M6PR binding compounds and conjugates

Abstract

The present disclosure provides a class of compounds comprising a ligand moiety that specifically binds to a cell surface mannose-6-phosphate receptor (M6PR). The M6PR binding compound can trigger the receptor to internalize the bound compound into the cell. Ligand moieties of the present disclosure may be linked to a variety of moieties of interest without affecting specific binding to M6PR and its function. Also provided are compounds that are conjugates of a ligand moiety linked to a biomolecule, such as an antibody, that can utilize a cellular pathway to remove a specific target protein from the cell surface or extracellular environment. For example, the conjugates described herein can isolate and / or degrade a target molecule of interest in the lysosome of a cell. Methods of targeting proteins for isolation and / or lysosomal degradation using the conjugates are also provided.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 439,806, filed on January 18, 2023, which is hereby incorporated by reference in its entirety. 1. Background Technology

[0003] Many therapeutic agents act by binding to functionally important sites on a target protein, thereby modulating the activity of the protein or acting on the target protein by recruiting immune effectors (as in many monoclonal antibody drugs). However, there is an untapped library of medically important human proteins that are considered "undruggable" because these proteins are not easily amenable to currently available therapeutic targeting methods. Therefore, there is a need for therapies that can target a wider range of proteins.

[0004] Mannose-6-phosphate is a monosaccharide ligand that plays a key role in the intracellular retention and secretion of the lysosomal hydrolases to which they are attached. When this sugar residue is incorporated into newly synthesized enzymes, it can guide their transport from the Golgi apparatus to the lysosomes where they are active. The membrane-bound cell surface mannose-6-phosphate receptor (M6PR) plays a role in many biological processes, including the secretion and internalization of these lysosomal enzymes. Endocytosis of the M6PR allows compounds with mannose 6-phosphate (M6P) ligands to be internalized into cells and transported to lysosomes.

[0005] Alternative ligands that can bind to cell surface M6PR and subsequently translocate across the cell membrane are of great interest. 2. Summary of the Invention

[0006] The present disclosure provides a class of compounds comprising a ligand portion that specifically binds to a cell surface mannose-6-phosphate receptor (M6PR). Cell surface M6PR binding compounds can trigger the receptor to internalize the bound compound into the cell. The ligand portion of the present disclosure can be connected to a variety of moieties of interest without affecting the specific binding to the cell surface M6PR and its function. Also provided is a compound, which is a conjugate of a ligand portion connected to a biomolecule such as an antibody, and the conjugate can utilize a cellular pathway to remove a specific protein of interest from the cell surface or from the extracellular environment. For example, the conjugates described herein can isolate and / or degrade a target molecule of interest in the lysosome of a cell. Also provided herein are compositions comprising such conjugates and methods of using the conjugates to target a polypeptide of interest for chelation and / or lysosomal degradation, as well as methods of using the conjugates to treat a disease or condition. 3. Description of the Figures

[0007] Figure 1Representative native mass spectrometry (MS) analysis of deglycosylated matuzumab is shown for the exemplary conjugate matuzumab-(Compound A) conjugate.

[0008] Figure 2 Representative native mass spectrometry (MS) analysis of deglycosylated matuzumab is shown for the exemplary conjugate matuzumab-(Compound 520 (I-7)) conjugate.

[0009] Figure 3 Time course activity of cetuximab-(Compound A) and cetuximab-(Compound 520 (I-7)) conjugates on surface EGFR levels in Hela parental and M6PR knockout (KO) cells as measured by surface staining is shown.

[0010] Figure 4 Time course activity of matuzumab-(Compound A) and matuzumab-(Compound 520 (I-7)) conjugates on surface EGFR levels in Hela parental and M6PR KO cells as measured by surface staining is shown.

[0011] Figure 5 Intracellular protein immunoblot images illustrating dose response of cetuximab-(Compound A), cetuximab-(Compound 520 (I-7)), matuzumab-(Compound A), and matuzumab-(Compound 520 (I-7)) conjugates on total EGFR levels in Hela parental and M6PR KO cells are shown.

[0012] Figure 6 Time course activity of cetuximab-(Compound A), cetuximab-(Compound 520 (I-7)), matuzumab-(Compound A), and matuzumab-(Compound 520 (I-7)) conjugates on relative EGFR normalized levels in Hela parental and M6PR KO cells is shown.

[0013] Figures 7A to 7F Fluorescently labeled matuzumab (mtz) or human IgG isotype antibody (isotype) ([ab]): untagged control ( Figure 7A ), Compound 520 (I-7) Figure 7B ), Compound 602 (I-8) Figure 7C ), Compound 603 (I-9) Figure 7D ), Compound 605 (I-11) Figure 7E ), and Compound 716 (I-12) Figure 7FBinding affinity curves of various exemplary conjugates of M6PR to M6PR. Binding to M6PR was determined by ELISA. Conjugates of compound 520 (I-7) (m or DAR = 8) and compound 605 (I-11) (m or DAR = 4) showed the highest and lowest binding affinities, respectively. d4 is DAR 4. d8 is DAR 8. RFU is relative fluorescence units.

[0014] Figures 8A to 8C Serum pharmacokinetic (PK) analysis of exemplary conjugates of rIgG1 (anti-IgG2a) antibodies in mice is depicted. Compound 520 (I-7) (DAR = 8 for d8) and (DAR = 4 for d4) in mouse serum were measured using ELISA at 0.5, 1, 2, 6, and 24 hours after administration. Figure 8A ), compound 604 (I-10) and compound 605 (I-11) ( Figure 8B ), and compound 603 (I-9) and compound 716 (I-12) ( Figure 8C UNLB is an antibody control.

[0015] Figure 9 The intracellular uptake of exemplary anti-IgG2a conjugates and bound target proteins in Jurkat cells over time is shown. The conjugates were detected via fluorescent Alexa488-conjugated target IgG2a-antibody, and the intracellular fluorescence level (MFI) was determined after 1 hour and 24 hours using FACS.

[0016] Figure 10 Plotted are the relative intracellular uptake of 10 nM exemplary anti-IgG2a conjugates and bound target protein (Alexa488-conjugated target IgG2a-antibody) into Jurkat cells as a percentage of the uptake of the reference compound 520 (I-7) (d8 is DAR=8) conjugate after 24 hours.

[0017] Figure 11 is a graph showing the results of M6PR binding assays of various antibody conjugates of exemplary compounds with varying DAR loadings.

[0018] Figure 12 is a graph of cell fluorescence (MFI) versus antibody conjugate concentration ([Ab]), demonstrating that exemplary M6PR-binding antibody conjugates exhibit robust uptake of target protein into Jurkat cells after 1 hour of incubation.

[0019] Figure 13Plots of cell fluorescence (MFI) versus antibody conjugate concentration ([Ab]) are shown demonstrating that various antibody conjugates of exemplary M6PR or ASGPR binding compounds exhibit comparable strong uptake into HepG2 cells after 1 hour of incubation.

[0020] Figure 14 Plots demonstrating CI-M6PR dependent cellular uptake of exemplary antibody conjugates binding to Alexa 488 labeled IgE targets in CI-M6PR knock out (KO) cells versus wild type (WT) K562 cells are shown.

[0021] Figure 15 Plots of cellular uptake of various conjugates of omalizumab (anti-IgE) in Jurkat cells versus exemplary M6PR binding compounds (conjugates binding to Alexa 488 labeled target IgE) are shown.

[0022] Figure 16 Plots demonstrating cellular uptake activity comparisons of specific exemplary conjugates from the plots of Figure 15 are shown.

[0023] Figure 17 Plots demonstrating cellular uptake activity comparisons of specific exemplary conjugates from the plots of Figure 15 are shown.

[0024] Figure 18 Plots of cellular uptake of various conjugates of omalizumab (anti-IgE) in Jurkat cells binding to Alexa 488 labeled target IgE versus exemplary M6PR ligand-linkers are shown.

[0025] Figure 19 Plots demonstrating cellular uptake activity comparisons of specific exemplary conjugates from the plots of Figure 18 are shown.

[0026] Figure 20 Plots demonstrating cellular uptake activity comparisons of specific exemplary conjugates from the plots of Figure 18 are shown.

[0027] Figure 21 Plots demonstrating cellular uptake activity comparisons of specific exemplary conjugates from the plots of Figure 18 are shown.

[0028] Figure 22 Plots of M6PR binding affinity data for various exemplary cetuximab (anti-EGFR) conjugates of the disclosure are shown.

[0029] Figure 23FIG. 1 shows a graph illustrating cellular uptake activity of a particular exemplary target-binding conjugate of the disclosure.

[0030] Figure 24 FIG. 2 shows a synthetic scheme for M6PR binding moieties suitable for connection to linkers and / or a moiety of interest.

[0031] Figure 25 FIG. 2 shows a synthetic scheme for M6PR binding moieties suitable for connection to linkers and / or a moiety of interest. 4. DETAILED DESCRIPTION

[0032] As outlined above, the present disclosure provides a class of compounds comprising a particular ligand moiety X that specifically binds to a cell surface mannose-6-phosphate receptor (M6PR) (also referred to as a M6PR binding moiety or M6PR ligand moiety). The M6PR binding moieties of the present disclosure can be connected to a variety of moieties of interest without affecting the specific binding to cell surface M6PR and its function. The present inventors have demonstrated that the compounds of the present disclosure can exploit the function of cell surface M6PR in biological systems, for example, for internalization and / or sequestration into lysosomes of a cell, and in some cases, subsequent lysosomal degradation of the target molecule. The compounds of the present disclosure are useful in a variety of applications. In some embodiments, the M6PR binding moiety X enables intracellular delivery of a moiety of interest. In some embodiments, the compound is a bifunctional compound comprising a M6PR binding moiety X connected to a target binding moiety for internalization and / or lysosomal degradation of the bound target molecule.

[0033] Accordingly, the present disclosure provides a compound of Formula (XI) comprising one or more M6PR binding moieties connected to a moiety of interest Y:

[0034]

[0035] or a salt thereof, wherein:

[0036] X is a M6PR binding moiety (e.g., as described herein);

[0037] n is 1 to 500 (e.g., X is connected via a monovalent or multivalent linker, as described herein);

[0038] m is 1 to 500 (e.g., 1 to 100 or 1 to 10);

[0039] L is a linker; and

[0040] Y is a moiety of interest (e.g., as described herein).

[0041] Compounds and conjugates of the disclosure and methods are described in greater detail below. A particular class of M6PR binding compounds is described. In some embodiments, the compounds are biomolecule conjugates comprising one or more linked M6PR binding moieties. Linkers (L) and moieties of interest (Y) for use in M6PR binding compounds and biomolecule conjugates are also described. Methods in which the compounds and conjugates of the disclosure are used are also described.

[0042] 4.1. M6PR Binding Moieties

[0043] As outlined above, M6PR binding moieties of the disclosure (also referred to as M6PR ligand moieties) can be linked to a variety of moieties of interest without affecting specific binding to cell surface M6PR and its function. The inventors have demonstrated that M6PR binding moieties having the specific structure described below can bind with high affinity to cell surface M6PR and, when configured via linkers of bifunctional compounds according to the disclosure, can exploit the function of cell surface M6PR in biological systems, for example for internalization and / or degradation of target molecules.

[0044] The terms “mannose-6-phosphate receptor” and “M6PR” refer to receptors of the mannose-6-phosphate receptor family. M6PRs are transmembrane glycoprotein receptors that target enzymes to lysosomes in cells. P6Rs endogenously transport proteins with N-glycans capped with mannose-6-phosphate (M6P) residues to lysosomes and cycle between endosomes, the cell surface, and the Golgi complex. See, e.g., Ghosh et al., Nat. Rev. Mol. Cell Biol. 2003; 4:202-213. The M6PR family includes the non-cation-dependent mannose-6-phosphate receptor (CI-M6PR). CI-M6PR is also known as insulin-like growth factor 2 receptor (IGF2R) and is encoded by the IGF2R gene in humans (see, e.g., NCBI Reference Sequence: NM_000876.3 and NCBI Gene ID: 3482). CI-M6PR binds insulin-like growth factor 2 (IGF-2) and mannose-6-phosphate (M6P)-tagged proteins. Compounds of the disclosure can specifically bind to cell surface M6PR, for example internalizing CI-M6PR cell surface receptors. In particular embodiments, the surface CI-M6PR is human CI-M6PR. It will be understood that the terms M6PR and CI-M6PR are used interchangeably when referring to the binding properties of M6PR binding moieties and compounds of the disclosure.

[0045] A compound (e.g., as described herein) comprising such a M6PR binding moiety (X) can bind to other receptors, e.g., can bind with lower affinity in, e.g., an immunoassay or other assay known in the art. In particular embodiments, X or a compound as described herein comprising such X specifically binds to a cell surface CI-M6PR with at least 2 logs, 2.5 logs, 3 logs, 4 logs, or more higher affinity than the affinity with which X or the compound binds to another cell surface receptor. In particular embodiments, X or a compound as described herein comprising such X specifically binds to CI-M6PR with an affinity (K d ) of 20 mM or less. In particular embodiments, the affinity (K d ) of such binding is 10 mM or less, 1 mM or less, 100 uM or less, 10 uM or less, 1 uM or less, 100 nM or less, 10 nM or less, or 1 nM or less. The terms “binds,” “binds to,” “specifically binds” or “specifically binds to” are used interchangeably herein.

[0046] M6PR binding compounds of the present disclosure comprise a moiety (X) (e.g., as described herein) that is a D-mannopyranoside analog that specifically binds to a cell surface receptor M6PR. M6PR binding compounds can be monovalent or multivalent (e.g., divalent or trivalent or higher), with monovalent compounds comprising a single M6PR ligand moiety, and monovalent compounds comprising two or more such moieties.

[0047] 4.1.1. Alpha-linked pyranose ring

[0048] The M6PR binding moiety of a compound of the present disclosure can comprise a linked pyranose ring described by formula (II):

[0049]

[0050] wherein:

[0051] W is a hydrophilic head group;

[0052] Z 1 is selected from optionally substituted (C1-C3)alkylene and optionally substituted vinylene;

[0053] Z 2 is selected from O, S, NR 21 , and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl.

[0054] In some embodiments of Formula (II), Z 2 is a linking moiety attached at the anomeric or 1 -position to the pyranose ring, in its alpha configuration as shown in the following Formula (IIa):

[0055]

[0056] 4.1.2. Beta-linked pyranose rings

[0057] The inventors have demonstrated that while M6PR binding compounds having the anomeric alpha configuration of Formula (IIa) can provide good binding and internalization activity at the receptor, in some cases, by constructing the central pyranose ring of the M6PR binding moiety with a beta-configuration at the anomeric position, more potent binding and internalization activity at the M6PR can be conferred. In some embodiments, such M6PR binding moieties can improve stability at the pyranose ring.

[0058] Thus, in some embodiments of Formula (II), Z 2 is a linking moiety attached at the anomeric or 1 -position to the sugar ring, in its beta configuration as shown in the following Formula (IIb):

[0059]

[0060] 4.2. M6PR binding compounds

[0061] While moieties of Formula (II) can exhibit binding activity for M6PR, the inventors have demonstrated that when a particular type of cyclic group is attached via the linking moiety Z 2 adjacent to the pyranose ring (II) of Formula (II) results in a M6PR binding moiety that exhibits desirable binding activity.

[0062] Thus, in some embodiments of Formula (II), the M6PR binding moiety (X) can be described by Formula (III):

[0063]

[0064] or a prodrug or salt thereof, wherein:

[0065] W is a hydrophilic head group;

[0066] Z 1 is selected from optionally substituted (Ci-C3)alkylene and optionally substituted vinylene;

[0067] Z 2 is selected from O, S, NR 21 and C(R 22 )2, wherein each R 21independently selected from H and optionally substituted (Ci-C6)alkyl, and each R 22 independently selected from H, halogen (e.g., F), and optionally substituted (Ci-C6)alkyl;

[0068] A is independently an optionally substituted cyclic group; and

[0069] Z 3 is independently a linking moiety.

[0070] In some embodiments of Formula (II)-(III), W is a non-hydrolysable hydrophilic head group.

[0071] In some embodiments of Formula (II)-(III), Z 2 is optionally substituted ethenylene. In some embodiments of Formula (II)-(III), Z 2 is optionally substituted ethenylene.

[0072] In some embodiments of Formula (II)-(III), Z 2 is O. In some embodiments of Formula (II)-(III), Z 2 is S. In some embodiments of Formula (II)-(III), Z 2 is -NR 21 -. In some embodiments of Formula (II)-(III), Z 2 is -C(R 22 )2-, wherein each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (Ci-C6)alkyl. In some embodiments of Formula (II)-(III), Z 2 is -CH2-.

[0073] In some embodiments of Formula (II)-(III), A is an optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocycle, or optionally substituted cycloalkyl. In some embodiments of Formula (II)-(III), A is independently an optionally substituted aryl or heteroaryl linking moiety (e.g., an optionally substituted monocyclic or bicyclic aryl or heteroaryl).

[0074] Exemplary Z 3 linking moieties of Formula (II)-(III) are described herein.

[0075] Such M6PR binding moieties of Formula (III) can be linked to a moiety or molecule of interest to produce a bifunctional compound that undergoes efficient M6PR-mediated cellular internalization. The inventors have further demonstrated that when the moiety or molecule of interest is a target protein binding moiety, the M6PR binding compound also effects M6PR-mediated internalization and / or degradation of the bound target protein.

[0076] Thus, in some embodiments of Formula (XI), the M6PR-binding compound has Formula (XII):

[0077]

[0078] or a prodrug or salt thereof, wherein:

[0079] W is a hydrophilic head group;

[0080] Z 1 is selected from optionally substituted (C1-C3)alkylene and optionally substituted vinylene;

[0081] Z 2 is selected from O, S, NR 21 , and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl;

[0082] A is independently an optionally substituted cyclic group;

[0083] Z 3 is independently a linking moiety;

[0084] n is 1 to 500;

[0085] L is a linker;

[0086] Y is a moiety of interest; and

[0087] m is 1 to 100.

[0088] In some embodiments of Formula (XI) to (XII), m is 1, and the cell surface M6PR-binding compound has Formula (XIII):

[0089]

[0090] or a prodrug or salt thereof, wherein:

[0091] W is a hydrophilic head group;

[0092] Z 1 is selected from optionally substituted (C1-C3)alkylene and optionally substituted vinylene;

[0093] Z 2 is selected from O, S, NR 21 , and C(R 22 )2, wherein each R 21independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl;

[0094] A is independently an optionally substituted cyclic group;

[0095] Z 3 is independently a linking moiety;

[0096] n is 1 to 500;

[0097] L is a linker; and

[0098] Y is a moiety of interest (e.g., as described herein).

[0099] In some embodiments of Formula (XIII), Y is a chemoselective linking group. In some embodiments of Formula (XIII), n is 1. In some embodiments of Formula (XIII), Y is a chemoselective linking group that is connected to “n” M6PR binding moieties (Xn-) via a single linker -L-. In some embodiments of Formula (XIII), n is 2, 3, 4, or 5. In some embodiments of Formula (XIII), n is 5 to 10. In some embodiments of Formula (XIII), n is 10 to 100, such as 20 to 80 or 20 to 50. In some embodiments of Formula (XIII), when n is 5 or greater, then L is a polypeptide-containing linker (e.g., as described herein).

[0100] In some embodiments of Formulas (XII) to (XIII), when n is 1 and A is phenyl, then: i) L comprises a backbone consisting of at least 16 contiguous atoms (e.g., at least 18 contiguous atoms, or at least 20 contiguous atoms, in some cases up to about 200 contiguous atoms); ii) Y is a biomolecule; and / or ii) Z 3 is an amide, sulfonamide, urea, or thiourea linkage to the linking moiety L.

[0101] In some embodiments of Formula (XII), Z 2 is a linking moiety connected to the sugar ring at the anomeric or 1 position, in the alpha configuration as shown in Formula (IIa), such that the compound has Formula (XIIa):

[0102]

[0103] In some embodiments of Formula (XII), Z 2 is a linking moiety connected to the sugar ring at the anomeric or 1 position, in the beta configuration as shown in Formula (IIb), such that the compound has Formula (XIIb):

[0104]

[0105] In some embodiments of formula (XI) to (XIIb), the plurality of M6PR binding moieties (e.g., M6PR binding moieties of formula (III)) are connected to different attachment sites on the moiety of interest Y via a plurality of linkers L. In some embodiments, when Y is a biomolecule, the compound of formula (XI) to (XIIb) can be referred to as a conjugate.

[0106] 4.2.1. Hydrophilic head group and linker moiety

[0107] In some embodiments of formula (II) to (XIII), the M6PR binding moiety (X) comprises an analogue of a D-mannopyranose ring having a hydrophilic head group or a precursor or prodrug thereof, which analogue is connected to the 5-position of the sugar ring via a linker moiety (Z 1 ) of 1 to 6 atoms in length, such as 1 to 5, 1 to 4, or 1 to 3 atoms in length, for example, 1 or 2 atoms in length. It will be appreciated that the length of the linker moiety can be selected in conjunction with the hydrophilic head group.

[0108] The hydrophilic head group (W) can be any suitable negatively charged group or salt thereof. In some embodiments, the hydrophilic head group is a neutral, polar, hydrophilic group. Typically, the hydrophilic head group is capable of hydrogen bonding or electrostatic interaction with the M6PR under aqueous or physiological conditions, similar to the phosphate group of M6P. The hydrophilic head group can be a bioisostere (e.g., structural or functional mimic) of the 6-phosphate group of a naturally occurring mannose-6-phosphate ligand. In some embodiments, the hydrophilic head group is non-hydrolysable, i.e., cleavage of the hydrophilic head group from the Z 1 linker moiety and / or the pyranose ring of X to which the hydrophilic head group is attached is stable under physiological conditions.

[0109] The hydrophilic head group is typically a small group, such as a heteroatom-containing functional group or a single heterocycle, and in some cases, the MW of the hydrophilic head group is less than 200, such as less than 150 or less than 100.

[0110] In some embodiments, the hydrophilic head group is a phosphate ester or a bioisostere, such as a carboxylate or a malonate. In some embodiments, the hydrophilic head group is a thiophosphonate.

[0111] In some embodiments of Formula (II) to (XIII), the hydrophilic head group is not a phosphonate, thiophosphonate, or dithiophosphonate, as such groups would have a phosphonate linkage to the compound, which can be unstable under physiological conditions and susceptible to cleavage (e.g., by phosphatases in biological systems or by chemical means). For example, the 6-phosphonate group of M6P exhibits undesirable stability compared to phosphonate analogs or other more stable head groups. In addition to phosphonates, the present disclosure provides alternative non-hydrolysable hydrophilic head groups that retain the binding and internalization activity of the resulting M6PR binding compounds.

[0112] In any of the embodiments of Formula (II) to (XIII), the hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, -NR 3 P=O(OH)2, -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, -(CR 2 R 2 )-P=O(OH)2, -SO2OH (i.e., -SO3H), -S(O)OH, -OSO2OH, -COOH, -CN, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 ), -CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHC(O)CO2H, -NHSO2NHR 3 , -NHC(O)NHS(O)2R 3 , -NHSO2R 3 , -NHSO3H, or a salt thereof,

[0113] wherein:

[0114] R 1 and R 2 are independently hydrogen, SR 3 , halo, or CN, and R 3 and R 4 are independently H, C 1-6 alkyl or substituted C 1-6 alkyl (e.g., -CF3or -CH2CF3);

[0115] A, B, and C are each independently CH or N; and

[0116] D is each independently O or S.

[0117] In some embodiments of formula (II) to (XIII), the hydrophilic head group W is a phosphate or thiophosphate, for example, -OP=O(OH)2, -SP=O(OH)2, -OP=O(SH)(OH), -SP=O(SH)(OH), -OP=S(OH)2, -OP=O(N(R 3 )2)(OH), or -OP=O(R 3 )(OH), or a salt thereof. In some embodiments of formula (II) to (XIII), the hydrophilic head group W is non-hydrolysable and thus is not selected from a phosphate or thiophosphate, for example, -OP=O(OH)2, -SP=O(OH)2, -OP=O(SH)(OH), -SP=O(SH)(OH), -OP=S(OH)2, -OP=O(N(R 3 )2)(OH), or -OP=O(R 3 )(OH), or a salt thereof.

[0118] In some embodiments of formula (II) to (XIII), the hydrophilic head group W is charged, for example, it is capable of forming a salt under aqueous or physiological conditions. In some embodiments of formula (II) to (XIII), the hydrophilic head group W is selected from -NR 3 P=O(OH)2, -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, -(CR 2 R 2 )-P=O(OH)2, -COOH, -CH(COOH)2, -CR 1 R 2 COOH, and -NHC(O)CO2H.

[0119] In some embodiments of formula (II)-(XIII), the hydrophilic head group W is a phosphate or thiophosphonate ester (e.g., -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), or -P=S(SH)(OH), or a salt thereof). In some embodiments of formula (II)-(XIII), the hydrophilic head group W is a phosphate ester or a salt thereof. In some embodiments of formula (II)-(XIII), the hydrophilic head group W is -CO2H or a salt thereof. In some embodiments of formula (II)-(XIII), the hydrophilic head group W is a malonic acid ester (e.g., -CH(COOH)2, or a salt thereof).

[0120] In some embodiments of formula (II)-(XIII), the hydrophilic head group W is selected from -SO2OH (i.e., -SO3H), -S(O)OH, -OSO2OH, and -NHSO3H. In some embodiments of formula (II)-(XIII), the hydrophilic head group W is a sulfonate (e.g., -SO3H, or a salt thereof).

[0121] In some embodiments, the hydrophilic head group W is neutral hydrophilic. In some embodiments of formula (II)-(XIII), the hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, -CN, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 ), -CONHSO2R 3 , -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHSO2NHR 3 , -NHC(O)NHS(O)2R 3 , and -NHSO2R 3 .

[0122] In some embodiments of formula (II)-(XIII), the hydrophilic head group W comprises a heterocycle, such as or a salt thereof,

[0123] wherein each A, B, and C is independently CH or N; and each D is independently O or S.

[0124] In some embodiments of formula (II) to (XIII), the hydrophilic head group W comprises a 5-membered heterocyclic ring, such as or salts thereof.

[0125] In some embodiments of formula (II) to (XIII), the hydrophilic head group W is attached to the pyranose ring via Z 1 Z 1 is selected from optionally substituted (Ci-C2)alkylene and optionally substituted vinylene. Z 1 may be selected in conjunction with W so as to provide a desired spacing between the 5 position of the ring and the charged or polar center of W. For example, when W is malonate having a CH atom connecting the two carboxylic acid groups, Z 1 may be methylene, which together with the CH atom provide a desired two carbon spacing between the ring and the COOH groups.

[0126] In some embodiments of formula (II) to (XIII), Z 1 is methylene or substituted methylene. In some embodiments of formula (II) to (XIII), Z 1 is ethylene or substituted ethylene. In some embodiments of formula (II) to (XIII), Z 1 is vinylene or substituted vinylene. In some embodiments of formula (II) to (XIII), Z 1 is substituted with one or more halogen (e.g., fluorine).

[0127] In some embodiments of formula (III), the M6PR binding moiety (X) is described by one of formula (IV-1) to (IV-3):

[0128]

[0129] wherein R a , R b , R c and R d are independently H or F.

[0130] In some embodiments of formula (IV-1) to (IV-3), Z 2 is O.

[0131] In some embodiments of formula (IV-1) to (IV-3), Z 2 is S.

[0132] In some embodiments of formula (IV-1) to (IV-3), Z 2 is -NR 21 -.

[0133] In some embodiments of Formula (IV-1) to (IV-3), Z 2 is -C(R 22 )2-, wherein each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl. In some embodiments of Formula (IV-1) to (IV-3), Z 2 is -CH2-.

[0134] In some embodiments of Formula (IV-1) to (IV-3), R a , R b , R c , and R d are each H.

[0135] In some embodiments of Formula (IV-1), R a is H, and R b is F. In some embodiments of Formula (IV-1), R a and R b are each F.

[0136] In some embodiments of Formula (IV-2), R c is H. In some embodiments of Formula (IV-2), R c is F.

[0137] In some embodiments of Formula (IV-3), R d is H. In some embodiments of Formula (IV-3), R d is F.

[0138] In some embodiments of Formula (IV-1) and (IV-3), W is selected from P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH or a salt thereof. In some embodiments of Formula (IV-1) and (IV-3), W is -P=O(OH)2or a salt thereof. In some embodiments of Formula (IV-1) and (IV-3), W is COOH or a salt thereof.

[0139] In some embodiments of Formula (IV-1), R a and R b are each F, and W is -P=O(OH)2or a salt thereof. In some embodiments of Formula (IV-1), R a and R b are each H, and W is -P=O(OH)2or a salt thereof. In some embodiments of Formula (IV-1), R a is F, R b is H, and W is -P=O(OH)2or a salt thereof.

[0140] In some embodiments of formula (IV-1) to (IV-3), Z 2 is attached to the anomeric position of the pyranose ring having an alpha configuration. In such cases, the M6PR binding moiety (X) of (IV-1) to (IV-3) can be referred to as formula (IV-A1) to (IV-A3), respectively.

[0141] In some embodiments of formula (IV-A1) to (IV-A3), Z 2 is S. In some embodiments of formula (IV-A1) to (IV-A3), Z 2 is O. In some embodiments of formula (IV-A1) to (IV-A3), Z 2 is -CH2-. In some embodiments of formula (IV-A1) to (IV-A3), Z 2 is -CF2-.

[0142] In some embodiments of formula (IV-A1) and (IV-A3), W is selected from -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH or a salt thereof. In some embodiments of formula (IV-A1) and (IV-A3), W is -P=O(OH)2or a salt thereof. In some embodiments of formula (IV-A1) and (IV-A3), W is COOH or a salt thereof.

[0143] In some embodiments of formula (IV-A1), R a and R b are each F, and W is -P=O(OH)2or a salt thereof. In some embodiments of formula (IV-A1), R a and R b are each H, and W is -P=O(OH)2or a salt thereof. In some embodiments of formula (IV-A1), R a is F, R b is H, and W is -P=O(OH)2or a salt thereof.

[0144] In some embodiments of formula (IV-1) to (IV-3), Z 2 is attached to the anomeric position of the pyranose ring having a beta configuration. The inventors have demonstrated that compounds comprising M6PR binding moieties having a beta -glycosidic configuration can have at least equivalent binding and / or cellular uptake activity compared to conjugates having the corresponding alpha-glycosidic configuration. In some embodiments, such M6PR binding moieties having a beta-glycosidic configuration can improve stability compared to reference compounds having a beta-glycosidic configuration. Accordingly, in some embodiments of formula (IV), the M6PR binding moiety (X) is described by one of formula (IV-B1) to (IV-B3):

[0145]

[0146] where R a 、R b 、R c and R d are independently H or F.

[0147] In some embodiments of Formulas (IV-B1) to (IV-B3), Z 2 is S. In some embodiments of Formulas (IV-B1) to (IV-B3), Z 2 is O. In some embodiments of Formulas (IV-B1) to (IV-B3), Z 2 In some embodiments of formulas (IV-B1) to (IV-B3), Z 2 It is -CF2-.

[0148] In some embodiments of Formulas (IV-B1) and (IV-B3), W is selected from -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH or salts thereof.

[0149] In some embodiments of formula (IV-B1) and (IV-B3), W is selected from –P=O(OH)2, –P=S(OH)2, –P=O(SH)(OH), –P=S(SH)(OH), and –COOH, or a salt thereof. In some embodiments of formula (IV-B1) and (IV-B3), W is –P=O(OH)2 or a salt thereof. In some embodiments of formula (IV-B1) and (IV-B3), W is COOH or a salt thereof.

[0150] In some embodiments of Formula (IV-B1), R a and R b Each is F, and W is -P=O(OH)2 or a salt thereof. In some embodiments of Formula (IV-B1), R a and R b Each is H, and W is -P=O(OH)2 or a salt thereof. In some embodiments of Formula (IV-B1), R a F, R b is H, and W is -P=O(OH)2 or a salt thereof.

[0151] The inventors have demonstrated that conjugates comprising an M6PR binding moiety having a β-S-glycosidic configuration can have at least equivalent or higher binding and / or cellular uptake activity than conjugates having the corresponding α-S-glycosidic configuration or conjugates having an α-O-glycosidic configuration. Figure 19 .

[0152] Thus, in some embodiments of formula (IV-B1) to (IV-B3), the M6PR binding moiety (X) is described by one of formulae (IV-BS1) to (IV-BS3):

[0153]

[0154] wherein R a , R b , R c , and R d are independently H or F.

[0155] In some embodiments of formula (IV-BS1) to (IV-BS3), R a , R b , R c , and R d are each H.

[0156] In some embodiments of formula (IV-BS1), R a is H and R b is F. In some embodiments of formula (IV-BS1), R a and R b are each F.

[0157] In some embodiments of formula (IV-BS2), R c is H. In some embodiments of formula (IV-B2), R c is F.

[0158] In some embodiments of formula (IV-BS3), R d is H. In some embodiments of formula (IV-BS3), R d is F.

[0159] In some embodiments of formula (IV-BS1) to (IV-BS3), Z 2 is S. In some embodiments of formula (IV-BS1) to (IV-BS3), Z 2 is O. In some embodiments of formula (IV-BS1) to (IV-BS3), Z 2 is -CH2-. In some embodiments of formula (IV-BS1) to (IV-BS3), Z 2 is -CF2-.

[0160] In some embodiments of formula (IV-BS1) and (IV-BS3), W is selected from P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH, or a salt thereof. In some embodiments of formula (IV-BS1) and (IV-BS3), W is -P=O(OH)2, or a salt thereof. In some embodiments of formula (IV-BS1) and (IV-BS3), W is COOH, or a salt thereof.

[0161] In some embodiments of formula (IV-BS1), R a and R b are each F, and W is -P=O(OH)2, or a salt thereof. In some embodiments of formula (IV-BS1), R a and R b are each H, and W is -P=O(OH)2, or a salt thereof. In some embodiments of formula (IV-BS1), R a is F, R b is H, and W is -P=O(OH)2, or a salt thereof.

[0162] In some embodiments, a mannose ring or an analog thereof of an M6PR binding moiety can be incorporated into a compound of the disclosure through linkage of the linkage moiety to a Z 2 group linked at the anomeric or 1 position of the sugar ring.

[0163] In some embodiments, an M6PR binding moiety is incorporated into a compound of the disclosure through linkage of the linkage moiety to a Z 3 group linked to a cyclic group A. It will be appreciated that in a compound of formula (III), the cyclic group linked to Z 2 may be considered to be part of the M6PR binding moiety (X) and to achieve the desired binding properties for M6PR.

[0164] 4.2.2. Cyclic Group A

[0165] Cyclic group A of formula (III) to (XIII) can be a monocyclic or bicyclic group. Bicyclic groups of interest can be fused bicyclic groups or bicyclic groups containing two monocyclic rings connected via covalent bonds. Cyclic group A of formula (III) to (XIII) can be an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocycle (e.g., a saturated heterocycle), or an optionally substituted cycloalkyl.

[0166] The cyclic group A of formula (III)-(XIII) can be a monocyclic aryl or monocyclic heteroaryl group. In some embodiments of formula (III)-(XIII), A is a 5-membered monocyclic heteroaryl group. In some embodiments of formula (III)-(XIII), A is a 6-membered monocyclic aryl or heteroaryl group. In some embodiments of formula (III)-(XIII), A can be a polycyclic aryl or polycyclic heteroaryl group, such as a bicyclic aryl or bicyclic heteroaryl group. In some embodiments of formula (III)-(XIII), A is a fused bicyclic group. In some embodiments of formula (III)-(XIII), A is a bicyclic group comprising two aryl and / or heteroaryl monocycles connected via covalent bonds. In some embodiments of formula (III)-(XIII), A is a bicyclic aryl or bicyclic heteroaryl group having two 6-membered rings. In some embodiments of formula (III)-(XIII), A is a bicyclic aryl or bicyclic heteroaryl group having one 6-membered ring connected or fused to a 5-membered ring via covalent bonds.

[0167] In some embodiments of formula (III)-(XIII), A is selected from optionally substituted phenyl, optionally substituted pyridyl, optionally substituted biphenyl, optionally substituted naphthalene, optionally substituted quinoline, optionally substituted triazole, and optionally substituted phenylene triazole.

[0168] In some embodiments of formula (III)-(XIII), A is not phenyl (also referred to as phenylene in the context of formula (III), e.g., 1,4-phenylene).

[0169] In some embodiments of formula (III)-(XIII), A is substituted with at least one OH substituent. In some embodiments of formula (III)-(XIII), A is substituted with 1, 2, or more OH groups. In some embodiments of formula (III)-(XIII), A is substituted with at least one optionally substituted (Ci-C6)alkyl group.

[0170] In some embodiments of formula (III)-(XIII), A is optionally substituted 1,4-phenylene, optionally substituted 1,3-phenylene, or optionally substituted 2,5-pyridyl.

[0171] In some embodiments of formula (III)-(XIII), A is selected from:

[0172]

[0173] wherein:

[0174] R 11 to R 14independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR 25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ;and

[0175] R 25 are independently selected from H and optionally substituted (C1-C6)alkyl.

[0176] In some embodiments of Formulas (III) through (XIII), A is optionally substituted fused bicyclic aryl or optionally substituted fused bicyclic heteroaryl.

[0177] In some embodiments of Formulas (III) to (XIII), A is optionally substituted naphthalene or is optionally substituted quinoline.

[0178] In some embodiments of Formulas (III) to (XIII), A is selected from:

[0179]

[0180] in:

[0181] R 11 and R 13 to R 14 independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR 25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ;

[0182] s is 0 to 3; and

[0183] Each R 25 are independently selected from H and optionally substituted (C1-C6)alkyl.

[0184] In some embodiments of Formulas (III) to (XIII), A is selected from:

[0185]

[0186]

[0187] In some embodiments of formula (III)-(XIII), A is an optionally substituted bicyclic aryl or an optionally substituted bicyclic heteroaryl of the formula:

[0188]

[0189] or a salt thereof, wherein:

[0190] Cy is independently a monocyclic aryl or a monocyclic heteroaryl;

[0191] R 11 to R 15 are independently selected from H, halogen, OH, optionally substituted (Ci-C6)alkyl, optionally substituted (Ci-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 , and -NHCOR 25 ;

[0192] s is 0 to 4; and

[0193] each R 25 is independently selected from H and optionally substituted (Ci-C6)alkyl.

[0194] In some embodiments, when Cy is an optionally substituted phenyl, then A is an optionally substituted biphenyl of the formula:

[0195]

[0196] In some embodiments of formula (III)-(XIII), A is selected from:

[0197]

[0198] In some embodiments, when Cy is a triazole, then A is selected from:

[0199]

[0200] In some embodiments, at least one of R 11 to R 15 is OH (e.g., at least two are OH).

[0201] In some embodiments, each of R 11 to R 15 is H.

[0202] 4.2.3. Linker Moieties Z 3

[0203] Linker moieties Z 3may be any convenient linking moiety that connects linker L to ring A. In some embodiments of formula (III)-(XIII), Z 3 has a main chain of 3 or fewer atoms.

[0204] In some embodiments of formula (III)-(XIII), Z 3 is selected from a covalent bond, -O-, 23 -NR 23 CO-, -CONR 23 -, 23 CO2-, -OCONR 23 -, 23 C(=X 1 )NR 23 -, 24 = N-, -CR 24 = N-X 2 -, 23 )SO2- and -SO2N(R 23 )-; wherein X 1 and X 2 are selected from O, S and NR 23 ; and R 23 and R 24 are independently selected from H, C (1-3) -alkyl (e.g., methyl) and substituted C (1-3) -alkyl.

[0205] In some embodiments of formula (III)-(XIII), Z 3 is a covalent bond that connects A to L.

[0206] In some embodiments of formula (III)-(XIII), Z 3 is an optionally substituted amido, urea or thiourea.

[0207] In some embodiments of formula (III)-(XIII), Z 3 is

[0208]

[0209] wherein:

[0210] X 1 is O or S;

[0211] t is 0 or 1; and

[0212] each R 23 is independently selected from H, C (1-3) -alkyl (e.g., methyl or ethyl) and substituted C (1-3) -alkyl. In Z3 In some embodiments, X 1 For O. In Z 3 In some embodiments, X 1 For S. In Z 3 In some embodiments, t is 0, and X 1 is O, so that Z 3 is an amide group. 3 In some embodiments, t is 1, so that Z 3 For urea or thiourea.

[0213] In some embodiments of Formulas (III) to (XIII), Z 3 -N(R 23 )SO2- or -SO2N(R 23 )-. In some embodiments of formulas (III) to (XIII), Z 3 It is -NHSO2- or -SO2NH-.

[0214] In some embodiments of Formulas (III) to (XIII), Z 3 -N(R 23 )CO-or-CON(R 23 )-. In some embodiments of formulas (III) to (XIII), Z 3 It is -NHCO- or -CONH-.

[0215] In some embodiments of Formulas (III) to (XIII), Z 3 -NHC(=X 1 )NH-, where X 1 is O or S. In some embodiments, X 1 is O (ie, Z 3 is -NHC(=O)NH-). In some embodiments, X 1 For S.

[0216] In some embodiments of Formulas (III) to (XIII), Z 3 is an optionally substituted triazole. 3 In the case of an optionally substituted triazole, it can be obtained synthetically from the click chemistry conjugation of an azide-containing precursor and an alkyne-containing precursor of the compound.

[0217] In some embodiments, Z 3 With the cyclic group A and / or the linking part Z 1 The combinatorial selection was performed to provide X with the desired M6PR binding and internalization properties.

[0218] In some embodiments of Formulas (III) to (XIII), -AZ 3- is selected from:

[0219]

[0220]

[0221] In some embodiments of formula (III)-(XIII), -A-Z 3 - is selected from:

[0222]

[0223] In some embodiments of formula (III)-(XIII), -A-Z 3 - is selected from:

[0224] In some embodiments of formula (II)-(XIb), -A-Z 3 - is selected from:

[0225] In some embodiments of formula (III)-(XIII), -A-Z 3 - is selected from:

[0226]

[0227]

[0228] In some embodiments of formula (III)-(XIII), Z 2 is O.

[0229] In some embodiments of formula (III)-(XIII), Z 2 is S.

[0230] In some embodiments of formula (III)-(XIII), Z 2 is -NR 21 -.

[0231] In some embodiments of formula (III)-(XIII), Z 2 is -C(R 22 )2-, wherein each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl. In some embodiments, Z 2 is -CH2-. In some embodiments, Z 2 is -CHF-. In some embodiments, Z 2 is -CF2-.

[0232] In some embodiments of formula (III)-(XIII), Z 2 - A-Z 3 - is:

[0233]

[0234] wherein:

[0235] Z 21 is O, S, or -C(R 22 )2-;

[0236] R 16 is OH or CH3; and

[0237] w is 0-4 (e.g., w is 0, 1, or 2).

[0238] In some embodiments, Z 21 is S or O. In some embodiments, Z 21 is -CH2-. In some embodiments, Z 21 is -CHF-. In some embodiments, Z 21 is -CF2-. In some embodiments, R 16 is OH and w is 1. In some embodiments, R 16 is CH3and w is 1. In some embodiments, w is 0.

[0239] In some embodiments of formula (III)-(XIII), -Z 2 - A-Z 3 - is:

[0240]

[0241] In some embodiments of formula (III)-(XII), -Z 2 - A-Z 3 - is:

[0242]

[0243] In some embodiments of formula (III)-(XIII), -Z 2 - A-Z 3 - is:

[0244]

[0245] In some embodiments of formula (III)-(XIII), -Z 2 - A-Z 3 - is:

[0246]

[0247] In some embodiments of formula (III)-(XIII), -Z 2 -A-Z 3 - is

[0248]

[0249] In some embodiments of formula (III)-(XIII), -Z 2 -A-Z 3 - is

[0250]

[0251] 4.2.4. Exemplary M6PR Ligands

[0252] Exemplary M6PR binding moieties X of formula (I)-(XIII) useful in the preparation of compounds and conjugates of the disclosure are shown in Table 1.

[0253]

[0254]

[0255]

[0256]

[0257]

[0258] Exemplary synthons or synthetic precursors useful in the preparation of compounds of the disclosure incorporating a desired M6PR binding moiety of interest are shown in Table 2. It will be appreciated that alternative synthons, including homologues and analogues of those shown in Table 2, are possible depending on the M6PR binding moiety and linker selected. It will be appreciated that the synthons of Table 2 can include structural precursors of the linking moiety Z 3 and structural elements that become part of the linker (L) in the compounds and conjugates of the disclosure. It will be appreciated that based on the exemplary synthetic precursors of Table 2, synthons corresponding to any of the binding moieties of Table 1 can be utilized to prepare compounds of the disclosure.

[0259]

[0260]

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267]

[0268] Other M6PR binding moieties of interest and their synones or synthetic precursors are shown in Table 3. X101-X103 show compounds with phosphate or phosphorothioate head groups. X109-X110 show exemplary compounds of Formula (V). In some embodiments, such M6PR binding moieties are used in reference compounds to assess compounds of Formula (XII).

[0269]

[0270]

[0271] 4.2.5. Disaccharides containing M6PR binding moieties

[0272] Various aspects of the present disclosure include compounds and conjugates of Formula (I) in which the M6PR binding moiety comprises a specific dimannose structure having a first pyranose ring (e.g., of Formula (II)) connected to a second 2,5-linked pyranose ring, which is further connected to a linker.

[0273] Figure 20 Selective cellular uptake activity is shown demonstrating a comparison between conjugates of compounds of Formula (III) and compounds having specific dimannose M6PR binding moieties. Conjugates of M6PR binding compounds 660 or 659 show comparable activity to conjugates of conjugates of compound 520 (I-7), each having a dimannose structure with a 2,5-linked pyranose ring connected to a linker.

[0274] Accordingly, various aspects of the present disclosure include cell surface M6PR binding compounds of Formula (XV):

[0275]

[0276] or a prodrug or salt thereof, wherein:

[0277] W is a non-hydrolysable hydrophilic head group;

[0278] Z 1 selected from optionally substituted (Ci-C3)alkylene and optionally substituted vinylene;

[0279] Z 4 selected from -Z 14 - and -Z 14 - A-, -A-, and -CH2-Z 14 -,

[0280] Z 14 selected from O, S, NR 21 and C(R 22 )2, wherein R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl;

[0281] A is an optionally substituted cyclic group (e.g., optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocycle, optionally substituted cycloalkyl);

[0282] n is 1 to 500;

[0283] m is 1 to 500;

[0284] L is a linker; and

[0285] Y is a moiety of interest.

[0286] In some embodiments of Formula (XV), Z4is -CH2-Z 14 -, 14 selected from O, S, NR 21 and C(R 22 )2.

[0287] In some embodiments of Formula (XV), Z 4 is -CH2-A-.

[0288] In some embodiments of Formula (XV), Z 4 is -A-.

[0289] In some embodiments of Formula (XV), A is a cyclic group (e.g., optionally substituted aryl or optionally substituted heteroaryl, e.g., as described above for Formula (III)). In some embodiments of Formula (XV), A is a cyclic group as defined above in Formula (III).

[0290] In some embodiments of Formula (XV), A is a triazole.

[0291] In some embodiments of Formula (XV), Z 4 is wherein “*” indicates attachment to linker L.

[0292] M6PR binding moieties of Formula (XV) can be useful in the various compounds and conjugates described herein.

[0293] In some embodiments of Formula (XV), m is 1 to 100, such as 1 to 5, 5 to 10, 10 to 20, 10 to 100, 20 to 80, or 20 to 50. In some embodiments of Formula (XV), m is 1, 2, 3, 4, or 5.

[0294] 4.2.6. Prodrugs

[0295] Various aspects of the present disclosure include prodrugs of any of the M6PR binding moieties described herein, which are incorporated into the compounds and conjugates of the present disclosure.

[0296] The term "prodrug" refers to an agent that is converted into a drug in vivo by some process (e.g., a prodrug is converted into the desired drug form upon reaching physiological pH).

[0297] Prodrug forms of any of the M6PR binding moieties described herein can be useful because, for example, particular therapeutic benefits can result from, for example, extending the half-life of the resulting compound or conjugate in the body or reducing the amount of active agent required.

[0298] Prodrugs can also be useful in some cases because they can be easier to administer than the parent drug. For example, a prodrug can be bioavailable by oral administration whereas the parent drug is not. The solubility of a prodrug in a pharmacological composition can also have been enhanced compared to the parent drug.

[0299] Prodrug derivatives of M6PR binding moieties typically comprise a precursor moiety substituent at a suitable labile site of the compound (e.g., a hydroxyl group of the pyranose ring of Formula (II)). A precursor moiety refers to a group that is removed by an enzymatic or chemical reaction when the prodrug is converted into the drug in vivo. For example, the precursor moiety can be an optionally substituted alkylacyl group attached to a hydroxyl group of the compound via an ester linkage. An exemplary alkylacyl precursor moiety group includes acetyl. In some embodiments, a prodrug derivative of one or more of the hydroxyl groups of the pyranose ring can be incorporated into the compound. For example, an ester precursor moiety can be incorporated at one or more of the hydroxyl groups at the 2, 3, and / or 4 positions of the sugar ring.

[0300] In some embodiments, a prodrug derivative of the hydrophilic head group (W) can be incorporated into the M6PR binding moieties and compounds of the present disclosure. For example, an ester precursor moiety can be incorporated onto a phosphonate or thiophosphonate head group, or an ester precursor moiety can be incorporated onto a carboxylic acid or malonic acid head group.

[0301] 4.3. Linkers

[0302] The terms“linker,”“linking moiety,” and“linking group” are used interchangeably and refer to a linking moiety that covalently links two or more moieties or compounds, such as a M6PR binding moiety and other moieties of interest. In some cases, a linker is divalent and links two moieties. In certain cases, a linker is a trivalent or higher multivalent branched linking group. In some cases, a linker linking two or more moieties has a linear or branched backbone of 500 atoms or fewer in length (e.g., 400 atoms or fewer, 300 atoms or fewer, 200 atoms or fewer, 100 atoms or fewer, 80 atoms or fewer, 60 atoms or fewer, 50 atoms or fewer, 40 atoms or fewer, 30 atoms or fewer, or even 20 atoms or fewer), e.g., as measured between the two or more moieties. A linking moiety can be a covalent bond linking two groups, or a straight chain or branched chain of between 1 and 500 atoms in length, e.g., about 1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 30, 40, 50, 100, 150, 200, 300, 400, or 500 carbon atoms in length, where the linker can be linear, branched, cyclic, or a single atom. In certain cases, one, two, three, four, five or more, ten or more, or even more carbon atoms of the linker backbone are optionally substituted with a heteroatom (e.g., a sulfur, nitrogen, or oxygen heteroatom). In certain cases, when the linker comprises a PEG group, every third atom of this segment of the linker backbone is substituted with an oxygen. The bonds between the backbone atoms can be saturated or unsaturated, typically there are no more than one, two, or three unsaturated bonds in the linker backbone. The linker can comprise one or more substituent groups, e.g., alkyl, aryl, or alkenyl groups. The linker can include, but is not limited to, one or more of the following: oligo(ethylene glycol), ether, thioether, disulfide, amide, carbonate, carbamate, tertiary amine, alkyl groups which can be linear or branched, e.g., methyl, ethyl, n-propyl, 1-methylethyl (isopropyl), n-butyl, n-pentyl, 1,1-dimethylethyl (tert-butyl), and the like. The linker backbone can comprise a cyclic group, e.g., an aryl, heterocyclic, cycloalkyl, or heterocyclic group, where 2 or more atoms (e.g., 2, 3, or 4 atoms) of the cyclic group are included in the backbone.

[0303] In some embodiments, a "linker" or linking moiety is derived from a molecule having two reactive ends, one for conjugation to a moiety of interest (Y), e.g., a biomolecule (e.g., an antibody), and the other for conjugation to a moiety that binds to a cell surface M6PR (denoted X). When Y is a polypeptide, the polypeptide conjugation reactive end of the linker is in some cases a site that is capable of conjugation to the polypeptide through a cysteine thiol or lysine amine group on the polypeptide, and thus can be a thiol-reactive group such as a maleimide or dibromomaleimide, or as defined herein, or an amine-reactive group such as an active ester (e.g., pentafluorophenyl ester or tetrafluorophenyl ester or NHS ester), or as defined herein.

[0304] In certain embodiments of the formulas described herein, linker L comprises one or more straight or branched carbon moieties and / or polyether (e.g., repeating units of -CH2CH2O-) moieties and combinations thereof. In certain embodiments, these linkers optionally have amide bonds, urea or thiourea bonds, carbamate bonds, ester bonds, amino bonds, ether bonds, sulfide bonds, sulfhydryl bonds, or other hetero-functional bonds. In certain embodiments, the linker comprises one or more of carbon atoms, nitrogen atoms, sulfur atoms, oxygen atoms, and combinations thereof. In certain embodiments, the linker comprises one or more of ether bonds, sulfide bonds, amine bonds, amide bonds, carbon-carbon bonds, carbon-nitrogen bonds, carbon-oxygen bonds, carbon-sulfur bonds, and combinations thereof. In certain embodiments, the linker comprises a straight chain structure. In certain embodiments, the linker comprises a branched chain structure. In certain embodiments, the linker comprises a cyclic structure.

[0305] In certain embodiments, L has a length of between about and In certain embodiments, L has a length of between about and In certain embodiments, L has a length of about In certain embodiments, L has a length of about In certain embodiments, L has a length of about

[0306] In certain embodiments, L is a linker between about and about In certain embodiments, L is between about and about In certain embodiments, L is between about and about In certain embodiments, L is between about and about In certain embodiments, L is between about and about In certain embodiments, L is between about and between, between and between, between With between, between With between, between With between, between With between, between With between, between With between or about With In certain embodiments, L is between about With A linker between , which comprises an optionally substituted arylene group connected to the cell surface M6PR binding portion (X), an optionally substituted heteroarylene group connected to X, an optionally substituted heterocycloalkene group connected to X, or an optionally substituted cycloalkylene group connected to X. In certain embodiments, L is between about With A linker between 1 and 2, comprising an optionally substituted arylene group connected to X, an optionally substituted heteroarylene group connected to X, an optionally substituted heterocyclenyl group connected to X, or an optionally substituted cycloalkylene group connected to X. In certain embodiments, L is between about With A linker between 1 and 2, comprising an optionally substituted arylene group connected to X, an optionally substituted heteroarylene group connected to X, an optionally substituted heterocyclenyl group connected to X, or an optionally substituted cycloalkylene group connected to X. In certain embodiments, L is between about With A linker between , which comprises an optionally substituted arylene group connected to X, an optionally substituted heteroarylene group connected to X, an optionally substituted heterocycloalkene group connected to X, or an optionally substituted cycloalkylene group connected to X.

[0307] In certain embodiments, L separates the cell surface M6PR binding moiety (Y) and Y (or Z) by a backbone comprising at least 10 contiguous atoms. In certain cases, the backbone is at least 12 contiguous atoms. In certain cases, the backbone is at least 14 contiguous atoms. In certain cases, the backbone is at least 16 contiguous atoms. In certain cases, the backbone is at least 18 contiguous atoms. In certain cases, the backbone is at least 20 contiguous atoms. In certain cases, the backbone is at least 22 contiguous atoms. In certain cases, the backbone is at least 24 contiguous atoms. In certain cases, the backbone is at least 26 contiguous atoms. In certain cases, the backbone is at least 28 contiguous atoms. In certain cases, the backbone is at least 30 contiguous atoms. In certain cases, the backbone is at least 32 contiguous atoms. In certain cases, the backbone is at least 34 contiguous atoms. In certain cases, the backbone is at least 36 contiguous atoms. In certain cases, the backbone is at least 38 contiguous atoms. In certain cases, the backbone is at least 40 contiguous atoms. In certain cases, the backbone is at most 50 contiguous atoms. In certain cases, the backbone is at most 60 contiguous atoms. In certain cases, the backbone is at most 70 contiguous atoms. In certain cases, the backbone is at most 80 contiguous atoms. In certain cases, the backbone is at most 90 contiguous atoms. In certain cases, the backbone is at most 100 contiguous atoms.

[0308] In certain embodiments, linker L separates cell surface M6PR binding moiety (X) and Y (or Z) by a chain of 4 to 500 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 4 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 6 to 50 contiguous atoms, by a chain of 11 to 50 contiguous atoms, by a chain of 16 to 50 contiguous atoms, by a chain of 21 to 50 contiguous atoms, by a chain of 26 to 50 contiguous atoms, by a chain of 31 to 50 contiguous atoms, by a chain of 36 to 50 contiguous atoms, by a chain of 41 to 50 contiguous atoms, or by a chain of 46 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 6 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 11 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 16 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 21 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 26 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 31 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 36 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 41 to 50 contiguous atoms. In certain embodiments, linker L separates X and Y (or Z) by a chain of 46 to 50 contiguous atoms.

[0309] In certain embodiments, linker L separates X and Y (or Z) by a chain of 4 or 5 contiguous atoms, by a chain of 6 to 10 contiguous atoms, by a chain of 11 to 15 contiguous atoms, by a chain of 16 to 20 contiguous atoms, by a chain of 21 to 25 contiguous atoms, by a chain of 26 to 30 contiguous atoms, by a chain of 31 to 35 contiguous atoms, by a chain of 36 to 40 contiguous atoms, by a chain of 41 to 45 contiguous atoms, or by a chain of 46 to 50 contiguous atoms.

[0310] In certain embodiments, linker L separates X and Y (or Z) by a chain of 50 or 55 contiguous atoms, by a chain of 56 to 60 contiguous atoms, by a chain of 61 to 65 contiguous atoms, by a chain of 66 to 70 contiguous atoms, by a chain of 71 to 75 contiguous atoms, by a chain of 76 to 80 contiguous atoms, by a chain of 81 to 85 contiguous atoms, by a chain of 86 to 90 contiguous atoms, by a chain of 91 to 95 contiguous atoms, or by a chain of 96 to 100 contiguous atoms.

[0311] In certain embodiments, linker L is a chain of 5 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted arylene connected to X, an optionally substituted heteroarylene connected to X, an optionally substituted heterocycloalkene connected to X, or an optionally substituted cycloalkylene connected to X. In certain embodiments, linker L is a chain of 7 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted arylene connected to X, an optionally substituted heteroarylene connected to X, an optionally substituted heterocycloalkene connected to X, or an optionally substituted cycloalkylene connected to X. In certain embodiments, linker L is a chain of 10 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted arylene connected to X, an optionally substituted heteroarylene connected to X, an optionally substituted heterocycloalkene connected to X, or an optionally substituted cycloalkylene connected to X. In certain embodiments, linker L is a chain of 15 to 400 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted arylene connected to X, an optionally substituted heteroarylene connected to X, an optionally substituted heterocycloalkene connected to X, or an optionally substituted cycloalkylene connected to X.

[0312] In certain embodiments, linker L is a chain of 5 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an arylene connected to X or an optionally substituted heteroarylene connected to X. In certain embodiments, linker L is a chain of 7 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an arylene connected to X or an optionally substituted heteroarylene connected to X. In certain embodiments, linker L is a chain of 10 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an arylene connected to X or an optionally substituted heteroarylene connected to X. In certain embodiments, linker L is a chain of 15 to 400 contiguous atoms separating X and Y (or Z), and the linker comprises an arylene connected to X or an optionally substituted heteroarylene connected to X.

[0313] In certain embodiments, linker L is a chain of 5 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted phenylene connected to X. In certain embodiments, linker L is a chain of 7 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted phenylene connected to X. In certain embodiments, linker L is a chain of 10 to 500 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted phenylene connected to X. In certain embodiments, linker L is a chain of 15 to 400 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted phenylene connected to X.

[0314] In certain embodiments, linker L is a chain of 16 to 400 contiguous atoms separating X and Y (or Z), and the linker comprises an optionally substituted arylene group attached to X, an optionally substituted heteroarylene group attached to X, an optionally substituted heterocycloalkene attached to X, or an optionally substituted cycloalkylene group attached to X.

[0315] It will be appreciated that the linker can be considered to be directly attached to the Z 3 or Z 4 group of the M6PR binding moiety (X) (e.g., as described herein). In some embodiments of Formula (III) or (V), the linker can be considered to be directly attached to the Z 3 or Z 4 group. Alternatively, the -Z 3 -L 1 - group or -Z 4 -L 1 - of the linker (e.g., as described herein) can be considered to be part of the linking moiety connecting Z 3 or Z 4 to Y. The disclosure is intended to encompass all such configurations of the M6PR binding moiety (X) and linker (L).

[0316] In some embodiments of Formula (XI) to (XIII), L is a linker of Formula (VII):

[0317]

[0318] wherein

[0319] L 1 and L 3 are independently linkers, and L 2 is a branched linking moiety, wherein L 1 to L 3 together provide a linear or branched linker between X and Y;

[0320] a, b, and c are independently 0 or 1;

[0321] ** indicates the point of attachment of X to L 1 via Z 1 ; and

[0322] *** indicates the point of attachment to Y;

[0323] wherein:

[0324] when n is 1, a is 1, and b is 0;

[0325] when n is >1, a is 1, and b is 1.

[0326] In certain embodiments of the linker of Formula (VII), L 1to L 3 each independently comprises one or more linking moieties independently selected from the group consisting of -C 1-20 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -NH C 1-6 -alkylene-, -NHCONH-C 1-6 -alkylene-, -NHCSNH-C 1-6 -alkylene-, -C 1-6 -alkylene-NHCO-, -C 1-6 -alkylene-CONH-, -C 1-6 -alkylene-NH-, - 1-6 -alkylene-NHCONH-, -C 1-6 -alkylene-NHCSNH-, -O(CH2) p -, -(OCH2CH2) p -, -NHCO-, -CONH-, -NHSO2-, -SO2NH-, -CO-, -SO2-, -O-, -S-, monocyclic heteroaryl (e.g., 1,2,3-triazole), monocyclic aryl (e.g., phenyl, e.g., 1,4-linked phenyl or 1,3-linked phenyl), monocyclic heterocycle (e.g., a pyrrolidine-2,5-dione, piperazine, or piperidine ring described herein), an amino acid residue (naturally or non-naturally occurring), -NH-, and -NMe-, wherein each p is independently 1 to 50.

[0327] In certain embodiments of the linker of Formula (VII), L 1 to L 3 Any one of -CH2CH2O- or -OCH2CH2-. In certain instances, the linker of Formula (VII) comprises 1 to 25 ethylene glycol moieties, such as 3 to 25, 5 to 25, 7 to 25, 10 to 25, 15 to 25, 17 to 25, 20 to 25, or 22 to 25 ethylene glycol moieties. In some instances, the linker of Formula (VII) comprises 3 or more ethylene glycol moieties, such as 5 or more, 7 or more, 10 or more, 15 or more, 20 or more, or even more ethylene glycol moieties.

[0328] In certain embodiments of the linker of Formula (VII), L 1 to L 3 Any one of -CH2CH2O- or -OCH2CH2-. In certain instances, the linker of Formula (VII) comprises 1 to 25 ethylene glycol moieties, such as 3 to 25, 5 to 25, 7 to 25, 10 to 25, 15 to 25, 17 to 25, 20 to 25, or 22 to 25 ethylene glycol moieties. In some instances, the linker of Formula (VII) comprises 3 or more ethylene glycol moieties, such as 5 or more, 7 or more, 10 or more, 15 or more, 20 or more, or even more ethylene glycol moieties.

[0329] wherein w1, u1, and q1 are independently 1 to 25 (e.g., 1 to 12, such as 1 to 6).

[0330] In certain embodiments of the linker of Formula (VII), n is 1, such that b is 0, and the linker has Formula (VIIa):

[0331]

[0332] wherein

[0333] L 1 and L 3 are independently linkers (e.g., as described herein), wherein L 1 together provide a straight linker between X and Y; 3

[0334] a is 1;

[0335] c is 0 or 1;

[0336] ** indicates a point of attachment of X via Z 1 to L 1 ; and

[0337] *** indicates a point of attachment to Y.

[0338] In certain embodiments of the linker of Formula (VIIa), the straight linker has a backbone of 20 or more contiguous atoms (such as 25 or more contiguous atoms or 30 or more contiguous atoms, and in some cases, up to 100 contiguous atoms) covalently connecting X and Y via Z 1 . In certain embodiments of Formula (VIIa), the straight linker separates X and Y (or Z 1 ) by a chain of 20 to 50 contiguous atoms. In certain embodiments, the straight linker separates X and Y (or Z 1 ) by a chain consisting of 21 to 50 contiguous atoms, by a chain consisting of 22 to 50 contiguous atoms, by a chain consisting of 23 to 50 contiguous atoms, by a chain consisting of 24 to 50 contiguous atoms, by a chain consisting of 25 to 50 contiguous atoms, by a chain consisting of 26 to 50 contiguous atoms, by a chain consisting of 27 to 50 contiguous atoms, by a chain consisting of 28 to 50 contiguous atoms, or by a chain consisting of 29 to 50 contiguous atoms. In certain embodiments of Formula (VIIa), the straight linker separates X and Y (or Z 1 ) by a chain of 30 to 60 contiguous atoms. In certain embodiments, the straight linker separates X and Y (or Z​1 ) are separated. In certain embodiments, a straight linker connects X and Y (or Z) by a chain consisting of 32 to 60 consecutive atoms. 1 ) are separated. In certain embodiments, a linear linker connects X and Y (or Z) by a chain consisting of 33 to 60 consecutive atoms. 1 ) are separated. In certain embodiments, a straight linker connects X and Y (or Z) by a chain consisting of 34 to 60 consecutive atoms. 1 ) are separated. In certain embodiments, a straight linker connects X and Y (or Z) by a chain consisting of 35 to 50 consecutive atoms. 1 ) are separated. In certain embodiments, a linear linker connects X and Y (or Z) by a chain consisting of 36 to 50 consecutive atoms. 1 ) are separated. In certain embodiments, a straight linker connects X and Y (or Z) by a chain consisting of 41 to 50 consecutive atoms. 1 ) are separated. In certain embodiments, a straight linker connects X and Y (or Z) by a chain consisting of 46 to 50 consecutive atoms. 1 ) separated by .

[0339] In certain other embodiments of Formula (VII), n is 2 or greater, such that L 1 To L 3 Together, a branch joint is provided between X and Y.

[0340] In certain embodiments of Formula (VII), n is 2 or greater, and L 2 Selected from:

[0341]

[0342] wherein each x and y is independently 1 to 10.

[0343] In certain embodiments of Formula (VII), L 1 To L 2 Contains a backbone consisting of 14 or more consecutive atoms between X and the branching atoms, such as 14 to 50, 14 to 40, 14 to 35, or 14 to 30 consecutive atoms between X and the branching atoms.

[0344] In certain embodiments of Formula (VII) or (VIIa), L 3 A backbone comprising 10 to 80 consecutive atoms, such as 12 to 70, 12 to 60 or 12 to 50 consecutive atoms.

[0345] In certain embodiments of Formula (VII) or (VIIa), wherein L 3 comprising a linking moiety selected from the group consisting of: (C 10 -C 20 -alkylene (e.g., C12 -alkylene) or -(OCH2CH2) p wherein p is 1 to 25, such as 3 to 25, 5 to 24, 7 to 25, 10 to 25, 15 to 25, or 20 to 24.

[0346] In certain embodiments, L is of Formula (VIIb):

[0347]

[0348] wherein each L 1 to L 5 are independently linking moieties that together provide a linear or branched linker between Z 1 and Y; a, b, c, d, and e are each independently 0, 1, or 2;

[0349] ** indicates the point of attachment of X via Z 1 to L 1 ; and

[0350] *** indicates the point of attachment to Y;

[0351] wherein:

[0352] when n is 1, a is 1, and c is 0; and

[0353] when n is >1, a is 1, and c is 1.

[0354] In certain embodiments of the linker of Formula (VIIb), L 1 to L 5 each independently comprises one or more linking moieties independently selected from the group consisting of: -C 1-20 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -NH C 1-6 -alkylene-, -NHCONH-C 1-6 -alkylene-, -NHCSNH-C 1-6 -alkylene-, -C 1-6 -alkylene-NHCO-, -C 1-6 -alkylene-CONH-, -C 1-6 -alkylene-NH-, -C 1-6 -alkylene-NHCONH-, -C 1-6 -alkylene-NHCSNH-, -O(CH2) p -, -(OCH2CH2) p-, -NHCO-, -CONH-, -NHSO2-, -SO2NH-, -CO-, -SO2-, -O-, -S-, monocyclic heteroaryl (e.g., 1,2,3-triazole), monocyclic aryl (e.g., phenyl, e.g., 1,4-linked phenyl or 1,3-linked phenyl), monocyclic heterocycle (e.g., a pyrrolidine-2,5-dione, piperazine, or piperidine ring as described herein), an amino acid residue (naturally or non-naturally occurring), -NH-, and -NMe-, wherein each p is independently 1 to 50.

[0355] In certain embodiments of Formula (VIIb), -(L 1 ) a comprises an optionally substituted alkylene- or ethylene glycol linking moiety. In certain instances, L 1 comprises an optionally substituted -C 1-6 -alkylene-. In certain instances, L 1 comprises an ethylene glycol linking moiety.

[0356] In certain embodiments of Formula (VIIb), L 1 is independently selected from:

[0357] -C 1-6 -alkylene-, -(CH2CH2O) t -, -C 1-6 -alkylene-NR 4 CO-, -C 1-6 -alkyleneCONH-, or OCH2, wherein t is 1 to 20; and R 4 is independently selected from H and optionally substituted (C1-C6)alkyl. In certain instances, L 1 is -C 1-6 -alkylene-, such as -C 1-3 -alkylene-. In certain instances, L 1 is -(CH2CH2O) t -, wherein t is 1 to 20, such as 1 to 15, 1 to 10, 1 to 8, 1 to 6, or 1 to 4. In certain instances, L 1 is -C 1-6 -alkylene-NR 4 CO-. In certain instances, L 1 is -C 1-6 -alkyleneCONH-. In certain instances, L 1 is or OCH2.

[0358] In some embodiments of Formula (VIIb), one or more L 1 is independently -CH2O-; -(CH2CH2O) t -, -NR 4CO-, -C 1-6 -alkylene-,

[0359] wherein R 13 is selected from H, halogen, OH, optionally substituted (C1-C6)alkyl, optionally substituted (C1-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 21 )2, -OCOR 21 , -COOR 21 , -CONHR 21 , and -NHCOR 21 ;

[0360] each r is independently 0 to 20, and L 1 is optionally further substituted. 1

[0361] In certain embodiments of Formula (VIIb), L 2 is independently selected from:

[0362] -NR 4 CO-C 1-6 -alkylene-, -CONR 4 -C 1-6 -alkylene,

[0363] -OCH2- and -(OCH2CH2) q -, wherein q is 1 to 10, u is 0 to 10, w is 1 to 10, and R 4 is independently selected from H and optionally substituted (C1-C6)alkyl. In certain instances, L 2 is -NR 4 CO-C 1-6 -alkylene-. In certain instances, L 2 is -CONR 4 -C 1-6 -alkylene.

[0364] In certain instances, L 2 is wherein w is 1, and u is 0 or 1.

[0365] In certain instances, L 2 is wherein w is 1, and u is 0 or 1.

[0366] In certain instances, L 2 is wherein w is 1, u is 0 or 1, and q is 1.​

[0367] In certain instances, L 2 is wherein u is 0 or 1.

[0368] In certain instances, L 2 is

[0369] In certain embodiments, L 2 is -OCH2-. In certain other embodiments, L 2 is (OCH2CH2) q -, and q is 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, or 1 to 2. In certain instances, q is 2 to 8, such as 2 to 6, 4 to 6, or 2 to 4.

[0370] In certain embodiments of formula (VIIb), L 4 is absent or independently selected from -C 1-6 -alkylene-, -(CH2CH2O) t -, -C 1-6 -alkylene-NHCO-, -C 1-6 -alkyleneCONH-, or OCH2, wherein t is 1 to 20. In certain instances, L 4 is absent. In certain instances, L 4 is -C 1-6 -alkylene-. In certain instances, L 4 is -(CH2CH2O) t -, wherein t is 1 to 20, such as 1 to 15, 1 to 12, 1 to 10, 1 to 8, 1 to 6, 1 to 4, or 1 to 3. In certain instances, L 4 is -C 1-6 -alkylene-NHCO-. In certain instances, L 4 is -C 1-6 -alkylene-CONH-. In certain instances, L 4 is OCH2.

[0371] In some embodiments of the subject compounds, n is 1, and L 3 in formula (VIIb) is absent.

[0372] In certain embodiments of the subject compounds, n is 2 or greater, and L 3 in formula (VIIb) is a branched linking moiety.

[0373] Thus, in some embodiments of formula (VIIb), L 3 is a branched linking moiety, e.g., a trivalent linking moiety. For example, L3 The linking moieties can have one of the following general formulae:

[0374]

[0375] In some embodiments of Formula (VIIb), the branched linking moieties can have a higher valence and be described by one of the following general formulae:

[0376] etc.

[0377] wherein any two L 3 groups can be connected directly or via an optional linear linking moiety (e.g., as described herein).

[0378] In some embodiments of Formula (VIIb), the branched linking moieties can include one, two, or more L 3 moieties, each of which is a trivalent moiety that, when connected together, can provide multiple branching points for covalent attachment of the ligand and can be described by one of the following general formulae:

[0379] wherein t is 0 to 500, such as 0 to 100, 0 to 20, or 0 to 10.

[0380] In some embodiments, the branched linking moieties (e.g., L 3 ) comprise one or more of the following: an amino acid residue (e.g., Asp, Lys, Orn, Glu, Ser), an N-substituted amido group (-N(-)C(=0)-), a tertiary amino group, a polyol (e.g., an O-substituted glycerol), etc.

[0381] In some embodiments of Formula (VIIb), one or more L 3 is a branched moiety selected from the following:

[0382]

[0383] wherein each x and y is each independently 1 to 10, such as 1 to 6, 1 to 3, for example, 1 or 2. In some cases, each x is 1, 2, or 3, for example, 2.

[0384] In some embodiments of Formula (VIIb), one or more L 5 is independently -CH2O-; -(CH2CH2O) t -, -NR 4 CO-, -C 1-6 -alkylene-,

[0385] wherein R13 selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 21 )2.-OCOR 21 、-COOR 21 、-CONHR 21 and-NHCOR 21 ;

[0386] Each r is independently 0 to 20, and L 5 Any L in the section 5 The moieties are optionally further substituted.

[0387] In some cases, L 5 is –CH2O–. In some cases, L 5 =–(CH2CH2O) t –, wherein t is 1 to 20, such as 1 to 15, 1 to 12, 1 to 10, 1 to 8, 1 to 6 or 1 to 4. In some cases, L 5 for –NR 4 CO–, where R 4 is H or optionally substituted (C1-C6) alkyl. 5 -C 1-6 -alkylene-.

[0388] In some cases, L 5 for wherein r is 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0389] In some cases, L 5 for wherein each r is independently 0 to 20, such as 0 to 15, 0 to 10, 0 to 8 or 0 to 5, and R 13 is H or optionally substituted (C1-C6)alkyl.

[0390] In some cases, L 5 for wherein r is 0 to 20, such as 0 to 15, 0 to 10, 0 to 8 or 0 to 5, and R 13 is H or optionally substituted (C1-C6)alkyl.

[0391] In some cases, L 5 for wherein r is 0 to 20, such as 0 to 15, 0 to 10, 0 to 8 or 0 to 5, and R 13 is H or optionally substituted (C1-C6)alkyl.

[0392] In certain instances, L 5 is wherein r is 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5, and R 13 is H or optionally substituted (Ci-C6)alkyl.

[0393] In certain instances, L 5 is wherein each r is independently 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0394] In certain instances, L 5 is wherein each r is independently 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0395] In certain instances, L 5 is wherein each r is independently 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0396] In certain instances, L 5 is wherein each r is independently 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0397] In certain instances, L 5 is wherein r is 0 to 20, such as 0 to 15, 0 to 10, 0 to 8, or 0 to 5.

[0398] In certain embodiments of Formula (VIIb), a is 1. In certain instances, at least one of b, c, d, and e is not 0. In certain instances, b is 1 or 2. In certain instances, c is 1 or 2. In certain instances, e is 1 or 2. In certain instances, b, d, and e are independently 1 or 2. In certain instances, a, b, d, and e are each 1, and c is 0.

[0399] In some embodiments of Formula (VIIb), L 5 comprises one or more of an amino acid residue (e.g., Asp, Lys, Orn, Glu, Ser), an amino acid analog, an N-substituted amido group (-N(-)C(=0)-), a tertiary amino group, a polyol (e.g., an O-substituted glycerol), and the like. Analogues of amino acids include, but are not limited to, unsaturated amino acids, and others known in the art. Amino acids include L-amino acids, D-amino acids, or both, and can contain any of a variety of amino acid modifications or analogues known in the art.

[0400] In some embodiments of Formula (VIIb), L 1 to L 5 comprises one or more of the following units: wherein R a is (C1-C6)alkyl or substituted (C1-C6)alkyl, e.g., (C1-C6)alkyl optionally substituted with an amine, a tertiary amine, an optionally substituted alkoxy, an optionally substituted carboxyl, an optionally substituted aryl, or an optionally substituted heteroaryl. It will be understood that R a may be attached to the M6PR binding moiety.

[0401] In certain embodiments of Formula (VIIb), a is 1. In certain cases, at least one of b, c, d, and e is not 0. In certain cases, b is 1 or 2. In certain cases, c is 1 or 2. In certain cases, e is 1 or 2. In certain cases, b, d, and e are independently 1 or 2. In certain cases, a, b, d, and e are each 1, and c is 0.

[0402] In certain embodiments of Formula (VII), (VIIa), or (VIIb), the linker comprises 20 to 100 contiguous atoms, such as 20 to 90, 20 to 80, 20 to 70, 20 to 60, 20 to 50, 20 to 40, or 20 to 30 contiguous atoms. In certain cases, the linker comprises 25 to 100 contiguous atoms, such as 30 to 100, 35 to 100, 40 to 100, 45 to 100, 50 to 100, 55 to 100, 60 to 100, 65 to 100, 70 to 100, 75 to 100, 80 to 100, 85 to 100, 90 to 100, or 95 to 100 contiguous atoms.

[0403] In certain embodiments of Formula (VII), (VIIa), or (VIIb), the linker comprises 25 or more contiguous atoms, such as 26 or more, 27 or more, 28 or more, 29 or more, or 30 or more contiguous atoms. In certain embodiments of Formula (VII), (VIIa), or (VIIb), the linker comprises 30 or more contiguous atoms, such as 31 or more, 32 or more, 33 or more, 34 or more, 35 or more, 36 or more, 37 or more, 38 or more, 39 or more, 40 or even more contiguous atoms.

[0404] In certain embodiments where the linker of Formula (VII) or (VIIb) is a branched linker, each branch of the linker comprises a straight linker of 14 or more contiguous atoms to connect to Z 1each X moiety is covalently attached to a branching point of the linker. In certain instances, each branch of the linker comprises a straight linker of 15 or more contiguous atoms to the branching point. In certain instances, each branch of the linker comprises a straight linker of 16 or more contiguous atoms to the branching point. In certain instances, each branch of the linker comprises a straight linker of 18 or more contiguous atoms to the branching point. In certain instances, each branch of the linker comprises a straight linker of 20 or more contiguous atoms to the branching point. In certain instances, each branch of the linker comprises a straight linker of 22 or more contiguous atoms to the branching point.

[0405] In certain embodiments of Formula (VII) or (VIIb), the linker is a branched linker comprising a branching point via Z 1 each X moiety is covalently attached to a branching point of the linker and the straight linker covalently attaching the branching point to Y. In certain instances, the straight linker covalently attaching the branching point to Y is 12 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 15 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 20 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 25 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 30 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 40 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 50 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 60 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 70 or more contiguous atoms. In certain instances, the straight linker covalently attaching the branching point to Y is 80 or more contiguous atoms.

[0406] In some embodiments, the linker comprises a polypeptide scaffold in which some or all of the side chain groups of the amino acid residues have been modified to connect to an M6PR binding portion (e.g., as described herein). It should be understood that the M6PR binding portion (e.g., as described herein) can be conjugated to the amino acid residues (such as Asp, Lys, Orn, Glu, and Ser) of the polypeptide-containing linker via convenient conjugation chemistry. In some embodiments, the linker contains a polylysine polypeptide. In some embodiments, the linker contains a polyornithine polypeptide. In some embodiments, the linker contains a polyserine polypeptide. In some embodiments, the linker contains a polyaspartic acid polypeptide. The polypeptide can be a randomly polymerized polymer with an average length or a polymer of a defined length prepared, for example, in a controlled step-by-step manner. In some cases, the polypeptide linker segment has a length of 10 to 100 amino acid residues (such as 20 to 90 or 20 to 50 amino acid residues). In some embodiments, the N-terminus or C-terminus of the polypeptide linker segment is modified to contain a linking unit (e.g., as described herein) that connects to another M6PR binding portion. In some embodiments, the N-terminus or C-terminus of the polypeptide linker segment is modified with one or more linking units suitable for attachment to the Y moiety of interest (eg, as described herein).

[0407] In some embodiments, the linker comprises a scaffold of Formula (VIIIa) or (VIIIb):

[0408]

[0409] in:

[0410] L 0 is a linking moiety (e.g., one or more amino acid residues), a linked M6PR binding moiety, an optionally substituted alkyl group, or an optionally substituted aryl or heteroaryl group;

[0411] R a is (C1-C6) alkyl or substituted (C1-C6) alkyl (e.g., (C1-C6) alkyl optionally substituted with amine, tertiary amine, optionally substituted alkoxy, optionally substituted carboxyl, optionally substituted aryl, or optionally substituted heteroaryl, or optionally substituted heteroaryl), a derivative of an amino acid side chain group (e.g., lysine, serine, aspartic acid, glutamic acid, ornithine, etc.), or a linked M6PR binding portion;

[0412] r is 1 to 10 (e.g., r is 1 to 5);

[0413] t is 1 to 11 (e.g., t is 1 to 5);

[0414] u is 0 to 5 (e.g., u is 0, 1, or 2); and

[0415] s is 1 to 50 (e.g., s is 1 to 20, 1 to 10, or 1 to 5).

[0416] It will be appreciated that the C-terminal carboxylic acid group of Formula (VIIIa) to (VIIIb) can enable coupling (e.g., via a chemoselective linking group) to additional linking moieties (e.g., one or more amino acid residues) and / or a moiety of interest (Y) (e.g., as described herein).

[0417] In some embodiments of (VIIIa) or (VIIIb), r is 1 to 3. In some embodiments of (VIIIa) or (VIIIb), t is 3 to 11, such as 3 to 5. In some embodiments of (VIIIa) or (VIIIb), u is 1. In some embodiments of (VIIIa) or (VIIIb), s is at least 2. In some embodiments of (VIIIa) or (VIIIb), s is 2 to 10, such as 2 to 5, e.g., 2 or 3.

[0418] In some embodiments of (VIIIa) or (VIIIb), r is 1 to 3, t is 3 to 5, u is 0 or 1, and s is 2 to 5 (e.g., 2 or 3).

[0419] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 1, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 1, and u is 0.

[0420] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 2, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 2, and u is 0.

[0421] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 3, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 1, r is 3, and u is 0.

[0422] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 1, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 1, and u is 0.

[0423] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 2, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 2, and u is 0.

[0424] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 3, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 2, r is 3, and u is 0.

[0425] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 1, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 1, and u is 0.

[0426] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 2, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 2, and u is 0.

[0427] In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 3, and u is 1. In some embodiments of (VIIIa) or (VIIIb), t is 3, s is 3, r is 3, and u is 0.

[0428] 4.3.1. Exemplary Linkers and Connecting Moieties

[0429] Exemplary linkers and connecting moieties that can be used to prepare compounds of the present disclosure (e.g., linkers and connecting moieties that connect the M6PR binding moiety (X) to the moiety of interest (Y) in Formulas (XI) to (XV)) are shown in Tables 4 to 6.

[0430] In certain embodiments, the linker comprises a straight linker or linking moiety as shown in Table 4. In certain embodiments, the linker comprises a straight linker or linking moiety as shown in Table 5. In certain embodiments, the linker comprises a straight linker or linking moiety as shown in Table 6. It will be appreciated that various terminal modifications to the exemplary linking moieties may be incorporated based on the synthetic procedures and / or conjugation chemistry used in the preparation of the compound.

[0431] Table 4 shows various exemplary linkers or linking moieties that can be used in the compounds described herein. In some embodiments of Formulas (XI) to (XV), the compound comprises any one of the linkers or linking moieties listed in Table 4.

[0432]

[0433]

[0434]

[0435]

[0436]

[0437]

[0438]

[0439]

[0440] Table 6 illustrates exemplary synthetic precursors for linker components used to prepare compounds of the disclosure, for example via conjugation chemistry. It will be appreciated that the disclosure also encompasses various homologues of the structures shown in Table 6, which provide linkers of various lengths. It will be appreciated that alternative chemoselective linkers and other chemical functional groups can also be incorporated as desired to prepare desired linkers.

[0441]

[0442]

[0443]

[0444]

[0445]

[0446]

[0447]

[0448]

[0449]

[0450] 4.4. Chemoselective Linkers

[0451] In certain embodiments of Formula (XI) to (XV), Y is a chemoselective linker or a precursor thereof. A chemoselective linker is a group having a reactive functional group or functionality that is compatible with conjugation to a second moiety. For example, the chemoselective linker (or a precursor thereof) can be one member of a pair of groups that are relevant to conjugation chemistry, such as azido-alkyne click chemistry, copper-free click chemistry, Staudinger ligation, tetrazine ligation, hydrazine-iso-Pictet-Spengler (HIPS) ligation, cysteine-reactive ligation chemistry (e.g., thiol-maleimide, thiol-haloacetamide, or alkyne thiolate chemistry), amine active ester coupling, tyrosine-specific conjugation chemistry (e.g., e-Y-CLICK), methionine-specific conjugation chemistry (e.g., oxaaziridine-based or ReACT chemistry), reductive amination, aryl acid dialkyl ester chemistry, and the like.

[0452] Table 6 illustrates exemplary synthetic precursors for preparing linker components of the compounds of the disclosure and having various chemoselective linkers. Various other chemical functionalities can also be incorporated as desired to prepare the desired linker.

[0453] Chemoselective linkers that can be used to link two moieties include, but are not limited to, an amino group (e.g., an N-terminal amino group of a polypeptide or a lysine side chain group), an azido group, an aryl azide, an alkyne group (e.g., an ethynyl group or a cyclooctyne or derivative), an active ester (e.g., an N-hydroxysuccinimide (NHS) ester, a sulfo-NHS ester, or a PFP ester or thioester), a haloacetamide (e.g., an iodoacetamide or a bromoacetamide), a chloroacetyl, a bromoacetyl, a hydrazide, a maleimide, a vinyl sulfone, a 2-sulfonylpyridine, a cyano-alkyne, a thiol group (e.g., a cysteine residue), a disulfide or protected thiol group, an isocyanate, an isothiocyanate, an aldehyde, a ketone, an alkoxyamine, a hydrazide, an aminooxy group, a phosphine, a HIPS hydrazino-indolyl group or an aza-HIPS hydrazino-pyrrolopyridyl group, a tetrazine, a cyclooctene, a squaric acid, and the like.

[0454] In some cases, a chemoselective linker is capable of spontaneously conjugating to a compatible chemical group when the two groups are contacted under suitable conditions (e.g., copper-free click chemistry conditions). In some cases, a chemoselective linker is capable of conjugating to a compatible chemical group when the two groups are contacted in the presence of a catalyst or other reagent (e.g., copper-catalyzed click chemistry conditions).

[0455] In some embodiments, the chemoselective linker is a photoactive linker. For example, upon irradiation with ultraviolet light, a diazirine group can form a reactive carbene that can insert into C-H, N-H, and O-H bonds of a second moiety.

[0456] In some cases, Y is a reactive functional group or a precursor of a functional group that is capable of conjugating to a compatible group of a second moiety. For example, a carboxylic acid is a precursor of a selective chemical linkage group.

[0457] In certain embodiments, Y is a reactive moiety capable of forming a covalent bond to the polypeptide (e.g., to an amino acid side chain of a polypeptide having a compatible reactive group). The reactive moiety can be referred to as a selective chemical linkage group.

[0458] Example selective chemical linkage groups and their synthetic precursors that can be suitable for use in the compounds of the disclosure are shown in Table 6B.

[0459]

[0460]

[0461]

[0462] In Table 6B, may represent the point of attachment of Y to the linking moiety or the attached X moiety (e.g., M6PR binding moiety).

[0463] 4.5. Conjugates

[0464] Various aspects of the disclosure include conjugates of the compounds described herein (e.g., compounds of Formula (XIII)) in which Y is a selective chemical linkage group) with another moiety of interest. When preparing such conjugates, one or more M6PR ligand-linker compounds can be linked or conjugated to another moiety of interest. For example, when the moiety of interest is a biomolecule, the selective chemical linkage group of the M6PR ligand-linker compound can be conjugated at one or more sites of the biomolecule. It will be appreciated that such biomolecule conjugates of the disclosure can be encompassed by Formulas (XI), (XII), and (II) to (III), and by the following formulas.

[0465] In some embodiments, the conjugates of the disclosure are described by Formula (XII):

[0466]

[0467] or a prodrug or salt (e.g., pharmaceutically acceptable salt) thereof, wherein:

[0468] W is a non-hydrolysable hydrophilic head group;

[0469] Z 1 is selected from the group consisting of optionally substituted (C1-C3)alkylene and optionally substituted vinylene;

[0470] Z 2 is selected from the group consisting of O, S, NR21 and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl;

[0471] each A is independently a cyclic group (e.g., an optionally substituted aryl or heteroaryl linking moiety);

[0472] each Z 3 is independently a linking moiety;

[0473] n is 1 to 500;

[0474] m is 1 to 100;

[0475] L is a linker; and

[0476] Y is a biomolecule.

[0477] In some embodiments of Formula (XII), when A is phenyl and Z 2 is O, then:

[0478] (i) W is -P(O)(OH)2; or

[0479] (ii) linker L comprises a backbone of at least 16 contiguous atoms, and Y is a target binding moiety.

[0480] In some embodiments of Formula (XII), the cell surface mannose-6-phosphate receptor (M6PR) binding conjugate has Formula (XIIa):

[0481]

[0482] In some embodiments of Formula (XII), the cell surface mannose-6-phosphate receptor (M6PR) binding conjugate has Formula (XIIa):

[0483]

[0484] In some embodiments, the moiety of interest linked to the M6PR binding moiety is a biomolecule. In some embodiments, the moiety of interest is a biomolecule. In some embodiments, the biomolecule is selected from a polypeptide (e.g., a peptide or a protein), a polynucleotide, a polysaccharide, a glycan, a glycoprotein, a lipid, an enzyme, an antibody, and an antibody fragment.

[0485] In some embodiments, the moiety of interest Y is selected from a small molecule, a small molecule drug, a chemotherapeutic agent, a cytotoxic agent, a diagnostic agent, a dye, a fluorophore, etc. In some embodiments, m is 1, wherein one M6PR binding moiety is linked to Y.

[0486] In some embodiments, one Y biomolecule is conjugated to a single moiety (X) that specifically binds to a cell surface M6PR via a linker L. In some embodiments, one Y biomolecule is conjugated to one (X n -L)-group, where when n = 1, the (X n -L)-group is referred to as monovalent; and when n > 1, the (X n -L)-group is referred to as multivalent (e.g., divalent, trivalent, etc.). It will be appreciated that in some embodiments of the formulae described herein, where Y is a biomolecule, Y can be conjugated to two or more (X n -L)-groups, where each (X n -L)-group can itself be monovalent or multivalent (e.g., divalent, trivalent, etc.). In such cases, the ratio of (X n -L)-groups to biomolecule can be 2 or greater.

[0487] In some embodiments of formula (XII), the conjugate is produced from the conjugation of a compound of formula (XIII) (where Y is a chemoselective linking group) to a biomolecule, where the conjugate has formula (XXI):

[0488]

[0489] or a prodrug or a pharmaceutically acceptable salt thereof, wherein:

[0490] n is 1 to 3;

[0491] m is a loading of 1 to 20;

[0492] L is a linker;

[0493] P is a biomolecule that specifically binds to a target protein;

[0494] Z 5 is a residue linking moiety produced from the covalent linkage of a chemoselective linking group located at the terminus of the linker of formula (XIII) to a compatible group of P. In some embodiments of formula (XXI), Z 2 is connected to the anomeric position of the pyranose ring having the beta configuration. Depending on the chemoselective linking group and conjugation chemistry used, m can be an average loading (also referred to herein as DAR), or m can be a specific loading (e.g., m is 1 or 2).

[0495] In some embodiments of formula (XXI), the conjugate has formula (XXIa):

[0496]

[0497] In some embodiments of Formula (XXI), the conjugate has Formula (XXIa):

[0498]

[0499] In some embodiments of Formula (XXI) to (XXIb), n is 1.

[0500] In some embodiments of Formula (XXI) to (XXIb), n is 2.

[0501] In some embodiments of Formula (XXI) to (XXIb), n is 3.

[0502] In some embodiments of Formula (XXI) to (XXIb), n is 4.

[0503] In some embodiments of Formula (XXI) to (XXIb), n is 5 or greater, such as n is 5 to 500, 5 to 100, 5 to 50, 5 to 20, or 5 to 10. In some embodiments of Formula (XXI) to (XXIb), n is 5. In some embodiments of Formula (XXI) to (XXIb), n is 10 to 100, such as 10 to 50, 10 to 20, or 20 to 50. In some embodiments of Formula (XXI) to (XXIb), L comprises a polypeptide, such as a polylysine or a polyservine derivative. In some embodiments of Formula (XXI) to (XXIb), L is a polypeptide-containing linker, wherein there is one M6PR binding moiety (X) per amino acid residue of the polypeptide attached to L.

[0504] In some embodiments of Formula (XXI) to (XXIb), m is the average loading of M6PR binding moieties (X) on biomolecule P. For example, when X is attached to P using lysine coupling chemistry, and P comprises multiple lysine residues, it is understood that m can refer to the average loading.

[0505] In some embodiments of Formula (XXI) to (XXIb), m is 1 to 10, such as 1 to 8, 1 to 7, or 1 to 6. In some embodiments of Formula (XXI) to (XXIb), m is 2 to 20, such as 2 to 10, 2 to 8, 2 to 7, or 2 to 6. In some embodiments of Formula (XXI) to (XXIb), m is at least 3. In some embodiments of Formula (XXI) to (XXIb), m is at least 4.

[0506] In some embodiments of Formula (XXI) to (XXIb), m is about 8, about 7, about 6, about 5, about 4, about 3, or about 2.

[0507] In some embodiments of Formulas (XXI)-(XXIb), n is 1 and m is 1-10. In some embodiments of Formulas (XXI)-(XXIb), m is 2-8 (e.g., 2-6 or 3-5). In some embodiments of Formulas (XXI)-(XXIb), m is about 4.

[0508] In some embodiments of Formulas (XXI)-(XXIb), m is a particular loading of M6PR binding moiety (X) on biomolecule P. For example, when X is linked to P via a linker using site-specific conjugation chemistry, it can be appreciated that m can refer to a particular loading. In some embodiments of Formulas (XXI)-(XXIb), m is 1. In some embodiments, biomolecule P is a polypeptide having a single conjugation site. In some embodiments of Formulas (XXI)-(XXIb), m is 2. In some embodiments, biomolecule P is an antibody. In some embodiments, biomolecule P is an antibody fragment.

[0509] In some embodiments of Formulas (XXI)-(XXIb), n is 2 and m is 1-6 (e.g., 2-6 or 3-5). In some embodiments of Formulas (XXI)-(XXIb), m is about 4.

[0510] In some embodiments of Formulas (XXI)-(XXIb), n is 3 and m is 1-6 (e.g., 2-6 or 3-5).

[0511] In some embodiments of Formulas (XXI)-(XXIb), Z 5 is a residue moiety resulting from covalent attachment of a thiol-reactive chemoselective linkage (e.g., a maleimide) to one or more cysteine residues of P, e.g., wherein represents a point of attachment to linker L, and represents a point of attachment to P.

[0512] In some embodiments of Formulas (XXI)-(XXIb), Z 5 is a residue moiety resulting from covalent attachment of an amine-reactive chemoselective linkage (e.g., a PFP ester, TFP ester, or NHS ester) to one or more lysine residues (i.e., amide bond -CONH-) of P.

[0513] Additional residue moieties Z 5 and the chemoselective linkages from which they are derived are described herein.

[0514] In some embodiments of Formulas (XXI)-(XXIb), L is a covalent bond. 3A straight linker having a backbone of 16 or more contiguous atoms covalently linked to P (e.g., a backbone of 16 to 100, 18 to 100, or 20 to 100 contiguous atoms). In some embodiments of formula (XXI) to (XXIb), L is a branched linker having a backbone consisting of 14 or more contiguous atoms (e.g., 14 to 50, or 14 to 30 atoms) between Z 3 and the branching atom of the linker.

[0515] 4.5.1. Target binding moiety

[0516] In preferred embodiments, the moiety of interest is a molecule that specifically binds to a target of interest, i.e., a target binding moiety. Thus, the compounds of the disclosure can be referred to as target protein degradation compounds or conjugates. In such cases, the conjugates of the disclosure can achieve cellular uptake of the target upon non-covalent binding of the target to the conjugate, followed by lysosomal degradation. The inventors have demonstrated that conjugates of the disclosure having a particular M6PR binding moiety of desired affinity, with a linker of desired valency and length, can specifically bind to both the M6PR and the target with high affinity. The conjugates of the disclosure can thus achieve internalization and sequestration of the bound target protein in the lysosome of a cell and subsequent degradation of the target protein.

[0517] The target binding moiety can be any moiety that has an affinity for the target of less than 1 mM (such as 300 nM or less, 100 nM or less, 30 nM or less, 10 nM or less, 3 nM or less, or 1 nM or less), e.g., as measured in an in vitro binding assay. In some embodiments, the target binding moiety has an affinity for the target protein of 10 nM or less, such as 1 nM or less.

[0518] In some embodiments, the target binding moiety is a biomolecule. In some embodiments, the target binding moiety is a biomolecule that specifically binds to the target protein. In some embodiments, the biomolecule is selected from the group consisting of a polypeptide (e.g., a peptide or a protein), a polynucleotide, a polysaccharide, a glycan, an antibody, an antibody fragment, and a glycoprotein. It will be appreciated that the term “polypeptide” encompasses antibodies, antibody fragments, and glycoproteins.

[0519] In some embodiments, the target binding moiety is a polynucleotide that specifically binds to a target molecule, such as a target protein or a target nucleic acid. The terms polynucleotide and nucleic acid can be used interchangeably. In some embodiments, the target binding moiety is a nucleic acid aptamer that specifically binds to a target molecule, such as a target protein.

[0520] In some embodiments, the target binding moiety is a glycan. In some embodiments, the target binding moiety comprises a glycan epitope of an autoantibody.

[0521] 4.5.1.1 Immunotherapy with genetically engineered hematopoietic cells of polypeptides

[0522] In some embodiments, such as Formula (XXI), the target binding moiety is a polypeptide (e.g., a peptide or protein target binding motif, a protein domain, an engineered polypeptide, a glycoprotein, an antibody or antibody fragment) that specifically binds to a target molecule, such as a target protein. In some embodiments, the target binding moiety of the bifunctional compounds of the present disclosure comprises a polypeptide that binds to a soluble (e.g., secreted) target protein of interest. In some embodiments, the target binding moiety is a polypeptide ligand of a target that includes a receptor ligand or a receptor binding portion or fragment of the receptor ligand that binds to a target cell surface receptor.

[0523] Depending on the source, the target binding polypeptide can contain L-amino acids, D-amino acids, or both, and can contain any of a variety of naturally occurring amino acids, non-naturally occurring amino acids, and / or amino acid modifications or analogs known in the art. Useful modifications include, for example, N-terminal acetylation, amidation, methylation, and the like.

[0524] In certain embodiments, the polypeptide (P) of the conjugate comprises a polypeptide that binds to a soluble (e.g., secreted) target protein of interest. In certain embodiments, for example, the target protein of interest is a ligand that binds to a cell surface receptor, and P comprises a ligand binding portion of the cell surface receptor or a bioisostere thereof, e.g., an extracellular domain of the cell surface receptor, e.g., a ligand binding domain of an extracellular domain of the cell surface receptor. In certain embodiments, the target protein of interest is a cell surface receptor, and P comprises a ligand that binds to the cell surface receptor or a receptor binding portion of the ligand or a bioisostere thereof.

[0525] In some embodiments, the polypeptide (P) of the conjugate of the present disclosure is a synthetic D protein binder of a target protein of interest, e.g., a VEGF-A binding or PD1 binding D protein as described in WO2020198074 and WO2020198075.

[0526] Conjugates of polypeptides (i.e., Y is P), e.g., conjugates of antibodies (Ab) and compounds (Xn-LY, wherein Y is a chemoselective linking group), can be prepared using a variety of bifunctional protein coupling agents, such as BMPS, EMCS, GMBS, HBVS, LC-SMCC, MBS, MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH, Sulfo-EMCS, Sulfo-GMBS, Sulfo-KMUS, Sulfo-MBS, Sulfo-SIAB, Sulfo-SMCC, Sulfo-SMPB, and SVSB (succinimidyl (4-vinylsulfone)benzoate). The present disclosure further contemplates that the conjugates described herein can be prepared using any suitable method disclosed in the art (see, e.g., Bioconjugate Techniques (Ed. Hermanson, 2nd ed., 2008)).

[0527] In certain embodiments of the conjugates described herein, L is bonded to the lysine residue of P through an amide bond. In certain embodiments of the conjugates described herein, L is bonded to the cysteine ​​residue of P through a thioether bond.

[0528] 4.5.1.2 Antibodies

[0529] In some embodiments, such as of Formula (XXI), the target binding moiety is an antibody or antibody fragment that specifically binds to a target moiety, such as a target protein.

[0530] Thus, provided herein is a conjugate of the following formula (XXII):

[0531]

[0532] or a prodrug thereof or a pharmaceutically acceptable salt thereof, wherein:

[0533] n is 1 to 20;

[0534] m is the average load from 1 to 80;

[0535] Each X is a moiety that binds to cell surface M6PR (e.g., X has Formula (III) as described herein);

[0536] Each L is a connector;

[0537] Each Z 5 is the residue resulting from the covalent attachment of the chemoselective linking group to the compatible group of the Ab; and

[0538] Ab is an antibody or antibody fragment that specifically binds to the target protein.

[0539] In some embodiments of Formula (XXII), L is a linker (e.g., as described herein). In some embodiments of Formula (XXII), Xn-L-Z 5 - is derived from a compound of Formula (XIII) (e.g., as described herein), wherein Y is a chemoselective linking group.

[0540] In some embodiments of Formula (XXII), L is a linker of the following formula:

[0541]

[0542] wherein L 1 , L 2 , L 3 , L 4 , L 5 , a, b, c, d, e, and n are as defined herein.

[0543] In certain embodiments of Formula (XXII), L is selected from the linkers of Tables 4-5.

[0544] In Formula (XXII), Z 5 may be any convenient residue moiety resulting from covalent attachment or conjugation of a chemoselective linking group (Y) to a compatible reactive group of an antibody (Ab). In some cases, the compatible reactive group of an antibody (Ab) is a group that can be naturally part of a biomolecule. In some cases, the compatible reactive group of an antibody (Ab) is a group that is incorporated into or into a biomolecule prior to conjugation. In such cases, the antibody (Ab) can be a modified version of the biomolecule. For example, a functional group (e.g., an amino group, a carboxylic acid group, or a thiol group) of a biomolecule can be modified (e.g., using a chemical reagent, such as a 2-haloacetyl reagent or a 2-iminothiolane, etc., or via coupling of a linker group comprising a chemoselective linking group such as an azide, an alkyne, etc.) to introduce a compatible chemoselective linking group.

[0545] In some embodiments of Formula (XXII), Z 5 is selected from

[0546]

[0547] wherein represents a point of attachment to the linker L,

[0548] wherein represents a point of attachment to Ab,

[0549] W is CH2, N, O, or S; and

[0550] Ab is an antibody.

[0551] In certain embodiments of Formula (XXII), Z 5 is selected from

[0552]

[0553] wherein represents a point of attachment to L,

[0554] wherein represents a point of attachment to Ab; and

[0555] Ab is an antibody.

[0556] In certain embodiments of Formula (XXII), Z 5 is selected from

[0557] wherein represents a point of attachment to L, wherein represents a point of attachment to Ab.

[0558] In certain embodiments of Formula (XXI) to (XXII), Z 5 is derived from a chemoselective linking group disclosed herein.

[0559] In certain embodiments of Formula (XXI) to (XXII), n is 1. In certain embodiments, n is 2. In certain embodiments, n is 3. In certain embodiments, n is 4. In certain embodiments, n is 5.

[0560] The M6PR binding moiety can be covalently linked to the antibody or antibody fragment via an optional linking moiety. The M6PR binding moiety can be covalently linked to the antibody or antibody fragment via a site-specific cysteine modification (e.g., L443C) on the antibody or antibody fragment and a thiol-reactive chemoselective linking group. The M6PR binding moiety can be covalently linked to the antibody or antibody fragment via one or more lysine residues on the antibody or antibody fragment and an amine-reactive chemoselective linking group.

[0561] The M6PR binding moiety can be linked to the target-binding antibody or antibody fragment via a chimeric protein fusion, via an optional spacer sequence.

[0562] In some embodiments, the conjugate of the present disclosure comprises an antibody (Ab). In some embodiments, the Ab is a monoclonal antibody. In some embodiments, the Ab is a human antibody. In some embodiments, the Ab is a humanized antibody. In some embodiments, the Ab is a chimeric antibody. In some embodiments, the Ab is a full-length antibody comprising two heavy chains and two light chains. In some embodiments, the Ab is an IgG antibody, e.g., an IgGl, IgG2, IgG3, or IgG4 antibody. In some embodiments, the Ab is a single chain antibody. In some embodiments, the target-binding moiety is an antigen-binding fragment of an antibody, e.g., a Fab fragment.

[0563] In some embodiments, the antibody or antibody fragment specifically binds to a cancer antigen.

[0564] In some embodiments, the antibody or antibody fragment specifically binds to a liver cell antigen.

[0565] In some embodiments, the antibody or antibody fragment specifically binds to an antigen presented on a macrophage.

[0566] In some embodiments, the antibody or antibody fragment specifically binds to intact complement or a fragment thereof. In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within intact complement or a fragment thereof.

[0567] In some embodiments, the antibody or antibody fragment specifically binds to a cell surface receptor. In some embodiments, the antibody or antibody fragment specifically binds to a cell surface receptor ligand.

[0568] In some embodiments, the antibody or antibody fragment specifically binds to an epidermal growth factor (EGF) protein (e.g., a human EGF). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within an EGF protein.

[0569] In some embodiments, the antibody or antibody fragment specifically binds to an epidermal growth factor receptor (EGFR) protein (e.g., a human EGFR). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within an EGFR protein. In some embodiments, the antibody or antibody fragment comprises a complementarity determining region (CDR) present in cetuximab. In some embodiments, the antibody or antibody fragment comprises a variable light chain and a variable heavy chain present in cetuximab. In some embodiments, the antibody is cetuximab. In some embodiments, the antibody or antibody fragment comprises a CDR present in matuzumab. In some embodiments, the antibody or antibody fragment comprises a variable light chain and a variable heavy chain present in matuzumab. In some embodiments, the antibody is matuzumab.

[0570] In some embodiments, the antibody or antibody fragment specifically binds to a vascular endothelial growth factor (VEGF) protein (e.g., a human VEGF protein). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within a VEGF protein.

[0571] In some embodiments, the antibody or antibody fragment specifically binds to a vascular endothelial growth factor receptor (VEGFR) protein (e.g., a human VEGFR protein). In some embodiments, the antibody or antibody fragment specifically binds to a vascular endothelial growth factor receptor 2 (VEGFR2) protein (e.g., a human VEGFR2 protein). In some embodiments, the antibody or antibody fragment specifically binds to a vascular endothelial growth factor receptor 3 (VEGFR3) protein (e.g., a human VEGFR3 protein). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within one or more of a VEGFR protein, a VEGFR2 protein, or a VEGFR3 protein.

[0572] In some embodiments, the antibody or antibody fragment specifically binds to a fibroblast growth factor (FGF) (e.g., a human FGF). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within a FGF protein.

[0573] In some embodiments, the antibody or antibody fragment specifically binds to a fibroblast growth factor receptor (FGFR) (e.g., a human FGFR). In some embodiments, the antibody or antibody fragment specifically binds to a fibroblast growth factor receptor 2 (FGFR2) protein (e.g., a human FGFR2 protein, e.g., an FGFR2b protein). In some embodiments, the antibody or antibody fragment specifically binds to a fibroblast growth factor receptor 3 (FGFR3) protein (e.g., a human FGFR3 protein). In some embodiments, the antibody or antibody fragment specifically binds to one or more immunodominant epitopes within one or more of a FGFR protein, a FGFR2 protein, or a FGFR3 protein.

[0574] In some embodiments, the antibody specifically binds to a receptor tyrosine kinase cMET protein. In some embodiments, the antibody specifically binds to one or more immunodominant epitopes within a receptor tyrosine kinase cMET protein.

[0575] In some embodiments, the antibody specifically binds to a CD47 protein (e.g., a human CD47 protein). In some embodiments, the antibody specifically binds to one or more immunodominant epitopes within a CD47 protein.

[0576] In some embodiments, the antibody specifically binds to an immune checkpoint inhibitor. In some embodiments, the antibody binds to one or more immunodominant epitopes within an immune checkpoint inhibitor. In some embodiments, the antibody specifically binds to a programmed death protein (e.g., human PD-1). In some embodiments, the antibody specifically binds to one or more immunodominant epitopes within a PD-1 protein.

[0577] In some embodiments, the antibody specifically binds to a programmed death ligand-1 (PD-L1) protein (e.g., human PD-L1). In some embodiments, the antibody specifically binds to one or more immunodominant epitopes within a PD-L1 protein.

[0578] In some embodiments, the antibody binds to TIM3. In some embodiments, the antibody binds to one or more immunodominant epitopes within TIM3.

[0579] In some embodiments, the antibody specifically binds to a lectin. In some embodiments, the antibody specifically binds to one or more immunodominant epitopes within a lectin. In some embodiments, the antibody specifically binds to a SIGLEC. In some embodiments, the antibody binds to one or more immunodominant epitopes within a SIGLEC. In some embodiments, the antibody binds to a cytokine receptor. In some embodiments, the antibody binds to one or more immunodominant epitopes within a cytokine receptor. In some embodiments, the antibody binds to sIL6R. In some embodiments, the antibody binds to one or more immunodominant epitopes within sIL6R. In some embodiments, the antibody binds to a cytokine. In some embodiments, the antibody binds to one or more immunodominant epitopes within a cytokine. In some embodiments, the antibody binds to MCP-1, TNF (e.g., TNF-a), IL1a, IL1b, IL4, IL5, IL6, IL12 / IL23, IL13, IL17, or p40. In some embodiments, the antibody binds to one or more immunodominant epitopes within MCP-1, TNF (e.g., TNF-a), IL1a, IL1b, IL4, IL5, IL6, IL12 / IL23, IL13, IL17, or p40.

[0580] In some embodiments, the antibody binds to a major histocompatibility protein (e.g., an MHC class I or class II molecule). In some embodiments, the antibody binds to one or more immunodominant epitopes within a major histocompatibility protein (e.g., an MHC class I or class II molecule). In some embodiments, the antibody binds to a beta 2 microglobulin. In some embodiments, the antibody binds to one or more immunodominant epitopes within a beta 2 microglobulin.

[0581] In some embodiments, the target binding moiety is a biologic agent that is an antagonist of a TNF protein (e.g., TNF-a). Numerous biologic agents (e.g., monoclonal antibody drugs) have been developed to inhibit the binding of TNF to TNF receptors and have proven to be clinically effective in a number of autoinflammatory diseases.

[0582] In certain embodiments of the conjugates described herein, L is bonded to a lysine residue of P through an amide bond. In certain embodiments of the conjugates described herein, L is bonded to a cysteine residue of P through a thioether bond. In certain embodiments of the conjugates described herein, L is bonded to a lysine residue of Ab through an amide bond, as shown above. In certain embodiments of the conjugates described herein, L is bonded to a cysteine residue of Ab through a thioether bond, as shown above. In certain embodiments of the conjugates described herein, L is bonded to two cysteine residues of Ab through two thioether bonds, wherein the two cysteine residues are from a broken cysteine-cysteine disulfide bond in Ab, as shown above. In certain embodiments, the broken cysteine-cysteine disulfide bond is an interchain disulfide bond.

[0583] In certain embodiments of the conjugates described herein, when L is bonded to a lysine residue of P through an amide bond, m is an integer from 1 to 80. In certain embodiments of the conjugates described herein, when L is bonded to a cysteine residue of P through a thioether bond, m is an integer from 1 to 8.

[0584] In certain embodiments, conjugation to the polypeptide P or antibody Ab can be performed via site-specific conjugation. Site-specific conjugation can, for example, result in uniform loading and a maximum reduction of conjugate subpopulations in which antigen binding or pharmacokinetics can be altered. In certain embodiments, for example, conjugation can include engineering cysteine substitutions at positions on the polypeptide or antibody (e.g., on the heavy and / or light chains of the antibody) that provide reactive thiol groups and do not disrupt polypeptide or antibody folding and assembly or alter polypeptide or antibody binding (see, e.g., Junutula et al., J. Immunol. Meth. 2008; 332: 41-52; and Junutula et al., Nature Biotechnol. 2008; 26: 925-32; see also WO 2006 / 034488, incorporated by reference in its entirety). In another non-limiting approach, selenocysteine is co-translationally inserted into a polypeptide or antibody sequence by recoding the stop codon UGA from stop to selenocysteine insertion, allowing site-specific covalent conjugation at the nucleophilic selenol group of selenocysteine in the presence of other natural amino acids (see, e.g., Hofer et al., Proc. Natl. Acad. Sci. USA 2008; 105: 12451-56; and Hofer et al., Biochemistry 2009; 48(50): 12047-57). Other non-limiting techniques that allow site-specific conjugation to polypeptides or antibodies include engineering unnatural amino acids at specific ligation sites (including, e.g., p-acetylphenylalanine (p-acetyl-Phe), p-azidomethyl-N-phenylalanine (p-azidomethyl-Phe), and azidolysine (azido-Lys)), and can further include engineering unique functional tags (including, e.g., LPXTG, LLQGA, sialic acid, and GlcNac) for enzyme-mediated conjugation. See Jackson, Org. Process Res. Dev. 2016; 20: 852-866; and Tsuchikama and An, Protein Cell 2018; 9(1): 33-46, the contents of each of which are incorporated by reference in their entirety. See also US 2019 / 0060481 Al and US 2016 / 0060354 Al, the contents of each of which are incorporated by reference in their entirety. All such methods are contemplated for making the conjugates described herein.

[0585] The loading of the compounds of Formula (I) and (III)-(IIIb) with the polypeptides (e.g., antibodies) described herein is represented by “m” in the various formulas, and the loading is the average number of “Xn-L-” or “Xn-” units per conjugate molecule. As used herein, the term “DAR” refers to the average of “m” or the loading of the conjugate. The number of “X” moieties (e.g., M6P moieties) per unit of “Xn-L-” or “Xn-” is represented by “n” in the formulas. The term “valency / valencies” refers to the number of “X” moieties per unit (“n”). It will be appreciated that the loading or DAR does not necessarily equal the number of “X” moieties per conjugate molecule. For example, where there is one “X” moiety per unit (n = 1; valency is “1”), and there is one “Xn-L-” unit per conjugate (m = 1), there will be 1 x 1 = 1 “X” moiety per conjugate. However, where there are two “X” moieties per unit (n = 2; valency is “2”), and there are four “Xn-L-” units per conjugate (m = 4), there will be 2 x 4 = 8 “X” moieties per conjugate. Thus, for the conjugates described herein, the total number of “X” moieties per conjugate molecule will be n x m. As used herein, the term “total valency / total valencies” refers to the total number of “X” moieties per conjugate molecule (n x m; total valency).

[0586] The DAR (loading) can range from 1 to 80 units per conjugate. The conjugates provided herein can include a collection of polypeptides, antibodies, or antigen binding fragments conjugated to a range of units (e.g., 1 to 80 units). The average number of units per polypeptide or antibody in a preparation of conjugates from a conjugation reaction can be characterized by routine means such as mass spectrometry. The quantitative distribution of DAR (loading) with respect to m can also be determined. In some cases, separation, purification, and characterization of homogenous conjugates where “m” is a certain value can be achieved by means such as electrophoresis.

[0587] In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 80. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 70. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 60. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 50. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 40. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 35. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 30. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 25. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 20. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 18. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 15. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 12. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 10. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 9. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 8. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 7. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 6. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 5. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 4. In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to 3. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 12. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 10. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 9. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 8. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 7. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 6. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 5. In certain embodiments, the DAR of the conjugates provided herein ranges from 2 to 4. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 12. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 10. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 9. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 8. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 7. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 6. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 5. In certain embodiments, the DAR of the conjugates provided herein ranges from 3 to 4.

[0588] In certain embodiments, the DAR of the conjugates provided herein ranges from 1 to about 8; from about 2 to about 6; from about 3 to about 5; from about 3 to about 4; from about 3.1 to about 3.9; from about 3.2 to about 3.8; from about 3.2 to about 3.7; from about 3.2 to about 3.6; from about 3.3 to about 3.8; or from about 3.3 to about 3.7.

[0589] In certain embodiments, the DAR of the conjugates provided herein is about 1, about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, or higher. In some embodiments, the DAR of the conjugates provided herein is about 3.1, about 3.2, about 3.3, about 3.4, about 3.5, about 3.6, about 3.7, about 3.8, or about 3.9.

[0590] In some embodiments, the DAR of the conjugates provided herein ranges from 2 to 20, from 2 to 19, from 2 to 18, from 2 to 17, from 2 to 16, from 2 to 15, from 2 to 14, or from 2 to 13. In some embodiments, the DAR of the conjugates provided herein ranges from 3 to 20, from 3 to 19, from 3 to 18, from 3 to 17, from 3 to 16, from 3 to 15, from 3 to 14, or from 3 to 13. In some embodiments, the DAR of the conjugates provided herein is about 1. In some embodiments, the DAR of the conjugates provided herein is about 2. In some embodiments, the DAR of the conjugates provided herein is about 3. In some embodiments, the DAR of the conjugates provided herein is about 4. In some embodiments, the DAR of the conjugates provided herein is about 3.8. In some embodiments, the DAR of the conjugates provided herein is about 5. In some embodiments, the DAR of the conjugates provided herein is about 6. In some embodiments, the DAR of the conjugates provided herein is about 7. In some embodiments, the DAR of the conjugates provided herein is about 8. In some embodiments, the DAR of the conjugates provided herein is about 9. In some embodiments, the DAR of the conjugates provided herein is about 10. In some embodiments, the DAR of the conjugates provided herein is about 11. In some embodiments, the DAR of the conjugates provided herein is about 12. In some embodiments, the DAR of the conjugates provided herein is about 13. In some embodiments, the DAR of the conjugates provided herein is about 14. In some embodiments, the DAR of the conjugates provided herein is about 15. In some embodiments, the DAR of the conjugates provided herein is about 16. In some embodiments, the DAR of the conjugates provided herein is about 17. In some embodiments, the DAR of the conjugates provided herein is about 18. In some embodiments, the DAR of the conjugates provided herein is about 19. In some embodiments, the DAR of the conjugates provided herein is about 20.

[0591] In some embodiments, the DAR of the conjugates provided herein is about 25. In some embodiments, the DAR of the conjugates provided herein is about 30. In some embodiments, the DAR of the conjugates provided herein is about 35. In some embodiments, the DAR of the conjugates provided herein is about 40. In some embodiments, the DAR of the conjugates provided herein is about 50. In some embodiments, the DAR of the conjugates provided herein is about 60. In some embodiments, the DAR of the conjugates provided herein is about 70. In some embodiments, the DAR of the conjugates provided herein is about 80.

[0592] In certain embodiments, less than the theoretical maximum number of units are conjugated to the polypeptide (e.g., antibody) during the conjugation reaction. The polypeptide can contain, for example, lysine residues that do not react with the compound or conjugation reagent. Typically, for example, an antibody does not contain many free and reactive cysteine sulfhydryl groups with which to attach drug units; indeed, most cysteine sulfhydryl residues in antibodies exist in disulfide bridge form. In certain embodiments, the antibody can be reduced under partial or full reducing conditions with a reducing agent such as dithiothreitol (DTT) or tricarbonyl ethyl phosphine (TCEP) to generate reactive cysteine sulfhydryl groups. In certain embodiments, the antibody is subjected to denaturing conditions to reveal reactive nucleophilic groups, such as lysines or cysteines. In some embodiments, the compound is conjugated via a lysine residue on the antibody. In some embodiments, the linker unit or drug unit is conjugated via a cysteine residue on the antibody.

[0593] In certain embodiments, the amino acid to which the unit is attached is in the heavy chain of the antibody. In certain embodiments, the amino acid to which the unit is attached is in the light chain of the antibody. In certain embodiments, the amino acid to which the unit is attached is in the hinge region of the antibody. In certain embodiments, the amino acid to which the unit is attached is in the Fc region of the antibody. In certain embodiments, the amino acid to which the unit is attached is in the constant region of the antibody (e.g., CH1, CH2, or CH3 of the heavy chain or CH1 of the light chain). In yet other embodiments, the amino acid to which the unit or drug unit is attached is in the VH framework region of the antibody. In yet other embodiments, the amino acid to which the unit is attached is in the VL framework region of the antibody.

[0594] The DAR (loading) of the conjugate can be controlled in different ways, for example, by: (i) limiting the molar excess of compound or conjugation reagent relative to the polypeptide, (ii) limiting the conjugation reaction time or temperature, (iii) partial or limiting reduction conditions for cysteine sulfhydryl modification, (iv) engineering the amino acid sequence of the polypeptide by recombinant techniques such that the number and location of cysteine residues are modified to control the number and / or location of linker-drug attachments (such as for thio-mAbs prepared as disclosed in WO 2006 / 034488, incorporated herein by reference in its entirety).

[0595] It will be appreciated that preparations of conjugates described herein can result in mixtures of conjugates having one or more units attached to a polypeptide (e.g., an antibody) distributed among the mixture. Individual conjugate molecules can be identified in the mixture by mass spectrometry and separated by HPLC (e.g., hydrophobic interaction chromatography), including such methods known in the art. In certain embodiments, uniform conjugates having a single DAR (loading) value can be isolated from the conjugate mixture by electrophoresis or chromatography.

[0596] 4.5.1.3 Small Molecules

[0597] In some embodiments, the target binding portion of the bifunctional compounds of the present disclosure is a small molecule that specifically binds to a target molecule, such as a target protein. In some embodiments, the bifunctional compounds include a small molecule inhibitor or ligand of a target protein. The small molecule target binding portion can be covalently linked to one or more M6PR binding portions via a linker. The linker can be linked to the small molecule via substitution at any suitable position of the small molecule, such that binding to the target protein is substantially retained.

[0598] In some embodiments, the target binding portion is a small molecule inhibitor or antagonist of a target protein (e.g., as described herein). Any convenient small molecule known to bind to a target of interest can be suitable for use in the subject compounds and conjugates.

[0599] In some embodiments, the target binding portion is a small molecule inhibitor or antagonist of a VEGF. In some embodiments, the target binding portion is a small molecule inhibitor or antagonist of PD-L1.

[0600] In some embodiments, the target binding portion is a small molecule inhibitor or antagonist of an EGFR protein, a VEGFR protein, a FGFR2 protein, or a FGFR3 protein.

[0601] In some embodiments, the target binding portion is a small molecule inhibitor or antagonist of a TNF protein (e.g., TNF-a). TNF-a (TNFa) is a soluble cytokine produced by monocytes and macrophages as part of the immune and inflammatory processes and is involved in a variety of cellular responses, including differentiation, proliferation, inflammation, and cell death. TNFa is a type II transmembrane protein that can be cleaved and secreted in soluble form. Both the transmembrane and soluble bioactive forms of TNFa are homotrimeric complexes that signal through TNF receptors 1 and 2 (TNF-R1 and TNF-R2). TNFa is directly involved in systemic inflammation by modulating intracellular NF-KB, JNK, and p38-MAPK signaling pathways.

[0602] The TNFα binding moiety can be a TNFα inhibitor, such as a competitive inhibitor of TNF receptor binding or an allosteric inhibitor of TNF signaling. The compounds of the present disclosure can include potent TNFα inhibitors, for example, inhibitors with sub-micromolar inhibitory activity. In some embodiments, the TNFα inhibitor is an allosteric inhibitor. In some embodiments, the TNFα binding moiety is an allosteric desymmetrizing TNFα inhibitor. An allosteric desymmetrizing TNFα inhibitor refers to a compound that binds to an allosteric site within TNFα and stabilizes the trimer unit in a non-symmetric conformation that allows the TNFα trimer to recruit only two of the three copies of the TNF receptor (TNFR, e.g., TNFR1), resulting in a dysfunctional TNFα-TNFR signaling complex.

[0603] See, e.g., the articles by Xiao et al. in Journal of Medicinal Chemistry 2020 63(23), 15050-15071 and McMillan et al. in Nature Communications (2021) 12:582, which disclose analysis of x-ray co-crystal structures of exemplary inhibitors that bind to TNFα. Allosteric desymmetrizing TNFα inhibitors can act via a specific mechanism of action to provide potent inhibitory activity. For example, (a) the TNFα inhibitor binding site is a cavity within the TNFα trimer created via movement of monomer A, (b) the inhibitor stabilizes the TNFα trimer in an inactive conformation by forming key π-π and hydrogen bonding interactions, (c) the allosteric desymmetrizing TNFα inhibitor binds to the TNFα trimer, resulting in major disruption of one TNFR binding site and minor disruption of the second site, while the third site remains intact, and (d) the allosteric desymmetrizing TNFα inhibitor modulates TNF-R activity through an allosteric mechanism rather than direct competition with TNFR. Thus, binding of the allosteric desymmetrizing TNFα inhibitor to the symmetric TNFα trimer can result in the formation of an asymmetric trimer, which prevents recruitment of the three TNF receptor molecules necessary for signaling.

[0604] 4.5.2. Target

[0605] As outlined above, the bifunctional compounds of the present disclosure can comprise a moiety of interest (Y) that specifically binds to a target molecule. The target molecule can be a cell surface molecule or an extracellular molecule.

[0606] In some embodiments of the compounds and methods of the disclosure, the target molecule is a cell surface molecule. By "cell surface molecule" is meant a target molecule that is associated with a cell membrane, e.g., because the molecule has a domain that inserts into or spans the cell membrane, e.g., a cell membrane tethering domain or a transmembrane domain. The cell surface molecule can be any cell surface molecule that is required for targeting degradation via the endosomal / lysosomal pathway. In some embodiments, the cell surface molecule is a cell surface receptor.

[0607] Cell surface receptors of interest include, but are not limited to, stem cell receptors, immune cell receptors, growth factor receptors, cytokine receptors, hormone receptors, receptor tyrosine kinases, receptors in the epidermal growth factor receptor (EGFR) family (e.g., HER2 (human epidermal growth factor receptor 2), etc.), receptors in the fibroblast growth factor receptor (FGFR) family, receptors in the vascular endothelial growth factor receptor (VEGFR) family, receptors in the platelet-derived growth factor receptor (PDGFR) family, receptors in the transmembrane rearrangement (RET) receptor family, receptors in the Eph receptor family, receptors in the discoidin domain receptor (DDR) family, and mucins (e.g., MUC1). In some embodiments, the cell surface molecule is CD71 (transferrin receptor). In certain aspects, the cell surface receptor is an immune cell receptor selected from the group consisting of a T cell receptor, a B cell receptor, a natural killer (NK) cell receptor, a macrophage receptor, a monocyte receptor, a neutrophil receptor, a dendritic cell receptor, a mast cell receptor, a basophil cell receptor, and an eosinophil cell receptor.

[0608] In some embodiments, the moiety of interest (Y) specifically binds to a cell surface molecule that does not mediate its action through a specific molecular interaction (and thus is not susceptible to blockade), but rather through a global biophysical or aggregation effect. Non-limiting examples of such cell surface molecules are mucins. Examples of mucins include, but are not limited to, MUC1, MUC16, MUC2, MUC5AC, MUC4, CD43, CD45, GPIb, etc.

[0609] In some embodiments, the cell surface molecule to which the moiety of interest specifically binds is present on an immune cell. By "cancer cell" is meant a cell that exhibits a tumor cell phenotype, which can be characterized by one or more of the following, for example: abnormal cell growth, abnormal cell proliferation, loss of density-dependent growth inhibition, nonadherent dependent growth potential, ability to promote tumor growth and / or development in an immunocompromised non-human animal model, and / or any appropriate indicator of cellular transformation. "Cancer cell" is used interchangeably herein with "tumor cell," "malignant cell," or "cancerous cell," and encompasses cancer cells of solid tumors, semisolid tumors, hematological tumors (e.g., leukemic cells, lymphoma cells, myeloma cells, etc.), primary tumors, metastatic tumors, etc. In some embodiments, the cell surface molecule present on a cancer cell is a tumor-associated antigen or a tumor-specific antigen. In certain aspects, the cell surface molecule to which the moiety of interest (Y) specifically binds is present on an immune cell. In some embodiments, the cell surface molecule is present on an immune cell selected from the group consisting of T cells, B cells, natural killer (NK) cells, macrophages, monocytes, neutrophils, dendritic cells, mast cells, basophils, and eosinophils. In certain aspects, the cell surface molecule present on an immune cell is an inhibitory immune receptor. As used herein, an "inhibitory immune receptor" is a receptor present on an immune cell that negatively regulates an immune response. Examples of inhibitory immune receptors that can be inhibited according to the methods of the present disclosure include inhibitory immune receptors of the Ig superfamily, including but not limited to: CD200R, CD300a (IRp60; mouse MAIR-I), CD300f (IREM-1), CEACAM1 (CD66a), FcyRIIb, ILT-2 (LIR-1; LILRB1; CD85j), ILT-3 (LIR-5; CD85k; LILRB4), ILT-4 (LIR-2; LILRB2), ILT-5 (LIR-3; LILRB3; mouse PIR-B); LAIR-1, PECAM-1 (CD31), PILR-a (FDF03), SIRL-1, and SIRP-a. Further examples of inhibitory immune receptors that can be inhibited according to the methods of the present disclosure include sialic acid-binding Ig-like lectin (Siglec) receptors, e.g., Siglec 7, Siglec 9, etc. Additional examples of inhibitory immune receptors that can be inhibited according to the methods of the present disclosure include C-type lectins, including but not limited to: CLEC4A (DCIR), Ly49Q, and MICL. Details regarding inhibitory immune receptors can be found, e.g., in Steevels et al. (201 1) Eur. J. Immunol. 41(3): 575-587. In some embodiments, the cell surface molecule present on an immune cell is a ligand for an inhibitory immune receptor.In certain aspects, the cell surface molecule present on the immune cell is an immune checkpoint molecule. Non-limiting examples of immune checkpoint molecules to which the moiety of interest (Y) can specifically bind include PD-1, PD-L1, CTLA4, TIM3, LAG3, TIGIT, and members of the B7 family.

[0610] In some embodiments of the compounds and methods of the disclosure, the target molecule is an extracellular molecule. By "extracellular molecule" is meant a soluble molecule outside the cell membrane of any cell in the vicinity of the soluble molecule. The extracellular molecule can be any extracellular molecule that is required for targeting degradation via the endosomal / lysosomal pathway.

[0611] In some embodiments, the extracellular molecule is a soluble target protein. In some embodiments, the extracellular molecule is a secreted protein that accumulates in disease (e.g., alpha-synuclein), a cholesterol carrier (e.g., ApoB), an infectious virulence (e.g., AB toxin, ESAT-6), an infectious particle (e.g., whole virus, whole bacteria, etc.), a coagulation factor (e.g., Factor IX), a target of any FDA-approved antibody that binds to an extracellular molecule (e.g., TNFa), any chemokine or cytokine (e.g., mediators of sepsis or chronic inflammation such as IL-1), a proteinaceous hormone (e.g., insulin, ACTH, etc.), a proteinaceous mediator of affective disorders, a proteinaceous mediator of energy homeostasis (e.g., leptin, ghrelin, etc.), a proteinaceous allergen or antibody to such an allergen present in the bloodstream (e.g., to peanut allergy), a proteinaceous toxin (e.g., snake venom hyaluronidase, etc.), an autoantibody, etc.

[0612] In some embodiments, the target molecule is an extracellular molecule that is an antibody, e.g., an antibody that specifically binds to a cell surface molecule or a different extracellular molecule. In some embodiments, the antibody is an autoantibody. In some embodiments, the target is human immunoglobulin A (IgA). IgA is a specific antibody that plays a key role in the immune function of the mucosa. In the blood, IgA interacts with an Fc receptor expressed on immune effector cells called CD89 to initiate inflammatory responses. Abnormal IgA expression is associated with many autoimmune disorders and immune-mediated disorders. In some embodiments, the target is human immunoglobulin G (IgG). The Fc region of IgG includes a conserved N-glycosylation site at asparagine 297 in the constant region of the heavy chain. Various N-glycans can attach to this site. N-glycan IgG composition is associated with several autoimmune, infectious, and metabolic diseases. Additionally, overexpression of IgG4 is associated with IG4-related diseases. In some embodiments, the target is human immunoglobulin E (IgE). IgE is a class of immunoglobulins that play an important role in type I hypersensitivity reactions, which can manifest as various allergic diseases and conditions.

[0613] In some embodiments, the extracellular molecule is a ligand for a cell surface receptor. Cell surface receptor ligands of interest include, but are not limited to, growth factors (e.g., epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), etc.), cytokines (e.g., interleukins, interferons, tumor necrosis factor (TNF), transforming growth factor b (TGF-b), including any particular isoform of such cytokines), hormones, etc. In certain aspects, the moiety of interest (Y) specifically binds apolipoprotein E4 (ApoE4).

[0614] 4.5.3. Moiety of Interest for Intracellular Delivery

[0615] In some embodiments, the moiety of interest is a molecule that does not bind to an extracellular target, but is itself a molecule that is desired to be delivered intracellularly. In some embodiments, the moiety of interest is selected from an enzyme (e.g., a lysosomal enzyme), a nanoparticle, a viral composition (e.g., a viral particle), a therapeutic protein, a therapeutic antibody.

[0616] In some embodiments, the moiety of interest Y is selected from a small molecule, a small molecule drug, a chemotherapeutic agent, a cytotoxic agent, a diagnostic agent, a dye, a fluorophore, etc.

[0617] In some embodiments, the moiety of interest Y is a nanoparticle suitable for delivery of one or more agents or cargo within a nanoparticle.

[0618] 4.5.3.1 Conjugates for Enzyme Replacement Therapy

[0619] In some embodiments, the moiety of interest is a lysosomal enzyme for delivery to cells for enzyme replacement therapy, such as acid alpha-glucosidase (GAA). Lysosomal enzymes of interest that can be suitable for conjugates of the present disclosure include, but are not limited to, acid alpha-glucosidase, acid beta-galactosidase-1, acid sphingomyelinase, alpha-D-mannosidase, alpha-fucosidase, alpha-galactosidase A, alpha-glucosaminyl acetyltransferase, alpha-glucosidase, alpha-L-iduronidase, alpha-N-acetylgalactosaminidase, alpha-acetylglucosaminidase, alpha-D-neuraminidase, arylsulfatase A, arylsulfatase B, beta-galactosidase, beta-glucuronidase, beta-mannosidase, cathepsin D, cathepsin K, ceramidase, cystinosine, ganglioside activator GM2, galactocerebrosidase, glucocerebrosidase, heparan sulfate liptase, hexosaminidase A, hexosaminidase B, hyaluronidase, iduronate-2-sulfatase, LAMP2, lysosomal acid lipase, N-acetylglucosamine-1-phosphotransferase, N-acetylgalactosamine-6-sulfatase, N-acetylglucosamine-1-phosphotransferase, N-acetylglucosamine-6-sulfate sulfatase, N-aspartyl-beta- glucosaminidase, palmitoyl thioesterase-1, acid phosphatase, protectin / tissue protease A (PPCA), sialate transporters, tripeptidyl peptidase 1.

[0620] Conjugation to enzymes can be achieved using the methods described herein for preparing polypeptide and antibody conjugates.

[0621] 4.5.3.2 Modified viral compositions for viral transduction

[0622] In particular embodiments, Y is a viral composition comprising a viral particle, viral capsid, viral envelope, or viral protein. In some embodiments, the viral composition is a viral particle comprising a transgene. In some embodiments, the viral protein is a viral capsid protein or a viral envelope protein. Conjugation of one or more compounds of the present disclosure to a viral composition results in a modified viral composition that can achieve enhanced viral transduction compared to an untagged viral composition.

[0623] In certain aspects, provided herein are modified viral compositions comprising a viral composition, e.g., a viral particle, viral capsid, or viral protein (e.g., a viral capsid protein or envelope protein), linked (e.g., conjugated directly or indirectly via an intervening linker sequence) to a M6PR binding moiety that binds to a cell surface receptor. In certain embodiments, the modified viral composition comprises a viral particle comprising a polynucleotide that optionally comprises a transgene (e.g., a transgene useful for therapeutic applications).

[0624] The modified virus compositions (e.g., virus conjugates) presented herein can comprise any of the virus compositions described herein, such as any of the virus particles, capsids, or virus proteins (e.g., capsid proteins or envelope proteins) or fragments thereof described herein.

[0625] In certain aspects, the virus compositions described herein can comprise a virus particle. The terms “virus particle” or “viral particle” or “virus vector” or “viral vector” are used interchangeably herein. A “virus particle” refers to a viral capsid and a polynucleotide (DNA or RNA), which can comprise a viral genome, a portion of a viral genome, or a polynucleotide derived from a viral genome (e.g., one or more ITRs), which optionally comprises a transgene. In certain instances, the virus particle further comprises an envelope (which typically comprises a lipid portion and envelope proteins) that surrounds or partially surrounds the capsid.

[0626] A virus particle can be referred to as a “recombinant viral particle” or “recombinant virus particle,” as used herein, which refers to a virus particle that has been genetically altered, such as by deletion or other mutation of an endogenous viral gene and / or addition or insertion of a heterologous nucleic acid construct into the polynucleotide of the virus particle. Thus, a recombinant virus particle generally refers to a virus particle comprising a capsid shell or casing (and optionally an outer envelope) that encloses a polynucleotide sequence comprising sequences of viral origin and sequences of non-viral origin (i.e., a polynucleotide heterologous to the virus). The polynucleotide sequence typically is a sequence of interest for genetic alteration of a cell.

[0627] In certain aspects, the virus compositions described herein can comprise a “virus capsid,” “empty viral particle” or “empty virus particle,” or “capsid” or “empty particle,” as used herein in the context of a virus, refers to a three-dimensional casing or shell comprising viral capsid proteins, optionally surrounded or partially surrounded by an outer envelope. In particular embodiments, the virus composition is a virus particle or fragment thereof, a virus capsid or fragment thereof, a virus protein (e.g., a virus capsid protein or fragment thereof or an envelope protein or fragment thereof).

[0628] In some embodiments, the viruses used in the modified viral compositions provided herein are adenoviruses (AVs); adeno-associated viruses (AAVs); retroviruses (e.g., lentiviruses (LVs), rhabdoviruses, murine leukemia viruses); herpes simplex viruses, coronaviruses, reoviruses, and the like. In some embodiments, the viral vectors, viral particles, or viral proteins used in the present disclosure are derived from nonenveloped viruses, e.g., adeno-associated viruses (AAVs).

[0629] In some embodiments, lentiviral vectors can be used for CAR-T gene delivery, vaccines, or research tools, e.g., introducing genes into mature T cells by delivering chimeric antigen receptors (CARs) or cloned T cell receptors to generate immunity to cancer.

[0630] Naturally occurring AAV forms a viral particle comprising a three-dimensional capsid shell or coat (“capsid”) composed of capsid proteins (VP1, VP2, and VP3) and an AAV viral genome contained within the capsid.

[0631] The modified AAV compositions (e.g., AAV conjugates or fusions) presented herein can comprise any of the AAV compositions described herein, e.g., any of the AAV particles, capsids, or capsid proteins or fragments thereof described herein. The term “AAV capsid protein” or “AAV cap protein” refers to a protein encoded by an AAV capsid (cap) gene (e.g., VP1, VP2, and VP3) or a variant or fragment thereof. The term includes capsid proteins expressed from or derived from AAV (e.g., recombinant AAV, such as chimeric AAV). For example, the term includes, but is not limited to, capsid proteins derived from any AAV serotype, such as AAV1, AAV2, AAV2i8, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, AAV rh10, AAV11, AAV12, AAV13, AAV-DJ, AAV3b, AAV LK03, AAV rh74, AAV Anc81, Anc82, Anc83, Anc84, Anc110, Anc113, Anc126, or Anc127, AAV_go.1, AAV hu.37, or AAV rh.8, or variants thereof.

[0632] 4.5.3.3 Bridging moieties that bind viral compositions

[0633] In some embodiments, Y is a bridging moiety that specifically binds to a viral composition (e.g., a viral particle, viral capsid, viral envelope, or viral protein (e.g., a viral capsid protein or envelope protein)) described above, wherein the binding is not via a covalent bond. Such conjugates can be used to enhance intracellular delivery and viral transduction of the target viral composition.

[0634] Any suitable portion of a viral particle, viral capsid, viral envelope, or viral protein (e.g., viral capsid protein or envelope protein) can be suitable for use in the bridging moiety conjugate of the present disclosure.

[0635] In certain embodiments, the bridging moiety is a polypeptide that specifically binds to a viral composition. In some embodiments, the bridging moiety is a polypeptide that binds to a viral composition (e.g., viral particle, viral capsid, viral envelope) or viral protein (e.g., viral capsid protein or viral envelope protein). In certain aspects, when the viral protein is part of a viral particle, the bridging composition binds to a viral capsid protein or viral envelope protein.

[0636] In certain embodiments, the bridging moiety is an antibody or antibody fragment (e.g., antigen binding fragment of an antibody) that specifically binds to a viral composition. In certain embodiments, a bridging moiety that binds to a viral protein can also bind to a viral particle, e.g., via binding to a viral protein incorporated into a viral particle. Likewise, in certain embodiments, a bridging moiety that binds to a viral particle can also bind to a viral protein, even if the viral protein is not incorporated into a viral particle. The viral particle can be an AAV viral particle. The viral protein can be an AAV capsid protein.

[0637] In some embodiments, the bridging moiety of the present disclosure specifically binds to an AAV composition, e.g., an AAV particle, AAV capsid, or AAV viral protein (e.g., AAV capsid protein, e.g., VP1, VP2, or VP3 protein).

[0638] Antibodies or antigen-binding (e.g., binding to the bridging compositions and bridging moieties presented herein) fragments that can be used in conjunction with the modified viral compositions provided herein include, but are not limited to, monoclonal antibodies, antibody compositions with polyepitopic or monovalent specificity, polyclonal or monovalent antibodies, multivalent antibodies, multispecific antibodies (e.g., bispecific antibodies, so long as they exhibit the desired biological activity), formed from at least two intact antibodies, single chain antibodies, and fragments thereof (e.g., domain antibodies).

[0639] 4.6. Exemplary Conjugates

[0640] Exemplary monomer compounds of the present disclosure comprising a chemoselective linker are shown in Table 7, which can be used to prepare conjugates of a moiety of interest.

[0641]

[0642]

[0643] Exemplary dimeric (n = 2) compounds of the present disclosure are shown in Table 8, which include chemoselective linkers and can be used to make conjugates of a moiety of interest.

[0644]

[0645] Exemplary monomeric (n = 1) compounds of the present disclosure are shown in Table 9, which include chemoselective linkers and can be used to make conjugates of a moiety of interest.

[0646]

[0647]

[0648]

[0649]

[0650]

[0651]

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658]

[0659]

[0660]

[0661]

[0662]

[0663]

[0664]

[0665]

[0666]

[0667]

[0668]

[0669]

[0670]

[0671]

[0672]

[0673]

[0674] The structures of exemplary multivalent (n > 1) compounds of the present disclosure are shown in Table 12, which can be used to make conjugates of moieties of interest.

[0675]

[0676]

[0677]

[0678]

[0679]

[0680]

[0681]

[0682]

[0683]

[0684]

[0685]

[0686]

[0687]

[0688]

[0689]

[0690]

[0691]

[0692]

[0693] The structures of exemplary multivalent (n > 1) compounds of the present disclosure are shown in Table 12B, which can be used to make conjugates of moieties of interest.

[0694]

[0695]

[0696]

[0697]

[0698]

[0699]

[0700]

[0701]

[0702]

[0703]

[0704]

[0705]

[0706]

[0707]

[0708]

[0709]

[0710]

[0711] 4.7. Additional experimental observations

[0712] Without being bound by any particular mechanism or theory, the binding affinity of the M6PR ligand can be inversely related to the longer half-life of the resulting compound and conjugate within a certain desired range, and the selection of a desired binding affinity can be used to modulate (e.g., modify) the pharmacokinetic properties of the conjugates described herein. In certain embodiments, a compound or conjugate having a structure described herein can be selected to have a binding affinity for a cell surface M6PR, thereby achieving a combination of desired pharmacokinetic properties (e.g., sufficient half-life) while providing sufficient stable target uptake and / or degradation.

[0713] 4.8. Pharmaceutical Compositions

[0714] In another embodiment, provided herein is a pharmaceutical composition comprising one or more conjugates disclosed herein and a pharmaceutically acceptable carrier.

[0715] In certain embodiments, a pharmaceutical composition provided herein contains a therapeutically effective amount of one or more of the conjugates provided herein in a pharmaceutically acceptable carrier, and optionally one or more additional prophylactic or therapeutic agents. The pharmaceutical composition can be used to prevent, treat, manage, or ameliorate a disease or disorder described herein, or one or more symptoms thereof.

[0716] Pharmaceutically acceptable carriers suitable for administration of the conjugates provided herein include any such carriers known to those skilled in the art to be suitable for a particular mode of administration.

[0717] The conjugates described herein can be formulated as the sole pharmaceutically active ingredient in a composition, or can be combined with other active ingredients.

[0718] In certain embodiments, the conjugates are formulated into one or more suitable pharmaceutical preparations, such as sterile solutions, suspensions, powders, sustained-release formulations, or elixirs for parenteral administration, or transdermal patch preparations and dry powder inhalers.

[0719] In the compositions provided herein, the conjugates described herein can be mixed with a suitable pharmaceutically acceptable carrier. The concentration of the conjugate in the composition can be, for example, an amount effective to deliver therapy, prophylaxis, or amelioration of a condition or disorder described herein, or a symptom thereof, at the time of administration.

[0720] In certain embodiments, the pharmaceutical compositions provided herein are for single dose administration. To formulate the composition, a fraction by weight of the conjugate is dissolved, suspended, dispersed, or otherwise mixed in a selected carrier in an effective concentration, such that the treated condition is alleviated, prevented, or one or more symptoms are ameliorated.

[0721] The concentration of the conjugate in the pharmaceutical compositions provided herein will depend on, for example, the physicochemical characteristics of the conjugate, the dosage schedule and amount administered, and other factors known to those skilled in the art.

[0722] The pharmaceutical compositions described herein are provided in unit dosage forms (such as sterile parenteral (e.g., intravenous) solutions or suspensions containing an appropriate amount of the compound or a pharmaceutically acceptable derivative thereof) for administration to a subject, such as a human or animal (e.g., a mammal). Also provided are pharmaceutical compositions for administration to humans and animals in unit dosage forms, including oral or nasal solutions or suspensions and oil-in-water emulsions containing an appropriate amount of the conjugate or a pharmaceutically acceptable derivative thereof. In certain embodiments, the conjugate is formulated and administered in unit dosage forms or multiple dosage forms. As used herein, a unit dosage form refers to a physically discrete unit suitable for use in a human or animal (e.g., mammal) subject and packaged individually as known in the art. Each unit dose contains a predetermined amount of the conjugate sufficient to produce the desired therapeutic effect in combination with the desired pharmaceutical carrier, vehicle, or diluent. Examples of unit dosage forms include ampoules and syringes and individually packaged capsules. Unit dosage forms can be administered in fractions or multiples thereof. A multiple dosage form is a plurality of identical unit dosage forms packaged in a single container so as to be administered in separate unit dosage forms. Examples of multiple dosage forms include vials, capsule bottles, or bottles.Thus, in certain aspects, a multiple dosage form is a plurality of unit doses that are not separated in packaging.

[0723] In certain embodiments, the conjugates herein are in the form of liquid pharmaceutical preparations. Liquid pharmaceutically administrable preparations can be prepared, for example, by dissolving, dispersing or otherwise mixing the conjugate and an optional pharmaceutical adjuvant in a carrier (e.g., water, saline, aqueous dextrose, glycerol, ethylene glycol, etc.) to form a solution or suspension. In certain embodiments, the pharmaceutical compositions to be administered provided herein may also contain a small amount of non-toxic auxiliary substances, such as wetting agents, emulsifiers, solubilizers, and pH buffers.

[0724] Actual methods for preparing such dosage forms are known or will be apparent to those skilled in the art; for example, see, for example, Remington: The Science and Practice of Pharmacy (2012) 22nd ed., Pharmaceutical Press, Philadelphia, Pa. Dosage forms or compositions containing from 0.005% to 100% antibody, the balance being made up of non-toxic carriers, can be prepared.

[0725] In certain embodiments, parenteral administration is characterized by injection, either subcutaneously, intramuscularly, or intravenously, is also contemplated herein. Injectable preparations can be prepared in conventional forms, either as liquid solutions or suspensions, solid forms suitable for solution or suspension in liquid prior to injection, or as emulsions. The injectable preparations, solutions, and emulsions also contain one or more excipients. Suitable excipients are, for example, water, saline, dextrose, glycerol, or ethanol. Other routes of administration can include enteral administration, intracerebral administration, intranasal administration, intraarterial administration, intracardiac administration, intraosseous infusion, intrathecal administration, and intraperitoneal administration.

[0726] Formulations for parenteral administration include sterile solutions, sterile dry soluble products ready for injection (such as lyophilized powders, including tablets for subcutaneous injection) prepared in advance for combination with a solvent prior to use, sterile suspensions ready for injection, sterile dry insoluble products ready for combination with a vehicle prior to use, and sterile emulsions. The solutions can be aqueous or non-aqueous.

[0727] If administered intravenously, suitable carriers include physiological saline or phosphate buffered saline (PBS), as well as solutions containing thickening and solubilizing agents, such as glucose, polyethylene glycol, and polypropylene glycol, and mixtures thereof.

[0728] Pharmaceutically acceptable carriers for use in parenteral formulations include aqueous vehicles, non-aqueous vehicles, antimicrobial agents, isotonic agents, buffering agents, antioxidants, local anesthetics, suspending and dispensing agents, emulsifying agents, chelating agents or cyclodextrin derivatives, and other pharmaceutically acceptable substances.

[0729] Pharmaceutically acceptable carriers further include ethanol, polyethylene glycol, and propylene glycol for aqueous vehicles, and sodium hydroxide, hydrochloric acid, citric acid or lactic acid for pH adjustment.

[0730] In certain embodiments, intravenous or intraarterial infusion of sterile aqueous solutions containing the conjugates described herein is an effective mode of administration. Another embodiment is a sterile aqueous or oleaginous solution or suspension containing the conjugates described herein, which is injected as necessary to produce the desired pharmacological effect.

[0731] In certain embodiments, the pharmaceutical formulation is a lyophilized powder, which can be reconstituted for administration as a solution, emulsion, and other mixtures. It can also be reconstituted and formulated as a solid or gel.

[0732] The lyophilized powder is prepared by dissolving the conjugate provided herein in a suitable solvent. In some embodiments, the lyophilized powder is sterile. The suitable solvent may contain excipients that improve the stability of the powder or the reconstituted solution prepared from the powder or other pharmacological components. Excipients that can be used include, but are not limited to, dextrose, sorbitol, fructose, corn syrup, xylitol, glycerol, glucose, sucrose or other suitable agents. The suitable solvent may also contain a buffer, such as citrate, sodium phosphate or potassium phosphate or other such buffers known to those skilled in the art, which, in certain embodiments, are approximately neutral pH. The solution is then sterile filtered and then lyophilized under standard conditions known to those skilled in the art to provide an example of a formulation. In certain embodiments, the resulting solution will be dispensed into vials for lyophilization. The lyophilized powder can be stored under appropriate conditions, such as at about 4°C to room temperature.

[0733] Reconstitution of the lyophilized powder with water for injection provides a formulation for parenteral administration.For reconstitution, the lyophilized powder is added to sterile water or other suitable carrier.

[0734] In certain embodiments, the conjugates provided herein can be formulated for topical administration or local application, such as in the form of gels, creams, and lotions for topical application to the skin and mucous membranes, such as in the eye, as well as for application to the eye or for intracisternal or intraspinal application. Topical administration is contemplated for transdermal delivery and may also be used for application to the eye or mucous membranes, or for inhalation therapy. Nasal solutions of the active compound, alone or in combination with other pharmaceutically acceptable excipients, may also be administered.

[0735] 4.9. Usage

[0736] In one aspect, provided herein are methods for removing a polypeptide of interest (target protein) from the surface of a cell using a conjugate as described herein. In one aspect, provided herein are methods for removing a polypeptide of interest (target protein) from the extracellular environment using a conjugate as described herein. For example, in one embodiment, provided herein are methods for removing a polypeptide of interest (target protein) from the surface of a cell using a conjugate as described herein by isolating the target protein in the lysosome of the cell. In another embodiment, provided herein are methods for removing a polypeptide of interest (target protein) from the extracellular space (extracellular environment) using a conjugate as described herein by isolating the target protein in the lysosome of the cell. In another embodiment, provided herein are methods for removing a polypeptide of interest (target protein) from the surface of a cell using a conjugate as described herein by isolating the target protein in the lysosome of the cell and degrading the target protein. In another embodiment, provided herein are methods for removing a polypeptide of interest (target protein) from the surface of a cell using a conjugate as described herein by isolating the target protein in the lysosome of the cell and degrading the target protein.

[0737] Removal of a target protein can refer to reducing or depleting a target protein from the cell surface, or from the extracellular space or extracellular environment, i.e., reducing or depleting the amount of target protein in the cell surface or extracellular environment. In some embodiments, the method is a method of reducing the amount or level of a target protein in a biological system or cell sample.

[0738] In one aspect, provided herein is a method of isolating a polypeptide of interest (target protein) in the lysosome of a cell using a conjugate described herein. In one aspect, provided herein is a method of isolating a polypeptide of interest (target protein) in the lysosome of a cell and degrading the polypeptide of interest using a conjugate described herein.

[0739] In one aspect, provided herein is a method of degrading a polypeptide of interest (target protein) using a conjugate described herein.

[0740] In one aspect, provided herein is a method of depleting a polypeptide of interest (target protein) described herein by lysosomal pathway degradation by a cell.

[0741] In another aspect, provided herein is a method of depleting a polypeptide of interest (target protein) described herein by administering to a subject in need thereof an effective amount of a conjugate described herein or a pharmaceutically acceptable salt or a pharmaceutical composition described herein. In certain embodiments, the subject is a mammal (e.g., a human).

[0742] In certain embodiments, the target protein is a membrane-bound protein. In certain embodiments, the target protein is a cell surface receptor. In certain embodiments, the target protein is an extracellular protein.

[0743] In certain embodiments, the target protein is a VEGF protein, an EGFR protein, a VEGFR protein, a PD-L1 protein, a FGFR2 protein, or a FGFR3 protein.

[0744] In another aspect, provided herein is a method of treating a disease or disorder by administering to a subject (e.g., a human) in need thereof an effective amount of a conjugate described herein or a pharmaceutically acceptable salt or a pharmaceutical composition described herein.

[0745] The term “administer,” “administration,” or “administering” refers to the act of injecting or otherwise physically delivering a substance (e.g., a conjugate or a pharmaceutical composition provided herein) to a subject or patient (e.g., a human), such as by mucosal, topical, intradermal, parenteral, intravenous, intramuscular delivery, and / or any other physical delivery method described herein or known in the art. In a specific embodiment, administration is by intravenous infusion.

[0746] The term "effective amount" or "therapeutically effective amount" refers to the amount of a therapeutic agent (e.g., a conjugate or pharmaceutical composition provided herein) that is sufficient to treat, diagnose, prevent, delay onset of, reduce and / or ameliorate the severity and / or duration of a given condition, disorder or disease and / or symptoms associated therewith. The term also encompasses the necessary dosage required to palliate, delay or ameliorate the progression of a given disease, to palliate, delay or ameliorate the recurrence, development or onset of a particular disease, and / or to improve or enhance the prophylactic or therapeutic effect of other therapies, or as a bridging therapy to other therapies. In some embodiments, "effective amount" as used herein also refers to the amount of a conjugate described herein to achieve a specified result.

[0747] In certain embodiments, when the condition or disease is cancer, an "effective amount" or "therapeutically effective amount" means the amount of a conjugate or pharmaceutical composition provided herein that, when administered to a human with cancer, is sufficient to effect treatment of the cancer. "Treating" or "treatment" of cancer includes one or more of:

[0748] (1) limiting / inhibiting the growth of the cancer, e.g., limiting its development;

[0749] (2) reducing / preventing the spread of the cancer, e.g., reducing / preventing metastasis;

[0750] (3) relieving the cancer, e.g., causing regression of the cancer,

[0751] (4) reducing / preventing recurrence of the cancer; and

[0752] (5) reducing symptoms of the cancer.

[0753] The terms "subject" and "patient" are used interchangeably. A subject can be a mammal such as a non-primate (e.g., a cow, pig, horse, cat, dog, goat, rabbit, rat, mouse, etc.) or a primate (e.g., a monkey or a human), e.g., a human. In certain embodiments, a subject is a mammal, e.g., a human, diagnosed with a disease or disorder provided herein. In another embodiment, a subject is a mammal, e.g., a human, at risk of developing a disease or disorder provided herein. In certain embodiments, a subject is a human.

[0754] The term "therapies / therapy" can refer to any regimen, method, composition, formulation, and / or agent that can be used to prevent, treat, manage, or ameliorate a disease or disorder or a symptom thereof (e.g., a disease or disorder described herein or one or more symptoms or conditions associated therewith). In certain embodiments, the term "therapy" refers to a pharmaceutical therapy, an adjuvant therapy, radiation, surgery, a biological therapy, a supportive therapy, and / or other therapy that can be used to treat, manage, prevent, or ameliorate a disease or disorder or one or more symptoms thereof. In certain embodiments, the term "therapy" refers to a therapy other than a conjugate described herein or a pharmaceutical composition thereof.

[0755] In certain embodiments, a disease or disorder is treated by depleting a target protein through degradation via the lysosomal pathway.

[0756] In certain embodiments, a disease or disorder is treated by depleting certain proteins, such as, for example, soluble proteins (e.g., secreted proteins), cell surface proteins (e.g., cell surface receptor proteins, such as tyrosine kinase receptors, soluble cytokine receptors, and immune checkpoint receptors, e.g., EGFR, VEGFR, FGFR, and PD-L1), agglutinins, complement, lipoproteins, transport proteins, MHC class I and II molecules, cytokines, chemokines, and / or receptors, or fragments or subunits of any of the foregoing.

[0757] In certain embodiments, a disease or disorder is a cancer.

[0758] In certain embodiments, a cancer is selected from the group consisting of bladder cancer, breast cancer, cervical cancer, cholangiocarcinoma, endometrial cancer, hepatocellular carcinoma, kidney cancer, melanoma, myeloid neoplasms, non-small cell lung cancer (NSCLC), Ewing sarcoma, and Hodgkin lymphoma.

[0759] In certain embodiments, a cancer is a solid tumor.

[0760] In certain embodiments, a disease or disorder is an inflammatory or autoimmune disease.

[0761] In certain embodiments, a disease or disorder is an inflammatory disease.

[0762] In certain embodiments, a disease or disorder is an autoimmune disease.

[0763] 4.10. DEFINITIONS

[0764] It should be understood that the present disclosure is not limited to the particular embodiments described since such embodiments can of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present disclosure will be limited only by the appended claims.

[0765] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure.

[0766] It must be noted that, as used herein and in the appended claims, the singular form "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a compound" includes a single compound as well as a combination of two or more compounds, reference to "a substituent" includes a single substituent as well as two or more substituents, and the like.

[0767] In describing and claiming the present application, certain terms are used that will be further described as set forth below. It will be understood that the definitions provided herein are not intended to be mutually exclusive. Thus, some chemical moieties can fall within the definition of more than one term.

[0768] As used herein, the phrases "for example," "for instance," "such as," or "including" are meant to introduce examples that further clarify more general recitations of "a", "an", or "the". These examples are only meant to be helpful in understanding the present disclosure and are not intended to be limiting in any way.

[0769] The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present application is not entitled to antedate such publications by virtue of prior application. Further, the dates of publication provided can be different from the actual publication dates which can need to be independently confirmed.

[0770] The terms "protein" and "polypeptide" are used interchangeably. Proteins can include moieties other than amino acids (e.g., can be glycoproteins) and / or can be otherwise processed or modified. One of ordinary skill in the art will understand that a "protein" can be an intact protein chain (with or without a signal sequence) produced by a cell, or can be a protein portion thereof. One of ordinary skill will understand that a protein can sometimes include more than one protein chain, e.g., attached non-covalently or covalently, e.g., linked by one or more disulfide bonds or associated by other means. In certain embodiments, a polypeptide can exist as a single chain or two or more associated chains, e.g., can exist as a multimer, e.g., a dimer, a trimer. The terms also encompass amino acid polymers that have been modified by natural processes, such as post- translational processes and / or have been artificially modified, e.g., by disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or any other manipulation or modification. Also included within the definition are, for example, polypeptides containing one or more analogs of an amino acid (including, but not limited to, unnatural amino acids, etc.) and other modifications known in the art. A polypeptide can contain L-amino acids, D-amino acids, or both, and can contain any of a number of amino acid modifications or analogs known in the art. Useful modifications include, for example, terminal acetylation, amidation, methylation, etc. In some embodiments, a protein can include natural amino acids, unnatural amino acids, synthetic amino acids, and combinations thereof. In some embodiments, a protein is an antibody, an antibody fragment, a biologically active portion thereof, and / or a characteristic portion thereof.

[0771] The terms "antibody" and "immunoglobulin" are terms of art and are used interchangeably in their broadest sense to include certain types of immunoglobulin molecules that comprise one or more antigen binding domains that specifically bind to an antigen or epitope.

[0772] In certain embodiments, an isolated antibody (e.g., a monoclonal antibody) or antigen binding fragment thereof described herein that specifically binds to a protein of interest (e.g., EGFR) is conjugated to one or more lysosomal targeting moieties, e.g., via a linker.

[0773] An "antigen" is a moiety or molecule that contains an epitope to which an antibody can specifically bind. Thus, an antigen is also specifically bound by an antibody. In particular embodiments, the antigen bound by an antibody described herein is a protein of interest, e.g., EGFR (e.g., human EGFR) or a fragment thereof, or an extracellular domain of, e.g., EGFR (e.g., human EGFR).

[0774] An "epitope" is a term of art and refers to a local region of an antigen to which an antibody can specifically bind. An epitope can be a linear epitope of contiguous amino acids, or can comprise amino acids from two or more non-contiguous regions of an antigen.

[0775] In the context of antibody binding, the terms "bind," "binds," "binding," or "specifically binds" or "specifically binds to" refer to the binding of an antibody to an antigen (e.g., an epitope) as understood by one of skill in the art. For example, a molecule that specifically binds to an antigen can bind to other polypeptides, typically with lower affinity, as determined by, e.g., immunoassays, Biacore TM , KinExA 3000 instrument (Sapidyne Instruments, Boise, ID), or other assays known in the art. In a specific embodiment, a molecule that specifically binds to an antigen has an affinity (K d ) for that antigen that is at least 2 logs, 2.5 logs, 3 logs, 4 logs (higher affinity) lower than the K d of the molecule binding to another antigen. In another specific embodiment, a molecule that specifically binds to an antigen does not cross-react with other proteins. In another specific embodiment, when EGFR is the protein of interest, a molecule that specifically binds to an antigen does not cross-react with other non-EGFR proteins.

[0776] Antibodies specifically include, but are not limited to, full-length antibodies (e.g., intact immunoglobulins), antibody fragments, monoclonal antibodies, polyclonal antibodies, recombinantly produced antibodies, monospecific antibodies, multispecific antibodies (including bispecific antibodies), human antibodies, humanized antibodies, chimeric antibodies, synthetic antibodies, tetrameric antibodies comprising two heavy chains and two light chain molecules, antibody light chain monomers, antibody heavy chain monomers, antibody light chain dimers, antibody heavy chain dimers, antibody light chain / antibody heavy chain pairs, antibodies with two light chain / heavy chain pairs (e.g., identical pairs), intrabodies, heteroconjugate antibodies, single-domain antibodies, univalent antibodies, bivalent antibodies (including monospecific or bispecific bivalent antibodies), single-chain antibodies or single-chain Fvs (scFv), camelized antibodies, affybodies, Fab fragments, F(ab') fragments, F(ab')2 fragments, disulfide-linked Fvs (sdFv), anti-idiotypic (anti-Id) antibodies (including, e.g., anti-anti-Id antibodies), and epitope-binding fragments of any of the above.

[0777] Antibodies can be of any type (e.g., IgG, IgE, IgM, IgD, IgA or IgY), any class (e.g., IgGl, IgG2, IgG3, IgG4, IgAl or IgA2), or any subclass (e.g., IgG2a or IgG2b) of immunoglobulin molecule. In certain embodiments, the antibodies described herein are IgG antibodies (e.g., human IgG) or a class (e.g., human IgGl, IgG2, IgG3 or IgG4) or subclass thereof.

[0778] In particular embodiments, the antibody is a 4-chain antibody unit comprising two heavy (H) chain / light (L) chain pairs, where the amino acid sequences of the H chains are identical and the amino acid sequences of the L chains are also identical. In specific embodiments, the H and L chains comprise constant regions, e.g., human constant regions. In yet more specific embodiments, the L chain constant region of such an antibody is a kappa or lambda light chain constant region, e.g., a human kappa or lambda light chain constant region. In another specific embodiment, the H chain constant region of such an antibody comprises a gamma heavy chain constant region, e.g., a human gamma heavy chain constant region. In particular embodiments, such an antibody comprises an IgG constant region, e.g., a human IgG constant region.

[0779] The term “constant region” or “constant domain” is an antibody term well known in the art (sometimes referred to as “Fc”) and refers to the portion of an antibody, e.g., the carboxy-terminal portion of the light and / or heavy chains, that is not directly involved in binding of the antibody to an antigen, but which can exhibit various effector functions, such as interaction with Fc receptors. The term refers to the portion of an immunoglobulin molecule that has an amino acid sequence that is generally more conserved than the variable domains of immunoglobulins.

[0780] The term “heavy chain” when used to refer to an antibody can refer to any of the different types based on the amino acid sequence of the constant domain, e.g., alpha (a), delta (d), epsilon (e), gamma (g), and mu (m), which give rise to the IgA, IgD, IgE, IgG, and IgM classes, respectively, of antibodies, including subclasses of IgG, e.g., IgGl, IgG2, IgG3, and IgG4.

[0781] The term “light chain” when used to refer to an antibody can refer to any of the different types based on the amino acid sequence of the constant domain, e.g., kappa (k) or lambda (l). Light chain amino acid sequences are well known in the art. In specific embodiments, the light chain is a human light chain.

[0782] The term “monoclonal antibody” is an art-recognized term that refers to an antibody obtained from a population of substantially homogeneous antibodies. The term “monoclonal” is not limited to any particular method for making the antibody. Typically, the population of monoclonal antibodies can be produced by a cell, a population of cells, or a cell line. In specific embodiments, a “monoclonal antibody” as used herein is an antibody produced by a single cell (e.g., a hybridoma or host cell producing a recombinant antibody), where the antibody specifically binds to an epitope, as determined, e.g., by ELISA or other antigen binding or competitive binding assays known in the art or provided herein. In particular embodiments, a monoclonal antibody can be a chimeric antibody or a humanized antibody. In certain embodiments, a monoclonal antibody is a monovalent antibody or a multivalent (e.g., bivalent) antibody. In particular embodiments, a monoclonal antibody is a monospecific or a multispecific antibody (e.g., a bispecific antibody).

[0783] The term "variable region" or "variable domain" refers to the portion of an antibody, typically a portion of a light chain or a heavy chain, typically about the amino-terminal 110 to 120 amino acids of a mature heavy chain and about the amino-terminal 90 to 100 amino acids of a mature light chain. The variable region includes the complementarity determining regions (CDRs), which are flanked by framework regions (FRs). Generally, the spatial orientation of the CDRs and FRs is as follows, in the direction N-terminal to C-terminal: FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Without wishing to be bound by any particular mechanism or theory, it is believed that the CDRs of the light and heavy chains are primarily responsible for binding the antibody to an antigen and for the specificity of the antibody for an epitope. In particular embodiments, the numbering of amino acid positions of the antibodies described herein is according to the EU index as seen, e.g., in Kabat et al. (1991) Sequences of Proteins of Immunological Interest, 5th Ed. U.S. Department of Health and Human Services, NIH Publication No. 91-3242. In certain embodiments, the variable region is a human variable region.

[0784] In certain aspects, the CDRs of an antibody can be determined according to: (i) the Kabat numbering system (Kabat et al., (1971) Ann. NY Acad. Sci. 190:382-391 and Kabat et al., (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, US Department of Health and Human Services, NIH Publication No. 91-3242); or (ii) the Chothia numbering scheme, which is referred to herein as the "Chothia CDRs" (see, e.g., Chothia and Lesk, 1987, J. Mol. Biol., 196:901-917; Al-Lazikani et al., 1997, J. Mol. Biol., 273:927-948; Chothia et al., 1992, J. Mol. Biol., 227:799-817; Tramontano et al., 1990, J. Mol. Biol. 215(1):175-82; U.S. Pat. No. 7,709,226; and Martin, A., "Protein Sequence and Structure Analysis of Antibody Variables Domains,” in Antibody Engineering, Kontermann and Dübel, eds., Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001)); or (iii) the ImMunoGeneTics (IMGT) numbering system, e.g., as described in Lefranc, 1999, The Immunologist, 7:132-136 and Lefranc et al., 1999, Nucleic Acids Res., 27:209-212 (“IMGTCDRs”); or (iv) the AbM numbering system, referred to herein as “AbM CDRs,” e.g., as described in MacCallum et al., 1996, J. Mol. Biol., 262:732-745.See also, e.g., Martin, A., “Protein Sequence and Structure Analysis of Antibody Variable Domains,” in Antibody Engineering, Kontermann and Dübel, eds., Chapter 31, pp. 422-439, Springer-Verlag, Berlin (2001)); or (v) the Contact Number System, which is referred to herein as “Contact CDR” (Contact definitions are based on analysis of available complex crystal structures (bioinf.org.uk / abs) (see, e.g., MacCallum et al., 1996, J. Mol. Biol., 262: 732-745)).

[0785] The terms “full-length antibody,” “intact antibody,” and “whole antibody” are used herein interchangeably to refer to an antibody in its substantially complete form, as opposed to an antibody fragment as defined below. The terms specifically refer to an antibody that has heavy chains with Fc regions.

[0786] An “antibody fragment” comprises only a portion of an intact antibody, wherein the portion, when present in the intact antibody, retains at least one, two, three, and up to most or all of the functions normally associated with that portion. In one aspect, an antibody fragment includes the antigen binding site of the intact antibody, and thus retains the ability to bind antigen. In another aspect, an antibody fragment, such as an antibody fragment comprising an Fc region, retains at least one biological function normally associated with that Fc region, when present in the intact antibody. Such functions can include FcRn binding, antibody half-life modulation, conjugating function, and complement binding. In another aspect, an antibody fragment is a monovalent antibody that has an in vivo half-life that is substantially similar to that of an intact antibody. For example, such an antibody fragment can include an antigen binding arm linked to an Fc sequence that is capable of conferring in vivo stability to the fragment. Antibody fragments suitable for use in the compounds of the present disclosure include, e.g., Fv fragments, Fab fragments, F(ab’)2 fragments, Fab’ fragments, scFv (sFv) fragments, and scFv-Fc fragments.

[0787] "Polynucleotide" or "nucleic acid" are used interchangeably herein and refer to a polymeric form of nucleotides of any length, either deoxyribonucleotides or ribonucleotides or their analogs. Polynucleotides can have any three-dimensional structure and can perform any function, known or unknown. Non-limiting examples of polynucleotides include a gene, a gene fragment, an exon, an intron, messenger RNA (mRNA), transfer RNA, ribosomal RNA, ribozymes, cDNA, recombinant polynucleotides, branched polynucleotides, plasmids, vectors, isolated DNA of any sequence, control regions, isolated RNA of any sequence, nucleic acid probes, and primers. A nucleic acid molecule can be linear or circular. The nucleotides can be deoxyribonucleotides, ribonucleotides, modified nucleotides or bases, and / or their analogs, or any substrate that can be incorporated by DNA or RNA polymerase or by a synthetic reaction. A polynucleotide can comprise modified nucleotides, such as methylated nucleotides and their analogs. A nucleic acid molecule can be an aptamer.

[0788] The term "purified" refers to the isolation of a substance (compound, polynucleotide, protein, polypeptide, polypeptide composition) such that the substance of interest comprises a substantial percentage of the sample in which it is found. Typically in a sample, a substantially purified component comprises 50%, 80-85%, 90-99%, such as at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% of the sample. Techniques for purifying polynucleotides, polypeptides, and viral particles of interest are well known in the art and include, for example, ion-exchange chromatography, affinity chromatography, and sedimentation by density.

[0789] The terms "treatment" and "treating," and the like, refer to obtaining a desired pharmacologic and / or physiologic effect, such as, for example, reducing tumor burden. The effect can be prophylactic in terms of completely or partially preventing a disease or symptom attributable to the disease and / or therapeutic in terms of a partial or complete cessation of disease or symptoms. "Treatment" as used herein covers any treatment of a disease in a mammal, particularly in a human, and includes: (a) preventing the disease or symptom of the disease from occurring in a subject which can be predisposed to the disease but has not yet been diagnosed as having it (e.g., including diseases that can be associated with or caused by a primary disease, such as liver fibrosis that can result in the context of chronic HCV infection); (b) inhibiting the disease, i.e., arresting its development; and (c) relieving the disease, i.e., causing regression of the disease (e.g., reducing tumor burden).

[0790] The terms "individual," "host," "subject," and "patient" are used interchangeably herein and refer to an animal, including, but not limited to, humans and non-human primates, including simians and humans; rodents, including rats and mice; bovids; equids; ovines; felines; canines; and the like. "Mammal" means one or more members of any mammalian species, and includes, by way of example, canines; felines; equids; bovids; ovines; rodents; and the like, as well as primates (e.g., non-human primates) and humans. Non-human animal models, e.g., mammals, e.g., non-human primates, murines, lagomorphs, and the like, can be used for experimental studies.

[0791] A "therapeutically effective amount" or "effective amount" refers to the amount of a compound that, when administered to a mammal or other subject for treating a disease, disorder, or condition, is sufficient to effect treatment for that disease, disorder, or condition. The "therapeutically effective amount" will vary depending on the compound, the disease and its severity, and the age, weight, etc., of the subject to be treated.

[0792] Unless specifically indicated otherwise, where compounds can exist in alternative tautomeric, regioisomeric, and / or stereoisomeric forms, all alternative isomers are intended to be encompassed within the scope of the claimed subject matter. For example, where a compound is described as a specific optical isomer, D- or L-, both optical isomers are encompassed herein. For example, where a compound is described as having one of two tautomeric forms, both tautomers are intended to be encompassed herein. Thus, the compounds provided herein can be enantiomerically pure, or stereoisomeric or diastereomeric mixtures. The compounds provided herein can contain chiral centers. Such chiral centers can have the (R) or (S) configuration, or can be a mixture thereof. The chiral centers of the compounds provided herein can be epimerized in vivo. As such, one of skill in the art will recognize that administration of a compound in its (R) form is equivalent to administration of the compound in its (S) form, and the like, for compounds that are epimerized in vivo.

[0793] The present disclosure also encompasses all suitable isotopic variations of a compound of the disclosure, whether radioactive or not. An isotopic variation of a compound of the disclosure is understood to mean a compound of the disclosure in which at least one atom has been exchanged for another atom of the same atomic number but different atomic mass, but an atomic mass that is different from that which normally or predominantly occurs in nature. Examples of isotopes that can be incorporated into a compound of the disclosure are isotopes of hydrogen, carbon, nitrogen, oxygen, fluorine, chlorine, bromine and iodine, such as 2 H (deuterium), 3 H (tritium), 13 C, 14 C,15 N, 17 O, 18 O, 18 F, 36 Cl, 82 Br, 123 I, 124 I, 125 I, 129 I and 131 I. Particular isotopic variants of the compounds according to the present disclosure, particularly those in which one or more radioactive isotopes have been incorporated, are also within the scope of the present disclosure. For example, it can be beneficial to use compounds for imaging or quantifying the amount of the compound in the body of a subject. Such isotopically enriched compounds are still intended to be encompassed by the scope of the present disclosure. 3 H, 14 C and / or 18 F. Isotopically-labeled compounds are useful in this regard. In addition, incorporation of isotopes such as deuterium can afford certain therapeutic advantages resulting from greater metabolic stability, for example, increased in vivo half-life or reduced dosage requirements. In some embodiments, hydrogen atoms of the compounds described herein can be replaced by deuterium atoms. In certain embodiments, “deuterated” applied to a chemical group means that the chemical group is enriched in deuterium in an amount substantially greater than its natural abundance, unless otherwise indicated. Isotopic variants of the compounds according to the present disclosure can be prepared by various methods, including for example, the methods described below and in the working examples.

[0794] Accordingly, any of the embodiments described herein are intended to include salts, single stereoisomers, mixtures of stereoisomers, and / or isotopic forms of the compounds.

[0795] “Pharmaceutically acceptable excipient,” “pharmaceutically acceptable diluent,” “pharmaceutically acceptable carrier,” and “pharmaceutically acceptable adjuvant” mean an excipient, diluent, carrier and adjuvant that is useful in preparing a pharmaceutical composition manipulated safely, and that is generally non-toxic and biologically or otherwise, and includes an excipient, diluent, carrier and adjuvant that is acceptable for veterinary use as well as human pharmaceutical use. “Pharmaceutically acceptable excipient, diluent, carrier and adjuvant” as used in the specification and claims includes one and more than one such excipient, diluent, carrier and adjuvant.

[0796] “Pharmaceutical composition” is intended to encompass compositions suitable for the delivery of compounds to subjects such as mammals, especially humans. Typically, the “pharmaceutical composition” will be sterile, and preferably free of contaminants that interfere with the desired effects in the subject (e.g., the compounds in the pharmaceutical composition are pharmaceutical grade). The pharmaceutical composition can be designed for administration to a subject or patient in need thereof via a variety of different routes of administration, including oral, buccal, rectal, parenteral, intraperitoneal, intradermal, intratracheal, intramuscular, subcutaneous, and the like.

[0797] The term “pharmaceutically acceptable” means approved by a regulatory agency of the Federal or a state government or listed in the U.S. Pharmacopeia, European Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans.

[0798] The term “pharmaceutically acceptable salt” refers to those salts which are appropriate for use in contact with the tissues of humans and lower animals without undue toxicity, irritation, allergic response, and the like, and are commensurate with a reasonable benefit / risk ratio. Pharmaceutically acceptable salts are well known in the art. For example, S. M. Berge et al., describe pharmaceutically acceptable salts in detail in J. Pharmaceutical Sciences, 66: 1-19 (1977). Salts can be prepared in situ during the final isolation and purification of the conjugate compounds, or separately by reacting the free base function or group of a compound with a suitable organic acid. Examples of pharmaceutically acceptable salts include, but are not limited to, nontoxic acid addition salts, or salts of amino groups formed with inorganic acids.

[0799] “Acyl” refers to the group H-C(O)-, alkyl-C(O)-, substituted alkyl-C(O)-, alkenyl-C(O)-, substituted alkenyl-C(O)-, alkynyl-C(O)-, substituted alkynyl-C(O)-, cycloalkyl-C(O)-, substituted cycloalkyl-C(O)-, cycloalkenyl-C(O)-, substituted cycloalkenyl-C(O)-, aryl-C(O)-, substituted aryl-C(O)-, heteroaryl-C(O)-, substituted heteroaryl-C(O)-, heterocyclyl-C(O)-, and substituted heterocyclyl-C(O)-, wherein alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocyclyl, and substituted heterocyclyl are as defined herein. For example, acyl includes the “acetyl” group CH3C(O)-

[0800] The term "alkyl" means a branched or unbranched saturated hydrocarbon group (i.e., a monoradical) typically, but not necessarily, containing from 1 to about 24 carbon atoms, such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl, and the like. Typically, but not necessarily, alkyl groups herein can contain from 1 to about 18 carbon atoms, and such groups can contain from 1 to about 12 carbon atoms. The term "lower alkyl" means an alkyl group having from 1 to 6 carbon atoms. "Substituted alkyl" means an alkyl group substituted with one or more substituent groups, and this includes the case where two hydrogen atoms from the same carbon atom are replaced by substituents in an alkyl substituent (i.e., a substituted alkyl group can include a -C(=0)- moiety). The terms "heteroatom-containing alkyl" and "heteroalkyl" mean an alkyl substituent in which at least one carbon atom is replaced by a heteroatom, as described in further detail below. The terms "alkyl" and "lower alkyl" include linear, branched, cyclic, unsubstituted, substituted, and / or heteroatom-containing alkyl or lower alkyl groups, respectively, unless otherwise indicated.

[0801] The term "substituted alkyl" means to include alkyl groups as defined herein in which one or more carbon atoms in the alkyl chain are optionally replaced by a heteroatom, such as -0-, -N-, -S-, -S(0)n- (where n is 0 to 2), -NR- (where R is hydrogen or alkyl) and have from 1 to 5 substituents selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, aminoacyl, aminoacyloxy, oxyaminoacyl, azido, cyano, halogen, hydroxyl, oxo, thioketo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocyclooxy, sulfenyl, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclooxy, hydroxyamino, alkoxyamino, nitro, -SO-alkyl, -SO-aryl, -SO-heteroaryl, -S02-alkyl, -S02-aryl, -S02-heteroaryl, and -NRaRb; wherein R' and R" can be the same or different and are selected from hydrogen, optionally substituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, heteroaryl, and heterocycle.

[0802] The term "alkenyl" refers to straight-chain, branched, or cyclic hydrocarbon groups with 2 to about 24 carbon atoms that contain at least one double bond, such as ethenyl, n- propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, icosyenyl, tetracosyenyl, and the like. Typically, although not necessarily, alkenyl groups herein can contain 2 to about 18 carbon atoms, and such groups can further contain 2 to 12 carbon atoms. The term "lower alkenyl" means alkenyl groups having 2 to 6 carbon atoms. The term "substituted alkenyl" refers to alkenyl groups that are substituted with one or more substituent groups, and the terms "heteroatom-containing alkenyl" and "heteroalkenyl" refer to alkenyl groups in which at least one carbon atom is replaced with a heteroatom. The terms "alkenyl" and "lower alkenyl" include straight chain, branched chain, cyclic, unsubstituted, substituted, and / or heteroatom-containing alkenyl and lower alkenyl groups, respectively, unless otherwise indicated.

[0803] The term "alkynyl" refers to straight-chain or branched hydrocarbon groups of 2 to 24 carbon atoms that contain at least one triple bond, such as ethynyl, n-propynyl, and the like. Typically, although not necessarily, alkynyl groups herein can contain 2 to about 18 carbon atoms, and such groups can further contain 2 to 12 carbon atoms. The term "lower alkynyl" means alkynyl groups having 2 to 6 carbon atoms. The term "substituted alkynyl" refers to alkynyl groups that are substituted with one or more substituent groups, and the terms "heteroatom-containing alkynyl" and "heteroalkynyl" refer to alkynyl groups in which at least one carbon atom is replaced with a heteroatom. The terms "alkynyl" and "lower alkynyl" include straight chain, branched chain, unsubstituted, substituted, and / or heteroatom-containing alkynyl and lower alkynyl groups, respectively, unless otherwise indicated.

[0804] The term "alkoxy" refers to an alkyl group bonded through a single terminal ether linkage; that is, an "alkoxy" group can be represented as -O-alkyl, where alkyl is as defined above. A "lower alkoxy" group refers to an alkoxy group containing 1 to 6 carbon atoms and includes, for example, methoxy, ethoxy, n-propyloxy, isopropyloxy, t-butyloxy, and the like. Substituents herein considered to be "Ci-C6alkoxy" or "lower alkoxy" can contain, for example, 1 to 3 carbon atoms, and as further examples, such substituents can contain 1 or 2 carbon atoms (i.e., methoxy and ethoxy).

[0805] The term "substituted alkoxy" refers to the groups substituted alkyl-O-, substituted alkenyl-O-, substituted cycloalkyl-O-, substituted cycloalkenyl-O-, and substituted alkynyl-O-, where substituted alkyl, substituted alkenyl, substituted cycloalkyl, substituted cycloalkenyl, and substituted alkynyl are as defined herein.

[0806] The term "aryl" refers to an aromatic substituent, which typically (but not necessarily) contains 5 to 30 carbon atoms and includes a single aromatic ring or multiple aromatic rings that are fused, directly linked, or indirectly linked (such that different aromatic rings are bound to a common group, such as a methylene or ethylene moiety). An aryl group may, for example, contain 5 to 20 carbon atoms, and as a further example, an aryl group can contain 5 to 12 carbon atoms. For example, an aryl group can contain one aromatic ring or two or more fused or linked aromatic rings (i.e., biaryl, aryl-substituted aryl, etc.). Examples include phenyl, naphthyl, biphenyl, diphenyl ether, diphenylamine, benzophenone, and the like. "Substituted aryl" refers to an aryl moiety that is substituted with one or more substituent groups, and the terms "heteroatom-containing aryl" and "heteroaryl" refer to aryl substituents in which at least one carbon atom is replaced with a heteroatom, as will be described in further detail below. Aryl is intended to include stable cyclic, heterocyclic, polycyclic, and polyheterocyclic unsaturated C3-C30 14 moieties such as, but not limited to, phenyl, biphenyl, naphthyl, pyridyl, furanyl, thiophenyl, imidazolyl, pyrimidinyl, and oxazolyl; the aryl group can be further substituted with one to five members selected from the group consisting of C1-C8alkoxy, C1-C8branched or straight chain alkyl, acyloxy, carbamoyl, amino, N-acylamino, nitro, halogen, trifluoromethyl, cyano, and carboxy (see, e.g., Katritzky, Handbook of Heterocyclic Chemistry). If not otherwise specified, the term "aryl" includes unsubstituted, substituted, and / or heteroatom-containing aromatic substituents.

[0807] The term "aralkyl" refers to an alkyl group bearing an aryl substituent, and the term "alkaryl" refers to an aryl group bearing an alkyl substituent, wherein "alkyl" and "aryl" are as defined above. Typically, aralkyl and alkaryl groups herein contain 6 to 30 carbon atoms. An aralkyl and alkaryl group may, for example, contain 6 to 20 carbon atoms, and as a further example, such groups can contain 6 to 12 carbon atoms.

[0808] The term "alkylene" refers to a diradical alkyl group. Unless otherwise specified, such groups comprise a saturated hydrocarbon chain containing 1 to 24 carbon atoms, which can be substituted or unsubstituted, can contain one or more alicyclic groups, and can be heteroatom-containing. "Lower alkylene" refers to an alkylene bond containing 1 to 6 carbon atoms. Examples include methylene (--CH2--), ethylene (--CH2CH2--), propylene (--CH2CH2CH2--), 2-methylpropylene (--CH2--CH(CH3)--CH2--), hexylene (--(CH2)6--), and the like.

[0809] Similarly, the terms "alkylene," "alkynylene," "arylene," "aralkylene," and "alkarylene" refer to divalent radical alkyl, alkynyl, aryl, aralkyl, and alkaryl groups, respectively.

[0810] The term "amino" refers to the group -NRR', where R and R' are independently hydrogen or non-hydrogen substituents, including, for example, alkyl, aryl, alkenyl, aralkyl, and substituted and / or heteroatom-containing variations thereof.

[0811] The terms "halo" and "halogen" refer to a chloro, bromo, fluoro, or iodo substituent, in the conventional sense.

[0812] "Carboxyl" or "carboxy" refers to -CO2H or salts thereof.

[0813] "Cycloalkyl" refers to cyclic alkyl groups having from 3 to 10 carbon atoms, with single or multiple rings, including fused, bridged, and spiro ring systems. Examples of suitable cycloalkyl groups include, for example, adamantyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclooctyl, and the like. Such cycloalkyl groups include, for example, monocyclic structures such as cyclopropyl, cyclobutyl, cyclopentyl, cyclooctyl, and the like, or polycyclic structures such as adamantyl, and the like.

[0814] The term "substituted cycloalkyl" refers to a cycloalkyl group as defined herein having from 1 to 5 substituents or from 1 to 3 substituents selected from the group consisting of alkyl, substituted alkyl, alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, substituted amino, amino acyl, amino acyloxy, oxyamino acyl, azido, cyano, halogen, hydroxyl, oxo, thioxo, carboxyl, carboxylalkyl, thioaryloxy, thioheteroaryloxy, thioheterocycloxy, sulfenyl, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocycloxy, hydroxyamino, alkoxyamino, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -SO2-alkyl, -SO2-substituted alkyl, -SO2-aryl, and -SO2-heteroaryl.

[0815] The term "heteroatom-containing" as in "heteroatom-containing alkyl group" (also referred to as "heteroalkyl" group) or "heteroatom-containing aryl group" (also referred to as "heteroaryl" group) refers to a molecule, bond, or substituent in which one or more carbon atoms are replaced by an atom other than carbon, such as nitrogen, oxygen, sulfur, phosphorus, or silicon, typically nitrogen, oxygen, or sulfur. Similarly, the term "heteroalkyl" refers to a heteroatom-containing alkyl substituent, the term "heterocycloalkyl" refers to a heteroatom-containing cycloalkyl substituent, the term "heterocyclic" or "heterocycle" refers to a heteroatom-containing cyclic substituent, the terms "heteroaryl" and "heteroaromatic" refer to a heteroatom-containing "aryl" and "aromatic" substituent, respectively, and the like. Examples of heteroalkyl groups include alkoxyaryl, alkylthioalkyl-substituted alkyl, N-alkylated aminoalkyl, and the like. Examples of heteroaryl substituents include pyrrolyl, pyrrolidinyl, pyridyl, quinolyl, indolyl, furanyl, pyrimidinyl, imidazolyl, 1,2,4-triazolyl, tetrazolyl, and the like, and examples of heteroatom-containing alicyclic groups are pyrrolidinyl, morpholino, piperazinyl, piperidinyl, tetrahydrofuranyl, and the like.

[0816] "Heteroaryl" refers to an aromatic group having 1 to 15 carbon atoms, such as 1 to 10 carbon atoms and 1 to 10 heteroatoms selected from the group consisting of oxygen, nitrogen, and sulfur, within the ring. Such heteroaryl groups can have a single ring (e.g., pyridinyl, imidazolyl, or furanyl) or multiple condensed rings (e.g., in groups such as indolizinyl, quinolinyl, benzofuranyl, benzimidazolyl, or benzothiophenyl) in which at least one ring is aromatic, provided that the point of attachment is through an atom of the aromatic ring. In certain embodiments, the nitrogen and / or sulfur ring atoms of the heteroaryl group are optionally oxidized to provide an N-oxide (N→O), sulfinyl, or sulfonyl moiety. The term includes, for example, pyridinyl, pyrrolyl, indolyl, thiophenyl, and furanyl. Unless otherwise constrained by the definition, such heteroaryl groups can be optionally substituted with 1 to 5 substituents or 1 to 3 substituents selected from acyloxy, hydroxy, thioxy, acyl, alkyl, alkoxy, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, substituted alkyl, substituted alkoxy, substituted alkenyl, substituted alkynyl, substituted cycloalkyl, substituted cycloalkenyl, amino, substituted amino, aminoacyl, acylamino, alkylaryl, aryl, aryloxy, azido, carboxy, carboxyalkyl, cyano, halo, nitro, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclyloxy, aminoacyloxy, oxoacylamino, thioalkoxy, substituted thioalkoxy, thioaryloxy, thioheteroaryloxy, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -SO2-alkyl, -SO2-substituted alkyl, -SO2-aryl, and -SO2-heteroaryl, and trihalomethyl.

[0817] The terms "heterocycle," "heterocyclic," and "heterocyclyl" refer to a monocyclic or multiple condensed saturated or unsaturated ring, including fused bridged and spiro ring systems, and having from 3 to 15 ring atoms, including from 1 to 4 heteroatoms. The ring heteroatoms are selected from nitrogen, sulfur, and oxygen, wherein, in a fused ring system, one or more rings can be cycloalkyl, heterocycloalkyl, aryl, or heteroaryl, provided the point of attachment is through a non-aromatic ring. In certain embodiments, the nitrogen and / or sulfur atoms of the heterocyclyl group are optionally oxidized to provide N-oxide, -S(O)-, or -SO2- moieties.

[0818] Examples of heterocycles and heteroaryls include, but are not limited to, azetidine, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole, indole, indoline, indazole, purine, quinolizine, isoquinolizine, quinoline, phtalazine, naphthpyridine, quinoxaline, quinazoline, cinnoline, pteridine, carbazole, carbolin, phenanthridine, acridine, phenanthrolin, isothiazole, phenoxazine, isoxazole, phenothiazine, imidazolidine, imidazoline, piperidine, piperazine, indoline, phthalimide, 1,2,3,4-tetrahydroisoquinoline, 4,5,6,7-tetrahydrobenzo[b]thiophene, thiazole, thiazolidine, thiophene, benzo[b]thiophene, morpholino, thiomorpholino (also known as thiamorpholino), piperidino, pyrrolidine, tetrahydrofuranyl, and the like.

[0819] Unless otherwise constrained by the definition of a heterocyclic substituent, such heterocyclic groups can be optionally substituted with 1 to 5 or 1 to 3 substituents selected from the group consisting of alkoxy, substituted alkoxy, cycloalkyl, substituted cycloalkyl, cycloalkenyl, substituted cycloalkenyl, acyl, acylamino, acyloxy, amino, substituted amino, amino acyl, amino acyloxy, oxyamino acyl, azido, cyano, halogen, hydroxyl, oxo, thioxo, carboxyl, carboxylalkyl, thioaralkyoxy, thioheteroaralkyoxy, thioheterocyclyloxy, sulfido, thioalkoxy, substituted thioalkoxy, aryl, aryloxy, heteroaryl, heteroaryloxy, heterocyclyl, heterocyclyloxy, hydroxyamino, alkoxyamino, nitro, -SO-alkyl, -SO-substituted alkyl, -SO-aryl, -SO-heteroaryl, -SO2-alkyl, -SO2-substituted alkyl, -SO2-aryl, -SO2-heteroaryl, and a fused heterocyclic ring.

[0820] "Heteroatom-containing hydrocarbyl" means a hydrocarbyl group in which at least one carbon atom is replaced with a heteroatom. Unless otherwise specified, the term "hydrocarbyl" should be interpreted as including substituted and / or heteroatom-containing hydrocarbyl moieties.

[0821] "Substituted," as mentioned in some of the foregoing definitions, such as "substituted hydrocarboxy," "substituted alkyl," "substituted aryl," and the like, means that at least one hydrogen atom in the hydrocarboxy, alkyl, aryl, or other moiety is replaced with one or more non-hydrogen substituents. Examples of such substituents include, but are not limited to, functional groups and hydrocarbyl moieties C1-C24 alkyl (including C1-C18 alkyl, further including C1-C12 alkyl, and further including C1-C6 alkyl), C2-C24 alkenyl (including C2-C18 alkenyl, further including C2-C12 alkenyl, and further including C2-C6 alkenyl), C2-C24 alkynyl (including C2-C18 alkynyl, further including C2-C12 alkynyl, and further including C2-C6 alkynyl), C5-C30 aryl (including C5-C20 aryl, and further including C5-C12 aryl), and C6-C30 aralkyl (including C6-C20 aralkyl, and further including C6-C12 aralkyl). The above hydrocarbyl moieties can be further substituted by one or more functional groups or other hydrocarbyl moieties, such as those specifically listed. Unless otherwise indicated, any of the groups described herein are to be understood to include, in addition to unsubstituted groups, substituted and / or heteroatom-containing moieties, unless otherwise indicated.

[0822] "Sulfonyl" means SO2-alkyl, SO2-substituted alkyl, SO2-alkenyl, SO2-substituted alkenyl, SO2-cycloalkyl, SO2-substituted cycloalkyl, SO2-cycloalkenyl, SO2-substituted cycloalkenyl, SO2-aryl, SO2-substituted aryl, SO2-heteroaryl, SO2-substituted heteroaryl, SO2-heterocycle, and SO2-substituted heterocycle, wherein alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, substituted cycloalkyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, heterocycle, and substituted heterocycle are as defined herein. Sulfonyl includes, for example, methyl-SO2-, phenyl-SO2-, and 4-methylphenyl-SO2-.

[0823] The term "functional group" means a chemical group such as halo, hydroxyl, thio, Ci-C24alkoxy, C2-C24alkenyloxy, C2-C24alkynyloxy, C5-C20aryloxy, acyl (including C2-C24alkylcarbonyl (-CO-alkyl) and C6-C20arylcarbonyl (-CO-aryl)), acyloxy (-0-acyl), C2-C24alkoxycarbonyl (-(CO)-0-alkyl), C6-C20aryloxycarbonyl (-(CO)-0-aryl), halocarbonyl (-CO)-X, where X is halo), C2-C24alkylcarbonato (-0-(CO)-0-alkyl), C6-C20arylcarbonato (-0-(CO)-0-aryl), carboxyl (-COOH), carboxylato (-COO-), carbamoyl (-(CO)-NH2), mono-substituted C1-C24alkylcarbamoyl (-(CO)-NH(C1-C24alkyl)), di-substituted alkylcarbamoyl (-(CO)-N(C1-C24alkyl)2), mono-substituted arylcarbamoyl (-(CO)-NH-aryl), thiocarbamoyl (-(CS)-NH2), ureido (-NH-(CO)-NH2), cyano (-C≡N), isocyano (-N+≡C-), cyanato (-0-C≡N), isocyanato (-0-N+≡C-), isothiocyano (-S-C≡N), azido (-N=N+ =N-), formyl (-(CO)-H), thioformyl (-(CS)-H), amino (-NH2), mono- and di(C1-C24alkyl)-substituted amino, mono- and di(C5-C20aryl)-substituted amino, C2-C24alkylamino (-NH-(CO)-alkyl), C5-C20arylamino (-NH-(CO)-aryl), imino (-CR=NH, where R = hydrogen, C1-C24alkyl, C5-C20aryl, C6-C20alkylaryl, C6-C20arylalkyl, etc.), alkylimino (-CR=N(alkyl), where R = hydrogen, alkyl, aryl, alkylaryl, etc.), arylimino (-CR=N(aryl), where R = hydrogen, alkyl, aryl, alkylaryl, etc.), nitro (-NO2), nitroso (-NO), sulfo (-SO2-OH), sulfato (-SO2-O-), C1-C24alkylsulfonyl (-S-alkyl; also known as "alkylthio"), arylsulfonyl (-S-aryl;Also known as "arylthio"), C1-C24alkylsulfinyl (-(SO)-alkyl), C5-C20arylsulfinyl (-(SO)-aryl), C1-C24alkylsulfonyl (-SO2-alkyl), C5-C20arylsulfonyl (-SO2-aryl), phosphono (-P(O)(OH)2), phospho (-P(O)(O-)2), hypophosphorous (-P(O)(O-)), dioxo (-PO2), and phosphino (-PH2), mono- and di(C1-C24alkyl)-substituted phosphino, mono- and di(C5-C20aryl)-substituted phosphino. Additionally, the foregoing functional groups can be further substituted with one or more additional functional groups or one or more hydrocarbyl moieties, such as those specifically listed above, if the particular group permits.

[0824] "Link" or "linker" in the context of "linking group," "linking moiety," and the like means a linking moiety that connects two groups via a covalent bond. The linker can be straight-chained, branched, cyclic, or single-atom. Examples of such linking groups include alkyl, alkenylene, alkynylene, arylene, alkarylene, aralkylene, and functional group-containing linking moieties, including but not limited to: amido (-NH-CO-), ureylene (-NH-CO-NH-), imido (-CO-NH-CO-), epoxy (-O-), thio (-S-), dioxy (-O-O-), carbonyldioxy (-O-CO-O-), alkyldioxy (-O-(CH2)n-O-), oxylimino (-O-NH-), imino (-NH-), carbonyl (-CO-), and the like. In some cases, one, two, three, four, or five or more carbon atoms of the linker backbone can be optionally replaced with a sulfur, nitrogen, or oxygen heteroatom. The bonds between the backbone atoms can be saturated or unsaturated, typically there are no more than one, two, or three unsaturated bonds in the linker backbone. The linker can comprise one or more substituent groups, e.g., alkyl, aryl, or alkenyl groups. Linkers include, but are not limited to: poly(ethylene glycol) units (e.g., -(CH2-CH2-O)-); ethers, thioethers, amines, alkyl (e.g., (C1-C 12 )alkyl groups, which can be straight-chained or branched, e.g., methyl, ethyl, n-propyl, 1-methylethyl (isopropyl), n-butyl, n-pentyl, 1,1-dimethylethyl (tert-butyl), and the like. The linker backbone can comprise a cyclic group, e.g., an aryl, heterocycle, or cycloalkyl group, wherein 2 or more atoms (e.g., 2, 3, or 4 atoms) of the cyclic group are included in the backbone. The linker can be cleavable or non-cleavable. Any convenient orientation and / or linkage of the linker to the connected groups can be used.

[0825] When the term "substituted" is preceded by "optionally," the term "substituted" is optional. When the term "substituted" precedes a list of possible substituents, it is intended that the term apply to each member of the group that is substituted. For example, the phrase "substituted alkyl and aryl groups" is to be interpreted as "substituted alkyl and substituted aryl."

[0826] In addition to the disclosure herein, the term "substituted" when used in reference to a particular group or radical, can also mean that one or more hydrogen atoms of the particular group or radical are each independently replaced with the same or different substituent as defined below.

[0827] In addition to the groups disclosed herein for each term, unless otherwise indicated, the group of substituents for replacing one or more hydrogens on a saturated carbon atom in a specified group or radical (any two hydrogens on a single carbon atom can be replaced by =0, =NR 70 , =N-OR 70 , =N2, or =S) is -R 60 , halo, =0, -OR 70 , -SR 70 , -NR 80 R 80 , -CN, -OCN, -SCN, -NO, -NO2, =N2, -N3, -SO2R 70 , -SO2O – M + , -SO2OR 70 , -OSO2R 70 , -OSO2O – M + , -OSO2OR 70 , -P(O)(O – )2(M + )2, -P(O)(OR 70 )O – M + , -P(O)(OR 70 )2, -C(O)R 70 , -C(S)R 70 , -C(NR 70 )R 70 , -C(O)O – M + , -C(O)OR 70 , -C(S)OR 70 , -C(O)NR 80 R 80 , -C(NR 70 )NR 80 R 80 , -OC(O)R 70 , -OC(S)R 70-OC(O)O - M + -OC(O)OR 70 -OC(S)OR 70 -NR 70 C(O)R 70 -NR 70 C(S)R 70 -NR 70 CO2 – M + -NR 70 CO2R 70 -NR 70 C(S)OR 70 -NR 70 C(O)NR 80 R 80 -NR 70 C(NR 70 )R 70 -NR 70 C(NR 70 )NR 80 R 80 wherein R 60 is selected from the group consisting of optionally substituted alkyl, cycloalkyl, heteroalkyl, heterocycloalkylalkyl, cycloalkylalkyl, aryl, arylalkyl, heteroaryl, and heteroarylalkyl, each R 70 is independently hydrogen or R 60 ; each R 80 is independently R 70 , or alternatively, two R 80’ together with the nitrogen atom to which they are bonded form a 5-, 6-, or 7-membered heterocycloalkyl group, which can optionally include 1 to 4 additional heteroatoms selected from the group consisting of O, N, and S, wherein N can have a -H or C1-C3 alkyl substitution; and each M + is a counterion having a net single positive charge. Each M + may independently be, for example, an alkali metal ion such as K + , Na + , Li + ; an ammonium ion such as + N(R 60 )4; or an alkaline earth ion such as [Ca 2+ ] 0.5 , [Mg 2+ ] 0.5 , or [Ba 2+ ] 0.5(The subscript 0.5 indicates that one of the counterions for such divalent alkaline earth ions may be the ionized form of the compound of the present invention, while the other is a typical counterion such as chloride, or that two ionized compounds disclosed herein may serve as counterions for such divalent alkaline earth ions, or that a doubly ionized compound of the present invention may serve as counterions for such divalent alkaline earth ions.) As a specific example, -NR 80 R 80 It is meant to include -NH2, -NH-alkyl, N-pyrrolidinyl, N-piperazinyl, 4N-methyl-piperazin-1-yl and N-morpholinyl.

[0828] Except as otherwise disclosed herein, a substituent group for a hydrogen on an unsaturated carbon atom in a "substituted" alkene, alkyne, aryl, and heteroaryl group is -R 60 , halogenated, -O - M + 、-OR 70 、-SR 70 、-S – M + 、-NR 80 R 80 , trihalomethyl, -CF3, -CN, -OCN, -SCN, -NO, -NO2, -N3, -SO2R 70 、-SO3 – M + 、-SO3R 70 、-OSO2R 70 、-OSO3 – M + 、-OSO3R 70 、-PO3 -2 (M + )2、-P(O)(OR 70 )O – M + 、-P(O)(OR 70 )2、-C(O)R 70 、-C(S)R 70 、-C(NR 70 )R 70 、-CO2 – M + 、-CO2R 70 、-C(S)OR 70 、-C(O)NR 80 R 80 、-C(NR 70 )NR 80 R 80 、-OC(O)R 70 、-OC(S)R 70-OCO2 – M + -OCO2R 70 -OC(S)OR 70 -NR 70 C(O)R 70 -NR 70 C(S)R 70 -NR 70 CO2 – M + -NR 70 CO2R 70 -NR 70 C(S)OR 70 -NR 70 C(O)NR 80 R 80 -NR 70 C(NR 70 )R 70 and -NR 70 C(NR 70 )NR 80 R 80 wherein R 60 , R 70 , R 80 and M + are as previously defined, with the proviso that in the case of substituted alkenes or alkynes the substituents are other than -O - M + , -OR 70 , -SR 70 or -S – M + .

[0829] In addition to the groups disclosed for the various terms herein, unless otherwise indicated, substituents for the hydrogen on a nitrogen atom in a "substituted" heteroalkyl and cycloheteroalkyl group are -R 60 , -O - M + , -OR 70 , -SR 70 , -S - M + , -NR 80 R 80 , trihalomethyl, -CF3, -CN, -NO, -NO2, -S(O)2R 70 , -S(O)2O - M + , -S(O)2OR 70 , -OS(O)2R 70 , -OS(O)2O - M +-OS(O)2OR 70 -OS(O)2OR - -OS(O)2OR + -OS(O)2OR 70 -OS(O)2OR - -OS(O)2OR + -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 80 -OS(O)2OR 80 -OS(O)2OR 70 -OS(O)2OR 80 -OS(O)2OR 80 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 80 -OS(O)2OR 80 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 70 -OS(O)2OR 80 -OS(O)2OR 80 -OS(O)2OR 60 -OS(O)2OR 70 -OS(O)2OR 80 -OS(O)2OR +

[0830] In addition to the disclosure herein, in a certain embodiment, a substituted group has 1, 2, 3, or 4 substituents, 1, 2, or 3 substituents, 1 or 2 substituents, or 1 substituent.

[0831] ​Unless otherwise indicated, the nomenclature for substitutents not defined herein is established according to Section 9.3.1 of the IUPAC Blue Book. The nomenclature for substitutents defined herein is established according to the nomenclature rules agreed upon by the IUPAC-Higher Education Commission Nomenclature Committee and the Chemical Abstracts Service (CAS). For example, the substitutent "arylalkyloxycarbonyl" refers to the group (aryl)-(alkyl)-0-C(O)-.

[0832] For any group disclosed herein that contains one or more substituents, it is understood that such groups do not contain any substituents or substitutent patterns that are spatially impractical or synthetically unfeasible. In addition, subject compounds include all stereochemical isomers resulting from the substitutents of these compounds.

[0833] In certain embodiments, substitutents can contribute to optical isomerism and / or stereoisomerism of the compounds. Salts, solvates, hydrates, and prodrug forms of the compounds are also of interest. The disclosure includes all such forms. Thus, the compounds described herein include their salts, solvates, hydrates, prodrugs, and isomeric forms, including their pharmaceutically acceptable salts, solvates, hydrates, prodrugs, and isomers. In certain embodiments, the compounds can be metabolized into pharmaceutically active derivatives.

[0834] Unless otherwise indicated, a reference to an atom means to include isotopes of that atom. For example, a reference to H means to include 1 H, 2 H (i.e., D), and 3 H (i.e., T), and a reference to C means to include 12 C, and all isotopes of carbon, such as 13 C.

[0835] Unless otherwise indicated, the term "about" or "approximately" means acceptable error for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined. In certain embodiments, the term "about" or "approximately" means within 1, 2, or 3 standard deviations. In certain embodiments, the term "about" or "approximately" means within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.4%, 0.3%, 0.25%, 0.2%, 0.1%, or 0.05% of a given value or range. In certain embodiments, where an integer is required, the term "about" means within plus or minus 10% of a given value or range, rounded up or down to the nearest integer.

[0836] In the specification, if there is any discrepancy between the chemical name and the chemical structure, the chemical structure controls.

[0837] Definitions for other terms and concepts appear throughout the DETAILED DESCRIPTION.

[0838] M6PR-binding compounds and conjugates are described in International Application No. PCT / US2021 / 012846, filed January 8, 2021, the disclosure of which is incorporated by reference herein in its entirety.

[0839] 4.11. Additional Embodiments

[0840] Additional embodiments of the present disclosure are also described in the following clauses.

[0841] Clause 1. A cell surface mannose-6-phosphate receptor (M6PR)-binding compound of the following formula:

[0842]

[0843] or a salt thereof, wherein:

[0844] each W is independently a hydrophilic head group;

[0845] each Z 1 is independently selected from optionally substituted (C1-C3)alkylene and optionally substituted vinylene;

[0846] each Z 2 is independently selected from O, S, NR 21 , and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl;

[0847] each Ar is independently an optionally substituted aryl or heteroaryl linking moiety (e.g., an optionally substituted monocyclic or bicyclic aryl or heteroaryl);

[0848] each Z 3 is independently a linking moiety;

[0849] n is 1 to 500;

[0850] L is a linker; and

[0851] Y is a moiety of interest;

[0852] wherein when m is 1 and Ar is phenyl, then: i) L comprises a backbone of at least 16 contiguous atoms; ii) Y is a biomolecule; and / or ii) Z 3 is an amide, sulfonamide, urea, or thiourea.

[0853] Clause 2. The compound according to Clause 1, wherein each Ar is independently selected from optionally substituted phenyl, optionally substituted pyridyl, optionally substituted biphenyl, optionally substituted naphthalene, optionally substituted triazole, and optionally substituted phenylenetriazole.

[0854] Clause 3. The compound according to clause 2, wherein Ar is selected from optionally substituted 1,4-phenylene, optionally substituted 1,3-phenylene or optionally substituted 2,5-pyridylene.

[0855] Clause 4. The compound according to Clause 3, wherein the compound has one of the following formulae:

[0856]

[0857] or a salt thereof, wherein:

[0858] Each R 11 to R 14 independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR 25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ;and

[0859] Each R 25 are independently selected from H and optionally substituted (C1-C6)alkyl.

[0860] Clause 5. The compound according to Clause 1, wherein Ar is an optionally substituted fused bicyclic aryl or fused bicyclic heteroaryl.

[0861] Item 6. The compound according to Item 5, wherein Ar is optionally substituted naphthalene or optionally substituted quinoline.

[0862] Clause 7. The compound according to Clause 6, wherein the compound has one of the following formulae:

[0863]

[0864] or a salt thereof, wherein:

[0865] Each R 11 and R 13 to R 14 independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ;

[0866] s is 0 to 3; and

[0867] Each R 25 are independently selected from H and optionally substituted (C1-C6)alkyl.

[0868] Clause 8. The compound according to Clause 7, wherein the compound has one of the following formulae:

[0869]

[0870]

[0871] or a salt thereof.

[0872] Clause 9. The compound according to Clause 1, wherein Ar is optionally substituted bicyclic aryl or optionally substituted bicyclic heteroaryl, and the compound has the following formula:

[0873]

[0874] or a salt thereof, wherein:

[0875] Each Cy is independently a monocyclic aryl or a monocyclic heteroaryl;

[0876] Each R 11 to R 15 independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR 25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ;

[0877] s is 0 to 4; and

[0878] Each R 25 are independently selected from H and optionally substituted (C1-C6)alkyl.

[0879] Clause 10. The compound according to Clause 9, wherein Ar is an optionally substituted diphenyl group, Cy is an optionally substituted phenyl group, and the compound has the following formula:

[0880]

[0881] or a salt thereof.

[0882] Clause 11. The compound of clause 10, wherein the compound has one of the following formulae:

[0883] or a salt thereof.

[0884] Clause 12. The compound of any one of clauses 1-10, wherein Ar is substituted with at least one OH substituent.

[0885] Clause 13. The compound of any one of clauses 4, 6, 7, 9, and 10, wherein R 11 to R 15 are each H.

[0886] Clause 14. The compound of any one of clauses 4, 6, 7, 9, and 10, wherein R 11 to R 15 are at least one OH (e.g., at least two are OH).

[0887] Clause 15. The compound of any one of clauses 1-14, wherein:

[0888] Z 3 is selected from a covalent bond, -O-, -NR 23 -, -NR 23 CO-, -CONR 23 -, -NR 23 CO2-, -OCONR 23 -, -NR 23 C(=X 1 )NR 23 -, -CR 24 =N-, -CR 24 =N-X 2 -, -N(R 23 )SO2-, and -SO2N(R 23 )-;

[0889] X 1 and X 2 are selected from O, S, and NR 23 ; and

[0890] R 23 and R 24 are independently selected from H, C (1-3) -alkyl (e.g., methyl), and substituted C (1-3) -alkyl.

[0891] Clause 16. The compound of any one of clauses 1-15, wherein Z 3 is

[0892]

[0893] wherein: X 1 is O or S; t is 0 or 1; and each R 23 is independently selected from H, C (1-3) -alkyl (e.g., methyl), and substituted C (1-3) -alkyl.

[0894] Clause 17. The compound of clause 16, wherein Z 3 is -NHC(=X 1 )NH-, wherein X 1 is O or S.

[0895] Clause 18. The compound of any one of clauses 1 to 14, wherein Ar is a triazole, and the compound has one of the following formulae:

[0896]

[0897] Clause 19. The compound of clause 18, wherein Z 3 is an optionally substituted triazole, and the compound has one of the following formulae:

[0898]

[0899] or a salt thereof,

[0900] wherein:

[0901] each R 11 to R 14 is independently selected from H, halogen, OH, optionally substituted (C1-C6)alkyl, optionally substituted (C1-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 , and -NHCOR 25 ; and

[0902] each R 25 is independently selected from H and optionally substituted (C1-C6)alkyl.

[0903] Clause 20. The compound of any one of clauses 1 to 19, wherein -Ar-Z 3 is selected from:

[0904]

[0905]

[0906]

[0907] Clause 21. The compound of any one of clauses 1-20, wherein m is at least 2 and L is a branched linker covalently linking each Ar group to Y.

[0908] Clause 22. The compound of clause 21, wherein m is 2-20 (e.g., m is 2-6, such as 2 or 3).

[0909] Clause 23. The compound of clause 21, wherein: m is 20-500 (e.g., 20-400, 20-300, or 20-200 or 50-500 or 100-500); and L is an a-amino acid polymer (e.g., poly-L-lysine), wherein a plurality of -Ar-Z 3 groups are covalently linked to the polymer backbone via side chain groups (e.g., via conjugation to a side chain amino group of a lysine residue).

[0910] Clause 24. The compound of any one of clauses 21-23, wherein m is at least 2 and each Z 3 linking moiety is separated from each other Z 3 linking moiety by a chain of at least 16 contiguous atoms (e.g., a chain of at least 20, at least 25, or at least 30 contiguous atoms, and in certain cases, up to 100 contiguous atoms).

[0911] Clause 25. The compound of any one of clauses 1-24, wherein the compound has the following formula:

[0912]

[0913] or a salt thereof, wherein:

[0914] n is 1-500 (e.g., n is 1-20, 1-10, 1-6, or 1-5);

[0915] L 1 to L 7 each independently is a linking moiety, which together provide a linear or branched linker between the n Z 2 groups and Y, wherein -(L 1 ) a comprises a linking moiety Ar, which is an optionally substituted aryl or heteroaryl group;

[0916] a is 1 or 2; and

[0917] b, c, d, e, f, and g are each independently 0, 1, or 2.

[0918] Clause 26. The compound of clause 25, wherein the linear or branched linker separates each Z 2 and Y by a chain of at least 16 contiguous atoms (e.g., at least 20 contiguous atoms, at least 30 contiguous atoms, or 16 to 100 contiguous atoms).

[0919] Clause 27. The compound of any one of clauses 25 to 26, wherein n is 1 to 20.

[0920] Clause 28. The compound of any one of clauses 25 to 27, wherein n is at least 2 (e.g., n is 2 or 3).

[0921] Clause 29. The compound of clause 28, wherein d is >0, and L 4 is a branched linker moiety covalently linked to each L 1 linker moiety.

[0922] Clause 30. The compound of any one of clauses 25 to 29, wherein the compound has the following formula:

[0923]

[0924] wherein:

[0925] Ar is an optionally substituted aryl or heteroaryl group (e.g., a monocyclic, bicyclic, or tricyclic aryl or heteroaryl group);

[0926] Z 11 is a linker moiety (e.g., a covalent bond, a heteroatom, a group of length 1 to 3 atoms of the main chain, or a triazole);

[0927] r is 0 or 1; and

[0928] n is 1 to 6.

[0929] Clause 31. The compound of clause 30, wherein Ar is selected from the group consisting of an optionally substituted phenyl, an optionally substituted pyridyl, an optionally substituted biphenyl, an optionally substituted naphthalene, an optionally substituted quinoline, an optionally substituted triazole, an optionally substituted phenyl-triazole, an optionally substituted biphenyl-triazole, and an optionally substituted naphthalene-triazole.

[0930] Clause 32. The compound of clause 31, wherein Ar is an optionally substituted 1,4- phenylene.

[0931] Clause 33. The compound of any one of clauses 30 to 32, wherein Ar is substituted with at least one hydroxyl group.

[0932] Clause 34. The compound of any one of clauses 25 to 33, wherein L1 or Ar-(Z 11 ) r - selected from:

[0933]

[0934] wherein:

[0935] Cy is monocyclic aryl or heteroaryl;

[0936] r is 0 or 1;

[0937] s is 0 to 4;

[0938] R 11 to R 14 and each R 15 is independently selected from H, halogen, OH, optionally substituted (C1-C6)alkyl, optionally substituted (C1-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 , and -NHCOR 25 , wherein each R 25 is independently selected from H, C (1-6) -alkyl, and substituted C (1-6) -alkyl; and

[0939] Z 11 is selected from a covalent bond, -O-, -NR 23 -, -NR 23 CO-, -CONR 23 -, -NR 23 CO2-, -OCONR 23 -, -NR 23 C(=X 1 )NR 23 -, -CR 24 =N-, -CR 24 =N-X 2 -, and optionally substituted triazole, wherein X 1 and X 2 are selected from O, S, and NR 23 , wherein R 23 and R 24 are independently selected from H, C (1-3) -alkyl (e.g., methyl), and substituted C (1-3) -alkyl.

[0940] Clause 35. The compound of clause 34, wherein L 1 is

[0941]

[0942] Clause 36. The compound of clause 34, wherein L 1 is

[0943]

[0944] Clause 37. The compound of clause 34, wherein R 1 is selected from:

[0945]

[0946] Clause 38. The compound of any one of clauses 34 to 37, wherein r is 0.

[0947] Clause 39. The compound of any one of clauses 34 to 37, wherein r is 1, and Z 11 is selected from -0-, -NR 23 -, -NR 23 CO-, CONR 23 -, -NR 23 CO2-, -OCONR 23 -, -NR 23 C(=X 1 )NR 23 -, -CR 24 =N- and -CR 24 =N-X 2 -, wherein X 1 and X 2 are selected from O, S and NR 23 , and each R 23 and R 24 is independently selected from H, C (1-3) -alkyl (e.g., methyl) and substituted C (1-3) -alkyl.

[0948] Clause 40. The compound of any one of clauses 34 to 37, wherein r is 1, and Z 11 is

[0949] wherein: X 1 is O or S; t is 0 or 1; and each R 23 is independently selected from H, C (1-3) -alkyl (e.g., methyl) and substituted C (1-3) -alkyl.

[0950] Clause 41. The compound of clause 40, wherein Z 11 is -NHC(=X 1 )NH-, wherein X1 is O or S.

[0951] Clause 42. The compound of any one of clauses 34-37, wherein r is 1 and Z 11 is triazole.

[0952] Clause 43. The compound of any one of clauses 1-42, wherein Y is selected from the group consisting of a small molecule, a dye, a fluorophore, a monosaccharide, a disaccharide, a trisaccharide, and a chemoselective linker or a precursor thereof.

[0953] Clause 44. The compound of any one of clauses 1-42, wherein Y is a biomolecule.

[0954] Clause 45. The compound of clause 44, wherein the biomolecule is selected from the group consisting of a peptide, a protein, a polynucleotide, a polysaccharide, a glycoprotein, a lipid, an enzyme, an antibody, and an antibody fragment.

[0955] Clause 46. The compound of any one of clauses 1-45, wherein Y is a moiety that specifically binds a target protein.

[0956] Clause 47. The compound of clause 46, wherein the target protein is a membrane-bound protein.

[0957] Clause 48. The compound of clause 46, wherein the target protein is an extracellular protein.

[0958] Clause 49. The compound of any one of clauses 46-49, wherein Y is selected from the group consisting of an antibody, an antibody fragment (e.g., an antigen-binding fragment of an antibody), a chimeric fusion protein, an engineered protein domain, a D-protein binder of a target protein, an aptamer, a peptide, an enzyme substrate, and a small molecule inhibitor or ligand.

[0959] Clause 50. The compound of clause 49, wherein Y is an antibody or antibody fragment that specifically binds the target protein, and the compound has the following formula:

[0960]

[0961] or a pharmaceutically acceptable salt thereof, wherein:

[0962] n is 1-20;

[0963] m is an average loading of 1-80;

[0964] Ab is an antibody or antibody fragment that specifically binds the target protein; and

[0965] Z is a residue moiety resulting from covalent linkage of a chemoselective linker to a compatible group of Ab.

[0966] Clause 51. The compound of clause 49, wherein Y is a small molecule inhibitor or ligand of the target protein.

[0967] Clause 52. The compound of any one of clauses 1-51, wherein the hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, -OP=O(OH)2, -SP=O(OH)2, -NR 3 P=O(OH)2, -OP=O(SH)(OH), -SP=O(SH)(OH), -OP=S(OH)2, -OP=O(N(R 3 )2)(OH), -OP=O(R 3 )(OH), -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, -(CR 2 R 2 )-P=O(OH)2, -SO2OH (i.e., -SO3H), -S(O)OH, -OSO2OH, -COOH, -CN, -CONH2, -CONHR 3 , 3 R 4 , -CONH(OH), -CONH(OR 3 ), -CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHC(O)CO2H, -NHSO2NHR 3 , -NHC(O)NHS(O)2R 3 , -NHSO2R 3 , -NHSO3H, or a salt thereof,

[0968] wherein: R 1 and R 2 are independently hydrogen, SR3 , halo or CN, and R 3 and R 4 are each independently H, C 1-6 alkyl or substituted C 1-6 alkyl (e.g., -CF3or -CH2CF3); A, B and C are each independently CH or N; and D is each independently O or S.

[0969] Clause 53. The compound of Clause 52, wherein W is selected from -P=O(OH)2, -SO3H, -COOH, and -CH(COOH)2, or a salt thereof.

[0970] Clause 54. The compound of any one of Clauses 1 to 53, wherein: Z 1 is -(CH2) j - or -(C(R 22 )2) j -, wherein each R 22 is independently selected from H, halo (e.g., F), and optionally substituted (C1-C6)alkyl; and j is 1 to 3.

[0971] Clause 55. The compound of any one of Clauses 1 to 53, wherein Z 1 is -CH=CH-.

[0972] Clause 56. The compound of any one of Clauses 1 to 55, wherein Z 2 is O or S.

[0973] Clause 57. The compound of any one of Clauses 1 to 55, wherein Z 2 is -NR 21 -.

[0974] Clause 58. The compound of any one of Clauses 1 to 55, wherein Z 2 is -C(R 22 )2-, wherein each R 22 is independently selected from H, halo (e.g., F), and optionally substituted (C1-C6)alkyl.

[0975] Clause 59. The compound of any one of Clauses 1 to 53, wherein: Z 1 is selected from -(CH2) j -, substituted (C1-C3)alkylene, and -CH=CH-; j is 1 to 3; and Z 2 is selected from O and CH2.

[0976] Clause 60. The compound of Clause 60, wherein Z 1is -(CH2)2-, -CH2-CF2-, or -CH2-CHF-; and Z 2 is O.

[0977] Clause 61. The compound of clause 60, wherein Z 1 is -(CH2)2-, -CH2-CF2-, or -CH2-CHF-; and Z 2 is CH2.

[0978] Clause 62. The compound of clause 60, wherein: Z 1 is -CH=CH-; and Z 2 is O.

[0979] Clause 63. The compound of clause 60, wherein: Z 1 is -CH=CH-; and Z 2 is CH2.

[0980] Clause 64. The compound of any one of clauses 1 to 63, wherein X is selected from:

[0981]

[0982]

[0983] Clause 65. The compound of any one of clauses 25 to 64, wherein n is 1 to 6 (e.g., n is 1 to 5 or 2 to 6 or 1, 2, or 3), and wherein:

[0984] when d is 0, n is 1;

[0985] when d is 1, n is 1 to 3; and

[0986] when d is 2, n is 1 to 6.

[0987] Clause 66. The compound of any one of clauses 25 to 65, wherein:

[0988] each L 2 is independently selected from -C 1-6 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -O(CH2) p -alkylene-, -O(CH2) p -, wherein p is 1 to 10; and

[0989] each L 3 is independently selected from:

[0990] and -(OCH2CH2) q wherein q is 1 to 10, u is 0 to 10, and w is 1 to 10.

[0991] Clause 67. The compound of any one of clauses 25 to 66, wherein when n is 2 or greater, there is at least one L 4 and is a branched linking moiety.

[0992] Clause 68. The compound of any one of clauses 25 to 67, wherein each L 4 is independently selected from:

[0993] -OCH2CH2-,

[0994] wherein each x and y is each independently 1 to 10.

[0995] Clause 69. The compound of any one of clauses 25 to 68, wherein:

[0996] each L 5 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, or -(OCH2CH2) r -;

[0997] each L 6 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene- or -(OCH2CH2) s -;

[0998] each L 7 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, -(OCH2CH2) t - or -OCH2-; and

[0999] r, s, and t are each independently 1 to 20.

[1000] Clause 70. The compound of any one of clauses 25 to 69, wherein a is 1.

[1001] Clause 71. The compound of any one of clauses 25-70, wherein at least one of b, c, e, f, and g is not 0.

[1002] Clause 72. The compound of any one of clauses 25-71, wherein at least one of b or c is not 0, and at least one of e, f, and g is not 0.

[1003] Clause 73. The compound of any one of clauses 25-72, wherein a, b, and c are each independently 1 or 2.

[1004] Clause 74. The compound of any one of clauses 1-73, wherein the linker L is selected from any one of the structures in Tables 2-3.

[1005] Clause 75. The compound of any one of clauses 1-74, wherein the compound is selected from the compounds in Tables 5-9.

[1006] Clause 76. A cell surface receptor-binding conjugate of Formula (I):

[1007] X n -L—Y

[1008] (I)

[1009] or a salt thereof, wherein:

[1010] X is a moiety that binds to a cell surface mannose-6-phosphate receptor (M6PR);

[1011] n is 1 to 500 (e.g., n is 1 to 20, 1 to 10, 1 to 6, or 1 to 5); and

[1012] L is a linker;

[1013] Y is a biomolecule that specifically binds to a target protein.

[1014] Clause 77. The conjugate of clause 76, wherein the conjugate has the following formula:

[1015]

[1016] or a pharmaceutically acceptable salt thereof, wherein:

[1017] n is 1 to 20;

[1018] m is an average loading of 1 to 80;

[1019] Ab is an antibody or antibody fragment that specifically binds to the target protein; and

[1020] Z is a residue moiety resulting from covalent attachment of a chemoselective linking group to a compatible group of Ab.

[1021] Clause 78. The conjugate of clause 76 or 77, wherein n is 1 to 6.

[1022] Clause 79. The conjugate of clause 76 or 77, wherein n is 2 or less.

[1023] Clause 80. The conjugate of clause 79, wherein n is 1.

[1024] Clause 81. The conjugate of clause 76 or 77, wherein n is at least 2.

[1025] Clause 82. The conjugate of clause 81, wherein n is 2.

[1026] Clause 83. The conjugate of clause 81, wherein n is 3.

[1027] Clause 84. The conjugate of clause 81, wherein n is 4.

[1028] Clause 85. The conjugate of any one of clauses 76 to 84, wherein m is 1 to 20.

[1029] Clause 86. The conjugate of any one of clauses 76 to 84, wherein m is 1 to 12.

[1030] Clause 87. The conjugate of any one of clauses 76 to 86, wherein m is at least about 2.

[1031] Clause 88. The conjugate of any one of clauses 76 to 86, wherein m is at least about 3.

[1032] Clause 89. The conjugate of any one of clauses 76 to 86, wherein m is at least about 4.

[1033] Clause 90. The conjugate of any one of clauses 77 to 89, wherein Z is a residue moiety resulting from covalent attachment of a thiol-reactive chemoselective linking group to one or more cysteine residues of Ab.

[1034] Clause 91. The conjugate of any one of clauses 76 to 89, wherein Z is a residue moiety resulting from covalent attachment of an amine-reactive chemoselective linking group to one or more lysine residues of Ab.

[1035] Clause 92. The conjugate of any one of clauses 76 to 91, wherein X is a moiety that binds M6PR and has the following formula:

[1036]

[1037] or salts thereof, wherein:

[1038] each W is independently a hydrophilic head group;

[1039] each Z 1 is independently selected from optionally substituted (C1-C3)alkylene and optionally substituted vinylene; and

[1040] each Z 2 is independently selected from O, S, NR 21 , and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl.

[1041] Clause 93. The conjugate of clause 92, wherein the hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, -OP=O(OH)2, -SP=O(OH)2, -NR 3 P=O(OH)2, -OP=O(SH)(OH), -SP=O(SH)(OH), -OP=S(OH)2, -OP=O(N(R 3 )2)(OH), -OP=O(R 3 )(OH), -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, -(CR 2 R 2 )-P=O(OH)2, -SO2OH (i.e., -SO3H), -S(O)OH, -OSO2OH, -COOH, -CN, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 ), -CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR3 -SO2NR 3 R 4 -SO2NHCOR 3 -NHCOR 3 -NHC(O)CO2H, -NHSO2NHR 3 -NHC(O)NHS(O)2R 3 -NHSO2R 3 -NHSO3H, or salts thereof,

[1042] wherein: R 1 and R 2 are independently hydrogen, SR 3 , halo, or CN, and R 3 and R 4 are independently H, C 1-6 alkyl, or substituted C 1-6 alkyl (e.g., -CF3or -CH2CF3); A, B, and C are each independently CH or N; and D is each independently O or S.

[1043] Clause 94. The conjugate of clause 93, wherein W is selected from -P=O(OH)2, -SO3H, -CO2H, and -CH(CO2H)2, or salts thereof.

[1044] Clause 95. The conjugate of any one of clauses 92-94, wherein Z 1 is -(CH2) j - and j is 1-3.

[1045] Clause 96. The conjugate of any one of clauses 92-95, wherein Z 1 is -CH=CH-.

[1046] Clause 97. The conjugate of any one of clauses 92-96, wherein Z 2 is O or S.

[1047] Clause 98. The conjugate of any one of clauses 92-96, wherein Z 2 is -NR 21 -.

[1048] Clause 99. The conjugate of any one of clauses 92-96, wherein Z 2 is -C(R 22 )2-.

[1049] Clause 100. The conjugate of any one of clauses 92-94, wherein: Z 1selected from -(CH2) j -, substituted (C1-C3)alkylene, and -CH=CH-; j is 1 to 3; and Z 2 is selected from O and CH2.

[1050] Clause 101. The conjugate of clause 100, wherein Z 1 is -(CH2)2-, -CH2-CF2-, or -CH2-CHF-; and Z 2 is O.

[1051] Clause 102. The conjugate of clause 100, wherein Z 1 is -(CH2)2-, -CH2-CF2-, or -CH2-CHF-; and Z 2 is CH2.

[1052] Clause 103. The conjugate of clause 100, wherein Z 1 is -CH=CH-; and Z 2 is O.

[1053] Clause 104. The conjugate of clause 100, wherein Z 1 is -CH=CH-; and Z 2 is CH2.

[1054] Clause 105. The conjugate of any one of clauses 92 to 104, wherein X is selected from:

[1055]

[1056]

[1057] Clause 106. The conjugate of clauses 76 to 105, wherein the linker L has the formula (IIa):

[1058] -[(L 1 ) a -(L 2 ) b -(L 3 ) c n -(L 4 ) d -(L 5 ) e -(L 6 ) f -(L 7 ) g -

[1059] (IIa)

[1060] wherein​

[1061] each L 1 to L 7 are independently linking moieties and together provide a straight chain or branched linker between X and Y;

[1062] a is 1 or 2;

[1063] b, c, d, e, f, and g are each independently 0, 1, or 2;

[1064] n is 1 to 6 (e.g., n is 1 to 5 or 2 to 6, or 1, 2, or 3).

[1065] Clause 107. The conjugate of clause 108, wherein:

[1066] when d is 0, n is 1;

[1067] when d is 1, n is 1 to 3; and

[1068] when d is 2, n is 1 to 6.

[1069] Clause 111. The conjugate of clause 109 or 110, wherein -(L 1 ) a comprises an optionally substituted aryl or heteroaryl linking moiety.

[1070] Clause 112. The conjugate of clause 111, wherein each L 1 is independently selected from

[1071] wherein v is 0 to 10, and z is 0 to 10.

[1072] Clause 113. The conjugate of any one of clauses 109 to 112, wherein:

[1073] each L 2 is independently selected from -C 1-6 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -O(CH2) p - and -(OCH2CH2) p - wherein p is 1 to 10; and

[1074] each L 3 is independently selected from:

[1075] - and -(OCH2CH2) qwherein q is 1 to 10, u is 0 to 10, and w is 1 to 10.

[1076] Clause 114. The conjugate of any one of clauses 109 to 113, wherein when n is 2 or greater, there is at least one L 4 and is a branched linking moiety.

[1077] Clause 115. The conjugate of any one of clauses 109 to 114, wherein each L 4 is independently selected from the group consisting of: -OCH2CH2-,

[1078] wherein each x and y is each independently 1 to 10.

[1079] Clause 116. The conjugate of any one of clauses 109 to 115, wherein:

[1080] each L 5 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, or -(OCH2CH2) r -;

[1081] each L 6 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene- or -(OCH2CH2) s -;

[1082] each L 7 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, -(OCH2CH2) t - or -OCH2-; and r, s, and t are each independently 1 to 20.

[1083] Clause 117. The conjugate of any one of clauses 109 to 116, wherein a is 1.

[1084] Clause 118. The conjugate of any one of clauses 109 to 117, wherein at least one of b, c, e, f, and g is not 0.

[1085] Clause 119. The conjugate of any one of clauses 109-118, wherein at least one of b or c is not 0, and at least one of e, f, and g is not 0.

[1086] Clause 120. The conjugate of any one of clauses 109-119, wherein a, b, and c are each independently 1 or 2.

[1087] Clause 121. The conjugate of any one of clauses 109-120, wherein the linker L is selected from any one of the structures of Tables 2-3.

[1088] Clause 122. The conjugate of clause 76 or 77, wherein the conjugate is selected from:

[1089] i) a conjugate derived from conjugation of a compound of any one of the structures of the compound table described herein to a biomolecule;

[1090] ii) a conjugate derived from conjugation of a compound of any one of the structures of the compound table described herein to a polypeptide; or

[1091] iii) a conjugate derived from conjugation of a compound of any one of the structures of the compound table described herein to an antibody or antibody fragment.

[1092] Clause 123. The conjugate of any one of clauses 77-122, wherein the antibody or antibody fragment is an IgG antibody.

[1093] Clause 124. The conjugate of any one of clauses 77-122, wherein the antibody or antibody fragment is a humanized antibody.

[1094] Clause 125. The conjugate of any one of clauses 77-124, wherein the antibody or antibody fragment specifically binds to a secreted or soluble protein.

[1095] Clause 126. The conjugate of any one of clauses 77-124, wherein the antibody or antibody fragment specifically binds to a cell surface receptor.

[1096] Clause 127. A method of internalizing a target protein in a cell comprising a M6PR cell surface receptor, the method comprising contacting a cell sample comprising the cell and the target protein with an effective amount of a compound of any one of clauses 1-75 or a conjugate of any one of clauses 76-132, wherein the compound or conjugate specifically binds the target protein and specifically binds a cell surface receptor to facilitate cellular uptake of the target protein.

[1097] Clause 128. The method of clause 127, wherein the target protein is a membrane-bound protein.

[1098] Clause 129. The method of clause 127, wherein the target protein is an extracellular protein.

[1099] Clause 130. The method of any one of clauses 127-129, wherein the compound or conjugate comprises an antibody or antibody fragment (Ab) that specifically binds the target protein.

[1100] Clause 131. A method of reducing the level of a target protein in a biological system, the method comprising contacting the biological system with an effective amount of a compound of any one of clauses 1-75 or a conjugate of any one of clauses 76-126, wherein the compound or conjugate specifically binds the target protein and specifically binds a M6PR cell surface receptor of a cell in the biological system to facilitate cellular uptake and degradation of the target protein.

[1101] Clause 134. The method of any one of clauses 131-133, wherein the biological system is a human subject.

[1102] Clause 135. The method of any one of clauses 131-133, wherein the biological system is an in vitro cell sample.

[1103] Clause 136. The method of any one of clauses 131-135, wherein the target protein is a membrane-bound protein.

[1104] Clause 137. The method of any one of clauses 131-135, wherein the target protein is an extracellular protein.

[1105] Clause 138. A method of treating a disease or disorder associated with a target protein, the method comprising: administering to a subject in need thereof an effective amount of a compound of any one of clauses 1-75 or a conjugate of any one of clauses 76-126, wherein the compound or conjugate specifically binds the target protein.

[1106] Clause 139. The method of clause 138, wherein the disease or disorder is an inflammatory disease.

[1107] Clause 140. The method of clause 138, wherein the disease or disorder is an autoimmune disease.

[1108] Clause 141. The method of clause 138, wherein the disease or disorder is a cancer.

[1109] Clause 151. A compound having the following formula (I):

[1110]

[1111] or salts, single stereoisomers, mixtures of stereoisomers, or isotopic forms thereof, wherein: X is a moiety that binds to a M6PR cell surface receptor;

[1112] L is a linker of the formula:

[1113] -[(L 1 ) a -(L 2 ) b -(L 3 ) c n -(L 4 ) d -(L 5 ) e (L 6 ) f -(L 7 ) g -; and

[1114] wherein

[1115] each L 1 is independently

[1116] each L 2 is independently -C 1-6 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene, -(OCH2) p -; or -(OCH2CH2) p -;

[1117] each L 3 is independently or -(OCH2CH2) q -;

[1118] each L 4 is independently -OCH2CH2-,

[1119] each L 5 is independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, or -(OCH2CH2) r -;​

[1120] each L 6 independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene- or -(OCH2CH2) s -;

[1121] each L 7 independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, -(OCH2CH2) t - or -OCH2-;

[1122] each of p, q, r, s, and t is independently an integer from 1 to 20; a is 1 or 2; each of b, c, d, e, f, and g is independently 0, 1, or 2; each of u, v, w, x, y, and z is independently an integer from 1 to 10;

[1123] n is an integer from 1 to 5; wherein when d is 0, n is 1, when d is 1, n is an integer from 1 to 3, and when d is 2, n is an integer from 1 to 5;

[1124] Y is a moiety selected from the group consisting of:

[1125]

[1126] wherein represents a point of attachment to L;

[1127] R is hydrogen or fluoro;

[1128] each R' is independently hydrogen or halo;

[1129] G is selected from -F, -Cl, -Br, -I, -O-methanesulfonyl, and -O-toluenesulfonyl;

[1130] J is selected from -Cl, -Br, -I, -F, -OH, -O-N-succinimidyl, -O-(4-nitrophenyl), -O-pentafluorophenyl, -O-tetrafluorophenyl, and -O-C(O)-OR J' ; and R J' is -C1-C8alkyl or -aryl.

[1131] Clause 154. The compound of Clause 151, wherein a is 1.

[1132] Clause 155. The compound of Clause 151, wherein at least one of b, c, e, f, and g is not 0.

[1133] Clause 156. The compound of clause 151, wherein at least one of b or c is not 0, and at least one of e, f, and g is not 0.

[1134] Clause 157. The compound of clause 151, wherein a, b, and c are each independently 1 or 2.

[1135] Clause 158. The compound of clause 151, wherein each X is independently selected from one of the following formulas:

[1136]

[1137] wherein,

[1138] R” is selected from the group consisting of –OH, –CR 1 R 2 OH, –P=O(OH)2, P(=O)R 1 OH, -PH(=O)OH, –(CR 1 R 2 )-P=O(OH)2, –SO2OH, –S(O)OH, –OSO2OH, –COOH, -CONH2, –CONHR 3 , –CONR 3 R 4 , –CONH(OH), –CONH(OR 3 )–CONHSO2R 3 , –CONHSO2NR 3 R 4 , –CH(COOH)2, –CR 1 R 2 COOH, –SO2R 3 , –SOR 3 R 4 , –SO2NH2, –SO2NHR 3 , –SO2NR 3 R 4 , –SO2NHCOR 3 , –NHCOR 3 , -NHC(O)NHS(O)2R 3 , –NHSO2R 3 ,

[1139] j is an integer from 1 to 3;

[1140] R 1 and R 2 are each independently hydrogen, halo, or CN;

[1141] R 3 and R 4 each independently is C 1-6 alkyl;

[1142] A, B, and C are each independently CH or N; and

[1143] D is each independently O or S.

[1144] Clause 159. The compound of Clause 151, wherein each X is independently selected from one of the following formulas:

[1145]

[1146] wherein

[1147] R” is selected from the group consisting of: -OH, -CR 1 R 2 OH, -P=O(OH)2, P(=O)R 1 OH, -PH(=O)OH, - (CR 1 R 2 )-P=O(OH)2, -SO2OH, -S(O)OH, -OSO2OH, -COOH, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 )-CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHC(O)NHS(O)2R 3 , -NHSO2R 3 ,

[1148] j is an integer from 1 to 3;

[1149] R 1 and R 2are each independently hydrogen, halo or CN;

[1150] R 3 and R 4 Each independently is C 1-6 alkyl;

[1151] A, B and C are each independently CH or N;

[1152] D is independently O or S.

[1153] Clause 161. A conjugate of the formula:

[1154]

[1155] or a pharmaceutically acceptable salt thereof,

[1156] in:

[1157] X is the part that binds to the M6PR cell surface receptor;

[1158] L is a linker of the formula:

[1159] -[(L 1 ) a -(L 2 ) b -(L 3 ) c ] n -(L 4 ) d -(L 5 ) e -(L 6 ) f -(L 7 ) g -;and

[1160] in

[1161] Each L 1 Independently

[1162] Each L 2 Independently for –C 1-6 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene, –(OCH2) p – or – (OCH2CH2) p –

[1163] Each L 3 Independently or –(OCH2CH2)q -;

[1164] each L 4 independently -OCH2CH2-,

[1165] each L 5 independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, or -(OCH2CH2) r -;

[1166] each L 6 independently -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene- or -(OCH2CH2) s -;

[1167] each L 7 independently -NHCO-C 1-6 -alkylene-, -CONH-C1-6-alkylene-, C 1-6 -alkylene-, -(OCH2CH2) t - or -OCH2-;

[1168] p, q, r, s and t are each independently an integer from 1 to 20; a is 1 or 2; b, c, d, e, f and g are each independently 0, 1 or 2; u, v, w, x, y and z are each independently an integer from 1 to 10;

[1169] n is an integer from 1 to 5; wherein when d is 0, n is 1, when d is 1, n is an integer from 1 to 3, and when d is 2, n is an integer from 1 to 5;

[1170] Z is selected from the group consisting of

[1171]

[1172] wherein denotes the point of attachment to L,

[1173] wherein denotes the point of attachment to P,

[1174] X is CH2, NH, O or S; and

[1175] P is a polypeptide.

[1176] Clause 162. The conjugate of clause 161, wherein P comprises an antibody or an antigen-binding fragment of an antibody.

[1177] Clause 163. A conjugate of the following formula:

[1178]

[1179] or a pharmaceutically acceptable salt thereof,

[1180] wherein:

[1181] X is a moiety that binds to a M6PR cell surface receptor;

[1182] L is a linker of the following formula:

[1183] -[(L 1 ) a -(L 2 ) b -(L 3 ) c ] n -(L 4 ) d -(L 5 ) e -(L 6 ) f -(L 7 ) g - and

[1184] wherein

[1185] each L 1 is independently

[1186] each L 2 is independently –C 1-6 -alkylene–, –NHCO-C 1-6 -alkylene–, –CONH-C 1-6 -alkylene, –(OCH2) p – or –(OCH2CH2) p –;

[1187] each L 3 is independently or –(OCH2CH2) q –;

[1188] each L 4 is independently –OCH2CH2–,

[1189] each L5 -alkylene-, -CONH-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, or -(OCH2CH2) r -;

[1190] each L 6 -alkylene-, -CONH-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene- or -(OCH2CH2) s -; each L 7 -alkylene-, -CONH-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -C 1-6 -alkylene-, -(OCH2CH2) t - or -OCH2-;

[1191] p, q, r, s, and t are each independently an integer from 1 to 20; a is 1 or 2; b, c, d, e, f, and g are each independently 0, 1, or 2; u, v, w, x, y, and z are each independently 1, 2, 3, 4, 5, or 6;

[1192] n is an integer from 1 to 5; wherein when d is 0, n is 1, when d is 1, n is an integer from 1 to 3, and when d is 2, n is an integer from 1 to 5;

[1193] m is an integer from 1 to 8;

[1194] Z is selected from the group consisting of: wherein represents a point of attachment to L, wherein represents a point of attachment to ; and is an antibody.

[1195] Clause 166. The conjugate of any one of clauses 161-165, wherein each X is independently selected from one of the following formulas:

[1196] wherein

[1197] R” is selected from the group consisting of: -OH, -CR 1 R 2 OH, -P=O(OH)2, P(=O)R 1 OH, -PH(=O)OH, -(CR 1 R 2)-P=O(OH)2、-SO2OH、-S(O)OH、-OSO2OH、-COOH、-CONH2、-CONHR 3 、–CONR 3 R 4 、–CONH(OH),–CONH(OR 3 )–CONHSO2R 3 , –CONHSO2NR 3 R 4 、–CH(COOH)2、–CR 1 R 2 COOH, –SO2R 3 ,–SOR 3 R 4 , –SO2NH2, –SO2NHR 3 , –SO2NR 3 R 4 ,–SO2NHCOR 3 ,–NHCOR 3 、-NHC(O)NHS(O)2R 3 、–NHSO2R 3 、

[1198] j is an integer from 1 to 3;

[1199] R 1 and R 2 are each independently hydrogen, halo or CN;

[1200] R 3 and R 4 Each independently is C 1-6 alkyl;

[1201] A, B, and C are each independently CH or N; and

[1202] D is independently O or S.

[1203] Clause 167. The conjugate according to any one of clauses 161 to 165, wherein each X is independently selected from one of the following formulae:

[1204]

[1205] in

[1206] R” is selected from the group consisting of: –OH, –CR 1 R 2 OH, –P=O(OH)2, P(=O)R 1 OH, -PH(=O)OH, –(CR1 R 2 )-P=O(OH)2, -SO2OH, -S(O)OH, -OSO2OH, -COOH, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 )-CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHC(O)NHS(O)2R 3 , -NHSO2R 3 ,

[1207]

[1208] j is an integer from 1 to 3;

[1209] R 1 and R 2 are each independently hydrogen, halo, or CN;

[1210] R 3 and R 4 are each independently C 1-6 alkyl;

[1211] A, B, and C are each independently CH or N;

[1212] D is each independently O or S.

[1213] Clause 169. A pharmaceutical composition comprising the conjugate or pharmaceutically acceptable salt according to any one of clauses 161-168 and a pharmaceutically acceptable carrier.

[1214] Clause 170. The pharmaceutical composition of clause 169, wherein m is an integer from 4 to 8.

[1215] Clause 171. The pharmaceutical composition comprising the conjugate or pharmaceutically acceptable salt of clause 170, wherein m is 4.

[1216] Clause 172. The conjugate of any one of clauses 163-168, wherein the antibody is an IgG antibody.

[1217] Clause 173. The conjugate of any one of clauses 163-168, wherein the antibody is a humanized antibody.

[1218] Clause 174. The conjugate of any one of clauses 163-168, wherein the antibody specifically binds to a secreted or soluble protein.

[1219] Clause 175. The conjugate of any one of clauses 163-168, wherein the antibody specifically binds to a cell surface receptor.

[1220] Clause 176. The conjugate of any one of clauses 163-168, wherein the antibody specifically binds to a Programmed Death-Ligand-1 (PD-L1) protein.

[1221] Clause 177. The conjugate of any one of clauses 163-168, wherein the antibody specifically binds to a Vascular Endothelial Growth Factor (VEGF) protein.

[1222] Clause 178. The conjugate of any one of clauses 163-168, wherein the antibody specifically binds to a Fibroblast Growth Factor Receptor 2 (FGFR2) protein or a Fibroblast Growth Factor Receptor 3 (FGFR3) protein.

[1223] Clause 179. The conjugate of any one of clauses 163-168, wherein the antibody is cetuximab.

[1224] Clause 180. The conjugate of any one of clauses 163-168, wherein the antibody is mytominus.

[1225] Clause 181. The conjugate of any one of clauses 163-168, wherein the antibody is atezolizumab.

[1226] Clause 182. A method of treating a disease or disorder by administering to a subject in need thereof an effective amount of the conjugate or pharmaceutically acceptable salt of any one of clauses 163-168 or the pharmaceutical composition of clause 169.

[1227] Clause 183. The method of clause 182, wherein the disease or disorder is an inflammatory disease.

[1228] Clause 184. The method of clause 182, wherein the disease or disorder is an autoimmune disease.

[1229] Clause 185. The method of clause 182, wherein the disease or disorder is cancer.

[1230] 5. Examples

[1231] The examples in this section are provided in illustrative, rather than a limiting fashion.

[1232] 5.1. Preparation of Compounds

[1233] The following illustrative schemes and examples illustrate how to prepare and test the compounds described herein. Although these examples represent only a portion of the embodiments, it is to be understood that the following examples are illustrative and not limiting. Unless otherwise indicated, all substituent definitions are consistent with the foregoing. Relevant reagents and starting materials are readily available to one of ordinary skill in the art. The specific steps of each of the routes described can be combined in different ways, or steps from different schemes combined, to prepare the compounds described herein.

[1234] Synthetic methods of the present disclosure for preparing M6PR binding moieties, precursors thereof, and conjugates thereof (which methods can be applicable to the preparation of compounds and synths thereof) are described in International Application No. PCT / US2021 / 012846 (published as WO 2021 / 142377) and PCT Publication No. WO 2020132100, the disclosures of which are incorporated by reference herein in their entirety.

[1235] 5.1.1. Preparation of M6PR binding moiety synths

[1236] Synthesis of Synth A-10 and Compound A. (2-((2R,3S,4S,5S,6R)-3,4,5- trihydroxy-6-(4-isothiocyanatophenoxy)tetrahydro-2H-pyran-2-yl)ethyl)phosphonic acid (Compound A)

[1237]

[1238] (((2R,3S,4S,5R,6R)-2-(4-nitrophenoxy)-6(((trimethylsilyl)oxy)methyl)tetrahydro- 2H-pyran-3,4,5-triyl)tris(oxy))tris(trimethylsilyl) (A-2)

[1239] A solution of (2R,3S,4S,5S,6R)-2-(hydroxymethyl)-6-(4-nitrophenoxy)tetrahydro-2H-pyran-3,4,5-triol (A-1) (1.0 equiv, 26.0 g, 86.37 mmol) in DMF (500 mL) was cooled to 0°C. Triethylamine (6.4 equiv, 288 mL, 552.0 mmol) and trimethylsilyl chloride (24.0 equiv, 70 mL, 2071.0 mmol) were then added to the above solution under a nitrogen atmosphere. The resulting mixture was stirred at room temperature under nitrogen for 24 hours. The reaction mixture was partitioned between ethyl acetate and water. The aqueous layer was extracted again with ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered, and purified by silica gel chromatography (hexane containing 0 to 5% ethyl acetate) to give intermediate A-2 as a colorless oil. Yield: 36.8 g (72.3%); 1 H NMR (400MHz, CDCl3) δ8.18 (dd, J=12.36, 3.16Hz, 2H), 7.16 (dd, J=12.4, 3.12Hz, 2H), 5.37 (d ,J=2.36Hz,1H),3.99-3.87(m,3H),3.72-3.69(m,2H),3.50-3.48(m,1H),0.2-0.07(m,36H).

[1240] ((2R,3R,4S,5S,6R)-6-(4-nitrophenoxy)-3,4,5-tris((trimethylsilyl)oxy)tetrahydro-2H-pyran-2-yl)methanol (A-3)

[1241] To a stirred solution of intermediate A-2 (1.0 equiv., 10.0 g, 16.97 mmol) in a mixture of DCM: methanol (8: 2 ratio, 100 mL) was added ammonium acetate (1.5 equiv., 1.96 g, 25.46 mmol) at room temperature under nitrogen. The resulting mixture was stirred at room temperature under nitrogen for 16 hours. The reaction mixture was partitioned between ethyl acetate and water. The aqueous layer was extracted again with ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered, concentrated in vacuo, and purified by silica gel chromatography (hexane containing 20% ​​to 30% ethyl acetate) to give intermediate A-3 as a white solid. Yield: 7.0 g (80%); LC-MS m / z 516.13 [M-1] - .

[1242] (2S,3R,4S,5S,6R)-6-(4-nitrophenoxy)-3,4,5-tris((trimethylsilyl)oxy)tetrahydro-2H-pyran-2-carbaldehyde (A-4)

[1243] To a stirred solution of oxalyl chloride (1.1 eq, 0.5 mL, 5.31 mmol) in DCM (5 mL) was added DMSO (2.2 eq, 0.76 mL, 10.62 mmol) in DCM (5 mL) at -78 °C over 5 min. After stirring at -78 °C for 20 min, a solution of intermediate A-3 (1.0 eq, 2.5 g, 4.83 mmol) in DCM (10 mL) was added to the mixture. The reaction mixture was continued to stir at -78 °C for 60 min, followed by the addition of triethylamine (5.0 eq, 3.4 mL, 24.15 mmol). The resulting mixture was allowed to reach room temperature over 1 h. The hazy mixture was diluted with DCM and washed with water followed by a brine solution. The organic layer was dried over sodium sulfate, filtered, concentrated under high vacuum to afford intermediate A-4 (2.2 g, crude) as a light brown gummy mass which was used in the next step without further purification.

[1244] ((E)-2-((2R,3R,4S,5S,6R)-6-(4-nitrophenoxy)-3,4,5-tri((trimethylsilyl)oxy)tetrahydro- 2H-pyran-2-yl)vinyl)diethyl phosphonate (A-5)

[1245] A stirred suspension of methylenebis(phosphonic acid) tetraethyl ester (1.5 eq, 1.85 g, 6.40 mmol) in dry THF (20 mL) was cooled to -78 °C and added with n-butyllithium in hexanes 2.0 M (1.25 eq, 2.6 ml, 5.33 mmol). The resulting mixture was stirred at -78 °C for 1 h, then added with intermediate A-4 (1.0 eq, 2.2 g, 4.27 mmol) in dry THF (10 mL) at -78 °C. The bath was removed, and the reaction mixture was allowed to reach room temperature and continued to stir for 12 h. A saturated aqueous NH4Cl solution was added, and extracted with ethyl acetate. The ethyl acetate layer was washed with water, then with a saturated brine solution. The organic layer was dried over sodium sulfate, filtered and concentrated. The crude was purified via silica gel chromatography (30-40% ethyl acetate in hexanes) to afford intermediate A-5 as a colorless gummy mass. Yield (1.3 g, 48%); LC-MS m / z 650.57 [M+1] + .

[1246] ((E)-2-((2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(4-nitrophenoxy)tetrahydro-2H-pyran- 2-yl)vinyl)diethyl phosphonate (A-6)

[1247] To a stirred solution of intermediate A-5 (1.0 eq, 1.3 g, 1.54 mmol) in methanol (15 mL) was added Dowex 50WX8 hydrogen form at room temperature under nitrogen atmosphere. The resulting mixture was stirred at room temperature under nitrogen for 2 h. The reaction mixture was filtered and washed with methanol, the filtrate was concentrated under vacuum to afford ((E)-2-((2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(4-nitrophenoxy)tetrahydro-2H-pyran-2- yl)vinyl)diethyl phosphonate (6) as a white solid. Yield: 0.78 g (90%); LC-MS m / z 434.17 [M+1] + .

[1248] (2R,3S,4S,5S,6R)-2-((E)-2-(diethoxyphosphoryl)vinyl)-6-(4-nitrophenoxy)tetrahydro- 2H-pyran-3,4,5-triyl triacetate (A-7)

[1249] To a stirred solution of intermediate A-6 (1.00 eq, 0.78 g, 1.80 mmol) in pyridine (10 mL) was added acetic anhydride (10.0 eq, 1.8 mL, 18.0 mmol) dropwise at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 16 h. The pyridine was removed under high vacuum and the residue was partitioned between ethyl acetate and 1 N aqueous HC1. The aqueous layer was extracted again with ethyl acetate. The combined organic layers were dried over sodium sulfate, filtered, concentrated and purified via silica gel chromatography (2.5% methanol in dichloromethane) to afford intermediate A-7 as a white solid. Yield: 1.0 g (100%); LC-MS m / z 560.17 [M+1] + .

[1250] (2R,3S,4S,5R,6R)-2-(4-aminophenoxy)-6-(2-(diethoxyphosphoryl)ethyl)tetrahydro-2H- pyran-3,4,5-triyl triacetate (A-8)

[1251] To a stirred solution of intermediate A-7 (1.0 eq, 1.0 g, 1.78 mmol) in methanol (15 mL) was added 10% palladium on carbon (0.200 g) at room temperature under nitrogen. The resulting mixture was stirred at room temperature under hydrogen pressure (100 psi) for 16 h. The reaction mixture was filtered through a bed of celite and washed with methanol, the filtrate was concentrated under vacuum to afford intermediate A-8 as a brown gummy gel. Yield: 0.700 g (73.6%); LC-MS m / z 532.21 [M+1] + .

[1252] (2-((2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(4-isothiocyanatophenoxy)tetrahydro- 2H-pyran-2-yl)ethyl)phosphonic acid (Compound A)

[1253] To a stirred solution of intermediate A-8 (1.00 eq, 2.0 g, 5.73 mmol) in acetonitrile (15 mL) was added dropwise bromotrimethylsilane (5.0 eq, 3.8 mL, 28.65 mmol) at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 16 h. The volatiles were removed on a rotary evaporator and the residue was dried under high vacuum. The crude residue was triturated with diethyl ether and dried under high vacuum to give intermediate A-9 as a brown solid. Yield: 2.2 g, crude. LC-MS m / z 476.0 [M+1] + .

[1254] (2-((2R,3S,4S,5S,6R)-6-(4-aminophenoxy)-3,4,5-trihydroxytetrahydro-2H-pyran- 2-yl)ethyl)phosphonic acid (A-10)

[1255] To a stirred solution of intermediate A-9 (1.0 eq, 2.0 g, 4.21 mmol) in a mixture of methanol:water (8:2, 15 mL) was added dropwise triethylamine (5.0 eq, 2.93 mL, 21.05 mmol) at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature for 16 h. The methanol was removed on a rotary evaporator and the residue was dried under high vacuum. The residue was taken up in water and purified by preparative HPLC (2% to 10% acetonitrile in water with 5 mM ammonium acetate). Fractions containing the desired product were combined and lyophilized to dryness to give intermediate A-10 as a brown solid. Yield: 0.350 g (25%); LC-MS m / z 348.0 [M-H] - .

[1256] Synthesis of (2-((2R,3S,4S,5S,6R)-3,4,5-trihydroxy-6-(4-isothiocyanatophenoxy)tetrahydro- 2H-pyran-2-yl)ethyl)phosphonic acid (Compound A)

[1257] To a stirred solution of intermediate A-10 (1.0 eq, 1.75 g, 5.01 mmol) in a mixture of ethanol: water (7:3) (20 ml) was added dropwise sulphuric acid (5.00 eq, 1.92 mL, 25.05 mmol) at 0°C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 3 hours. The volatiles were removed on a rotary evaporator and the residue was dried under high vacuum. The residue was taken up in water and purified by preparative HPLC (20% to 40% acetonitrile in water with 5.0 mmol ammonium acetate). Fractions containing the desired product were combined and lyophilized to dryness to give compound A as a white solid. Yield: 0.135 g (6.8%) LC-MS m / z 392.08 [M+1] + ; 1 H NMR (400 MHz, D20) δ 7.32 (d, J = 8.92 Hz, 2H), 7.12 (d, J = 8.96 Hz, 2H), 5.57 (s, 1H), 4.13 (s, 1H), 3.96 (dd, J = 9.16, 3.44 Hz, 1H), 3.59 - 3.48 (m, 2H), 2.03 - 1.88 (m, 1H), 1.68 - 1.54 (m, 2H), 1.27 - 1.15 (m, 1H).

[1258] Preparation of sub 8D

[1259]

[1260] DBU (0.05 eq, 0.025 mL, 0.168 mmol) was added to a stirred solution of (2R,3R,4S,5S,6S)-2-(2-(diethoxyphosphoryl)ethyl)-6-hydroxytetrahydro-2H-pyran-3,4,5- triyl triacetate (8A) (1.00 eq, 1.48 g, 3.36 mmol) and trichloroacetonitrile (10.0 eq, 3.4 mL, 33.6 mmol) in DCM (30 mL) at 0 °C under nitrogen. The resulting mixture was stirred at 0 °C under nitrogen. More DBU (0.0500 eq, 0.025 mL, 0.168 mmol) was added and the cold bath was removed. The resulting mixture was stirred at room temperature for 45 minutes. Most of the solvent was removed on a rotary evaporator. The residue was loaded onto a silica gel loaded column pre-equilibrated with dichloromethane solution containing 0.1% triethylamine and purified via silica gel chromatography (column pre-equilibrated with 30% ethyl acetate / hexanes containing 0.1% triethylamine) (hexanes containing 30% to 100% ethyl acetate). Fractions containing the desired product were combined and concentrated on a rotary evaporator. The residue was stripped twice from dry dichloromethane, dried under high vacuum for 30 minutes, then stored at -80 °C under nitrogen to give compound 8B as a colorless semi-solid. Yield: 1.26 g, 64%; 1 H NMR (300 MHz, chloroform-d) δ 8.74 (s, 1H), 6.21 (s, 1H), 5.45 (s, 1H), 5.34 (t, J = 11.2 Hz, 1H), 5.20 (t, J = 10.0 Hz, 1H), 4.16 - 4.00 (m, 4H), 4.00 - 3.88 (m, 1H), 2.18 (s, 3H), 2.07 (s, 3H), 2.00 (s, 3H), 1.95 - 1.64 (m, 4H), 1.31 (t, J = 7.3 Hz, 6H).

[1261] Compound 8B (1.00 eq, 1.25 g, 2.14 mmol) was dissolved in dry DCM (10 mL) under nitrogen with stirring. But-3-yn-1-ol (2.00 eq, 0.32 mL, 4.28 mmol) was added and the resulting mixture was cooled to -78 °C under nitrogen with stirring. A solution of boron trifluoride diethyl etherate (0.500 eq, 0.13 mL, 1.07 mmol) in dichloromethane (5 mL) was added slowly. The -78 °C cold bath was removed and the reaction mixture was allowed to warm slowly under nitrogen for 50 minutes. The reaction mixture was cooled with a water / ice bath and stirred for an additional 30 minutes at 0 °C under nitrogen before workup. The reaction mixture was partitioned between dichloromethane and saturated aqueous sodium bicarbonate solution. The aqueous layer was extracted again with dichloromethane. The combined organics were dried over sodium sulfate, filtered, and purified via silica gel chromatography (20% to 100% ethyl acetate in dichloromethane) to give compound 8C as a colorless viscous oil. Yield: 408 mg, 39%; LC-MS m / z 493.4 [M+1]+; 1 H NMR (300 MHz, Chloroform-d) δ 5.35 - 5.19 (m, 2H), 5.09 (t, J = 9.9 Hz, 1H), 4.79 (s, 1H), 4.21 - 3.98 (m, 4H), 3.91 - 3.68 (m, 2H), 3.64 - 3.50 (m, 1H), 2.55 - 2.44 (m, 2H), 2.15 (s, 3H), 2.05 (s, 3H), 1.98 (s, 3H), 2.07 - 1.62 (m, 5H), 1.32 (t, J = 7.2 Hz, 6H).

[1262] Bromotrimethylsilane (5.00 eq, 0.47 mL, 3.57 mmol) was slowly added to a stirred solution of compound 8C (1.00 eq, 352 mg, 0.715 mmol) in MeCN (7 mL) at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 3.5 hours. The volatiles were removed on a rotary evaporator and the residue was dried briefly under high vacuum. The residue was dissolved in methanol (7 mL) under stirring under nitrogen and sodium methoxide (25 wt% in methanol) (2.50 eq, 0.41 mL, 1.79 mmol) was added. The resulting mixture was stirred at room temperature under nitrogen for 1 hour. Acetic acid (3.00 eq, 0.12 mL, 2.14 mmol) was added and then the volatiles were removed on a rotary evaporator. The residue was taken up in water and purified by preparative HPLC (0 to 15% acetonitrile in water with 0.1% TFA). The bulk of the solvent was removed on a rotary evaporator at 30 °C and then the remaining portion was lyophilized to dryness to give compound 8D as a white solid. Yield: 208 mg, 94%; LC-MS m / z 311.3 [M+1]+; 1 H NMR (300 MHz, Heavy water) δ 4.88 - 4.80 (m, 1H), 3.93 (s, 1H), 3.84 - 3.70 (m, 2H), 3.70 - 3.56 (m, 2H), 3.48 (t, J = 9.7 Hz, 1H), 2.57 - 2.44 (m, 2H), 2.37 (s, 1H), 2.15 - 1.61 (m, 4H).

[1263] Synthesis of Compound B

[1264]

[1265] Compound B was synthesized using the procedure described for compound 8D, using but-3-yn-1-amine instead of but-3-yn-1-ol.

[1266] Alternatively, intermediate B-2 can also be prepared by adding pyridine to a solution of intermediate B-1 in excess acetic anhydride. The resulting mixture was stirred at 20 °C for 16 hours. The reaction solution was concentrated in vacuo and the residual pyridine was removed by azeotropic distillation with toluene followed by drying under high vacuum to give intermediate B-2.

[1267] Other M6PR binding moiety synthon comprising an amino linker at the 1 position of the pyranose ring can be prepared by adapting the method shown.

[1268] Synthesis of Synthon 38C

[1269]

[1270] To a nitrogen purged round bottom flask containing intermediate A-8 (1.00 eq, 218 mg, 0.398 mmol) was added (4-nitrophenyl)N-hex-5-ynylcarbamate (38A) (1.80 eq, 188 mg, 0.717 mmol) and anhydrous DCM (4 mL). To the reaction solution was added triethylamine (2.08 eq, 0.11 mL, 0.826 mmol) and the solution was stirred at 40 °C for 16 hours. The reaction mixture was then diluted with dichloromethane (30 mL) and washed with aqueous NaOH, water and brine. The organic layer was dried over anhydrous MgS04, filtered and concentrated in vacuo. The residue was purified by silica gel column chromatography eluting with methanol / chloroform to give compound 38B. Yield: 154 mg, 58 %); LCMS m / z 655.6 [M+l]+.

[1271] To a nitrogen purged round bottom flask containing compound 38B (1.00 eq, 170 mg, 0.260 mmol) was added acetonitrile (4 mL). The solution was cooled to 0 °C under nitrogen before dropwise addition of TMSBr (5.00 eq, 0.18 mL, 1.30 mmol). The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen. LCMS after 2 hours showed no SM remaining and product M+H = 599.6 was observed. The solvent was removed on a rotary evaporator and the residue was high vacuum dried. The resulting intermediate 2-[(2R,3R,4S,5S,6R)-3,4,5-triacetoxy-6-[4-(hex-5-ynylcarbamoylamido)phenoxy]tetrahydropyran-2- yl]ethyl phosphonic acid (155 mg, 0.259 mmol, 99.72 % yield) was dissolved in methanol (3 mL). To the stirring solution was added 25 wt% NaOMe in MeOH (2.50 eq, 0.14 mL, 0.649 mmol) under nitrogen. The resulting mixture was stirred at room temperature under nitrogen for 50 minutes. LCMS found most of starting material remaining. Another portion of 25 wt% NaOMe in MeOH (2.50 eq, 0.14 mL, 0.649 mmol) was added and stirred at 20 °C for 1 hour. Acetic acid (13.5 eq, 0.20 mL, 3.50 mmol) was added and the solvent was removed on a rotary evaporator. The residue was taken up in DMSO and purified by preparative HPLC (0 to 35% acetonitrile in water with 0.1% TFA). The purified product fractions were combined and lyophilized to dryness to give compound 38C as a white solid. Yield: 45 mg, 37 %; LCMS m / z 473.6 [M+l]+.

[1272] Synthesis of sub 39B / 53A

[1273]

[1274] To a nitrogen purged round bottom flask containing compound 39A (1.00 eq, 182 mg, 0.278 mmol) and anhydrous acetonitrile (1 mL) was added TMSBr (5.00 eq, 0.18 mL, 1.39 mmol) at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 3.5 hours. LCMS analysis showed no starting reagent remaining. The volatiles were removed on a rotary evaporator and the residue was briefly high vacuum dried. The residue was dissolved in methanol (1 mL) under nitrogen with stirring and sodium methoxide 25 wt% in MeOH (2.50 eq, 0.15 mL, 0.696 mmol) was added. The resulting mixture was stirred under nitrogen at room temperature for 30 minutes, acetic acid (5.00 eq, 0.080 mL, 1.39 mmol) was added to the reaction mixture and the volatiles were removed in vacuo. The residue was taken up in DMSO and purified by reverse phase preparative HPLC (0 to 35% acetonitrile in water with 0.1% TFA) to give purified fractions. The combined fractions were lyophilized to dryness to give compound 39B as a white solid. Yield: 65 mg, 50%; LCMS m / z 472.3 [M+l]+.

[1275] To a nitrogen purged round bottom flask containing compound 39A (1.00 eq, 182 mg, 0.278 mmol) and anhydrous acetonitrile (1 mL) was added TMSBr (5.00 eq, 0.18 mL, 1.39 mmol) at 0 °C under nitrogen. The cold bath was removed and the resulting mixture was stirred at room temperature under nitrogen for 3.5 hours. LCMS analysis showed no starting reagent remaining. The volatiles were removed on a rotary evaporator and the residue was briefly high vacuum dried. The residue was dissolved in methanol (1 mL) under nitrogen with stirring and sodium methoxide 25 wt% in MeOH (2.50 eq, 0.15 mL, 0.696 mmol) was added. The resulting mixture was stirred under nitrogen at room temperature for 30 minutes, acetic acid (5.00 eq, 0.080 mL, 1.39 mmol) was added to the reaction mixture and the volatiles were removed in vacuo. The residue was taken up in DMSO and purified by reverse phase preparative HPLC (0 to 35% acetonitrile in water with 0.1% TFA) to give purified fractions. The combined fractions were lyophilized to dryness to give compound 39B as a white solid. Yield: 65 mg, 50%; LCMS m / z 472.3 [M+l]+.

[1276] Synthesis of Sub 49B

[1277]

[1278] A solution of 2-(2-(2-(prop-2-yn-1-yloxy)ethoxy)ethoxy)ethan-1-amine (49A) (1.40 eq, 30.7 mg, 0.164 mmol) in NMP (0.6 mL) was added to intermediate A (1.00 eq, 45.8 mg, 0.117 mmol) in a 1 dram vial with a stir bar. The resulting mixture was capped and stirred at room temperature for 18 hours. The solid slowly dissolved to give a clear yellow solution. The reaction mixture was diluted with a mixture of ethanol and acetic acid, filtered, and purified by preparative HPLC (10% to 30% acetonitrile in water with 0.1% TFA). Fractions containing the desired product were combined. Most of the solvent was removed on a rotavapor at 29 °C and the remainder was lyophilized to dryness to give compound 49B as a white solid. Yield: 47.7 mg, 70%; LCMS m / z 579.4 [M+1]+; 1 H NMR (300 MHz, DMSO-d6, with D20) δ 7.28 (d, J = 8.6 Hz, 2H), 6.99 (d, J = 8.5 Hz, 2H), 5.32 (s, 1H), 4.16 - 4.05 (m, 2H), 3.85 - 3.76 (m, 1H), 3.74 - 3.41 (m, 13H), 3.40 - 3.24 (m, 3H), 2.02 - 1.82 (m, 1H), 1.72 - 1.40 (m, 2H), 1.34 - 1.07 (m, 1H).

[1279] Synthesis of Synthon 40A

[1280]

[1281] 40A was prepared from intermediate A using a similar procedure to Synthon 49B.

[1282] Synthesis of Synthon 59A

[1283]

[1284] 59A was prepared using a similar procedure to Synthon 49B.

[1285] Synthesis of Synthon 60B

[1286]

[1287] To a round bottom flask was added (2R,3R,4S,5S,6R)-2-(3-ethoxy-3-oxopropyl)-6-(4-(3-(hex-5-yn-1-yl)thioureido)phenoxy)tetrahydro-2H-pyran-3,4,5-triyl triacetate (60A) (1.00 eq, 244 mg, 0.491 mmol) and THF (4 mL). To the stirring solution was added 3M aqueous LiOH (10.4 eq, 1.7 mL, 5.10 mmol). The reaction solution was stirred at room temperature for 2 hours. The reaction solution was diluted with EtOAc (30 mL) and aqueous NH4CI. The organic phase was partitioned, washed with brine, dried over Na2S04, filtered and concentrated in vacuo. The product compound 60B (210 mg, 91% yield) was used in the next step without additional purification. LC-MS m / z 453.6 [M+1]+.

[1288] Synthesis of Sub 46C

[1289]

[1290] A solution of (2R,3S,4S,5R,6R)-6-(2-(diethoxyphosphoryl)ethyl)tetrahydro-2H-pyran- 2,3,4,5-tetrayl tetraacetate (46A) (1.0 eq, 5.00 g, 10.4 mmol) and (3-(5- hydroxypentanamido)propyl)benzylcarbamate (2.0 eq, 6.39 g, 20.7 mmol) in DCM (100 mL) was cooled at 0 °C, BF3-Et20 (12.0 eq, 15.4 mL, 124.0 mmol) was added dropwise and the reaction mixture was heated at 50 °C for 16 hours. The reaction was monitored by LCMS. Upon completion, the reaction mixture was cooled at 0 °C and neutralized with triethylamine. Then, the reaction mixture was diluted with DCM and washed with water. The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to give a crude which was purified by reverse column chromatography using C-18 column and 20% to 50% acetonitrile in water to give compound 46B as a colorless viscous liquid. Yield: 3.10 g, 35.83%; LCMS m / z 731.29 [M+1] + .

[1291] To a solution of compound 46B (1.0 eq, 2.6 g, 3.56 mmol) in methanol (26 mL) was added acetic acid (2.6 mL) and palladium on carbon (10%) (1.3 g) and the reaction mixture was stirred at room temperature under hydrogen atmosphere for 3 hours. Upon completion, the reaction mixture was filtered, the filtrate was concentrated and dried to give compound 46C as a colorless viscous liquid. Yield: 3.1 g (crude); LCMS m / z 597.27 [M+1] + .

[1292] Synthesis of Synthon 61A

[1293]

[1294] Synthesis of Synthon 62A

[1295]

[1296] Synthesis of Synthon 63A

[1297]

[1298]

[1299] Synthesis of 5-(3-bromophenyl)pent-4-yn-1-ol (2). To a solution of 1-bromo-3- iodobenzene (1, 16.8 g, 1.0 eq, 59.4 mmol) in tetrahydrofuran (90 mL) was added pent-4-yn-1-ol (1a, 5 g, 1.0 eq, 59.4 mmol), triethylamine (25.1 mL, 3.0 eq, 178 mmol) and copper (I) iodide (1.13 g, 0.1 eq, 5.94 mmol) and the reaction mixture was purged with argon gas stream for 15 minutes. Then tetrakis(triphenylphosphine)palladium (3.43 g, 0.05 eq, 2.97 mmol) was added to the reaction mixture and the reaction ...

Claims

1. A cell surface M6PR binding compound of Formula (XIIa): or a prodrug thereof or a salt thereof, wherein: W is a non-hydrolysable hydrophilic head group; each A is independently an optionally substituted aryl or heteroaryl linking moiety (e.g., an optionally substituted monocyclic or bicyclic aryl or heteroaryl); Z 1 selected from the group consisting of optionally substituted (Ci-C3)alkylene and optionally substituted ethenylene; Z 2 is selected from O, S, NR 21 and C(R 22 )2, wherein each R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl; n is 1 to 500; Each Z 3 independently a connecting portion; m is 1 to 100; L is a linker; and Y is a moiety of interest; (i) W is -P(0)(OH)2; or (ii) the linker L comprises a backbone of at least 16 contiguous atoms, and Y is a target binding moiety. wherein when A is phenyl, and Z 2 is O, then:

2. A cell surface mannose-6-phosphate receptor (M6PR) binding compound of Formula (XIa): or a prodrug thereof or a salt thereof, wherein: W is a non-hydrolysable hydrophilic head group; A is an optionally substituted cyclic group (e.g., an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted heterocycle, or an optionally substituted cycloalkyl); n is 1 to 500; m is 1 to 100; Z 1 selected from the group consisting of optionally substituted (Ci-C3)alkylene and optionally substituted ethenylene; Z 2 is selected from O, S, NR 21 and C(R 22 )2, wherein R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl; L is a linker; and Each Z 3 independently a connecting portion; Y is a moiety of interest.

4. The compound of claim 2 or 3, wherein W is a phosphonate, a thiophosphonate, a carboxylic acid, or a malonic acid, or a salt thereof.

5. The compound of any one of claims 2 to 4, wherein the compound comprises an M6PR binding moiety (X) having one of the following formulae:

6. The compound of claim 1, wherein the compound comprises an M6PR binding moiety (X) having one of the following formulae:

7. The compound of any one of claims 1 to 6, wherein A is an optionally substituted aryl or an optionally substituted heteroaryl, preferably A is independently selected from an optionally substituted phenyl, an optionally substituted pyridyl, an optionally substituted biphenyl, an optionally substituted naphthalene, an optionally substituted triazole, and an optionally substituted phenylene triazole.

3. The compound of claim 2, wherein Z is S. 2 is S.

8. The compound of claim 7, wherein A is selected from an optionally substituted 1,4- phenylene, an optionally substituted 1,3-phenylene, an optionally substituted 2,5-pyridylene, and a triazole.

9. The compound of claim 8, wherein A is selected from: wherein R a , R b , R c and R d are independently H or F. wherein: wherein R a , R b , R c and R d are independently H or F.

10. The compound of any one of claims 1 to 6, wherein A is an optionally substituted fused bicyclic aryl or an optionally substituted fused bicyclic heteroaryl.

11. The compound of claim 10, wherein A is an optionally substituted naphthalene or an optionally substituted quinoline.

12. The compound of claim 11, wherein A is selected from: wherein: R 11 to R 14 are independently selected from H, halogen, OH, optionally substituted (Ci-C6)alkyl, optionally substituted (Ci-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 , and -NHCOR 25 ; and R 25 is independently selected from H and optionally substituted (C1-C6)alkyl. s is 0 to 3; and 13. The compound of claim 12, wherein A is selected from:

14. The compound of any one of claims 1 to 6, wherein A is an optionally substituted bicyclic aryl or an optionally substituted bicyclic heteroaryl of the following formula: or a salt thereof, R 11 and R 13 to R 14 independently selected from H, halogen, OH, optionally substituted (C1-C6) alkyl, optionally substituted (C1-C6) alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2.-OCOR 25 、-COOR 25 、-CONHR 25 and-NHCOR 25 ; wherein: each R is independently selected from the group consisting of H, and optionally substituted (Ci-C6)alkyl. 25 is independently selected from the group consisting of H and optionally substituted (Ci-C6)alkyl. Cy is independently a monocyclic aryl or a monocyclic heteroaryl; s is 0 to 4; and 15. The compound of claim 14, wherein Cy is an optionally substituted phenyl, and A is an optionally substituted biphenyl of the following formula:

16. The compound of claim 15, wherein A is selected from:

17. The compound of claim 14, wherein Cy is a triazole, and A is selected from: R 11 to R 15 are independently selected from H, halogen, OH, optionally substituted (Ci-C6)alkyl, optionally substituted (Ci-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 and -NHCOR 25 ; ​ each R is independently selected from the group consisting of H, and optionally substituted (Ci-C6)alkyl. 25 is independently selected from the group consisting of H and optionally substituted (Ci-C6)alkyl. ​ ​ ​ 18. The compound of any one of claims 6-17, wherein A is substituted with at least one OH substituent.

19. The compound according to any one of claims 9 and 12-17, wherein R 11 at least one of R 15 is OH (e.g., at least two are OH).

20. The compound according to any one of claims 9 and 12 to 17, wherein R 11 to R 15 each is H.

21. The compound of any one of claims 1-20, wherein: Z 3 selected from a covalent bond, -O-, -NR 23 -, -NR 23 CO-, -CONR 23 -, -NR 23 CO2-, -OCONR 23 -, -NR 23 C(=X 1 )NR 23 -, -CR 24 =N-, -CR 24 =N-X 2 -, -N(R 23 )SO2- and -SO2N(R 23 )-, wherein: X 1 and X 2 is selected from O, S and NR 23 ; and R 23 and R 24 are independently selected from H, C (1-3) -alkyl (e.g., methyl) and substituted C (1-3) -alkyl.

22. The compound according to any one of claims 1 to 21, wherein Z 3 is wherein: X 1 is O or S; t is 0 or 1; and each R is independently selected from H, C 23 is independently selected from H, C (1-3) - alkyl (e.g., methyl) and substituted C (1-3) - alkyl.

23. The compound of claim 22, wherein Z is -NHC(=0)NH-. 3 is -NHC(=0)NH-.

24. The compound according to any one of claims 1 to 23, wherein -A-Z 3 - is selected from:

25. The compound according to any one of claims 1 and 4 to 24, wherein Z 2 is O.

26. The compound according to any one of claims 1 to 24, wherein Z 2 is S.

27. The compound according to any one of claims 1 and 4 to 24, wherein Z 2 is -NR 21 -.

28. The compound according to any one of claims 1 and 4 to 24, wherein Z 2 is -C(R 22 )2-, wherein each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl.

29. The compound of claim 28, wherein Z is -CH2- or -CF2-. 2 is -CH2- or -CF2-.

30. The compound according to any one of claims 1 and 5 to 24, wherein -Z 2 -Ar-Z 3 - is wherein: X is O, S, -CH2-, or -CF2; R 16 is OH; and w is 0-4 (e.g., w is 0, 1, or 2).

31. The compound of claim 30, wherein -Z 2 - Ar-Z 3 - is 32. A cell surface M6PR binding compound of Formula (XV): or a prodrug or salt thereof, wherein: W is a non-hydrolysable hydrophilic head group; Z 1 selected from the group consisting of optionally substituted (Ci-C3)alkylene and optionally substituted ethenylene; Z 4 selected from -Z 14 -, -Z 14 -A-, -A- and -CH2-Z 14 -, Z 14 selected from O, S, NR 21 and C(R 22 )2, wherein R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl; A is an optionally substituted cyclic group (e.g., optionally substituted aryl, optionally substituted heteroaryl, optionally substituted heterocycle, optionally substituted cycloalkyl); n is 1-500; m is 1-100; L is a linker; and Y is a moiety of interest.

33. The compound of claim 32, wherein Z is -CH2-Z 4 is -CH2-Z 14 wherein Z 14 is selected from O, S, NR 21 and C(R 22 )2.

34. The compound of claim 32, wherein Z is -CH2-A. 4 is -CH2-A.

35. The compound of claim 32, wherein Z is -A-. 4 35. The compound of claim 32, wherein Z is -A-. 4 35. The compound of claim 32, wherein Z is 36. The compound of claim 34 or 35, wherein A is an optionally substituted aryl or an optionally substituted heteroaryl.

37. The compound of claim 36, wherein A is a triazole.

38. The compound of claim 35, wherein Z 4 is wherein "*" indicates the connection to the linker L.

39. The compound according to any one of claims 1 to 38, wherein the non-hydrolysable hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, -NR 3 P=O(OH)2, -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, -CR 1 R 2 -P=O(OH)2, -SO2OH (i.e., -SO3H), -S(O)OH, -COOH, -CN, -CONH2, -CONHR 3 , -CONR 3 R 4 , -CONH(OH), -CONH(OR 3 ), -CONHSO2R 3 , -CONHSO2NR 3 R 4 , -CH(COOH)2, -CR 1 R 2 COOH, -SO2R 3 , -SOR 3 R 4 , -SO2NH2, -SO2NHR 3 , -SO2NR 3 R 4 , -SO2NHCOR 3 , -NHCOR 3 , -NHC(O)CO2H, -NHSO2NHR 3 , -NHC(O)NHS(O)2R 3 , -NHSO2R 3 , -NHSO3H, or a salt thereof, wherein: R 1 and R 2 are independently hydrogen, SR 3 , halo, or CN, and R 3 and R 4 are independently H, C 1-6 alkyl or substituted C 1-6 alkyl (e.g., -CF3or -CH2CF3); A, B, and C are each independently CH or N; and D is each independently O or S.

40. The compound of claim 39, wherein W is selected from -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), -COOH, and -CH(COOH)2, or a salt thereof.

41. The compound according to any one of claims 1 to 40, wherein Z 1 is -(C(R 22 )2) j - wherein each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (Ci-C6)alkyl, and j is 1 to 3.

42. The compound of claim 41, wherein Z 1 is -(CH2)2-, -CH2-CF2- or -CH2-CHF-.

43. The compound of claim 41, wherein Z is -CH2- or -CF2-. 1 is -CH2- or -CF2-.

44. The compound according to any one of claims 1 to 40, wherein Z 1 is -CH=CH-.

45. The compound of claim 41, wherein: Z 1 is -(CH2)2-, -CH2-CF2- or -CH2-CHF-; and W is selected from -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH, or a salt thereof.

46. The compound of claim 60, wherein: Z 1 is -CH=CH-; and W is selected from -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH, or a salt thereof.

47. The compound of claim 41, wherein: Z 1 is -CH2- or -CF2-; and W is -CH(COOH)2, or a salt thereof.

48. The compound of any one of claims 1-47, wherein n is 1-20 (e.g., 1-10, 1-6, or 1-3).

49. The compound of claim 48, wherein n is 1.

50. The compound of claim 49, wherein L comprises a straight linker having a backbone of 16 or more contiguous atoms covalently linked to Z 3 Y.

51. The compound of claim 48, wherein n is 2.

52. The compound of claim 48, wherein n is 3.

53. The compound of any one of claims 1-52, wherein L is of Formula (II): wherein L 1 and L 3 are independently linkers, and L 2 is the branched connecting part, where L 1 To L 3 Together, a straight or branched joint is provided between X and Y; a, b, and c are independently 0 or 1; **represents the attachment point of X via Z 1 with L 1 ; and *** indicates the point of attachment to Y; wherein: when n is 1, a is 1, and b is 0; when n is >1, a is 1, and b is 1.

54. The compound of claim 53, wherein L 1 to L 3 each independently comprises one or more linking moieties independently selected from the group consisting of -C 1-20 -alkylene-, -NHCO-C 1-6 -alkylene-, -CONH-C 1-6 -alkylene-, -NH C 1-6 -alkylene-, -NHCONH-C 1-6 -alkylene-, -NHCSNH-C 1-6 -alkylene-, -C 1-6 -alkylene-NHCO-, -C 1-6 -alkylene-CONH-, -C 1-6 -alkylene-NH-, -C 1-6 -alkylene-NHCONH-, -C 1-6 -alkylene-NHCSNH-, -O(CH2) p -, -(OCH2CH2) p -, -NHCO-, -CONH-, -NHSO2-, -SO2NH-, -CO-, -SO2-, -O-, -S-, pyrrolidine-2,5-dione, 1,2,3-triazole, -NH-, and -NMe-, wherein each p is independently 1 to 50.

55. The compound of claim 53 or 54, wherein L comprises repeating ethylene glycol moieties (e.g., -CH2CH2O- or -OCH2CH2-).

56. The compound of claim 55, wherein L comprises 1-25 ethylene glycol moieties (e.g., 3, 7, or 24 ethylene glycol moieties).

57. The compound of any one of claims 53-56, wherein L comprises one or more 1,2,3-triazole linking moieties.

58. The compound of claim 57, wherein L comprises one or more linking moieties selected from the following structures: wherein w1, u1, and q1 are independently 1 to 25 (e.g., 1 to 12, such as 1 to 6).

59. The compound of any one of claims 53-58, wherein n is 1.

60. The compound of any one of claims 53-58, wherein n is 2 or greater.

61. The compound of claim 60, wherein L 2 is selected from: wherein each x and y is independently 1-10.

62. The compound according to any one of claims 53 to 61, wherein L 1 to L 2 In Z 2 or Z 4 contains 14 or more contiguous atoms (e.g., such as 14 to 50 or 14 to 30 atoms) between the branching atom.

63. The compound according to any one of claims 53 to 62, wherein L 3 a backbone comprising 10 to 80 contiguous atoms (e.g., such as 12 to 50 atoms).

64. The compound of claim 63, wherein L 3 comprises a linking moiety selected from: 10 - C 20 - alkylene (e.g., C 12 - alkylene) or –(OCH2CH2) p –, wherein p is 1 to 25 (e.g., 3, 7, or 24).

65. The compound of any one of claims 53-64, wherein the linker of Formula (II) comprises 20-100 contiguous atoms.

66. The compound of claim 65, wherein the linker of Formula (II) comprises 25 or more contiguous atoms.

67. The compound of claim 65, wherein the linker of Formula (II) comprises 30 or more contiguous atoms.

68. The compound of any one of claims 1-67, wherein m is 1.

69. The compound of any one of claims 1-67, wherein m is at least 2.

70. The compound of claim 69, wherein m is 2-20 (e.g., m is 2-10).

71. The compound of claim 69, wherein: m is 20-500 (e.g., 20-400, 20-300, or 20-200 or 50-500 or 100-500); and L is an alpha-amino acid polymer (e.g., poly-L-lysine) in which a plurality of -Ar-Z 3 groups are covalently attached to the polymer backbone via side chain groups (e.g., via conjugation to a side chain amino group of a lysine residue).

72. The compound of any one of claims 1-71, wherein Y is selected from a small molecule, a dye, a fluorophore, a monosaccharide, a disaccharide, a trisaccharide, and a chemoselective linker or a precursor thereof.

73. The compound of any one of claims 1-71, wherein Y is a biomolecule.

74. The compound of claim 73, wherein the biomolecule is selected from a peptide, a protein, a polynucleotide, a polysaccharide, a glycoprotein, a lipid, an enzyme, an antibody, and an antibody fragment.

75. The compound of any one of claims 1-74, wherein Y is a moiety that specifically binds a target protein.

76. The compound of claim 76, wherein the target protein is a membrane-bound protein.

77. The compound of claim 76, wherein the target protein is a soluble extracellular protein.

78. The compound of any one of claims 74-77, wherein Y is selected from an antibody, an antibody fragment (e.g., an antigen-binding fragment of an antibody), a chimeric fusion protein, an engineered protein domain, a D-protein binder of a target protein, an aptamer, a peptide, and a small molecule inhibitor or ligand.

79. A target protein degradation conjugate of Formula (XXI): or a prodrug thereof, or a pharmaceutically acceptable salt thereof, wherein: n is 1-3; m is an average loading of 1-10; L is a linker; P is a biomolecule that specifically binds a target protein; Z 5 a residue linking moiety resulting from covalent attachment of a chemoselective linker of L to a compatible moiety of P; W is a non-hydrolysable hydrophilic head group; Z 1 selected from the group consisting of optionally substituted (Ci-C3)alkylene and optionally substituted ethenylene; Z 2 selected from O, S, NR 21 and C(R 22 )2, wherein R 21 is independently selected from H and optionally substituted (C1-C6)alkyl, and each R 22 is independently selected from H, halogen (e.g., F), and optionally substituted (C1-C6)alkyl; A is an optionally substituted cyclic group; and Z 3 is a linking moiety.

80. The conjugate of claim 79, wherein the conjugate is of Formula (XXIb):

81. The conjugate of claim 79 or 80, wherein Z 2 is S.

82. The conjugate of claim 79 or 80, wherein Z 2 is O.

83. The conjugate of claim 79 or 80, wherein Z 2 is -CH2- or -CF2-.

84. The conjugate of any one of claims 79-83, wherein A is an optionally substituted aryl or an optionally substituted heteroaryl.

85. The conjugate of any one of claims 79-84, wherein A is independently selected from the group consisting of optionally substituted phenyl, optionally substituted pyridyl, optionally substituted biphenyl, optionally substituted naphthalene, optionally substituted triazole, and optionally substituted phenylene triazole.

86. The conjugate of any one of claims 79-85, wherein A is selected from the group consisting of: wherein: R 11 to R 14 are independently selected from H, halogen, OH, optionally substituted (Ci-C6)alkyl, optionally substituted (Ci-C6)alkoxy, COOH, NO2, CN, NH2, -N(R 25 )2, -OCOR 25 , -COOR 25 , -CONHR 25 and -NHCOR 25 ; and R 25 is independently selected from H and optionally substituted (Ci-C6)alkyl.

87. The conjugate of any one of claims 84-86, wherein A is substituted with at least one OH substituent.

88. The conjugate of claim 86, wherein R 11 at least one of R 14 is OH (e.g., at least two are OH).

89. The conjugate of claim 86, wherein R 11 to R 15 each is H.

90. The conjugate of any one of claims 79-89, wherein: Z 3 is selected from a covalent bond, -O-, -NR 23 -, -NR 23 CO-, -CONR 23 -, -NR 23 CO2-, -OCONR 23 -, -NR 23 C(=X 1 )NR 23 -、-CR 24 =N-, -CR 24 =NX 2 、-N(R 23 )SO2- and -SO2N(R 23 )-,in: X 1 and X 2 is selected from O, S and NR 23 ; and R 23 and R 24 are independently selected from H, C (1-3) -alkyl (e.g., methyl) and substituted C (1-3) -alkyl.

91. The conjugate of any one of claims 79-90, wherein Z 3 is wherein: X 1 is O or S; t is 0 or 1; and each R is independently selected from H, C 23 is independently selected from H, C (1-3) - alkyl (e.g., methyl) and substituted C (1-3) - alkyl.

92. The conjugate of claim 91, wherein Z 3 is -NHC(=0)NH-.

93. The conjugate according to any one of claims 79 to 90, wherein -A-Z 3 - is selected from the group consisting of:

94. The conjugate of any one of claims 79 to 93, wherein the non-hydrolyzable hydrophilic head group W is selected from -OH, -CR 2 R 2 OH, –NR 3 P=O(OH)2, –P=O(OH)2, –P=S(OH)2, –P=O(SH)(OH), –P=S(SH)(OH), P(=O)R 1 OH, -PH(=O)OH, –CR 1 R 2 -P=O(OH)2, –SO2OH (i.e., –SO3H), –S(O)OH, –COOH, –CN, –CONH2, –CONHR 3 、–CONR 3 R 4 、–CONH(OH),–CONH(OR 3 ),–CONHSO2R 3 , –CONHSO2NR 3 R 4 、–CH(COOH)2、–CR 1 R 2 COOH, –SO2R 3 ,–SOR 3 R 4 , –SO2NH2, –SO2NHR 3 , –SO2NR 3 R 4 ,–SO2NHCOR 3 ,–NHCOR 3 、-NHC(O)CO2H、–NHSO2NHR 3 、-NHC(O)NHS(O)2R 3 、–NHSO2R 3 、–NHSO3H、 or their salts, wherein: R 1 and R 2 are independently hydrogen, SR 3 , halo, or CN, and R 3 and R 4 are independently H, C 1-6 alkyl, or substituted C 1-6 alkyl (e.g., -CF3or -CH2CF3); A, B, and C are each independently CH or N; and D is each independently O or S.

95. The conjugate of claim 94, wherein W is selected from the group consisting of -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), -COOH, and -CH(COOH)2, or a salt thereof.

96. The conjugate of any one of claims 79-95, wherein the conjugate comprises a M6PR binding moiety of one of the following formulas: wherein: W is selected from the group consisting of -P=O(OH)2, -P=S(OH)2, -P=O(SH)(OH), -P=S(SH)(OH), and -COOH, or a salt thereof; and R a , R b , R c , and R d are independently H or F.

97. The conjugate of any one of claims 79-96, wherein n is 1.

98. The conjugate of any one of claims 79-96, wherein n is 2.

99. The conjugate of any one of claims 79-96, wherein n is 3.

100. The conjugate of any one of claims 79-99, wherein Y is an antibody or antibody fragment that specifically binds to the target protein.

101. The conjugate of any one of claims 76-99, wherein m is 1-8 (e.g., 1-7 or 1-6).

102. The conjugate of claim 101, wherein m is about 8, about 6, about 5, about 4, about 3, or about 2.

103. The conjugate of any one of claims 79-96, wherein n is 1 and m is 1-10.

104. The conjugate of claim 103, wherein m is 2-8 (e.g., 2-6 or 3-5).

105. The conjugate of claim 104, wherein m is about 4.

106. The conjugate of any one of claims 79-96, wherein n is 2 and m is 1-6 (e.g., 2-6 or 3-5).

107. The conjugate of claim 106, wherein m is about 4.

108. The conjugate of any one of claims 79 to 107, wherein Z 5 is a residue moiety resulting from the covalent attachment of a thiol-reactive chemoselective linking group (e.g., a maleimide) to one or more cysteine residues of P.

109. The conjugate of any one of claims 79 to 107, wherein Z 5 is a residue moiety resulting from covalent attachment of an amine-reactive chemoselective linking group (e.g., a PFP ester or a TFP ester) to one or more lysine residues of P.

110. The conjugate of any one of claims 79-109, wherein L is a straight linker having a backbone of 16 or more contiguous atoms covalently linked to Z 3 P. In some embodiments, L is a straight linker having a backbone of 16 or more contiguous atoms covalently linked to Z 111. The conjugate of any one of claims 79 to 109, wherein L is a branched linker having a main chain of 14 or more contiguous atoms (e.g., such as 14 to 50 or 14 to 30 atoms) between the branched atom of the linker and Z 2 a branched linker having a main chain of 14 or more contiguous atoms (e.g., such as 14 to 50 or 14 to 30 atoms) between the branched atom of the linker and Z 112. The conjugate of any one of claims 79-111, wherein the linker L is selected from any one of the structures of Tables 4-5.

113. The conjugate of any one of claims 79-112, wherein the conjugate is derived from conjugation of a compound of any one of the structures of Tables 7-9, 12, and 13 to the biomolecule P.

114. The conjugate of claim 113, wherein P is an antibody or antibody fragment.

115. The conjugate of claim 114, wherein the antibody or antibody fragment is an IgG antibody.

116. The conjugate of claim 114 or 115, wherein the antibody or antibody fragment is a humanized antibody.

117. The conjugate of any one of claims 114 to 116, wherein the antibody or antibody fragment specifically binds to a secreted or soluble protein.

118. The conjugate of any one of claims 114 to 116, wherein the antibody or antibody fragment specifically binds to a cell surface receptor.

119. A method of internalizing a target protein in a cell comprising a cell surface M6PR, the method comprising contacting a cell sample comprising the cell and the target protein with an effective amount of a compound of any one of claims 1 to 78 or a conjugate of any one of claims 79 to 118, wherein the compound or conjugate specifically binds to the target protein and specifically binds to a cell surface receptor to facilitate cellular uptake of the target protein.

120. The method of claim 119, wherein the target protein is a membrane-bound protein.

121. The method of claim 119, wherein the target protein is an extracellular protein.

122. The method of any one of claims 119 to 121, wherein the compound or conjugate comprises an antibody or antibody fragment (Ab) that specifically binds to the target protein.

123. A method of reducing the level of a target protein in a biological system, the method comprising contacting the biological system with an effective amount of a compound of any one of claims 1 to 78 or a conjugate of any one of claims 79 to 118, wherein the compound or conjugate specifically binds to the target protein and specifically binds to a cell surface M6PR of a cell in the biological system to facilitate cellular uptake and degradation of the target protein.

124. The method of claim 123, wherein the biological system is a human subject.

125. The method of claim 123, wherein the biological system is an in vitro cell sample.

126. The method of any one of claims 123 to 125, wherein the target protein is a membrane-bound protein.

127. The method of any one of claims 123 to 125, wherein the target protein is an extracellular protein.

128. A method of treating a disease or disorder associated with a target protein, the method comprising:

128. A method of treating a disease or disorder in a subject in need thereof, the method comprising administering to the subject an effective amount of a compound of any one of claims 1 to 78 or a conjugate of any one of claims 79 to 118, wherein the compound or conjugate specifically binds to a target protein.

129. The method of claim 128, wherein the disease or disorder is an inflammatory disease.

130. The method of claim 128, wherein the disease or disorder is an autoimmune disease.

131. The method of claim 128, wherein the disease or disorder is a cancer.

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