen binding. For a review of scFv, see Plückthunin. The Pharmacology of Monoclonal Antibodies Volume 113, edited by Rosenburg and Moore, Springer-Verlag, New York, pp. 269-315 (1994).

[0085] Nanobodies (Nanobody® is a registered trademark of Ablynx), also known as single-domain antibodies (sdAbs) or single-variable-domain antibodies, are antibody fragments composed of a single monomeric variable antibody domain. Like intact antibodies, sdAbs can selectively bind to specific antigens. Nanobodies have a molecular weight of only 12-15 kDa, much smaller than common intact antibodies (150-160 kDa). Nanobodies are peptide chains of approximately 110 amino acids in length, containing a variable domain (VH) of heavy-chain antibodies or common IgG. Unlike intact antibodies, such as VHH or V... NAR Nanobodies do not exhibit complement system-triggered cytotoxicity because they lack an Fc region. Camelidae (e.g., VHH) and fish (e.g., V) NAR Nanobodies derived from [specific source] can bind to hidden antigens inaccessible to intact antibodies, such as binding to the active site of an enzyme. Nanobodies can be obtained by immunizing sharks or camelids with the desired antigen and subsequently isolating the mRNA encoding the heavy chain antibody. Camels are members of the family Camelidae, the only extant family in the suborder Callostome. Camels, dromedary camels, Bactrian camels, llamas, alpacas, llamas, and guanacos belong to this family. Alternatively, nanobodies can be prepared by screening synthetic libraries.

[0086] The “VHH domain,” also known as VHH, VHH antibody fragment, and VHH antibody, is a type of nanobody. VHH was initially described as an antigen-binding immunoglobulin (variable) domain of “heavy chain antibodies” (i.e., “antibodies lacking the light chain”; Hamers-Casterman et al. (1993) Nature 363: 446-448). The term “VHH domain” was chosen to distinguish these variable domains from the heavy chain variable domains present in conventional 4-chain antibodies (referred to herein as “VH domains”) and the light chain variable domains present in conventional 4-chain antibodies (referred herein as “VL domains”). For further description of VHH and nanobodies, refer to Muyldermans' review article (in J. Biotechnol. 74: 277-302, 2001), and the following patent applications mentioned as general background: WO 94 / 04678, WO 95 / 04079, WO 96 / 34103; WO 94 / 25591, WO 99 / 37681, WO 00 / 40968, WO 00 / 43507, WO 00 / 65057, WO 01 / 40310, WO 01 / 44301, EP 1134231 and WO 02 / 48193; WO 97 / 49805, WO 01 / 21817, WO 03 / 035694, WO 03 / 054016 and WO WO 03 / 055527; WO 03 / 050531; WO 01 / 90190; WO 03 / 025020; WO04 / 041867, WO 04 / 041862, WO 04 / 041865, WO 04 / 041863, WO 04 / 062551, WO 05 / 044858, WO06 / 40153, WO 06 / 079372, WO 06 / 122786, WO 06 / 122787, and WO 06 / 122825. As described in these references, nanobodies (particularly VHH sequences and partially humanized nanobodies) can be characterized in particular by the presence of one or more “marker residues” in one or more framework sequences. Further descriptions of nanobodies, including humanization and / or camelification of nanobodies, as well as other modifications, portions or fragments, derivatives or “nanobody fusions,” multivalent constructs (including some non-limiting examples of linker sequences), and various modifications and formulations thereof for increasing the half-life of nanobodies can be found, for example, in WO 08 / 101985 and WO 08 / 142164.

[0087] "Isolated" antibodies are antibodies (e.g., natural or recombinant) that have been identified, separated, and / or recovered from components of their production environment. Preferably, the isolated polypeptide does not associate with any other components from its production environment. Contaminant components of its production environment, such as those produced by recombinantly transfected cells, are substances that typically interfere with the research, diagnostic, or therapeutic use of the antibody and may include enzymes, hormones, and other proteins or non-protein solutes. In a preferred embodiment, the polypeptide will: (1) be purified to a level greater than 95% by weight, and in some embodiments greater than 99% by weight, as determined by, for example, the Lowry method; (2) be purified to a level sufficient to obtain at least 15 residues of the N-terminal or internal amino acid sequence using a twist-cup sequencer; or (3) be purified to a level of homogeneity obtained by SDS-PAGE under non-reducing or reducing conditions using Coomassie blue or, preferably, silver staining. Isolated antibodies include in situ antibodies from recombinant cells, since at least one component of the antibody's native environment will be absent. However, isolated peptides or antibodies are typically prepared through at least one purification step.

[0088] The "variable region" or "variable domain" of an antibody refers to the amino-terminal domain of either the heavy or light chain. The variable domains of the heavy and light chains are referred to as "VH" and "VL," respectively. These domains are typically the largest variable portion of an antibody (relative to other antibodies of the same class) and contain the antigen-binding site. Antibodies from camel species that consist only of a heavy chain have a single heavy-chain variable region, which is called a "VHH." Therefore, VHH is a special type of VH.

[0089] The term "variable" refers to the fact that the sequences of certain segments of a variable domain differ widely between antibodies. The V domain mediates antigen binding and defines the specificity of a particular antibody for its specific antigen. However, variability is not uniformly distributed across the entire span of the variable domain. Instead, in both the light and heavy chain variable domains, variability is concentrated in three segments called hypervariable regions (HVRs). The more highly conserved portions of the variable domain are called frame regions (FRs). The variable domains of the natural heavy and light chains each contain four FR regions, predominantly employing a β-sheet configuration, linked by three HVRs that form loops connecting β-sheet structures and, in some cases, forming portions of β-sheet structures. The HVRs in each chain are held together closely adjacent to each other by the FR regions and, together with HVRs from the other chain, contribute to the formation of antigen-binding sites for antibodies (see Kabat et al.). Sequences of Immunological Interest, 5th edition, National Institute of Health, Bethesda, Md. (1991)). The constant domain does not directly participate in the binding of antibodies to antigens, but exhibits various effector functions, such as antibody participation in antibody-dependent cytotoxicity.

[0090] As used herein, the term “CDR” or “complementarity-determining region” is intended to refer to a non-continuous antigenic combination site found within the variable region of both the heavy and light chain polypeptides. These specific regions have been described in the following literature: Kabat et al., J. Biol. Chem. 252:6609-6616 (1977); Kabat et al., US Dept. of Health and Human Services, “Sequences of proteins of immunological interest” (1991); Chothia et al., J. Mol. Biol. 196:901-917 (1987); Al-Lazikani B. et al., J. Mol. Biol. , 273:927-948 (1997); MacCallum et al., J. Mol. Biol. 262:732-745 (1996); Abhinandan and Martin, Mol. Immunol., 45: 3832-3839 (2008); Lefranc MP et al., Dev. Comp. Immunol. , 27: 55-77 (2003); and Honegger and Plückthun, J. Mol. Biol. , 309:657-670 (2001), where the definition includes overlap or subset of amino acid residues when compared with each other. However, the application of any definition to refer to the CDR of an antibody or its grafted antibody or variant is intended to fall within the scope of the terminology as defined and used herein. CDR prediction algorithms and interfaces are known in the art, including, for example, those by Abhinandan and Martin, Mol. Immunol., 45: 3832-3839 (2008); Ehrenmann F. et al., Nucleic Acids Res. , 38: D301-D307 (2010); and Adolf-Bryfogle J. et al., Nucleic Acids Res.References cited in this paragraph are incorporated herein by reference in their entirety for use in this application and may be included in one or more claims herein. In some embodiments, the CDR sequence provided herein is based on the IMGT definition. For example, the CDR sequence may be determined by the VBASE2 tool (www.vbase2.org / vbase2.php, see also Retter I, Althaus HH, Münch R, Müller W: VBASE2, an integrative V gene database. Nucleic Acids Res. 1 Jan 2005; 33 (Database issue): D671-4, which is incorporated herein by reference in its entirety).

[0091] The terms "Fc region," "Fc domain," or "Fc" refer to the C-terminal non-antigen-binding region of an immunoglobulin heavy chain containing at least a portion of a constant region. The terms include native Fc regions and variant Fc regions. In some embodiments, the Fc domain is selected from the group consisting of Fc fragments of IgG, IgA, IgD, IgE, IgM, and combinations and hybrids thereof. In some embodiments, the Fc domain is derived from human IgG. In some embodiments, the Fc domain comprises the Fc domain of human IgG1, IgG2, IgG3, IgG4, or combinations or hybrids of IgG. In some embodiments, the Fc domain has reduced effector function (e.g., as measured by antibody-dependent cytotoxicity (ADCC) levels, such as a reduction of at least about 30%, 40%, 50%, 60%, 70%, 80%, 85%, 90%, or 95% of effector function) compared to the corresponding wild-type Fc domain. In some embodiments, the human IgG heavy chain Fc region extends from Cys226 to the C-terminus of the heavy chain. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present without affecting the structure or stability of the Fc region. In some embodiments, the targeting portion comprises a variant Fc region with at least one amino acid substitution compared to the Fc region of wild-type IgG or wild-type antibody.

[0092] As used herein, the term "monoclonal antibody" refers to an antibody obtained from a substantially homogeneous group of antibodies, i.e., the individual antibodies constituting said group are identical except for possible naturally occurring mutations and / or post-translational modifications (e.g., isomerization, amidation) present in small amounts. Monoclonal antibodies are highly specific (targeting a single antigenic site). Unlike polyclonal antibody formulations, which typically comprise different antibodies targeting different determinants (epitopes), each monoclonal antibody targets a single determinant on the antigen. In addition to their specificity, monoclonal antibodies are advantageous because they are synthesized via hybridoma culture and are not contaminated by other immunoglobulins. The modifier "monoclonal" indicates the characteristics of an antibody obtained from a substantially homogeneous group of antibodies and should not be construed as requiring the production of said antibody by any particular method. For example, monoclonal antibodies to be used according to this application can be prepared by a variety of techniques, including, for example, hybridoma methods (e.g., Kohler and Milstein). Nature 256:495-97 (1975); Hongo et al., Hybridoma, 14 (3): 253-260 (1995); Harlow et al., Antibodies: A Laboratory Manual (Cold Spring Harbor Laboratory Press, 2nd edition, 1988); Hammerling et al., in: Monoclonal Antibodies and T - Cell Hybridomas 563-681 (Elsevier, NY, 1981), recombinant DNA methods (see, for example, U.S. Patent No. 4,816,567), phage display technology (see, for example, Clackson et al.), Nature 352: 624-628 (1991); Marks et al., J. Mol. Biol. 222: 581-597 (1992); Sidhu et al., J. Mol. Biol. 338(2): 299-310 (2004); Lee et al., J. Mol. Biol. 340(5): 1073-1093 (2004);Fellouse, Proc. Natl. Acad. Sci. USA 101(34): 12467-12472 (2004); and Lee et al., J. Immunol. Methods 284(1-2): 119-132 (2004)) and techniques for generating human antibodies or human-like antibodies in animals possessing partial or complete human immunoglobulin loci or genes encoding human immunoglobulin sequences (see, for example, WO 1998 / 24893; WO 1996 / 34096; WO 1996 / 33735; WO 1991 / 10741; Jakobovits et al., Proc. Natl. Acad. Sci. USA 90: 2551 (1993); Jakobovits et al., Nature 362: 255-258 (1993); Bruggemann et al., Year in Immunol. 7:33 (1993); U.S. Patent Nos. 5,545,807, 5,545,806, 5,569,825, 5,625,126, 5,633,425, and 5,661,016; Marks et al., Bio / Technology 10: 779-783 (1992); Lonberg et al., Nature 368: 856-859 (1994); Morrison, Nature 368: 812-813 (1994); Fishwild et al., Nature Biotechnol. 14: 845-851(1996); Neuberger, Nature Biotechnol. 14: 826 (1996); and Lonberg and Huszar, Intern. Rev. Immunol. 13: 65-93 (1995).

[0093] Monoclonal antibodies as used herein explicitly include “chimeric” antibodies (immunoglobulins) in which a portion of the heavy and / or light chains is identical or homologous to the corresponding sequence in an antibody derived from a specific species or belonging to a specific antibody class or subclass, while the remainder of one or more chains is identical or homologous to the corresponding sequence in an antibody derived from another species or belonging to another antibody class or subclass; and fragments of such antibodies, provided they exhibit the desired biological activity (US Patent No. 4,816,567; Morrison et al.). Proc. Natl. Acad. Sci. USA, 81:6851-6855 (1984)). Chimeric antibodies of interest in this paper include PRIMATTZFD® antibodies, wherein the antigen-binding region of the antibody is derived from antibodies produced by immunizing macaques, for example, with the antigen of interest. As used herein, “humanized antibody” is used as a subset of “chimeric antibody”.

[0094] A “humanized” form of a nonhuman (e.g., mouse) antibody is a chimeric antibody containing a minimal sequence derived from a nonhuman immunoglobulin. In one embodiment, the humanized antibody is a human immunoglobulin (receptor antibody) in which residues of the receptor’s HVR (defined below) are replaced by residues of the HVR from a nonhuman species (donor antibody) such as mouse, rat, rabbit, or nonhuman primate, possessing the desired specificity, affinity, and / or capability. In some cases, the framework (“FR”) residues of the human immunoglobulin are replaced by corresponding nonhuman residues. Furthermore, the humanized antibody may contain residues not present in the receptor antibody or donor antibody. These modifications can be made to further improve antibody performance, such as binding affinity. Typically, humanized antibodies will contain at least one and usually two substantially all of the variable domains, wherein all or substantially all of the hypervariable loops correspond to those hypervariable loops in non-human immunoglobulin sequences, and all or substantially all of the FR regions are those FR regions in human immunoglobulin sequences, but the FR regions may contain one or more individual FR residue substitutions that improve antibody performance (e.g., binding affinity, isomerization, immunogenicity, etc.). The number of these amino acid substitutions in the FRs is typically no more than 6 in the H chain and no more than 3 in the L chain. Humanized antibodies will optionally also contain at least a portion of the immunoglobulin constant region (Fc), typically at least a portion of the immunoglobulin constant region of a human immunoglobulin. Suitable human receptor antibodies may be selected from conventional databases, such as the KABAT database, the Los Alamos database, the AbM database, and the Swiss protein database, based on homology with the nucleotide and amino acid sequences of the donor antibody. Human antibodies characterized by homology (based on amino acids) with the frame regions of the donor antibody may be suitable for providing heavy chain constant regions and / or heavy chain variable frame regions for insertion into the donor CDR. Suitable receptor antibodies that provide either a constant region or a variable framework region of the light chain can be selected in a similar manner. It should be noted that the heavy and light chains of the receptor antibody do not need to be derived from the same receptor antibody. Several methods for generating such humanized antibodies have been described in the prior art (see, for example, EEP-A-0239400 and EP-A-054951). For further details, see, for example, Jones et al. Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-329 (1988); and Presta, Curr. Op. Struct. Biol. 2:593-596 (1992). See also, for example, Vaswani and Hamilton, Ann. Allergy, Asthma & Immunol. 1:105-115 (1998); Harris, Biochem. Soc. Transactions 23:1035-1038 (1995); Hurle and Gross, Curr. Op. Biotech. 5:428-433 (1994); and U.S. Patent Nos. 6,982,321 and 7,087,409.

[0095] "Human antibody" refers to an antibody having an amino acid sequence corresponding to that of human-produced antibodies, and / or an antibody prepared using any of the techniques disclosed herein for preparing human antibodies. This definition of human antibody explicitly excludes humanized antibodies containing non-human antigen-binding residues. Various techniques known in the art, including phage display libraries, can be used to generate human antibodies. Hoogenboom and Winter, J. Mol. Biol., 227:381 (1991); Marks et al., J. Mol. Biol., 222:581 (1991). Cole et al. also used this method to prepare human monoclonal antibodies. Monoclonal Antibodies and Cancer Therapy Alan R. Liss, 77 (1985); Boerner et al., J. Immunol., The method described in 147(1):86-95 (1991). See also van Dijk and van de Winkel, Curr. Opin. Pharmacol., 5:368-74 (2001). Human antibodies can be prepared by administering an antigen to a transgenic animal that has been modified to produce such antibodies in response to antigen stimulation, but whose endogenous loci have been disabled, for example, by immunizing xenogeneic mice (see, for example, U.S. Patents 6,075,181 and 6,150,584 regarding XENOMOUSE™ technology). Also see, for example, Li et al., regarding human antibodies generated via human B-cell hybridoma technology. Proc. Natl. Acad. Sci. USA, 103:3557-3562 (2006).

[0096] As used herein, “treatment” or “treating” is a method for achieving a beneficial or desired outcome (including clinical outcomes). For the purposes of this application, a beneficial or desired clinical outcome includes, but is not limited to, one or more of the following: reducing one or more symptoms caused by a disease, reducing the severity of the disease, stabilizing the disease (e.g., preventing or delaying the worsening of the disease), preventing or delaying the spread of the disease, preventing or delaying the onset or recurrence of the disease, delaying or slowing the progression of the disease, improving the disease state, providing remission of the disease (partial or complete), reducing the dosage of one or more other medications required to treat the disease, delaying the progression of the disease, improving quality of life, and / or prolonging survival. “Treatment” also encompasses reducing the pathological consequences of the disease. The methods of this application consider any one or more of these treatment aspects.

[0097] The terms “individual,” “subject,” and “patient” are used interchangeably herein to describe mammals, including humans. In some embodiments, the individual is a person. In some embodiments, the individual suffers from a disease or ailment (e.g., cancer). In some embodiments, the individual requires treatment.

[0098] As understood in the art, an "effective amount" means an amount of agent (e.g., a targeted conjugate) sufficient to produce a desired therapeutic outcome (e.g., reducing the severity or duration of one or more symptoms of cancer, stabilizing the severity of one or more symptoms of cancer, or eliminating one or more symptoms of cancer) or a desired diagnostic outcome. For therapeutic use, beneficial or desired outcomes include, for example, reducing one or more symptoms (biochemical, histological, and / or behavioral) caused by the disease, including its complications and intermediate pathological phenotypes as presented during disease development, improving the quality of life of those patients with the disease, reducing the dosage of other drugs required to treat the disease, enhancing the effect of another drug, delaying disease progression, and / or prolonging patient survival. In some embodiments, an effective amount of agent may prolong survival (including overall survival and progression-free survival); produce an objective response (including a complete or partial response); alleviate one or more signs or symptoms of the disease or disorder to some extent; and / or improve the quality of life of the subject.

[0099] The “percentage of amino acid sequence identity (%)” for the peptide and antibody sequences identified herein is defined as the percentage of amino acid residues in the candidate sequence that are identical to amino acid residues in the peptide being compared, after alignment and taking into account any conserved substitutions as part of the sequence identity. The alignment used to determine the percentage of amino acid sequence identity can be performed in various ways within the capabilities of those skilled in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, Megalign (DNASTAR), or MUSCLE software. Those skilled in the art can determine appropriate parameters for measuring the alignment, including any algorithms required to achieve maximum alignment across the full length of the compared sequences. However, for the purposes of this document, the amino acid sequence identity value % is generated using the sequence comparison computer program MUSCLE (Edgar, RC, Nucleic Acids Research 32(5):1792-1797, 2004; Edgar, RC, BMC Bioinformatics 5(1):113, 2004, each of which is incorporated herein by reference in its entirety for all purposes).

[0100] Amino acid substitutions may include, but are not limited to, the replacement of one amino acid in a peptide with another amino acid. Exemplary substitutions are shown in Table 1. Amino acid substitutions may be introduced into target antibodies, and products may be screened for desired activities (e.g., retention / improvement of antigen binding, reduced immunogenicity, or improved ADCC or CDC).

[0101] Table 1: Exemplary amino acid substitutions.

[0102]

[0103] Amino acids can be grouped based on their common side chain properties: (1) Hydrophobicity: Leucine, Met, Ala, Val, Leu, Ile; (2) Neutral hydrophilicity: Cys, Ser, Thr, Asn, Gln; (3) Acidic: Asp, Glu; (4) Alkaline: His, Lys, Arg; (5) Residues that affect chain orientation: Gly, Pro; (6) Aromatics: Trp, Tyr, Phe.

[0104] Non-conservative substitution would require replacing members of one of these categories with members of another category.

[0105] The term “polypeptide” or “peptide” is used herein to encompass all kinds of naturally occurring and synthetic proteins, including protein fragments of all lengths, fusion proteins, and modified proteins, including but not limited to glycoproteins, as well as all other types of modified proteins (e.g., proteins produced by phosphorylation, acetylation, myristylation, palmitoylation, glycosylation, oxidation, formylation, amidation, polyglutamylation, ADP-ribosylation, PEGylation, biotinylation, etc.).

[0106] The term "fusion" refers to the genetic linking of two polypeptide fragments to provide a single, continuous polypeptide ("fusion polypeptide"). The two polypeptide fragments can be linked directly to each other or connected via another polypeptide located between them. Conventional recombinant DNA techniques or chemical gene synthesis can be used to provide nucleic acids that genetically encode the fusion polypeptide.

[0107] As used herein, the term "epitope" refers to a specific atom or amino acid group on an antigen that an antibody binds to. If two antibody or antigen-binding fragments exhibit competitive binding to an antigen, they can bind to the same epitope within the antigen.

[0108] As used herein, the terms “specifically bind,” “specifically recognize,” and “specific to” refer to measurable and reproducible interactions, such as the binding between a target and a target moiety (e.g., a target peptide or antibody or its antigen-binding fragment). In some embodiments, specific binding is determined by the presence of a target in the presence of a heterogeneous population of molecules, including biomolecules (e.g., cell surface receptors). For example, a target moiety that specifically recognizes a target (which may be an epitope) is an antibody that binds to the target with greater affinity, affinity, ease, and / or longer duration compared to its binding to other molecules. In some embodiments, as measured, for example, by radioimmunoassay (RIA), the degree of binding of the target moiety to irrelevant molecules is less than about 10% of the binding of the target moiety to the target. In some embodiments, the target moiety that specifically binds to the target has ≤10 -5 M, ≤10 -6 M, ≤10 -7 M, ≤10 -8 M, ≤10 -9 M, ≤10 -10 M, ≤10 -11 M or ≤10 -12 The dissociation constant (KD) of M. In some embodiments, the targeting moiety specifically binds to an epitope on a protein that is conserved across proteins from different species. In some embodiments, specific binding may include, but is not required to be, exclusive binding. The binding specificity of the targeting moiety can be determined experimentally using methods known in the art. Such methods include, but are not limited to, Western blotting, ELISA, RIA, ECL, IRMA, EIA, BIACORE™, and peptide scanning.

[0109] As used herein, the terms “link,” “conjugate,” “ligate,” and “fuse” are used interchangeably to refer to the covalent or non-covalent connection of two chemical moieties. Connections can be direct or indirect, such as through a linker.

[0110] The term "pharmaceutical composition" refers to a formulation that is in a form that allows the bioactivity of the active ingredient contained therein to be effective and does not contain any additional components that would have unacceptable toxicity to a subject to whom the formulation will be administered.

[0111] "Pharmaceutically acceptable carriers" refer to one or more components in a pharmaceutical preparation that are non-toxic to the subject, other than the active ingredient. Pharmaceutically acceptable carriers include, but are not limited to, buffers, excipients, stabilizers, cryoprotectants, tension agents, preservatives, and combinations thereof. Preferably, pharmaceutically acceptable carriers or excipients meet the standards required for toxicological and manufacturing testing, and / or are included in the Inactive Ingredient Guide established by the U.S. Food and Drug Administration or other state / federal government, or listed in the United States Pharmacopeia or other recognized pharmacopoeia for use in mammals, and more specifically in humans.

[0112] The term "package insert" refers to instructions typically included in the commercial packaging of a therapeutic product, which contain information about the indications, usage, dosage, administration, combination therapy, contraindications, and / or warnings for using such a therapeutic product.

[0113] "Article" is any article (e.g., package or container) or kit that contains at least one reagent, such as a medicine for treating a disease or ailment (e.g., cancer), or a probe for specifically detecting a biomarker described herein. In some embodiments, the article or kit is promoted, distributed, or sold as a unit for performing the methods described herein.

[0114] It should be understood that the embodiments of the present invention described herein include “consisting of the embodiments” and / or “substantially consisting of the embodiments”.

[0115] References to “about” a value or parameter in this document include (and descriptions) changes to that value or parameter itself. For example, a description of “about X” includes a description of “X”.

[0116] As used in this article, mentioning "not" a certain value or parameter usually means and describes "other than a certain value or parameter". For example, "the method is not used to treat type X disease" means that the method is used to treat types of diseases other than X.

[0117] The term “about XY” as used in this article has the same meaning as “about X to about Y”.

[0118] Unless the context clearly indicates otherwise, as used herein and in the appended claims, the singular form “a / an” or “the” includes a plural referent.

[0119] As used herein in phrases such as “A and / or B”, the term “and / or” is intended to include both A and B; A or B; A (alone); and B (alone). Similarly, as used herein in phrases such as “A, B, and / or C”, the term “and / or” is intended to cover each of the following embodiments: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0120] II. Multispecific targeting conjugates One aspect of this application provides a multispecific targeting conjugate comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety (e.g., an sdAb, such as VHH) that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188) (hereinafter also referred to as a "PD-L1 / Trop-2 multispecific targeting conjugate"). In some embodiments, the multispecific targeting conjugate further comprises a cleavage site between the first targeting moiety and the conjugation site, and wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site. Therefore, in some embodiments, a multispecific targeting conjugate is provided comprising a first targeting moiety that specifically recognizes PD-L1 (e.g., a full-length antibody), a second targeting moiety that specifically recognizes Trop-2 (e.g., an sdAb, such as VHH), and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate further comprises a cleavage site between the first targeting moiety and the conjugation site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), and wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site. In some embodiments, a multispecific targeting conjugate is provided comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety (e.g., an sdAb, such as VHH) that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate includes an optional cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) between the first targeting moiety and the conjugation site, wherein the second targeting moiety conjugated to the effector molecule can be released from the multispecific targeting conjugate via cleavage at the optional cleavage site, wherein the multispecific targeting conjugate comprises the structure of Formula 1: (Formula 1);And wherein: A1 is the first targeting moiety; A2 is the second targeting moiety; P is an optional cleavage site; C is a conjugation site; L is a linker; D is an effector molecule; x = 0 or 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6). In some embodiments, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site. In some embodiments, the disease is a tumor (e.g., a solid tumor), and the condition is a tumor microenvironment. In some embodiments, cleavage occurs extracellularly, such as extracellularly within tumor cells in the tumor microenvironment. In some embodiments, the second targeting moiety comprises one or more (e.g., 1, 2, 3, 4, or 5, such as 2) anti-Trop-2 sdAbs (e.g., VHH). In some embodiments, the first and / or second targeting moiety comprises one or more targeting peptides or their antibody or antigen-binding fragments. In some embodiments, the antibody or its antigen-binding fragment is selected from the group consisting of: full-length antibodies, biantibodies, scFv, scFab, Fab, Fab', F(ab')2, single-domain antibodies (sdAb), dsFv, and combinations thereof. Any anti-PD-L1 targeting moiety described herein (e.g., see sections II and III) may be used as the first targeting moiety in a PD-L1 / Trop-2 multispecific targeting conjugate. Any anti-Trop-2 targeting moiety described herein (e.g., anti-Trop-2 VHH) (e.g., see sections II and IV) may be used as the second targeting moiety in a PD-L1 / Trop-2 multispecific targeting conjugate. In some embodiments, cleavage is performed by a protease.In some embodiments, the protease is selected from the group consisting of: urokinase plasminogen activator (uPA), podocyte oleoresin, plasmin, TMPRSS3, TMPRSS4, TMPRSS6, MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-10, MMP-12, MMP-13, MMP-14, MTI-MMP, cathepsin D, cathepsin K, cathepsin S, and ADAM. 10. ADAM12, ADAMTS, caspase-1, caspase-2, caspase-3, caspase-4, caspase-5, caspase-6, caspase-7, caspase-8, caspase-9, caspase-10, caspase-11, caspase-12, caspase-13, caspase-14, TACE, human neutrophil elastase, β-secretase, fibroblast-associated protein, proteolytic enzyme, PSMA, and PSA. In some embodiments, the protease is an MMP, such as MMP-9. In some embodiments, the cleavage site that can be cleaved by MMP comprises the amino acid sequence of any one of SEQ ID NO: 71 and 137-143. In some embodiments, the cleavage site that can be cleaved by MMP-9 comprises the amino acid sequence of SEQ ID NO: 71 or 142. In some embodiments, the protease is uPA. In some embodiments, the cleavage site that can be cleaved by uPA comprises the amino acid sequence of SEQ ID NO: 214. In some embodiments, the effector molecule is a therapeutic agent or oligonucleotide, such as a therapeutic agent. In some embodiments, the therapeutic agent is selected from the group consisting of: protein-based drugs, small molecule drugs, cytotoxic agents, toxins, immunomodulators, anti-inflammatory agents, anti-infective agents, and epigenetic regulators. In some embodiments, the therapeutic agent is ethatecan. In some embodiments, the multispecific targeting conjugate comprises two or more effector molecules. In some embodiments, x is 0. In some embodiments, x is 1. In some embodiments, the first targeting portion is located at the N-terminus of the second targeting portion. In some embodiments, the conjugate site comprises a transglutaminase conjugate site. In some embodiments, the transglutaminase conjugate site comprises any one of SEQ ID NO: 145-196, such as the amino acid sequence of SEQ ID NO: 147 or 188. In some embodiments, the transglutaminase conjugate site comprises two or more glutamine-containing tags fused in tandem with each other. In some implementations, L is represented by the following formula: (Gly). n -(PEG) m -VC-PAB-(DMAE) kWhere n, m, and k are integers, n≥1, m≥2, and k is 0 or 1. In some implementations, L is represented by the following formula: (Gly) n -(PEG) m -VA-PAB-(DMAE) k Where n, m, and k are integers, n≥1, m≥2, and k is 0 or 1. In some embodiments, L is (Gly)6-amido-PEG8-VA-PAB. In some embodiments, L is (Gly)6-amido-PEG8-VC-PAB. In some embodiments, L-(D) a The structure of inclusion A: Formula A, The wavy lines represent sites covalently linked to the conjugation site C. In some embodiments, the second targeting portion comprises one or more (e.g., 1 or 2) sdAbs that specifically recognize Trop-2 (anti-Trop-2 sdAbs, such as anti-Trop-2 VHH). In some embodiments, the second targeting portion comprises a first anti-Trop-2 sdAb (e.g., VHH) and a second anti-Trop-2 sdAb (e.g., VHH) fused in tandem with each other. In some embodiments, the first anti-Trop-2 sdAb (e.g., VHH) and the second anti-Trop-2 sdAb (e.g., VHH) bind to different Trop-2 epitopes. In some embodiments, the first targeting portion comprises one or more antibodies or antigen-binding fragments thereof that specifically recognize PD-L1 (anti-PD-L1 antibodies or antigen-binding fragments thereof).

[0121] The portion of the multispecific targeting conjugate described herein that does not contain an effector molecule (or otherwise does not contain an effector molecule linker) is also referred to herein as the "targeting portion" or "multispecific targeting portion," which includes a first targeting portion, a second targeting portion, and optional conjugation sites and / or cleavage sites. For example, A1-(P) of Formula 1. x The -C-A2 part is referred to as the target part in this paper.

[0122] In some embodiments, a multispecific targeting conjugate is provided, comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety (e.g., an sdAb, such as VHH) that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), and wherein the first targeting moiety comprises one or more (e.g., one) anti-PD-L1 antibodies or antigen-binding fragments thereof, wherein the anti-PD-L1 antibody or antigen-binding fragment thereof independently comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and H-CDR2 comprising the amino acid sequence of SEQ ID NO: 13. L-CDR3 containing the amino acid sequence of SEQ ID NO: 244; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249.In some embodiments, a multispecific targeting conjugate is provided, comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety (e.g., an sdAb, such as VHH) that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate further comprises a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) between the first targeting moiety and the conjugation site, wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site; and wherein the first targeting moiety comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, wherein the anti-PD-L1 antibody or antigen-binding fragment thereof independently comprises: i) comprising SEQ ID NO: H-CDR1 containing the amino acid sequence of SEQ ID NO: 8, H-CDR2 containing the amino acid sequence of SEQ ID NO: 13, L-CDR1 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249.In some embodiments, a multispecific targeting conjugate is provided comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety (e.g., an sdAb, such as VHH) that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate includes an optional cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) between the first targeting moiety and the conjugation site, wherein the second targeting moiety conjugated to the effector molecule can be released from the multispecific targeting conjugate via cleavage at the optional cleavage site, wherein the multispecific targeting conjugate comprises the structure of Formula 1: (Formula 1); Wherein: A1 is the first targeting portion; A2 is the second targeting portion; P is an optional cleavage site; C is a conjugation site; L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule; x = 0 or 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); and wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, the anti-PD-L1 antibodies or antigen-binding fragments thereof independently comprising: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and comprising SEQ ID NO: L-CDR3 containing the amino acid sequence of SEQ ID NO: 244; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. In some embodiments, one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 34; ii) a VH comprising the amino acid sequence of SEQ ID NO: 219 and a VL comprising the amino acid sequence of SEQ ID NO: 220; iii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 213; iv) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 33; v) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221; vi) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 213; vii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221. VL of the amino acid sequence of 222;viii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 221; ix) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 222; x) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 222; xi) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 224; xii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 225; xiii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 226; xiv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv ...4 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv) A VH containing the amino acid sequence of SEQ ID NO: 225 and a VL containing the amino acid sequence of SEQ ID NO: 226; xv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv) A VH containing the amino acid sequence of SEQ ID NO: 224 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv) A VH containing the amino acid sequence of SEQ ID NO: 225 and a VL VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226; xvii) VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; The first targeting portion comprises a VH containing the amino acid sequence of SEQ ID NO: 219 and a VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) a VH containing the amino acid sequence of SEQ ID NO: 250 and a VL containing the amino acid sequence of SEQ ID NO: 251. In some embodiments, the first targeting portion comprises a full-length anti-PD-L1 antibody. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain containing the amino acid sequence of SEQ ID NO: 89 and a light chain containing the amino acid sequence of SEQ ID NO: 90;ii) A heavy chain containing the amino acid sequence of SEQ ID NO: 79 and a light chain containing the amino acid sequence of SEQ ID NO: 80; iii) A heavy chain containing the amino acid sequence of SEQ ID NO: 81 and a light chain containing the amino acid sequence of SEQ ID NO: 82; iv) A heavy chain containing the amino acid sequence of SEQ ID NO: 83 and a light chain containing the amino acid sequence of SEQ ID NO: 84; v) A heavy chain containing the amino acid sequence of SEQ ID NO: 85 and a light chain containing the amino acid sequence of SEQ ID NO: 86; vi) A heavy chain containing the amino acid sequence of SEQ ID NO: 87 and a light chain containing the amino acid sequence of SEQ ID NO: 88; vii) A heavy chain containing the amino acid sequence of SEQ ID NO: 91 and a light chain containing the amino acid sequence of SEQ ID NO: 92; viiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 93 and a light chain containing the amino acid sequence of SEQ ID NO: 94; ix) A heavy chain containing the amino acid sequence of SEQ ID NO: 95 and a light chain containing the amino acid sequence of SEQ ID NO: 86. x) A light chain containing the amino acid sequence of SEQ ID NO: 96; x) A heavy chain containing the amino acid sequence of SEQ ID NO: 97 and a light chain containing the amino acid sequence of SEQ ID NO: 98; xi) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) A heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 103 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) A heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid sequence of SEQ ID NO: 106; xv) A heavy chain containing the amino acid sequence of SEQ ID NO: 107 and a light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) A heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 96. The light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) the heavy chain containing the amino acid sequence of SEQ ID NO: 111 and the light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) the heavy chain containing the amino acid sequence of SEQ ID NO: 113 and the light chain containing the amino acid sequence of SEQ ID NO: 114; xix) the heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116;xx) a heavy chain containing the amino acid sequence of SEQ ID NO: 117 and a light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) a heavy chain containing the amino acid sequence of SEQ ID NO: 119 and a light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) a heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; xxiii) a heavy chain containing the amino acid sequence of SEQ ID NO: 17 and a light chain containing the amino acid sequence of SEQ ID NO: 34;(or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor (e.g., a solid tumor). In some embodiments, the condition is the tumor microenvironment. In some embodiments, cleavage is carried out by a protease, such as MMP (e.g., MMP-9) or uPA. In some embodiments, the cleavage site that can be cleaved by MMP comprises the amino acid sequence of any one of SEQ ID NO: 71 and 137-143. In some embodiments, the cleavage site that can be cleaved by MMP-9 comprises the amino acid sequence of SEQ ID NO: 71. In some embodiments, the cleavage site that can be cleaved by uPA comprises the amino acid sequence of SEQ ID NO: 214. In some embodiments, the effector molecule is a therapeutic agent or oligonucleotide, such as a therapeutic agent. In some embodiments, the conjugation site comprises a transglutaminase conjugation site, such as one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. In some embodiments, the first targeting portion is located at the N-terminus of the second targeting portion. In some embodiments, the second targeting portion comprises one or more (e.g., 1 or 2) anti-Trop-2 sdAbs (e.g., VHH). In some embodiments, the second targeting portion comprises a first anti-Trop-2 sdAb and a second anti-Trop-2 sdAb fused in tandem with each other. In some embodiments, the first anti-Trop-2 sdAb and the second anti-Trop-2 sdAb bind to different Trop-2 epitopes. In some embodiments, one or more anti-Trop-2 sdAbs (e.g., VHH) are fused to the C-terminus of one or both heavy chains of a full-length anti-PD-L1 antibody (e.g., linked to each other via conjugation sites). In some embodiments, the linker-effect molecule conjugate (L-(D); a The structure of any of the formulas A and J (such as formula A).

[0123] In some embodiments, a multispecific targeting conjugate is provided, comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), and wherein the second targeting moiety comprises one or more (e.g., 1 or 2) VHHs (anti-Trop-2 VHHs) that specifically recognize Trop-2, wherein the VHHs independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; iii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; CDR1 containing the amino acid sequence of SEQ ID NO: 205, CDR2 containing the amino acid sequence of SEQ ID NO: 47, and CDR3 containing the amino acid sequence of SEQ ID NO: 53; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218.In some embodiments, a multispecific targeting conjugate is provided, comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate further comprises a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) between the first targeting moiety and the conjugation site, wherein the second targeting moiety conjugated to the effector molecule is release from the multispecific targeting conjugate via cleavage at the cleavage site; and wherein the second targeting moiety comprises one or more (e.g., 1 or 2) VHHs (anti-Trop-2 VHHs) that specifically recognize Trop-2, wherein the VHHs independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, and a CDR1 comprising the amino acid sequence of SEQ ID NO: 147 or 188. ii) CDR2 containing the amino acid sequence of SEQ ID NO: 42 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217 and CDR3 containing the amino acid sequence of SEQ ID NO: 218.In some embodiments, a multispecific targeting conjugate is provided comprising a first targeting moiety (e.g., a full-length antibody) that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule (e.g., essanotecan), wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the multispecific targeting conjugate includes an optional cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) between the first targeting moiety and the conjugation site, wherein the second targeting moiety conjugated to the effector molecule can be released from the multispecific targeting conjugate via cleavage at the optional cleavage site, wherein the multispecific targeting conjugate comprises the structure of Formula 1: (Formula 1); Wherein: A1 is the first targeting portion; A2 is the second targeting portion; P is an optional cleavage site; C is a conjugation site; L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule; x = 0 or 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, the anti-PD-L1 antibodies or antigen-binding fragments thereof independently comprising: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and comprising SEQ ID NO: L-CDR3 comprising the amino acid sequence of SEQ ID NO: 244; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 245, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 246, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 247, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 248, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 249; and wherein the second targeting portion comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2 (anti-Trop-2 VHHs), wherein the VHHs independently comprise: i) CDR1 comprising the amino acid sequence of SEQ ID NO: 37, CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) CDR1 comprising the amino acid sequence of SEQ ID NO: 53, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 245, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 246, H-CDR1 comprising the amino acid sequence of SEQ ID NO: 247, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 248, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 249; and wherein the second targeting portion comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2, said VHHs independently comprise: i) CDR1 comprising the amino acid sequence of SEQ ID NO: 37, CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) CDR1 comprising the amino acid sequence of SEQ ID NO: 53 CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 206;Or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 34; ii) a VH comprising the amino acid sequence of SEQ ID NO: 219 and a VL comprising the amino acid sequence of SEQ ID NO: 220; iii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 213; iv) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 33; v) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221; vi) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 213; vii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221. VL containing the amino acid sequence of SEQ ID NO: 222; viii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 221; ix) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 222; x) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; xi) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 224; xii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 225; xiii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224. VL containing the amino acid sequence of SEQ ID NO: 225; xv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226;xvii) VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 251. In some implementations, the first targeting portion comprises a full-length anti-PD-L1 antibody. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86; vi) a heavy chain comprising the amino acid sequence of SEQ ID NO: 87 and a light chain comprising the amino acid sequence of SEQ ID NO: 88; vii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 91 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; viii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98.x1) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) A heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 103 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) A heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid sequence of SEQ ID NO: 106; xv) A heavy chain containing the amino acid sequence of SEQ ID NO: 107 and a light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) A heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) A heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 109. The following amino acid sequences are listed: (xviii) light chain containing the amino acid sequence of SEQ ID NO: 113 and light chain containing the amino acid sequence of SEQ ID NO: 114; (xix) heavy chain containing the amino acid sequence of SEQ ID NO: 115 and light chain containing the amino acid sequence of SEQ ID NO: 116; (xx) heavy chain containing the amino acid sequence of SEQ ID NO: 117 and light chain containing the amino acid sequence of SEQ ID NO: 118; (xxi) heavy chain containing the amino acid sequence of SEQ ID NO: 119 and light chain containing the amino acid sequence of SEQ ID NO: 120; (xxii) heavy chain containing the amino acid sequence of SEQ ID NO: 121 and light chain containing the amino acid sequence of SEQ ID NO: 122; (xxiii) heavy chain containing the amino acid sequence of SEQ ID NO: 17 and light chain containing the amino acid sequence of SEQ ID NO: 34.(or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, one or more anti-Trop-2 VHHs independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, the second targeting portion comprises a first anti-Trop-2 VHH and a second anti-Trop-2 VHH fused in tandem with each other. In some embodiments, the first anti-Trop-2 VHH and the second anti-Trop-2 VHH bind to different Trop-2 epitopes. In some embodiments, the first targeting portion is located at the N-terminus of the second targeting portion. In some embodiments, one or more anti-Trop-2 VHHs are fused to the C-terminus of one or both heavy chains of a full-length anti-PD-L1 antibody (e.g., interconnected via conjugation sites). In some embodiments, cleavage is conditionally triggered at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor (e.g., a solid tumor). In some embodiments, the conditions are the tumor microenvironment. In some embodiments, cleavage is carried out by a protease, such as MMP (e.g., MMP-9) or uPA. In some embodiments, the cleavage site that can be cleaved by MMP comprises an amino acid sequence of any one of SEQ ID NO: 71 and 137-143. In some embodiments, the cleavage site that can be cleaved by MMP-9 comprises an amino acid sequence of SEQ ID NO: 71. In some embodiments, the cleavage site that can be cleaved by uPA comprises an amino acid sequence of SEQ ID NO: 214. In some embodiments, the effector molecule is a therapeutic agent or oligonucleotide, such as a therapeutic agent. In some embodiments, the conjugation site comprises a transglutaminase conjugation site, such as one comprising an amino acid sequence of any one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. In some implementations, the connector-effect molecular conjugate (L-(D)); a The structure of any of the formulas A and J (such as formula A).

[0124] In some embodiments, the first targeting portion (e.g., any anti-PD-L1 targeting portion described herein) is located at the N-terminus of the second targeting portion (e.g., any anti-Trop-2 targeting portion described herein). In some embodiments, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) the first targeting portion – optional adapter 1 – conjugation site – optional adapter 2 – the second targeting portion; ii) the first targeting portion – optional adapter 1 – cleavage site – optional adapter 2 – conjugation site – optional adapter 3 – the second targeting portion; iii) the first targeting portion – optional adapter 1 – the second targeting portion – optional adapter 2 – conjugation site; or iv) the first targeting portion – optional adapter 1 – cleavage site – optional adapter 2 – the second targeting portion – optional adapter 3 – conjugation site. In some embodiments, the first targeting portion comprises one or more anti-PD-L1 antibodies or antigen-binding fragments thereof (e.g., full-length antibodies). In some embodiments, the second targeting portion comprises one or more anti-Trop-2 antibodies or antigen-binding fragments thereof, such as anti-Trop-2 sdAb (e.g., VHH) or scFv.In some embodiments, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) an anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – conjugation site – optional linker 2 – anti-Trop-2 sdAb (e.g., VHH); ii) an anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – cleavage site – optional linker 2 – conjugation site – optional linker 3 – anti-Trop-2 sdAb (e.g., VHH); iii) an anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – conjugation site – optional linker 2 – first anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – second anti-Trop-2 sdAb (e.g., VHH); iv) an anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – cleavage site – optional linker 2 – conjugation site – optional linker 3 – first anti-Trop-2 sdAb (e.g., VHH) – optional linker 4 – second anti-Trop-2 v) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – anti-Trop-2 sdAb (e.g., VHH) – optional linker 2 – conjugation site; vi) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – cleavage site – optional linker 2 – anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – conjugation site; vii) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – primary anti-Trop-2 sdAb (e.g., VHH) – optional linker 2 – secondary anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – conjugation site; viiii) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional linker 1 – primary anti-Trop-2 sdAb (e.g., VHH) – optional linker 2 – conjugation site – optional linker 3 – secondary anti-Trop-2 sdAb (e.g., VHH); ix) anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – cleavage site – optional adapter 2 – first anti-Trop-2 sdAb (e.g., VHH) – optional adapter 3 – second anti-Trop-2 sdAb (e.g., VHH) – optional adapter 4 – conjugation site; or x) anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – cleavage site – optional adapter 2 – first anti-Trop-2 sdAb (e.g., VHH) – optional adapter 3 – conjugation site – optional adapter 4 – second anti-Trop-2 sdAb (e.g., VHH). Any peptide adapter described herein may be used herein, such as any one of SEQ ID NO: 207-209. In some embodiments, the cleavage site is an MMP (e.g., MMP-9) or uPA cleavage site.In some embodiments, the cleavage site comprises any one of SEQ ID NO: 71, 137-143, and 214, such as the amino acid sequence of SEQ ID NO: 71 or 214. In some embodiments, the conjugation site comprises any one of SEQ ID NO: 145-196, such as the amino acid sequence of SEQ ID NO: 147 or 188.

[0125] In some embodiments, the first targeting portion (e.g., any anti-PD-L1 targeting portion described herein) is located at the C-terminus of the second targeting portion (e.g., any anti-Trop-2 targeting portion described herein). In some embodiments, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) the second targeting portion – optional adapter 1 – conjugation site – optional adapter 2 – the first targeting portion; ii) the second targeting portion – optional adapter 1 – conjugation site – optional adapter 2 – cleavage site – optional adapter 3 – the first targeting portion; iii) conjugation site – optional adapter 1 – the second targeting portion – optional adapter 2 – the first targeting portion; or iv) conjugation site – optional adapter 1 – the second targeting portion – optional adapter 2 – cleavage site – optional adapter 3 – the first targeting portion. In some embodiments, the first targeting portion comprises one or more anti-PD-L1 antibodies or antigen-binding fragments thereof (e.g., full-length antibodies). In some embodiments, the second targeting portion comprises one or more anti-Trop-2 antibodies or antigen-binding fragments thereof, such as anti-Trop-2 sdAb (e.g., VHH) or scFv.In some embodiments, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) an anti-Trop-2 sdAb (e.g., VHH) – optional linker 1 – conjugation site – optional linker 2 – anti-PD-L1 antibody or its antigen-binding fragment; ii) an anti-Trop-2 sdAb (e.g., VHH) – optional linker 1 – conjugation site – optional linker 2 – cleavage site – optional linker 3 – anti-PD-L1 antibody or its antigen-binding fragment; iii) a primary anti-Trop-2 sdAb (e.g., VHH) – optional linker 1 – a secondary anti-Trop-2 sdAb (e.g., VHH) – optional linker 2 – conjugation site – optional linker 3 – anti-PD-L1 antibody or its antigen-binding fragment; iv) a primary anti-Trop-2 sdAb (e.g., VHH) – optional linker 1 – a secondary anti-Trop-2 sdAb (e.g., VHH) – Optional linker 2 – Conjugation site – Optional linker 3 – Cleavage site – Optional linker 4 – Anti-PD-L1 antibody or its antigen-binding fragment; v) Conjugation site – Optional linker 1 – Anti-Trop-2 sdAb (e.g., VHH) – Optional linker 2 – Anti-PD-L1 antibody or its antigen-binding fragment; vi) Conjugation site – Optional linker 1 – Anti-Trop-2 sdAb (e.g., VHH) – Optional linker 2 – Cleavage site – Optional linker 3 – Anti-PD-L1 antibody or its antigen-binding fragment; vii) Conjugation site – Optional linker 1 – First anti-Trop-2 sdAb (e.g., VHH) – Optional linker 2 – Second anti-Trop-2 sdAb (e.g., VHH) – Optional linker 3 – Anti-PD-L1 antibody or its antigen-binding fragment; viiii) First anti-Trop-2 sdAb (e.g., VHH) – Optional linker 1 – Conjugation site – Optional linker 2 – Second anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – anti-PD-L1 antibody or its antigen-binding fragment; ix) conjugate site – optional linker 1 – first anti-Trop-2 sdAb (e.g., VHH) – optional linker 2 – second anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – cleavage site – optional linker 4 – anti-PD-L1 antibody or its antigen-binding fragment; or x) first anti-Trop-2 sdAb (e.g., VHH) – optional linker 1 – conjugate site – optional linker 2 – second anti-Trop-2 sdAb (e.g., VHH) – optional linker 3 – cleavage site – optional linker 4 – anti-PD-L1 antibody or its antigen-binding fragment. Any peptide linker described herein may be used herein, for example, any one of SEQ ID NO: 207-209. In some embodiments, the cleavage site is an MMP (e.g., MMP-9) or uPA cleavage site.In some embodiments, the cleavage site comprises any one of SEQ ID NO: 71, 137-143, and 214, such as the amino acid sequence of SEQ ID NO: 71 or 214. In some embodiments, the conjugation site comprises any one of SEQ ID NO: 145-196, such as the amino acid sequence of SEQ ID NO: 147 or 188.

[0126] In some embodiments, the multispecific targeting conjugate comprises a full-length anti-PD-L1 antibody fused to one or more anti-Trop-2 sdAbs (e.g., VHH). In some embodiments, one or more anti-Trop-2 sdAbs (e.g., VHH) are fused to the C-terminus of one or two heavy chains, the C-terminus of one or two light chains, the N-terminus of one or two heavy chains, and / or the N-terminus of one or two light chains of the full-length anti-PD-L1 antibody. In some embodiments, two or more anti-Trop-2 sdAbs (e.g., VHH) are fused in tandem with each other and then fused to the C-terminus of one or two heavy chains, the C-terminus of one or two light chains, the N-terminus of one or two heavy chains, and / or the N-terminus of one or two light chains of the full-length anti-PD-L1 antibody. In some embodiments, one or more (e.g., 1 or 2) anti-Trop-2 sdAbs (e.g., VHH) are fused to the C-terminus of each heavy chain of the full-length anti-PD-L1 antibody. In some embodiments, the C-terminus of the heavy chain of the anti-PD-L1 antibody is fused to the N-terminus of the anti-Trop-2 sdAb (e.g., VHH). In some embodiments, the C-terminus of the light chain of the anti-PD-L1 antibody is fused to the N-terminus of the anti-Trop-2 sdAb (e.g., VHH). In some embodiments, the targeting portion comprises any of the anti-PD-L1 antibodies or antigen-binding fragments thereof described herein and / or any of the anti-Trop-2 antibodies or antigen-binding fragments thereof. In some embodiments, the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus, a fusion polypeptide: the heavy chain of the full-length anti-PD-L1 antibody – optional linker 1 – optional cleavage site (e.g., SEQ ID NO: 71 or 214) – optional linker 2 – conjugation site (e.g., SEQ ID NO: 147 or 188) – optional linker 3 – one or more anti-Trop-2 sdAbs (e.g., VHH).

[0127] In some embodiments, a multispecific targeting conjugate is provided, comprising: a first targeting moiety specifically recognizing PD-L1, a second targeting moiety specifically recognizing Trop-2, and an effector molecule (e.g., esanotecan), wherein the effector molecule is conjugated to the second targeting moiety via an effector molecule linker (L) via a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), wherein the first targeting moiety is a full-length anti-PD-L1 antibody, and wherein the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus, a fusion polypeptide: the heavy chain of a full-length anti-PD-L1 antibody – optional linker 1 – optional cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214) – optional linker 2 – conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188) – optional linker 3 – one or more (e.g., 1 or 2) anti-Trop-2 The sdAb (e.g., VHH); i) wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 17, the light chain comprises the amino acid sequence of SEQ ID NO: 34, and wherein the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 67, 69, 215, and 238-240; or ii) wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 241, the light chain comprises the amino acid sequence of SEQ ID NO: 242, and wherein the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 231-237. In some embodiments, the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 67, 69, and 215. In some embodiments, when the multispecific targeting conjugate comprises two anti-Trop-2 sdAbs (e.g., VHH), they may be the same or different and may bind to the same or different Trop-2 epitopes. In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethanotecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0128] In some implementations, multispecific targeting conjugates comprising the structure of Formula 1 are provided: (Equation 1) Wherein: A1 is a first targeting portion that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting portion that specifically recognizes Trop-2 (e.g., an sdAb, such as VHH); P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule (e.g., ethatecan); x = 0; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10 or 4-6). In some embodiments, the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, such as a full-length anti-PD-L1 antibody. In some implementations, multispecific targeting conjugates comprising the structure of Formula 1 are provided: (Equation 1) Wherein: A1 is the first targeting moiety that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is the second targeting moiety that specifically recognizes Trop-2 (e.g., an sdAb, such as VHH); P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amido-PEG8-VA-PAB); D is an effector molecule (e.g., ethatecan); x = 0; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); and wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, the anti-PD-L1 antibody or antigen-binding fragment thereof independently comprising: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 245, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 246, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 247, and L-CDR1 comprising the amino acid sequence of SEQ ID NO: 247. L-CDR2 comprising the amino acid sequence 248 and L-CDR3 comprising the amino acid sequence SEQ ID NO: 249. In some embodiments, the second targeting portion comprises one or more (e.g., 1 or 2) anti-Trop-2 antibodies or antigen-binding fragments thereof, such as a first anti-Trop-2 sdAb and a second anti-Trop-2 sdAb fused in tandem with each other. In some embodiments, a multispecific targeting conjugate comprising the structure of Formula 1 is provided: (Equation 1) Wherein: A1 is a first targeting moiety that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting moiety that specifically recognizes Trop-2; P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule (e.g., essanotecan); x = 0; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); and wherein the second targeting moiety comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2 (anti-Trop-2 VHHs), the VHHs independently comprising: i) comprising SEQ ID NO: CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 42, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; ii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 206. CDR3 of amino acid sequence 218. In some embodiments, multispecific targeting conjugates comprising the structure of formula 1 are provided: (Equation 1) Wherein: A1 is a first targeting portion that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting portion that specifically recognizes Trop-2; P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule (e.g., essanotecan); x = 0; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, wherein the anti-PD-L1 antibodies or antigen-binding fragments thereof independently comprise: i) comprising SEQ ID NO: The second targeting portion comprises H-CDR1 containing the amino acid sequence of SEQ ID NO: 8, H-CDR2 containing the amino acid sequence of SEQ ID NO: 13, L-CDR1 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249; and wherein the second targeting portion comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2. (Anti-Trop-2 VHH), wherein the VHH independently comprises: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63;iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, multispecific targeting conjugates containing the structure of Formula 1 are provided. (Equation 1) Wherein: A1 is a first targeting portion that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting portion that specifically recognizes Trop-2 (e.g., an sdAb, such as VHH); P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule (e.g., ethatecan); x = 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10 or 4-6). In some embodiments, the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, such as a full-length anti-PD-L1 antibody. In some implementations, multispecific targeting conjugates comprising the structure of Formula 1 are provided: (Equation 1) Wherein: A1 is the first targeting moiety that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is the second targeting moiety that specifically recognizes Trop-2 (e.g., an sdAb, such as VHH); P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amido-PEG8-VA-PAB); D is an effector molecule (e.g., ethatecan); x = 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); and wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, the anti-PD-L1 antibody or antigen-binding fragment thereof independently comprising: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 245, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 246, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 247, and L-CDR1 comprising the amino acid sequence of SEQ ID NO: 247. L-CDR2 comprising the amino acid sequence 248 and L-CDR3 comprising the amino acid sequence SEQ ID NO: 249. In some embodiments, the second targeting portion comprises one or more (e.g., 1 or 2) anti-Trop-2 antibodies or antigen-binding fragments thereof, such as a first anti-Trop-2 sdAb and a second anti-Trop-2 sdAb fused in tandem with each other. In some embodiments, a multispecific targeting conjugate comprising the structure of Formula 1 is provided: (Equation 1) Wherein: A1 is a first targeting moiety that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting moiety that specifically recognizes Trop-2; P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amido-PEG8-VA-PAB); D is an effector molecule (e.g., essanotecan); x = 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); and wherein the second targeting moiety comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2 (anti-Trop-2 VHHs), wherein the VHHs independently comprise: i) comprising SEQ ID NO: CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 42, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; ii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 206. CDR3 of amino acid sequence 218. In some embodiments, multispecific targeting conjugates comprising the structure of formula 1 are provided: (Equation 1) Wherein: A1 is a first targeting portion that specifically recognizes PD-L1 (e.g., a full-length antibody); A2 is a second targeting portion that specifically recognizes Trop-2; P is a cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214); C is a conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188); L is a linker (e.g., (Gly)6-amide-PEG8-VA-PAB); D is an effector molecule (e.g., essanotecan); x = 1; a = 1-20 (e.g., 1-10, such as 1); and b = 1-20 (e.g., 2-10, or 4-6); wherein the first targeting portion comprises one or more (e.g., 1) anti-PD-L1 antibodies or antigen-binding fragments thereof, wherein the anti-PD-L1 antibodies or antigen-binding fragments thereof independently comprise: i) comprising SEQ ID NO: The second targeting portion comprises H-CDR1 containing the amino acid sequence of SEQ ID NO: 8, H-CDR2 containing the amino acid sequence of SEQ ID NO: 13, L-CDR1 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249; and wherein the second targeting portion comprises one or more (e.g., 1 or 2) VHHs that specifically recognize Trop-2. (Anti-Trop-2 VHH), wherein the VHH independently comprises: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63;iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, two or more anti-Trop-2 antibodies or their antigen-binding fragments (e.g., sdAbs, such as VHH) bind to different Trop-2 epitopes. In some embodiments, one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 34; ii) a VH comprising the amino acid sequence of SEQ ID NO: 219 and a VL comprising the amino acid sequence of SEQ ID NO: 220; iii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 213; iv) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 33; v) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221; vi) a VH comprising the amino acid sequence of SEQ ID NO: 16 and a VL comprising the amino acid sequence of SEQ ID NO: 213; vii) a VH comprising the amino acid sequence of SEQ ID NO: 212 and a VL comprising the amino acid sequence of SEQ ID NO: 221. VL containing the amino acid sequence of SEQ ID NO: 222; viii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 221; ix) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 222; x) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; xi) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 224;xii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 225; xiii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 226; xiv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 224; xvi) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 226; xvii) A VH containing the amino acid sequence of SEQ ID NO: 227 and a VL containing the amino acid sequence of SEQ ID NO: 226; xviii) A VH containing the amino acid sequence of SEQ ID NO: 228 and a VL containing the amino acid sequence of SEQ ID NO: 225. VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 251. In some embodiments, the first targeting portion comprises a full-length anti-PD-L1 antibody. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86;vi) A heavy chain containing the amino acid sequence of SEQ ID NO: 87 and a light chain containing the amino acid sequence of SEQ ID NO: 88; vii) A heavy chain containing the amino acid sequence of SEQ ID NO: 91 and a light chain containing the amino acid sequence of SEQ ID NO: 92; viiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 93 and a light chain containing the amino acid sequence of SEQ ID NO: 94; ix) A heavy chain containing the amino acid sequence of SEQ ID NO: 95 and a light chain containing the amino acid sequence of SEQ ID NO: 96; x) A heavy chain containing the amino acid sequence of SEQ ID NO: 97 and a light chain containing the amino acid sequence of SEQ ID NO: 98; xi) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) A heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) A heavy chain containing the amino acid sequence of SEQ ID NO: The heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) the heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) the heavy chain containing the amino acid sequence of SEQ ID NO: 109 and the light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) the heavy chain containing the amino acid sequence of SEQ ID NO: 111 and the light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) the heavy chain containing the amino acid sequence of SEQ ID NO: 113 and the light chain containing the amino acid sequence of SEQ ID NO: 114; xix) the heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116; xx) the heavy chain containing the amino acid sequence of SEQ ID NO: The heavy chain containing the amino acid sequence of SEQ ID NO: 117 and the light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) the heavy chain containing the amino acid sequence of SEQ ID NO: 119 and the light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) the heavy chain containing the amino acid sequence of SEQ ID NO: 121 and the light chain containing the amino acid sequence of SEQ ID NO: 122; xxiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 17 and the light chain containing the amino acid sequence of SEQ ID NO: 34;(or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, one or more anti-Trop-2 VHHs independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, the second targeting portion comprises a first anti-Trop-2 VHH and a second anti-Trop-2 VHH fused in tandem with each other. In some embodiments, the first targeting portion is located at the N-terminus of the second targeting portion. In some embodiments, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor (e.g., a solid tumor). In some embodiments, the conditions are the tumor microenvironment. In some embodiments, cleavage is carried out by a protease, such as MMP (e.g., MMP-9) or uPA. In some embodiments, the cleavage site that can be cleaved by MMP comprises an amino acid sequence of any one of SEQ ID NO: 71 and 137-143. In some embodiments, the cleavage site that can be cleaved by MMP-9 comprises an amino acid sequence of SEQ ID NO: 71. In some embodiments, the cleavage site that can be cleaved by uPA comprises an amino acid sequence of SEQ ID NO: 214. In some embodiments, the effector molecule is a therapeutic agent or oligonucleotide, such as a therapeutic agent. In some embodiments, the conjugation site comprises a transglutaminase conjugation site, such as one comprising an amino acid sequence of any one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. In some embodiments, the linker-effect molecule conjugate (L-(D); a The structure of any of the formulas A and J (such as formula A).

[0129] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 3, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 4, and a second anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 3, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 4, and a second anti-Trop-2 sdAb. (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB).The full-length anti-PD-L1 antibody comprises: i) H-CDR1 containing the amino acid sequence of SEQ ID NO: 3, H-CDR2 containing the amino acid sequence of SEQ ID NO: 8, H-CDR3 containing the amino acid sequence of SEQ ID NO: 13, L-CDR1 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 3, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 4, and a second anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); wherein the first and second anti-Trop-2 sdAbs (e.g., VHH) independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47;ii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 3, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 4, and a second anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB);The full-length anti-PD-L1 antibody comprises: i) H-CDR1 containing the amino acid sequence of SEQ ID NO: 3, H-CDR2 containing the amino acid sequence of SEQ ID NO: 8, H-CDR3 containing the amino acid sequence of SEQ ID NO: 13, L-CDR1 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249; and wherein the first and second anti-Trop-2 antibodies... sdAb (e.g., VHH) independently comprises: i) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 42, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; ii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, and CDR3 containing the amino acid sequence of SEQ ID NO: 37. The CDR2 comprising the amino acid sequence of SEQ ID NO: 217 and the CDR3 comprising the amino acid sequence of SEQ ID NO: 218. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a VH comprising the amino acid sequence of SEQ ID NO: 17 and a VL comprising the amino acid sequence of SEQ ID NO: 34; ii) a VH comprising the amino acid sequence of SEQ ID NO: 219 and a VL comprising the amino acid sequence of SEQ ID NO: 220;iii) A VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 213; iv) A VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 33; v) A VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221; vi) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 213; vii) A VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 222; viiii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 221; ix) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 222; x) A VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 222; VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; xi) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 224; xii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 225; xiii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 225; xv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226; xvii) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226; xvii) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226;xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 251. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86; vi) a heavy chain comprising the amino acid sequence of SEQ ID NO: 87 and a light chain comprising the amino acid sequence of SEQ ID NO: 88; vii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 91 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; viii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) the heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: The heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108;xvi) A heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) A heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) A heavy chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 114; xix) A heavy chain containing the amino acid sequence of SEQ ID NO: 115 and a light chain containing the amino acid sequence of SEQ ID NO: 116; xx) A heavy chain containing the amino acid sequence of SEQ ID NO: 117 and a light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) A heavy chain containing the amino acid sequence of SEQ ID NO: 119 and a light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) A heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 120. The light chain comprising the amino acid sequence of SEQ ID NO: 122; xxiii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 17 and a light chain comprising the amino acid sequence of SEQ ID NO: 34; or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, the first and second anti-Trop-2 sdAbs (e.g., VHH) independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, the first anti-Trop-2 sdAb and the second anti-Trop-2 sdAb bind to different Trop-2 epitopes. One or more optional linkers may be the same or different (or absent), such as any one of SEQ ID NO: 144, 204, 207-211, and 252, or any one of SEQ ID NO: 207-209. The first and second anti-Trop-2 sdAbs (e.g., VHH) may be the same or different and may bind to the same or different Trop-2 epitopes. The first and second conjugation sites may be the same or different, such as any one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. The first and second effector molecules may be the same or different, for example, they may be therapeutic agents or oligonucleotides. The first and second effector molecule linkers may be the same or different. In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the linker-effector molecule conjugate comprises the structure of any of the formulas AJ (such as formula A).

[0130] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 231; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 231; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises a structure of formula AJ (such as formula A).

[0131] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 232; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 232; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0132] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 238; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 238; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0133] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 239; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 239; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0134] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 3, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214). (214) optional linker 5, second conjugation site (e.g., transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 6, and second anti-Trop-2 sdAb (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 3, and a first anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71);(c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, a second conjugation site comprising the amino acid sequence of SEQ ID NO: 3, a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) an H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 3, a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (f) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (e) a third polypeptide chain comprising the first light chain of H-CDR2 containing the amino acid sequence of SEQ ID NO: 13, H-CDR3 containing the amino acid sequence of SEQ ID NO: 20, L-CDR2 containing the amino acid sequence of SEQ ID NO: 25, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of a full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 3, and a first anti-Trop-2 sdAb (e.g., VHH);(b) A second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71; or a uPA cleavage site, e.g., SEQ ID NO: 214), optional linker 5, a second conjugation site (e.g., a transglutaminase conjugation site, e.g., SEQ ID NO: 147 or 188), optional linker 6, and a second anti-Trop-2 sdAb (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the first and second anti-Trop-2sdAbs (e.g., VHH) independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 53. CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217 and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of a full-length anti-PD-L1 antibody, optional linker 1, and a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71);(a) a second polypeptide chain comprising, from the N-terminus to the C-terminus: the second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 5, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 6, and a second anti-Trop-2 sdAb (e.g., VHH); (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: the second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 5, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 6, and a second anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 20. L-CDR2 containing the amino acid sequence of SEQ ID NO: 25 and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248 and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249;And wherein the first and second anti-Trop-2 sdAbs (e.g., VHH) independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; iii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 205, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; iv) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 206; or v) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37 ...37, a CDR3 comprising the amino acid sequence of SEQ ID NO: 37, a CDR3 comprising the amino acid sequence of SEQ ID NO: 37, a CDR3 comprising the amino acid sequence of SEQ ID NO: 37, a CDR3 comprising the amino acid sequence of SEQ ID NO CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a VH containing the amino acid sequence of SEQ ID NO: 17 and a VL containing the amino acid sequence of SEQ ID NO: 34; ii) a VH containing the amino acid sequence of SEQ ID NO: 219 and a VL containing the amino acid sequence of SEQ ID NO: 220; iii) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 213; iv) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 33; v) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221; vi) a VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 213; vii) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221. VL containing the amino acid sequence of SEQ ID NO: 16; viii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 221; ix) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 222;x) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 222; xi) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 224; xii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 225; xiii) A VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 226; xiv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 225; xv) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 224; xvi) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 226; xvii) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 226; xvii) A VH containing the amino acid sequence of SEQ ID NO: 223 and a VL containing the amino acid sequence of SEQ ID NO: 226; VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 251. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82;iv) A heavy chain containing the amino acid sequence of SEQ ID NO: 83 and a light chain containing the amino acid sequence of SEQ ID NO: 84; v) A heavy chain containing the amino acid sequence of SEQ ID NO: 85 and a light chain containing the amino acid sequence of SEQ ID NO: 86; vi) A heavy chain containing the amino acid sequence of SEQ ID NO: 87 and a light chain containing the amino acid sequence of SEQ ID NO: 88; vii) A heavy chain containing the amino acid sequence of SEQ ID NO: 91 and a light chain containing the amino acid sequence of SEQ ID NO: 92; viiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 93 and a light chain containing the amino acid sequence of SEQ ID NO: 94; ix) A heavy chain containing the amino acid sequence of SEQ ID NO: 95 and a light chain containing the amino acid sequence of SEQ ID NO: 96; x) A heavy chain containing the amino acid sequence of SEQ ID NO: 97 and a light chain containing the amino acid sequence of SEQ ID NO: 98; xi) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 94. The following are listed: a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) a heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) a heavy chain containing the amino acid sequence of SEQ ID NO: 103 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) a heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid sequence of SEQ ID NO: 106; xv) a heavy chain containing the amino acid sequence of SEQ ID NO: 107 and a light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) a heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) a heavy chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 10 ...01 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xviii) a heavy chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xvii) a heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid The light chain containing the amino acid sequence of SEQ ID NO: 114; xix) the heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116; xx) the heavy chain containing the amino acid sequence of SEQ ID NO: 117 and the light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) the heavy chain containing the amino acid sequence of SEQ ID NO: 119 and the light chain containing the amino acid sequence of SEQ ID NO: 120;xxii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 121 and a light chain comprising the amino acid sequence of SEQ ID NO: 122; xxiii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 17 and a light chain comprising the amino acid sequence of SEQ ID NO: 34; or xxiv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 241 and a light chain comprising the amino acid sequence of SEQ ID NO: 242. In some embodiments, the first and second anti-Trop-2 sdAbs (e.g., VHH) independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, the first anti-Trop-2 sdAb and the second anti-Trop-2 sdAb bind to different Trop-2 epitopes. One or more optional linkers may be the same or different (or absent), such as any one of SEQ ID NO: 144, 204, 207-211, and 252, or any one of SEQ ID NO: 207-209. The first and second anti-Trop-2 sdAbs (e.g., VHH) may be the same or different and may bind to the same or different Trop-2 epitopes. In some embodiments, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: protease, pH change, redox change, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor (e.g., a solid tumor). In some embodiments, the conditions are the tumor microenvironment. The first and second cleavage sites may be the same or different, such as any one of SEQ ID NO: 71, 137-143, and 214. The first and second conjugation sites may be the same or different, such as any one of SEQ ID NO: 145-196, for example SEQ ID NO: 147 or 188. The first and second effector molecules may be the same or different, for example, they may be therapeutic agents or oligonucleotides. The first and second effector molecule linkers may be the same or different. In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethanotecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the linker-effector molecule conjugate (L-(D); a The structure includes any of the formulas A and J (e.g., formula A).

[0135] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 233; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 233; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0136] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 234; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 234; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0137] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 3, and a second anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 5, a third anti-Trop-2 sdAb (e.g., VHH), optional linker 6, and a fourth anti-Trop-2 sdAb. (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 3, and a second anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 5, a third anti-Trop-2 sdAb (e.g., VHH), optional linker 6, and a fourth anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody;(e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 20; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 20; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 20 ... H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 3, and a second anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 5, a third anti-Trop-2 sdAb (e.g., VHH), optional linker 6, and a fourth anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethanotecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB);and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); wherein the first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; iii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 205, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; iv) a CDR3 comprising the amino acid sequence of SEQ ID NO: CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 2, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 3, and a second anti-Trop-2 sdAb (e.g., VHH); and (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 4, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 5, a third anti-Trop-2 sdAb (e.g., VHH), optional linker 6, and a fourth anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody;(e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, L-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 20; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and L-CDR3 comprising the amino acid sequence of SEQ ID NO: 20; or ii) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 244, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 20 ... The first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) independently comprise: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; iii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 58, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 63; CDR2 containing the amino acid sequence of SEQ ID NO: 47 and CDR3 containing the amino acid sequence of SEQ ID NO: 53; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 58, CDR2 containing the amino acid sequence of SEQ ID NO: 206 and CDR3 containing the amino acid sequence of SEQ ID NO: 206;Or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a VH containing the amino acid sequence of SEQ ID NO: 17 and a VL containing the amino acid sequence of SEQ ID NO: 34; ii) a VH containing the amino acid sequence of SEQ ID NO: 219 and a VL containing the amino acid sequence of SEQ ID NO: 220; iii) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 213; iv) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 33; v) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221; vi) a VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 213; vii) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221. VL containing the amino acid sequence of SEQ ID NO: 222; viii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 221; ix) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 222; x) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; xi) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 224; xii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 225; xiii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224. VL containing the amino acid sequence of SEQ ID NO: 225; xv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226;xvii) VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226; or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 226. VL of amino acid sequence 251. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86; vi) a heavy chain comprising the amino acid sequence of SEQ ID NO: 87 and a light chain comprising the amino acid sequence of SEQ ID NO: 88; vii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 91 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; viii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98.x1) A heavy chain containing the amino acid sequence of SEQ ID NO: 99 and a light chain containing the amino acid sequence of SEQ ID NO: 100; xii) A heavy chain containing the amino acid sequence of SEQ ID NO: 101 and a light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 103 and a light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) A heavy chain containing the amino acid sequence of SEQ ID NO: 105 and a light chain containing the amino acid sequence of SEQ ID NO: 106; xv) A heavy chain containing the amino acid sequence of SEQ ID NO: 107 and a light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) A heavy chain containing the amino acid sequence of SEQ ID NO: 109 and a light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) A heavy chain containing the amino acid sequence of SEQ ID NO: 111 and a light chain containing the amino acid sequence of SEQ ID NO: 109. The following are examples of amino acid sequences: xviii) a light chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 114; xix) a heavy chain containing the amino acid sequence of SEQ ID NO: 115 and a light chain containing the amino acid sequence of SEQ ID NO: 116; xx) a heavy chain containing the amino acid sequence of SEQ ID NO: 117 and a light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) a heavy chain containing the amino acid sequence of SEQ ID NO: 119 and a light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) a heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; xxiii) a heavy chain containing the amino acid sequence of SEQ ID NO: 17 and a light chain containing the amino acid sequence of SEQ ID NO: 34; or xxiv) a heavy chain containing the amino acid sequence of SEQ ID NO: 241 and a light chain containing the amino acid sequence of SEQ ID NO: 122. The light chain of the amino acid sequence 242. In some embodiments, the first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, i) the first and second anti-Trop-2 sdAbs bind to different Trop-2 epitopes;And / or ii) the third and fourth anti-Trop-2 sdAbs bind to different Trop-2 epitopes. In some embodiments, the first and second anti-Trop-2 sdAbs bind to a first Trop-2 epitope, and the third and fourth anti-Trop-2 sdAbs bind to a second Trop-2 epitope, wherein the first and second Trop-2 epitopes are different. In some embodiments, each of the first, second, third, and fourth anti-Trop-2 sdAbs binds to a different Trop-2 epitope. One or more optional connectors may be the same or different (or absent), such as any one of SEQ ID NO: 144, 204, 207-211, and 252, or any one of SEQ ID NO: 207-209. The first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) may be the same or different, and may bind to the same or different Trop-2 epitopes. The first and second conjugation sites may be the same or different, such as any one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. The first and second effector molecules may be the same or different, for example, they may be therapeutic agents or oligonucleotides. The first and second effector molecule linkers may be the same or different. In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the linker-effector molecule conjugate comprises the structure of any one of formula AJ (e.g., formula A).

[0138] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 235; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 235; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0139] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 236; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 236; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0140] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 237; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 237; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 242; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0141] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 67; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 67; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 68; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 68; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0142] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 215; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 215; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 68; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 68; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (e.g., formula A).

[0143] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71; or a uPA cleavage site, e.g., SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, e.g., SEQ ID NO: 147 or 188), optional linker 3, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 4, and a second anti-Trop-2 sdAb (e.g., VHH); (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 5, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 147 or 188), optional linker 3, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 4, and a second anti-Trop-2 sdAb (e.g., VHH); 71; or uPA cleavage site, such as SEQ ID NO: 214), optional linker 6, second conjugation site (e.g., transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 7, third anti-Trop-2 sdAb (e.g., VHH), optional linker 8 and fourth anti-Trop-2 sdAb (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amide-PEG8-VA-PAB). In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of a full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional linker 3, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 4, and a second anti-Trop-2 sdAb (e.g., VHH);(b) A second polypeptide chain comprising, from the N-terminus to the C-terminus: the second heavy chain of the full-length anti-PD-L1 antibody, optional linker 5, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71; or a uPA cleavage site, e.g., SEQ ID NO: 214), optional linker 6, a second conjugation site (e.g., a transglutaminase conjugation site, e.g., SEQ ID NO: 147 or 188), optional linker 7, a third anti-Trop-2 sdAb (e.g., VHH), optional linker 8, and a fourth anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 20. L-CDR2 containing the amino acid sequence of SEQ ID NO: 25 and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30; or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248 and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain, the first polypeptide chain comprising from the N-terminus to the C-terminus: a first heavy chain of a full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71);(a) a second polypeptide chain comprising, from the N-terminus to the C-terminus: the second heavy chain of the full-length anti-PD-L1 antibody, optional adapter 5, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, such as SEQ ID NO: 71; or a uPA cleavage site, such as SEQ ID NO: 214), optional adapter 6, a second conjugation site (e.g., a transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional adapter 7, a third anti-Trop-2 sdAb (e.g., VHH), optional adapter 8, and a fourth anti-Trop-2 sdAb. (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the first, second, third, and fourth anti-Trop-2 sdAb (e.g., VHH) independently comprises: i) a CDR1 comprising the amino acid sequence of SEQ ID NO: 37, a CDR2 comprising the amino acid sequence of SEQ ID NO: 42, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 47; ii) a CDR1 comprising the amino acid sequence of SEQ ID NO: 53, a CDR2 comprising the amino acid sequence of SEQ ID NO: 53, and a CDR3 comprising the amino acid sequence of SEQ ID NO: 53; CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 63; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 205 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 206;Or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217, and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising, from the N-terminus to the C-terminus: a first heavy chain of the full-length anti-PD-L1 antibody, optional linker 1, a first cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 71; or a uPA cleavage site, e.g., SEQ ID NO: 214), optional linker 2, a first conjugation site (e.g., a transglutaminase conjugation site, e.g., SEQ ID NO: 147 or 188), optional linker 3, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 4, and a second anti-Trop-2 sdAb (e.g., VHH); (b) a second polypeptide chain comprising, from the N-terminus to the C-terminus: a second heavy chain of the full-length anti-PD-L1 antibody, optional linker 5, a second cleavage site (e.g., an MMP cleavage site, such as an MMP-9 cleavage site, e.g., SEQ ID NO: 147 or 188), optional linker 3, a first anti-Trop-2 sdAb (e.g., VHH), optional linker 4, and a second anti-Trop-2 sdAb (e.g., VHH); 71; or uPA cleavage site, such as SEQ ID NO: 214), optional adapter 6, second conjugation site (e.g., transglutaminase conjugation site, such as SEQ ID NO: 147 or 188), optional adapter 7, third anti-Trop-2 sdAb (e.g., VHH), optional adapter 8 and fourth anti-Trop-2 sdAb (e.g., VHH); (c) a third polypeptide chain comprising the first light chain of the full-length anti-PD-L1 antibody; (d) a fourth polypeptide chain comprising the second light chain of the full-length anti-PD-L1 antibody; (e) a first effector molecule (e.g., ethatecan) conjugated to the first conjugation site via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to the second conjugation site via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); wherein the full-length anti-PD-L1 antibody comprises: i) H-CDR1 comprising the amino acid sequence of SEQ ID NO: 3, H-CDR2 comprising the amino acid sequence of SEQ ID NO: 8, H-CDR3 comprising the amino acid sequence of SEQ ID NO: 13, L-CDR1 comprising the amino acid sequence of SEQ ID NO: 20, and H-CDR3 comprising the amino acid sequence of SEQ ID NO: 20. L-CDR2 containing the amino acid sequence of SEQ ID NO: 25 and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30;Or ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 244, H-CDR2 containing the amino acid sequence of SEQ ID NO: 245, H-CDR3 containing the amino acid sequence of SEQ ID NO: 246, L-CDR1 containing the amino acid sequence of SEQ ID NO: 247, L-CDR2 containing the amino acid sequence of SEQ ID NO: 248, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249; and wherein the first, second, third, and fourth anti-Trop-2 sdAb (e.g., VHH) independently comprises: i) CDR1 containing the amino acid sequence of SEQ ID NO: 37, CDR2 containing the amino acid sequence of SEQ ID NO: 42, and CDR3 containing the amino acid sequence of SEQ ID NO: 47; ii) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58, and L-CDR3 containing the amino acid sequence of SEQ ID NO: 249. CDR3 containing the amino acid sequence of SEQ ID NO: 37; iii) CDR1 containing the amino acid sequence of SEQ ID NO: 205 and CDR3 containing the amino acid sequence of SEQ ID NO: 47; iv) CDR1 containing the amino acid sequence of SEQ ID NO: 53, CDR2 containing the amino acid sequence of SEQ ID NO: 58 and CDR3 containing the amino acid sequence of SEQ ID NO: 206; or v) CDR1 containing the amino acid sequence of SEQ ID NO: 216, CDR2 containing the amino acid sequence of SEQ ID NO: 217 and CDR3 containing the amino acid sequence of SEQ ID NO: 218. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a VH containing the amino acid sequence of SEQ ID NO: 17 and a VL containing the amino acid sequence of SEQ ID NO: 34; ii) a VH containing the amino acid sequence of SEQ ID NO: 219 and a VL containing the amino acid sequence of SEQ ID NO: 220; iii) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 213; iv) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 33; v) a VH containing the amino acid sequence of SEQ ID NO: 212 and a VL containing the amino acid sequence of SEQ ID NO: 221; vi) a VH containing the amino acid sequence of SEQ ID NO: 16 and a VL containing the amino acid sequence of SEQ ID NO: 213.vii) VH containing the amino acid sequence of SEQ ID NO: 212 and VL containing the amino acid sequence of SEQ ID NO: 222; viii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 221; ix) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 222; x) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 222; xi) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 224; xii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 225; xiii) VH containing the amino acid sequence of SEQ ID NO: 16 and VL containing the amino acid sequence of SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 ...225 and VL containing the amino acid sequence of SEQ ID NO: 226; xiv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xii) VH containing the amino acid sequence of VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 225; xv) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 224; xvi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226; xvii) VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix) VH containing the amino acid sequence of SEQ ID NO: 229 and VL containing the amino acid sequence of SEQ ID NO: 226; xx) VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 225 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 226; xxi) VH containing the amino acid sequence of SEQ ID NO: 224 and VL containing the amino acid sequence of SEQ ID NO: 225; xvii) VH containing the amino acid sequence of SEQ ID NO: 223 and VL containing the amino acid sequence of SEQ ID NO: 225; xvii) VH containing the amino acid sequence of SEQ ID NO: 227 and VL containing the amino acid sequence of SEQ ID NO: 226; xviii) VH containing the amino acid sequence of SEQ ID NO: 228 and VL containing the amino acid sequence of SEQ ID NO: 226; xix VH containing the amino acid sequence of SEQ ID NO: 230 and VL containing the amino acid sequence of SEQ ID NO: 220; xxii) VH containing the amino acid sequence of SEQ ID NO: 219 and VL containing the amino acid sequence of SEQ ID NO: 226;Or xxiii) VH containing the amino acid sequence of SEQ ID NO: 250 and VL containing the amino acid sequence of SEQ ID NO: 251. In some embodiments, the full-length anti-PD-L1 antibody comprises: i) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 90; ii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 79 and a light chain comprising the amino acid sequence of SEQ ID NO: 80; iii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 81 and a light chain comprising the amino acid sequence of SEQ ID NO: 82; iv) a heavy chain comprising the amino acid sequence of SEQ ID NO: 83 and a light chain comprising the amino acid sequence of SEQ ID NO: 84; v) a heavy chain comprising the amino acid sequence of SEQ ID NO: 85 and a light chain comprising the amino acid sequence of SEQ ID NO: 86; vi) a heavy chain comprising the amino acid sequence of SEQ ID NO: 87 and a light chain comprising the amino acid sequence of SEQ ID NO: 88; vii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 91 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; viii) a heavy chain comprising the amino acid sequence of SEQ ID NO: 89 and a light chain comprising the amino acid sequence of SEQ ID NO: 92; The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) the heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; xv) the heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) the heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) the heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) the heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: The heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) the heavy chain containing the amino acid sequence of SEQ ID NO: 109 and the light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) the heavy chain containing the amino acid sequence of SEQ ID NO: 111 and the light chain containing the amino acid sequence of SEQ ID NO: 112;xviii) A heavy chain containing the amino acid sequence of SEQ ID NO: 113 and a light chain containing the amino acid sequence of SEQ ID NO: 114; xix) A heavy chain containing the amino acid sequence of SEQ ID NO: 115 and a light chain containing the amino acid sequence of SEQ ID NO: 116; xx) A heavy chain containing the amino acid sequence of SEQ ID NO: 117 and a light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) A heavy chain containing the amino acid sequence of SEQ ID NO: 119 and a light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) A heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; xxiii) A heavy chain containing the amino acid sequence of SEQ ID NO: 17 and a light chain containing the amino acid sequence of SEQ ID NO: 34; or xxiv) A heavy chain containing the amino acid sequence of SEQ ID NO: 241 and a light chain containing the amino acid sequence of SEQ ID NO: 242. In some embodiments, the first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) independently comprise the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136, and 203. In some embodiments, i) the first and second anti-Trop-2 sdAbs bind to different Trop-2 epitopes;And / or ii) the third and fourth anti-Trop-2 sdAbs bind to different Trop-2 epitopes. In some embodiments, the first and second anti-Trop-2 sdAbs bind to a first Trop-2 epitope, and the third and fourth anti-Trop-2 sdAbs bind to a second Trop-2 epitope, wherein the first and second Trop-2 epitopes are different. In some embodiments, each of the first, second, third, and fourth anti-Trop-2 sdAbs binds to a different Trop-2 epitope. One or more optional connectors may be the same or different (or absent), such as any one of SEQ ID NO: 144, 204, 207-211, and 252, or any one of SEQ ID NO: 207-209. The first, second, third, and fourth anti-Trop-2 sdAbs (e.g., VHH) may be the same or different, and may bind to the same or different Trop-2 epitopes. In some embodiments, cleavage is triggered by conditions at the target site. In some embodiments, the conditions at the target site are selected from the group consisting of: proteases, pH changes, redox changes, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof. In some embodiments, the target site is a disease site, such as a tumor (e.g., a solid tumor). In some embodiments, the conditions are the tumor microenvironment. The first and second cleavage sites may be the same or different, such as any one of SEQ ID NO: 71, 137-143, and 214. The first and second conjugation sites may be the same or different, such as any one of SEQ ID NO: 145-196, for example, SEQ ID NO: 147 or 188. The first and second effector molecules may be the same or different, for example, they may be therapeutic agents or oligonucleotides. The first and second effector molecule linkers may be the same or different. In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the connector-effect molecular conjugate comprises the structure of any of formulas A and J (such as formula A). Exemplary multispecific targeting conjugates are shown below; Figure 1 middle.

[0144] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 240; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 240; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 90; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0145] In some embodiments, a multispecific targeting conjugate is provided, the multispecific targeting conjugate comprising: (a) a first polypeptide chain comprising the amino acid sequence of SEQ ID NO: 69; (b) a second polypeptide chain comprising the amino acid sequence of SEQ ID NO: 69; (c) a third polypeptide chain comprising the amino acid sequence of SEQ ID NO: 70; (d) a fourth polypeptide chain comprising the amino acid sequence of SEQ ID NO: 70; (e) a first effector molecule (e.g., ethatecan) conjugated to a first conjugation site within the first polypeptide chain via a first effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB); and (f) a second effector molecule (e.g., ethatecan) conjugated to a second conjugation site within the second polypeptide chain via a second effector molecule linker (e.g., (Gly)6-amido-PEG8-VA-PAB). In some embodiments, the multispecific targeting conjugate comprises a total of about 1 to about 20 effector molecules (e.g., ethatecan), such as about 2 to about 20 or about 4 to about 6 effector molecules. In some embodiments, the effector molecule is a therapeutic agent or an oligonucleotide. In some embodiments, the linker-effect molecule conjugate comprises the structure of any of the formulas A and J (such as formula A).

[0146] In some embodiments, a targeting conjugate is provided comprising a targeting moiety that specifically recognizes PD-L1, wherein the PD-L1 targeting moiety is a full-length anti-PD-L1 antibody comprising a heavy chain containing the amino acid sequence of SEQ ID NO: 17 and a light chain containing the amino acid sequence of SEQ ID NO: 34. In some embodiments, the targeting conjugate further comprises a linker-effect molecule conjugate of formula A conjugated to the PD-L1 targeting moiety via a transglutaminase conjugate site (e.g., any one of SEQ ID NO: 145-196, such as SEQ ID NO: 147 or 188). In some embodiments, the targeting conjugate further comprises one or more protease cleavage sites, such as any one of SEQ ID NO: 71, 137-143, and 214. In some embodiments, the protease cleavage site is located between the PD-L1 targeting moiety and the transglutaminase conjugate site. In some embodiments, the protease cleavage site is not located between the PD-L1 targeting moiety and the transglutaminase conjugate site.

[0147] In some embodiments, a targeting conjugate is provided comprising a targeting moiety that specifically recognizes Trop-2, wherein the Trop-2 targeting moiety comprises one or more anti-Trop-2 VHHs independently comprising an amino acid sequence of any one of SEQ ID NO: 50, 66, and 203. In some embodiments, the targeting conjugate further comprises a linker-effect molecule conjugate of formula A conjugated to the Trop-2 targeting moiety via a transglutaminase conjugate site (e.g., any one of SEQ ID NO: 145-196, such as SEQ ID NO: 147 or 188). In some embodiments, the targeting conjugate further comprises one or more protease cleavage sites, such as any one of SEQ ID NO: 71, 137-143, and 214. In some embodiments, the protease cleavage site is located between the Trop-2 targeting moiety and the transglutaminase conjugate site. In some embodiments, the protease cleavage site is not located between the Trop-2 targeting moiety and the transglutaminase conjugate site.

[0148] In some embodiments, the conjugation site (C) of the multispecific targeting conjugate may comprise any suitable number of glutamine-containing tags fused in tandem with each other. In some embodiments, the number of glutamine-containing tags fused in tandem with each other may be any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. In some embodiments, the multispecific targeting conjugate may comprise any suitable number of effector molecules (D) and effector linkers (L). In some embodiments, the number of effector molecules (D) may be any one of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20. In some implementations, the number of connectors L can be any one of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20.

[0149] The multispecific targeting conjugates described herein may include any of the following: targeting peptides, antibodies or their antigen-binding fragments, isolated antibody constructs, effector molecules, conjugation sites, cleavage sites (e.g., protease cleavage sites), peptide linkers, and effector molecule linkers as described in Parts II-IV and Section AG below.

[0150] In some embodiments, the multispecific targeting conjugate comprises a single effector molecule. In some embodiments, the multispecific targeting conjugate comprises multiple effector molecules. In some embodiments, the multispecific targeting conjugate comprises a single molecule of an effector molecule. In some embodiments, the multispecific targeting conjugate comprises two or more identical effector molecules. In some embodiments, the multispecific targeting conjugate comprises two or more distinct effector molecules. In some embodiments, the multispecific targeting conjugate comprises a single copy of each effector molecule. In some embodiments, the multispecific targeting conjugate comprises two or more copies of each effector molecule.

[0151] In some embodiments, the multispecific targeting conjugate has a high drug loading. The term "drug loading" refers to the ratio between the number of effector molecules and the number of targeting moieties (e.g., antibody or its antigen-binding fragment) in the multispecific targeting conjugate. For example, the drug loading of an antibody conjugated to a total of 8 effector molecules is 8. Each molecule of the multispecific targeting conjugate has an integer drug loading value. However, in a composition, different molecules of the multispecific targeting conjugate may have different drug loading values. Therefore, the composition may have an average drug loading value of integer or non-integer.

[0152] In some embodiments, the multispecific targeting conjugate has an effector-to-targeting moiety ratio (e.g., a first targeting moiety and / or a second targeting moiety) of at least about 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 17:1, 18:1, 19:1 or 20:1. In some embodiments, the multispecific targeting conjugate has an effector-to-targeting moiety ratio (e.g., a first targeting moiety and / or a second targeting moiety) of no more than about 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1 or 1:1. In some embodiments, the multispecific targeting conjugate has an effector-to-targeting moiety ratio (e.g., a first targeting moiety and / or a second targeting moiety) of about 1:1-2:1, 2:1-4:1, 4:1-6:1, 4:1-8:1, 1:1-10:1, 2:1-10:1, 1:1-16:1, 4:1-20:1, 10:1-20:1, 1:1-20:1 or 2:1-20:1.

[0153] In some implementations, the drug loading of the multispecific targeting conjugate is at least about 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 17:1, 18:1, 19:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1 or greater. In some implementations, the drug loading of the multispecific targeting conjugate is no more than one of about 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, or 2:1. In some implementations, the drug loading of the multispecific targeting conjugate is any one of about 2:1-4:1, 2:1-8:1, 2:1-10:1, 2:1-16:1, 4:1-20:1, 10:1-20:1, 20:1-40:1, 40:1-100:1, 2:1-20:1, 2:1-40:1, or 10:1-40:1.

[0154] The multispecific targeting portion of any multispecific targeting conjugates described herein (e.g., multispecific targeting conjugates that do not contain effector molecules) is also provided. In some embodiments, a multispecific targeting portion is provided, the multispecific targeting portion comprising: i) a first polypeptide chain and a second polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 231, and a third polypeptide chain and a fourth polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 242; ii) a first polypeptide chain and a second polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 232, and a third polypeptide chain and a fourth polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 242; iii) a first polypeptide chain and a second polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 233, and a third polypeptide chain and a fourth polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 242; iv) a first polypeptide chain and a second polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 234, and a third polypeptide chain and a fourth polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 242; v) a first polypeptide chain and a second polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 235, and a third polypeptide chain and a fourth polypeptide chain each comprising the amino acid sequence of SEQ ID NO: 242; vi) each comprising SEQ ID NO: 235, SEQ ID NO: 232, SEQ ID NO: 24 ... The following are examples of polypeptide chains: vii) first and second polypeptide chains containing the amino acid sequence of SEQ ID NO: 236, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 242; vii) first and second polypeptide chains each containing the amino acid sequence of SEQ ID NO: 237, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 242; viii) first and second polypeptide chains each containing the amino acid sequence of SEQ ID NO: 238, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 90; ix) first and second polypeptide chains each containing the amino acid sequence of SEQ ID NO: 239, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 90; x) first and second polypeptide chains each containing the amino acid sequence of SEQ ID NO: 67, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 68; xi) first and second polypeptide chains each containing the amino acid sequence of SEQ ID NO: 215, and third and fourth polypeptide chains each containing the amino acid sequence of SEQ ID NO: 242. The third and fourth polypeptide chains of amino acid sequence 68;xii) a first polypeptide chain and a second polypeptide chain, each comprising the amino acid sequence of SEQ ID NO: 240, and a third polypeptide chain and a fourth polypeptide chain, each comprising the amino acid sequence of SEQ ID NO: 90; or xiii) a first polypeptide chain and a second polypeptide chain, each comprising the amino acid sequence of SEQ ID NO: 69, and a third polypeptide chain and a fourth polypeptide chain, each comprising the amino acid sequence of SEQ ID NO: 90.

[0155] Also provided are isolated nucleic acids encoding one or more polypeptide chains of any of the multispecific targeting conjugates described herein, such as isolated nucleic acids encoding any of the multispecific targeting moieties described herein. Vectors containing such isolated nucleic acids and host cells containing such isolated nucleic acids or vectors are also provided.

[0156] A. Specifically recognizes the first target portion of PD-L1 The PD-L1 / Trop-2 multispecific targeting conjugates described herein contain a first targeting moiety that specifically recognizes PD-L1. In some embodiments, the first targeting moiety comprises one or more PD-L1 targeting peptides or one or more (e.g., 1, 2, 3, 4, or 5, such as 1) anti-PD-L1 antibodies or antigen-binding fragments thereof (or constitutes or substantially constitutes thereof). In some embodiments, the first targeting moiety comprises one or more (e.g., 1, 2, 3, 4, or 5, such as 1) anti-PD-L1 antibodies or antigen-binding fragments thereof. In some embodiments, the anti-PD-L1 antibody or antigen-binding fragment thereof is selected from the group consisting of: full-length antibodies, biantibodies, scFv, scFab, Fab, Fab', F(ab')2, sdAb, dsFv, and combinations thereof. The anti-PD-L1 antibody or antigen-binding fragment thereof may be human, humanized, murine, camelid, or chimeric. In some embodiments, the first targeting moiety is monospecific. In some embodiments, the first targeting moiety is multispecific (e.g., recognizing two or more distinct PD-L1 epitopes). In some embodiments, the first targeting moiety is monovalent. In some embodiments, the first targeting moiety is multivalent (e.g., comprising two or more anti-PD-L1 antigen-binding fragments, or a bivalent full-length anti-PD-L1 antibody or F(ab')2). Any anti-PD-L1 targeting moiety or isolated anti-PD-L1 antibody construct described herein (e.g., see below and Section III...

Claims

1. A multispecific targeting conjugate comprising a first targeting portion that specifically recognizes PD-L1, a second targeting portion that specifically recognizes Trop-2, and an effector molecule, wherein the effector molecule is conjugated to the second targeting portion via a conjugation site.

2. The multispecific targeting conjugate of claim 1, wherein the multispecific targeting conjugate further comprises a cleavage site between the first targeting portion and the conjugation site, and wherein the second targeting portion conjugated with the effector molecule is capable of being released from the multispecific targeting conjugate via cleavage at the cleavage site.

3. The multispecific targeting conjugate as described in claim 1 or 2, wherein the multispecific targeting conjugate comprises the structure of formula 1: (Equation 1) in: A1 is the first target portion; A2 is the second target portion; P is the cleavage site; C is the conjugation site; L stands for connector; D is the effector molecule; x = 0 or 1; a = 1-20; and b = 1-20。 4. The multispecific targeting conjugate as described in any one of claims 1-3, (i) wherein the first targeting portion and / or the second targeting portion comprises one or more targeting peptides or their antibody or antigen-binding fragments; and / or (ii) The effector molecule is a therapeutic agent or an oligonucleotide.

5. The multispecific targeting conjugate according to any one of claims 2-4, wherein the cleavage is triggered by conditions at the target site.

6. The multi-specific targeting conjugate as described in claim 5, (i) The conditions at the target site are selected from the group consisting of: protease, pH change, redox change, hypoxia, oxidative stress, hyperthermia, extracellular ATP concentration, and combinations thereof; and / or (ii) The target site is the disease site.

7. The multispecific targeting conjugate of claim 6, wherein the disease is a tumor, and wherein the condition is a tumor microenvironment.

8. The multispecific targeting conjugate of any one of claims 2-7, wherein the cleavage is performed by a protease.

9. The multispecific targeting conjugate of claim 8, wherein the protease is MMP or uPA.

10. The multi-specific targeting conjugate as described in claim 9, (i) wherein the cleavage site capable of being cleaved by the MMP comprises an amino acid sequence of any one of SEQ ID NO: 71 and 137-143; and / or (ii) wherein the cleavage site capable of being cleaved by the uPA contains the amino acid sequence of SEQ ID NO:

214.

11. The multispecific targeting conjugate of any one of claims 1-10, wherein the effector molecule is a therapeutic agent.

12. The multispecific targeting conjugate of claim 11, wherein the therapeutic agent is ethathecan.

13. The multispecific targeting conjugate of any one of claims 3, 4, 11 and 12, wherein x is 0.

14. The multispecific targeting conjugate of any one of claims 3, 4, 11 and 12, wherein x is 1.

15. The multispecific targeting conjugate as described in any one of claims 3-14, (i) where a is 1-10; and / or (ii) where b is 2-10.

16. The multispecific targeting conjugate of any one of claims 1-15, wherein the conjugation site comprises a transglutaminase conjugation site.

17. The multispecific targeting conjugate as described in claim 16, (i) wherein the transglutaminase conjugation site comprises an amino acid sequence of any one of SEQ ID NO: 145-196; and / or (ii) wherein the transglutaminase conjugate site comprises two or more glutamine-containing tags fused together in series.

18. The multispecific targeting conjugate as described in any one of claims 3-17, (i) where L is represented by the following formula: (Gly) n -(PEG) m -VC-PAB-(DMAE) k , where n, m and k are integers, n≥1, m≥2, and k is 0 or 1; (ii) Where L is represented by the following formula: (Gly) n -(PEG) m -VA-PAB-(DMAE) k , where n, m and k are integers, n≥1, m≥2, and k is 0 or 1; (iii) Where L is (Gly)6-amide-PEG8-VA-PAB; or (iv) Where L is (Gly)6-amide-PEG8-VC-PAB.

19. The multispecific targeting conjugate according to any one of claims 3-18, wherein L-(D) a The structure of inclusion A: Formula A, The wavy lines represent sites covalently connected to the ligation site C.

20. The multispecific targeting conjugate of any one of claims 1-19, wherein the second targeting portion comprises one or more sdAbs (anti-Trop-2 sdAbs) that specifically recognize Trop-2.

21. The multispecific targeting conjugate of claim 20, wherein the one or more anti-Trop-2 sdAbs are anti-Trop-2 VHHs, each of the anti-Trop-2 VHHs independently comprising: i) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 42 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations. ii) CDR1 containing the amino acid sequence of SEQ ID NO: 35 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 40 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 45 or a variant thereof containing up to 3 amino acid variations. iii) CDR1 containing the amino acid sequence of SEQ ID NO: 36 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 41 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 46 or a variant thereof containing up to 3 amino acid variations. iv) CDR1 containing the amino acid sequence of SEQ ID NO: 38 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 43 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 48 or a variant thereof containing up to 3 amino acid variations. v) CDR1 containing the amino acid sequence of SEQ ID NO: 39 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 44 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 49 or a variant thereof containing up to 3 amino acid variations. vi) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 63 or a variant thereof containing up to 3 amino acid variations. vii) CDR1 containing the amino acid sequence of SEQ ID NO: 51 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 56 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 61 or a variant thereof containing up to 3 amino acid variations. viii) CDR1 containing the amino acid sequence of SEQ ID NO: 52 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 57 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 62 or a variant thereof containing up to 3 amino acid variations. ix) CDR1 comprising the amino acid sequence of SEQ ID NO: 54 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 59 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 64 or a variant thereof comprising up to 3 amino acid variations; x) CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 60 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 65 or a variant thereof containing up to 3 amino acid variations. xi) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 205 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations. xii) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 206 or a variant thereof containing up to 3 amino acid variations. xiii) CDR1 comprising the amino acid sequence of SEQ ID NO: 55 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 60 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 243 or a variant thereof comprising up to 3 amino acid variations; or xiiiv) CDR1 containing the amino acid sequence of SEQ ID NO: 216 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 217 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 218 or a variant thereof containing up to 3 amino acid variations.

22. The multispecific targeting conjugate of claim 20 or 21, wherein one or more anti-Trop-2sdAbs are anti-Trop-2 VHHs, each of the anti-Trop-2 VHHs independently comprising the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136 and 203.

23. The multispecific targeting conjugate of any one of claims 20-22, wherein the second targeting portion comprises a first anti-Trop-2 sdAb and a second anti-Trop-2 sdAb fused in tandem with each other.

24. The multispecific targeting conjugate of claim 23, wherein the first anti-Trop-2 sdAb and the second anti-Trop-2 sdAb bind to different Trop-2 epitopes.

25. The multispecific targeting conjugate of any one of claims 1-24, wherein the first targeting portion comprises one or more antibodies or antigen-binding fragments thereof that specifically recognize PD-L1 (anti-PD-L1 antibody or antigen-binding fragment thereof).

26. The multispecific targeting conjugate of claim 25, wherein the one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) Heavy chain CDR1 ("H-CDR1") containing the amino acid sequence of SEQ ID NO: 3 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 8 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 13 or a variant thereof containing up to 3 amino acid variations; Light chain CDR1 ("L-CDR1") containing the amino acid sequence of SEQ ID NO: 20 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 25 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30 or a variant thereof containing up to 3 amino acid variations; ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 1 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 6 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 11 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 18 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 23 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 28 or a variant thereof containing up to 3 amino acid variations; iii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 2 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 7 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 12 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 19 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 24 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 29 or a variant thereof containing up to 3 amino acid variations; iv) H-CDR1 containing the amino acid sequence of SEQ ID NO: 4 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 9 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 14 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 21 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 26 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 31 or a variant thereof containing up to 3 amino acid variations; or v) H-CDR1 containing the amino acid sequence of SEQ ID NO: 5 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 10 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 15 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 22 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 27 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 32 or a variant thereof containing up to 3 amino acid variations.

27. The multispecific targeting conjugate of claim 25 or 26, wherein the one or more anti-PD-L1 antibodies or their antigen-binding fragments independently comprise: i) A heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; ii) A VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and a VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; iii) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; iv) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; v) A VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; vi) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; vii) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; viii) VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; ix) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; x) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; xi) VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL comprising the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xiii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xiv) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xv) VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL comprising the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xvi) VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xvii) VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 227, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xviii) VH comprising the amino acid sequence of SEQ ID NO: 228 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xix) VH comprising the amino acid sequence of SEQ ID NO: 229 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 229, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xx) VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xxi) VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; or xxii) VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO:

226.

28. The multispecific targeting conjugate of any one of claims 25-27, wherein the first targeting portion comprises a full-length anti-PD-L1 antibody.

29. The multispecific targeting conjugate of claim 28, wherein the full-length anti-PD-L1 antibody comprises: i) The heavy chain containing the amino acid sequence of SEQ ID NO: 89 and the light chain containing the amino acid sequence of SEQ ID NO: 90; ii) The heavy chain containing the amino acid sequence of SEQ ID NO: 79 and the light chain containing the amino acid sequence of SEQ ID NO: 80; iii) The heavy chain containing the amino acid sequence of SEQ ID NO: 81 and the light chain containing the amino acid sequence of SEQ ID NO: 82; iv) The heavy chain containing the amino acid sequence of SEQ ID NO: 83 and the light chain containing the amino acid sequence of SEQ ID NO: 84; v) The heavy chain containing the amino acid sequence of SEQ ID NO: 85 and the light chain containing the amino acid sequence of SEQ ID NO: 86; vi) The heavy chain containing the amino acid sequence of SEQ ID NO: 87 and the light chain containing the amino acid sequence of SEQ ID NO: 88; vii) The heavy chain containing the amino acid sequence of SEQ ID NO: 91 and the light chain containing the amino acid sequence of SEQ ID NO: 92; viii) The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) The heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) The heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) The heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) The heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) The heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) The heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) The heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) The heavy chain containing the amino acid sequence of SEQ ID NO: 109 and the light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) The heavy chain containing the amino acid sequence of SEQ ID NO: 111 and the light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) The heavy chain containing the amino acid sequence of SEQ ID NO: 113 and the light chain containing the amino acid sequence of SEQ ID NO: 114; xix) The heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116; xx) The heavy chain containing the amino acid sequence of SEQ ID NO: 117 and the light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) The heavy chain containing the amino acid sequence of SEQ ID NO: 119 and the light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) A heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; or xxiii) The heavy chain containing the amino acid sequence of SEQ ID NO: 17 and the light chain containing the amino acid sequence of SEQ ID NO:

34.

30. The multispecific targeting conjugate according to any one of claims 1-29, wherein the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus: i) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – conjugation site – optional adapter 2 – anti-Trop-2sdAb; ii) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – cleavage site – optional adapter 2 – conjugation site – optional adapter 3 – anti-Trop-2 sdAb; iii) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – conjugation site – optional adapter 2 – primary anti-Trop-2 sdAb – optional adapter 3 – secondary anti-Trop-2 sdAb; or iv) Anti-PD-L1 antibody or its antigen-binding fragment – ​​optional adapter 1 – cleavage site – optional adapter 2 – conjugation site – optional adapter 3 – first anti-Trop-2 sdAb – optional adapter 4 – second anti-Trop-2 sdAb.

31. The multispecific targeting conjugate of any one of claims 1-30, wherein the multispecific targeting conjugate comprises a full-length anti-PD-L1 antibody; wherein the multispecific targeting conjugate comprises, from the N-terminus to the C-terminus, a fusion polypeptide: the heavy chain of the full-length anti-PD-L1 antibody – optional linker 1 – optional cleavage site – optional linker 2 – conjugation site – optional linker 3 – one or more anti-Trop-2 sdAbs; wherein the heavy chain comprises the amino acid sequence of SEQ ID NO: 17, the light chain comprises the amino acid sequence of SEQ ID NO: 34; and wherein the fusion polypeptide comprises the amino acid sequence of any one of SEQ ID NO: 67, 69, 215, and 238-240.

32. An isolated antibody construct (anti-PD-L1 antibody construct) comprising a targeting portion that specifically recognizes PD-L1 (anti-PD-L1 targeting portion), wherein the anti-PD-L1 targeting portion comprises: i) H-CDR1 containing the amino acid sequence of SEQ ID NO: 3 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 8 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 13 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 20 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 25 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 30 or a variant thereof containing up to 3 amino acid variations; ii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 1 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 6 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 11 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 18 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 23 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 28 or a variant thereof containing up to 3 amino acid variations; iii) H-CDR1 containing the amino acid sequence of SEQ ID NO: 2 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 7 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 12 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 19 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 24 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 29 or a variant thereof containing up to 3 amino acid variations; iv) H-CDR1 containing the amino acid sequence of SEQ ID NO: 4 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 9 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 14 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 21 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 26 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 31 or a variant thereof containing up to 3 amino acid variations; or v) H-CDR1 containing the amino acid sequence of SEQ ID NO: 5 or a variant thereof containing up to 3 amino acid variations; H-CDR2 containing the amino acid sequence of SEQ ID NO: 10 or a variant thereof containing up to 3 amino acid variations; H-CDR3 containing the amino acid sequence of SEQ ID NO: 15 or a variant thereof containing up to 3 amino acid variations; L-CDR1 containing the amino acid sequence of SEQ ID NO: 22 or a variant thereof containing up to 3 amino acid variations; L-CDR2 containing the amino acid sequence of SEQ ID NO: 27 or a variant thereof containing up to 3 amino acid variations; and L-CDR3 containing the amino acid sequence of SEQ ID NO: 32 or a variant thereof containing up to 3 amino acid variations.

33. The isolated anti-PD-L1 antibody construct of claim 32, wherein the anti-PD-L1 targeting portion comprises: i) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; ii) A VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and a VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; iii) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; iv) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 33 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 33; v) A VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and a VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; vi) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 213 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 213; vii) VH comprising the amino acid sequence of SEQ ID NO: 212 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 212, and VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; viii) VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL comprising the amino acid sequence of SEQ ID NO: 221 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 221; ix) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; x) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 222 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 222; xi) VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and VL comprising the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xiii) A VH comprising the amino acid sequence of SEQ ID NO: 16 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 16, and a VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xiv) A VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and a VL comprising the amino acid sequence of SEQ ID NO: 225 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 225; xv) VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL comprising the amino acid sequence of SEQ ID NO: 224 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 224; xvi) VH comprising the amino acid sequence of SEQ ID NO: 223 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 223, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xvii) VH comprising the amino acid sequence of SEQ ID NO: 227 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 227, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xviii) VH comprising the amino acid sequence of SEQ ID NO: 228 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 228, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xix) VH comprising the amino acid sequence of SEQ ID NO: 229 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 229, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xx) VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 226; xxi) VH comprising the amino acid sequence of SEQ ID NO: 230 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 230, and VL comprising the amino acid sequence of SEQ ID NO: 220 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 220; or xxii) VH comprising the amino acid sequence of SEQ ID NO: 219 or a variant thereof having at least about 85% sequence identity with SEQ ID NO: 219, and VL comprising the amino acid sequence of SEQ ID NO: 226 or a variant thereof having at least about 85% sequence identity with SEQ ID NO:

226.

34. The isolated anti-PD-L1 antibody construct as described in claim 32 or 33, wherein the anti-PD-L1 targeting portion is a full-length antibody (full-length anti-PD-L1 antibody).

35. The isolated anti-PD-L1 antibody construct of claim 34, wherein the full-length anti-PD-L1 antibody comprises: i) The heavy chain containing the amino acid sequence of SEQ ID NO: 89 and the light chain containing the amino acid sequence of SEQ ID NO: 90; ii) The heavy chain containing the amino acid sequence of SEQ ID NO: 79 and the light chain containing the amino acid sequence of SEQ ID NO: 80; iii) The heavy chain containing the amino acid sequence of SEQ ID NO: 81 and the light chain containing the amino acid sequence of SEQ ID NO: 82; iv) The heavy chain containing the amino acid sequence of SEQ ID NO: 83 and the light chain containing the amino acid sequence of SEQ ID NO: 84; v) The heavy chain containing the amino acid sequence of SEQ ID NO: 85 and the light chain containing the amino acid sequence of SEQ ID NO: 86; vi) The heavy chain containing the amino acid sequence of SEQ ID NO: 87 and the light chain containing the amino acid sequence of SEQ ID NO: 88; vii) The heavy chain containing the amino acid sequence of SEQ ID NO: 91 and the light chain containing the amino acid sequence of SEQ ID NO: 92; viii) The heavy chain containing the amino acid sequence of SEQ ID NO: 93 and the light chain containing the amino acid sequence of SEQ ID NO: 94; ix) The heavy chain containing the amino acid sequence of SEQ ID NO: 95 and the light chain containing the amino acid sequence of SEQ ID NO: 96; x) The heavy chain containing the amino acid sequence of SEQ ID NO: 97 and the light chain containing the amino acid sequence of SEQ ID NO: 98; xi) The heavy chain containing the amino acid sequence of SEQ ID NO: 99 and the light chain containing the amino acid sequence of SEQ ID NO: 100; xii) The heavy chain containing the amino acid sequence of SEQ ID NO: 101 and the light chain containing the amino acid sequence of SEQ ID NO: 102; xiii) The heavy chain containing the amino acid sequence of SEQ ID NO: 103 and the light chain containing the amino acid sequence of SEQ ID NO: 104; xiv) The heavy chain containing the amino acid sequence of SEQ ID NO: 105 and the light chain containing the amino acid sequence of SEQ ID NO: 106; xv) The heavy chain containing the amino acid sequence of SEQ ID NO: 107 and the light chain containing the amino acid sequence of SEQ ID NO: 108; xvi) The heavy chain containing the amino acid sequence of SEQ ID NO: 109 and the light chain containing the amino acid sequence of SEQ ID NO: 110; xvii) The heavy chain containing the amino acid sequence of SEQ ID NO: 111 and the light chain containing the amino acid sequence of SEQ ID NO: 112; xviii) The heavy chain containing the amino acid sequence of SEQ ID NO: 113 and the light chain containing the amino acid sequence of SEQ ID NO: 114; xix) The heavy chain containing the amino acid sequence of SEQ ID NO: 115 and the light chain containing the amino acid sequence of SEQ ID NO: 116; xx) The heavy chain containing the amino acid sequence of SEQ ID NO: 117 and the light chain containing the amino acid sequence of SEQ ID NO: 118; xxi) The heavy chain containing the amino acid sequence of SEQ ID NO: 119 and the light chain containing the amino acid sequence of SEQ ID NO: 120; xxii) A heavy chain containing the amino acid sequence of SEQ ID NO: 121 and a light chain containing the amino acid sequence of SEQ ID NO: 122; or xxiii) The heavy chain containing the amino acid sequence of SEQ ID NO: 17 and the light chain containing the amino acid sequence of SEQ ID NO:

34.

36. The isolated anti-PD-L1 antibody construct according to any one of claims 32-35, wherein the isolated anti-PD-L1 antibody construct is multispecific.

37. The isolated anti-PD-L1 antibody construct according to any one of claims 32-36, wherein the isolated anti-PD-L1 antibody construct is a multispecific targeting conjugate, the multispecific targeting conjugate comprising a first targeting moiety that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule, wherein the first targeting moiety is an anti-PD-L1 targeting moiety, and wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site.

38. The isolated anti-PD-L1 antibody construct of claim 37, wherein the multispecific targeting conjugate further comprises a cleavage site between the first targeting portion and the conjugation site, and wherein the second targeting portion conjugated with the effector molecule is capable of being released from the multispecific targeting conjugate via cleavage at the cleavage site.

39. An isolated antibody construct (anti-Trop-2 antibody construct) comprising a targeting moiety that specifically recognizes Trop-2 (anti-Trop-2 targeting moiety), wherein the anti-Trop-2 targeting moiety is VHH (anti-Trop-2 VHH), the VHH comprising: i) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 42 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations. ii) CDR1 containing the amino acid sequence of SEQ ID NO: 35 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 40 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 45 or a variant thereof containing up to 3 amino acid variations. iii) CDR1 containing the amino acid sequence of SEQ ID NO: 36 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 41 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 46 or a variant thereof containing up to 3 amino acid variations. iv) CDR1 containing the amino acid sequence of SEQ ID NO: 38 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 43 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 48 or a variant thereof containing up to 3 amino acid variations. v) CDR1 containing the amino acid sequence of SEQ ID NO: 39 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 44 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 49 or a variant thereof containing up to 3 amino acid variations. vi) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 63 or a variant thereof containing up to 3 amino acid variations. vii) CDR1 containing the amino acid sequence of SEQ ID NO: 51 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 56 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 61 or a variant thereof containing up to 3 amino acid variations. viii) CDR1 containing the amino acid sequence of SEQ ID NO: 52 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 57 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 62 or a variant thereof containing up to 3 amino acid variations. ix) CDR1 comprising the amino acid sequence of SEQ ID NO: 54 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 59 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 64 or a variant thereof comprising up to 3 amino acid variations; x) CDR1 containing the amino acid sequence of SEQ ID NO: 55 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 60 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 65 or a variant thereof containing up to 3 amino acid variations. xi) CDR1 containing the amino acid sequence of SEQ ID NO: 37 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 205 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 47 or a variant thereof containing up to 3 amino acid variations. xii) CDR1 containing the amino acid sequence of SEQ ID NO: 53 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 58 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 206 or a variant thereof containing up to 3 amino acid variations. xiii) CDR1 comprising the amino acid sequence of SEQ ID NO: 55 or a variant thereof comprising up to 3 amino acid variations; CDR2 comprising the amino acid sequence of SEQ ID NO: 60 or a variant thereof comprising up to 3 amino acid variations; and CDR3 comprising the amino acid sequence of SEQ ID NO: 243 or a variant thereof comprising up to 3 amino acid variations; or xiiiv) CDR1 containing the amino acid sequence of SEQ ID NO: 216 or a variant thereof containing up to 3 amino acid variations; CDR2 containing the amino acid sequence of SEQ ID NO: 217 or a variant thereof containing up to 3 amino acid variations; and CDR3 containing the amino acid sequence of SEQ ID NO: 218 or a variant thereof containing up to 3 amino acid variations.

40. The isolated anti-Trop-2 antibody construct of claim 39, wherein the anti-Trop-2 VHH comprises the amino acid sequence of any one of SEQ ID NO: 50, 66, 123-136 and 203.

41. The isolated anti-Trop-2 antibody construct of claim 39 or 40, wherein the isolated anti-Trop-2 antibody construct comprises two or more anti-Trop-2 VHHs fused in tandem with each other.

42. The isolated anti-Trop-2 antibody construct according to any one of claims 39-41, wherein the isolated anti-Trop-2 antibody construct is multispecific.

43. The isolated anti-Trop-2 antibody construct according to any one of claims 39-42, wherein the isolated anti-Trop-2 antibody construct comprises a first anti-Trop-2 VHH and a second anti-Trop-2 VHH.

44. The isolated anti-Trop-2 antibody construct according to any one of claims 39-43, wherein the isolated anti-Trop-2 antibody construct is a multispecific targeting conjugate, the multispecific targeting conjugate comprising a first targeting moiety that specifically recognizes PD-L1, a second targeting moiety that specifically recognizes Trop-2, and an effector molecule, wherein the second targeting moiety is the anti-Trop-2 targeting moiety, and wherein the effector molecule is conjugated to the second targeting moiety via a conjugation site.

45. The isolated anti-Trop-2 antibody construct of claim 44, wherein the multispecific targeting conjugate further comprises a cleavage site between the first targeting portion and the conjugation site, and wherein the second targeting portion conjugated with the effector molecule is capable of being released from the multispecific targeting conjugate via cleavage at the cleavage site.

46. ​​A pharmaceutical composition comprising: i) an isolated anti-PD-L1 antibody construct according to any one of claims 32-38, or an isolated anti-Trop-2 antibody construct according to any one of claims 39-45; and ii) optionally a pharmaceutically acceptable carrier.

47. A pharmaceutical composition comprising one or more multispecific targeting conjugates as described in any one of claims 1-31, 37, 38, 44 and 45 and optionally a pharmaceutically acceptable carrier.

48. A method of treating an individual with Trop-2 positive cancer, the method comprising administering to the individual an effective amount of any one of claims 1-31, 37, 38, 44 and 45, or the pharmaceutical composition of claim 47.

49. A method for preparing a multispecific targeting conjugate according to any one of claims 1-31, 37, 38, 44 and 45, wherein the method comprises conjugating the effector molecule to the second targeting portion via the conjugation site.

50. The method of claim 49, wherein: The method includes the following steps: (a) Reacting a multispecific targeting portion comprising the first targeting portion, the second targeting portion, and the conjugation site with a linker reagent to form a multispecific targeting portion-linker intermediate; and (b) React the multispecific targeting portion-connector intermediate with the nucleophilic group of the effector molecule portion; This forms the aforementioned multi-specific targeting conjugate; Alternatively, the method may include the following steps: (c) Reacting the effector molecule with a linker reagent to form a linker-effector intermediate; and (d) React the linker-effect molecular intermediate with a conjugation site comprising the first targeting portion, the second targeting portion and the conjugation site; This forms the aforementioned multi-specific targeting conjugate; Alternatively, the method may include the following steps: (e) React the multispecific targeting portion comprising the first targeting portion, the second targeting portion and the conjugation site with the linker-effect molecule conjugate; This forms the multispecific targeting conjugate.

51. The method of claim 49 or 50, wherein the conjugation is carried out by transglutaminase-mediated conjugation.

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