TLR agonist compounds and conjugates

Abstract

The present invention relates to Toll-Like-Receptor (TLR) agonist compounds targeted to ACP3 and conjugates thereof, which can be used for the treatment of cancer.

Description

[0001] 96BM-850010-WO / 15124-WO-PCT

[0002] TLR AGONIST COMPOUNDS AND CONJUGATES

[0003] REFERENCE TO SEQUENCE LISTING

[0004] The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled 96BM-850010-WO_SequenceListing, created March 10, 2026, which is 4,438 bytes in size. The information in the electronic format of the Sequence Listing is incorporated herein by reference in its entirety.

[0005] FIELD OF THE INVENTION

[0006] The present disclosure relates to Toll-Like-Receptor (TLR) agonist compounds and conjugates thereof, which can be used for the treatment of cancer. In certain embodiments, the present disclosure describes Toll-Like-Receptor (TLR) agonist compounds having an ACP3 targeting moiety.

[0007] BACKGROUND

[0008] Recent advancements in cancer therapy have been largely driven by the widespread use of immune checkpoint inhibitors (ICIs). ICIs restore the anti-tumor immune response by blocking co-inhibitory signaling pathways, such as PD-1 / PD-L1 and CTLA-4. While ICIs have been successful for certain types of cancers, only a small fraction of patients respond to treatment either for acquisition of resistance mechanisms or for the inability of ICIs to treat ‘cold’ tumors. Indeed, patients with ‘hot’ tumors which are highly inflamed often show a favorable response to these drugs, while ‘cold’ tumors, which are characterized by poor T-cell infiltration or low PD-L1 expression, are more resistant to the use of ICIs.

[0009] A promising strategy to overcome the limitations of ICIs, particularly for ‘cold’ tumors, involves targeting antigen-presenting cells (APCs) via the activation of pattern recognition receptors (PRRs), including Toll-like receptors (TLRs). Activation of TLRs on APCs leads to the release of pro-inflammatory cytokines and enhances co-stimulatory molecule expression, ultimately boosting T-cell activity against tumors. For these reasons, Toll-like receptors (TLRs) have emerged as a critical target in cancer immunotherapy.

[0010] Toll-like receptors (TLRs), comprising a family of 10 functional receptors in humans, are a critical part of the innate pathogen recognition system(1). TLRs recognize different pathogen- and host-derived molecules and mediate cell activation and inflammation in order to initiate immune response.

[0011] Over the years, several TLR7 and TLR8 agonists have been developed and evaluated for therapeutic applications, particularly in antiviral and immuno-oncology settings(2). Indeed, small molecule agonists of TLR7 and TLR8 can induce a strong immune response in humans and animals.

[0012] TLR7, in particular, can be activated by synthetic analogues of guanosine, often based on purine-like or imidazoquinoline structures, and triggers downstream signaling pathways that activate the immune system.This has led to the development of several TLR7 agonists, which have been investigated for use in antiviral and cancer immunotherapy. While compounds such as those disclosed in US 8,728,486 B2, having an imidazoquinoline scaffold, and W02019 / 209811A1, having purine-like scaffold, have shown positive preliminary results, challenges remain in improving their potency, selectivity, and pharmacokinetic properties. A significant challenge in the use of TLR7 agonists is the potential for severe systemic toxicity, particularly when administered systemically, which can lead to dangerous side effects such as cytokine storms.

[0013] Immune-Stimulating Antibody Conjugates (ISACs) are a new class of drugs that takes inspiration from Antibody-Drug Conjugates (ADCs). ISACs are typically composed of a monoclonal antibody specific for a certain tumor antigen that can selectively deliver and release at the tumor site the conjugated immune-stimulating drug such as a TLR7 agonist.

[0014] While ISACs represent a promising strategy for the targeted delivery of TLR7 agonists, they still need to be improved, e.g., in terms of potency of the payload, stability of the conjugate, anti-tumor efficacy and / or tolerability, to ensure a potent antitumor effect limiting the systemic toxicities.

[0015] Small Molecule-Drug Conjugates (SMDCs) leverage small organic molecules as targeting vectors to selectively deliver TLR7 agonists to tumor sites, thereby improving drug localization and minimizing systemic exposure. This targeted approach allows for better tumor penetration and a controlled release of the immune-stimulating agents, reducing the risk of off-target toxicity. Therefore, SMDCs represent a promising strategy to overcome the limitations currently present in the delivery of TLR7 agonists. However, while SMDCs show considerable promise as a strategy for the targeted delivery of TLR7 agonists, further development is necessary, e.g., to improve their potency, stability, and / or targeting specificity.

[0016] Non-patent literature

[0017] (1) Kawai, T. et al. (2010). Nature immunology, 11(5), 373-384

[0018] (2) Patinote, C., et al. (2020). European Journal of Medicinal Chemistry, 193, 112238

[0019] Patent Literature

[0020] US 8,728,486 B2

[0021] WO2019 / 209811 A1

[0022] PROBLEMS SOLVED BY THE INVENTION

[0023] In view of the above background, the present invention addresses the need for improved agents that can be effectively used for the immune system activation, specifically for therapeutic applications, e.g., related to immunomodulation and cancer immunotherapy. In one particular aspect, it provides improved conjugates (e.g., SMDCs and / or ISACs) that can specifically target the tumor lesions and deliver efficiently TLR7 agonists tothe sites of disease, particularly in the context of tumor immunotherapy. In another aspect, it provides improved TLR7 agonist compounds (e.g., useful as potent payloads or payload precursors for SMDCs and / or ISACs, or useful as unconjugated small-molecule therapeutic agents with improved activity, tolerability and / or pharmacological properties).

[0024] SUMMARY OF THE INVENTION

[0025] As a solution to the above problems, the invention provides conjugates of Formula I and compounds of Formula II, as defined herein below and in the appended claims.

[0026] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows EC50 of compounds MB357, A78 or resiquimod on human (A) and murine (B) TLR7 measured using NF-KB-SEAP reporter HEK293 cells expressing the receptor.

[0028] FIG. 2 shows a quantification of cytokines (hIL6 and hTNFa) released by human Peripheral Blood Monocytes (PBMCs) after 24 hours of stimulation with compounds MB357 or A78.

[0029] FIG. 3 shows a quantification of cytokines (mIL6 and mTNFa) released by murine Bone Marrow Dendritic Cells (BMDCs) and Splenocytes after 24 hours of stimulation with compounds MB357 or A78.

[0030] FIG. 4 shows flow cytometry evaluation of CD86 and CD40 expression upregulation in Bone Marrow Dendritic Cells (CD11c+) cultured for 24 hours with compounds MB357, A78, or lib- 19 (A-C); and of CD40 expression upregulation in B Cells (B220+ splenocytes) cultured for 24 hours with compounds MB357 or A78 (D)

[0031] DETAILED DESCRIPTION OF THE INVENTION

[0032] The present inventors have identified Toll-Like-Receptor 7 (TLR7) agonists, i.e., TLR 7 agonist compounds and conjugates thereof, which are suitable for use in the treatment of cancer. The TLR7 agonists described herein have improved anticancer effect. In particular, the TLR7 agonist compounds and the related conjugates are immune-modulating agents that can be used for targeted therapy in diseases, such as cancer, with improved efficacy, potency, and minimal toxicity compared to existing treatments.

[0033] The compounds and conjugates are highly potent and selective TLR7 agonists (e.g., selective for TLR7 vs. TLR8), highly effective in stimulating cytokine release and promoting immune cell activation (e.g., CD86 and CD40 upregulation), and showing superior in vivo efficacy and tolerability, including advantageous doseresponse antitumor effects and minimal toxicity (e.g., in preclinical models).

[0034] Conjugates for site-specific delivery

[0035] The TLR7 agonists disclosed herein can be delivered to the site of intended action, e.g., by targeted delivery in a conjugate with a targeting moiety. Preferably, the targeting moiety is a small molecule or an antibody andits antigen is found at the locality of intended action, for example a tumor-associated antigen if the intended site of action is at a tumor (cancer). Preferably, the tumor-associated antigen is uniquely expressed or overexpressed by the cancer cell, compared to a normal cell. The tumor-associated antigen can be located on the surface of the cancer cell or in the tumor microenvironment (e.g., on the surface on stromal cells or in the extracellular matrix).

[0036] The TLR7 agonists of the invention can be conjugated to a tumor-targeting moiety (A) for tumor-specific targeting or for localized retention after administration. This conjugation can be achieved through various combinations of components, including a spacer (B), a cleavable or non-cleavable linker (C), and a self-immolative spacer (D). Each of B, C, and D may be arranged in any order, but it is preferred that they are arranged in the order -B-(C)c-(D)d-, more preferably wherein each of c and d is 1. The TLR7 agonist moiety (E) is included for its therapeutic action once delivered to the targeted site.

[0037] The TLR7 agonist conjugate of the present invention can have the following structure:

[0038] A - B - (-C-J— (-D-)— E

[0039] c d

[0040] I

[0041] or can be a pharmaceutically acceptable salt, solvate, hydrate, crystal form, tautomer, or diastereoisomer thereof.

[0042] Therein, A is a tumor-targeting moiety;. E is a TLR7 agonist moiety, B, C, and D can be collectively referred to as a “linking moiety” because they link E and A. Within the linking moiety, B is a spacer; C is a cleavable or non-cleavable linker; D is a self-immolative spacer. The subscripts c and d may each be 0 or an integer of 1 or more; preferably 0, 1, 2 or 3. That is, the presence of C and D is optional. In Formula I, each occurrence of B, C, and D may be in any order, but it is preferred that they are arranged in the order -B-(C)c-(D)d-, more preferably wherein each of c and d is 1. A, B, C, D and E will be discussed in more detail in the subsequent paragraphs.

[0043] As used herein, the disclosure refers to the conjugate, including its individual diastereoisomers, hydrates, solvates, crystal forms, tautomers, or pharmaceutically acceptable salts thereof.

[0044] The tumor-targeting moiety (A) is the component that binds specifically to tumor-associated antigens, directing the conjugate to the tumor site for targeted therapy. The spacer (B) is a molecular bridge that ensures the proper positioning of the therapeutic components, optimizing their effectiveness at the target site. The spacer B can advantageously modulate the physicochemical properties such as the permeability or solubility. The cleavable or non-cleavable linker (C) is an optional component that links the various parts of the conjugate. Advantageously, the linker can be highly stable in plasma and selectively and rapidly release the payload (e.g., the TLR7 agonist) only in the tissue of interest. Non-cleavable linkers are preferred when the targeting agent is specific for internalizing antigens (e.g., ACP3) since they rely on the complete endocytosis of the conjugateand lysosomal degradation to allow the payload release. The self-immolative spacer (D) is an optional element that facilitates the release of the active TLR7 agonist moiety after the cleavage of the linker in the target tissue. Advantageously, a cleavable linker is positioned adjacent (e.g., immediately upstream) to a self-immolative spacer; in which case the cleavage of the linker induces self-immolation of the spacer and release of the payload (E). Finally, the TLR7 agonist moiety (payload E) is a therapeutic component that activates the immune response upon reaching the tumor site, stimulating immune cells against cancer cells.

[0045] The conjugates of the invention comprising E, as defined herein, advantageously exhibit enhanced anticancer effects (even as compared to the respective unconjugated payload, or to reference compounds) and minimal toxicity.

[0046] As illustrated above, since the subscripts c and d can be 0 or an integer of 1 or more; preferably 0, 1, 2 or 3, the generic structure I can have different arrangements, including the following preferred arrangements:

[0047] A - B — (-C-) - E

[0048] c

[0049]

[0050] d

[0051] A - B - E

[0052] with the components being as defined hereinbelow. These combinations can be used with the components described in the following sections.

[0053] The conjugate of Formula I may also have a structure according to the following general formula, wherein multiple “arms” bearing a TLR7 payload E are attached to the same target binding moiety (especially when A is an antibody, an antibody derivative, or an antigen binding fragment thereof):

[0054] A— (— B - C - D - E)

[0055] 2-8

[0056] Preferably, the generic structure of Formula I, as well as all the other conjugate structures defined herein have the following arrangements:

[0057] A - B - C - D - E

[0058] A - B - C - E

[0059] A - B - E

[0060] More preferably, the generic structure of Formula I, as well as all the other conjugate structures defined herein have the following arrangement:A - B - C - D - E

[0061] Targeting moiety (A)

[0062] The targeting moiety (A) is a tumor-targeting moiety, preferably an ACP3-binding moiety, as defined in the claims or hereinbelow.

[0063] In the present disclosure, the targeting moiety (A) is preferably a small molecule moiety, e.g., having a molecular weight of 3000 Da or less, preferably 2500 Da or less, more preferably 2000 Da or less, even more preferably from 250 to 2000 Da. Preferably, the small molecule tumor-targeting moiety (A) is an ACP3-binding moiety.

[0064] Preferred ACP3-binding moieties are disclosed and claimed in PCT / EP2024 / 080350, the contents of which are incorporated herein by reference in its entirety.

[0065] Alternatively, the targeting moiety (A) may be a tumor-targeting antibody, derivative or antigen binding fragment thereof that binds to an antigen, preferably wherein the antigen is Acid Phosphatase 3 (ACP3). Linking moieties and their components

[0066] As illustrated above, the linking moiety may comprise a spacer B, an optional cleavable or non-cleavable linker C, and an optional self-immolative spacer D. c and d may each be 0 or an integer of 1 or more; preferably 0, 1, 2 or 3.

[0067] The linking moiety is a covalent bond or a moiety comprising a chain of atoms that covalently attaches A to the payload E, e.g., through one or more covalent bond(s). The overall linking moiety may be a cleavable or non-cleavable, multifunctional moiety which can be used to link one or more payload and / or binder moieties to form the targeted conjugate of the invention. As used herein, and unless specified otherwise, “linking moiety” refers to the fragment -B-(C)c-(D)d-.

[0068] The linking moiety or parts thereof, in particular spacer B, can be a single bond, or an optionally substituted Ci -5o aliphatic group, in which optionally one or more carbon atoms can be replaced by a heteroatom, a €’3.

[0069] 12 carbocyclic or a C1-12 heterocyclic group, and which can be saturated optionally contain one or more double or triple bonds. The structure of the compound may comprise more than one moiety E, e.g., 2 to 4 moieties E per molecule.

[0070] When cleavable linker units are present within the linking moiety, e.g., as unit C, release mechanisms can be identical to those specific to antibodies linked to payloads. Indeed, the nature of the binding moieties is independent in that respect. Therefore, there is envisaged pH-dependent [Leamon, C. P. et al. (2006) Bioconjugate Chem., 17. 1226; Casi, G. et al (2012) J. Am. Chem. Soc., 134. 5887], reductive [Bemardes, G. J. et al. (2012) Angew. Chem. Int. Ed. Engl., 51. 941; Yang, J. et al. (2006) Proc. Natl. Acad. Sci. USA, 103.

[0071] 13872] and enzymatic release [Doronina S. O. et al (2008) Bioconjugate Chem, 19, 1960; Sutherland, M. S. K.(2006) J. Biol. Chem. 281. 10540], In a specific setting, when functional groups are present on either the binding moiety or payloads (e.g., thiols, alcohols), a linkerless connection can be established thus releasing intact payloads, which simplifies substantially pharmacokinetic analysis.

[0072] By attaching a therapeutic effector (in particular: TLR7 agonist payload E) through a site-specific cleavable linker to a binding moiety specific to a marker of disease, the effector preferentially accumulates and acts at the intended site of action, thus increasing the effectively applied dose while reducing side effects. That is, the overall linking moiety generally may be cleavable or non-cleavable, yet it is preferred that, a cleavable linking moiety (e.g., comprising a cleavable unit C) is used, which is contemplated to be advantageous from the viewpoint of payload release, accumulation of (free) payload and / or anti-tumor activity. Nevertheless, while the presence of a cleavable linker C can be advantageous where release of the payload E is desirable, cleavable linkers should not be understood to be generally mandatory or essential for the functioning of the compounds of the present invention.

[0073] The linking moiety or parts thereof, in particular spacer B, can comprise or consist of a unit shown in the table below wherein the substituents R and Rnshown in the formulae may suitably be independently selected from H, halogen, substituted or unsubstituted (hetero)alkyl, (hetero)alkenyl, (hetero)alkynyl, (hetero)aryl, (hetero)arylalkyl, (hetero)cycloalkyl, (hetero)cycloalkylaryl, heterocyclylalkyl, a peptide, an oligosaccharide or a steroid group. Preferably, each of R, Rj, R2 and R3 is independently selected from H, OH, SH, NH2, halogen, cyano, carboxy, alkyl, cycloalkyl, aryl and heteroaryl, each of which is substituted or unsubstituted. Suitably R and Rnare independently selected from H, or C1-C7 alkyl or heteroalkyl. More suitably, R and Rnare independently selected from H, methyl or ethyl.Linker type Structure Release mechanism

[0074] Amide 0 Proteolysis

[0075] H

[0076] Ester 0 Hydrolysis

[0077] Carbamate 0 Hydrolysis

[0078] KAA

[0079] R = H, Me^ / NHRJWV

[0080] /

[0081] Hydrazone co iz Hydrolysis

[0082] 1 H

[0083] / M ) Co= o V c,

[0084] r

[0085] CMX ZIZ () 0

[0086] Thiazolidine O / = H Hydrolysis

[0087] X N

[0088] vWV / s—>

[0089] Methylene alkoxy carbamate 0 Hydrolysis

[0090] k A J

[0091] ^ O N O

[0092] 15

[0093] R

[0094] Disulfide Reduction

[0095]

[0096] Spacer B, unit(s) BL and / or unit(s) BS may suitably comprise as a cleavable bond a disulfide linkage since these linkages are stable to hydrolysis, while giving suitable drug release kinetics at the target in vivo, and can provide traceless cleavage of drug moieties including a thiol group.

[0097] Spacer B, unit(s) BL and / or unit(s) BS may be polar or charged in order to improve water solubility of the conjugate. For example, the linking moiety may comprise from about 1 to about 20, suitably from about 2 to about 10, residues of one or more known water-soluble oligomers such as peptides, oligosaccharides, glycosaminoglycans, polyacrylic acid or salts thereof, polyethylene glycol, polyhydroxyethyl (meth) acrylates, polysulfonates, etc. Suitably, the linking moiety may comprise a polar or charged peptide moiety comprising e.g., from 2 to 10 amino acid residues. Amino acids may refer to any natural or non-natural amino acid. The peptide linker suitably includes a free thiol group, preferably a N-terminal cysteine, for forming the said cleavable disulfide linkage with a thiol group on the drug moiety. Any peptide containing L- or D-aminoacids can be suitable; particularly suitable peptide linkers of this type are Asp-Arg-Asp-Cys and / or Asp-Lys-Asp-Cys.In these and other embodiments, the linking moiety may comprise a cleavable or non-cleavable peptide unit C that is specifically tailored so that it will be selectively enzymatically cleaved from the drug moiety by one or more proteases on the cell surface or the extracellular regions of the target tissue. The amino acid residue chain length of the peptide unit suitably ranges from that of a single amino acid to about eight amino acid residues. Numerous specific cleavable peptide sequences suitable for use in the present invention can be designed and optimized in their selectivity for enzymatic cleavage by a particular tumor-associated enzyme e.g., a protease. Cleavable peptides for use in the present invention include those which are optimized toward the proteases MMP-1, 2 or 3, or cathepsin B, C or D. Especially suitable are peptides cleavable by Cathepsin B. Cathepsin B is a ubiquitous cysteine protease. It is an intracellular enzyme, except in pathological conditions, such as metastatic tumors or rheumatoid arthritis. An example for a peptide cleavable by Cathepsin B is containing the sequence Val-Cit. Further examples of cleavable peptide units include cleavable peptide unit selected from Gly-Pro, Ala-Pro, Val-Pro, Arg-Pro, Ile-Pro, Pro-Pro, Gly-Cit, Ala-Cit, Val-Cit, Arg-Cit, Ile-Cit, Phe-Lys, Vai-Ala, GlyGlyPheGly, AlaAlaAsn, and Pro-Cit; preferably Gly-Pro or Val-Cit.

[0098] Preferably, the cleavable linker can be one or more of i, ii, iii, iv, v, vi, vii and viii:

[0099]

[0100] v. Disulfide:H V |

[0101]

[0102] 5 Preferably, the non-cleavable linker can be one or more of ix, x, xi, xii, xiii, xiv:

[0103] n = 1 to 8, preferably 2 to 6

[0104]

[0105] x

[0106]

[0107] ii. MC (Maleimidocaproyl):xiii. MCC (maleimidomethyl cyclohexane- 1 -carboxylate):

[0108]

[0109]

[0110] In any of the above embodiments, the linking moiety suitably further comprise(s) self-immolative moiety can or cannot be present after (e.g., C- terminal or N-terminal to) the (cleavable) linker C. The self-immolative linkers are also known as electronic cascade linkers. These linkers undergo elimination and fragmentation upon enzymatic cleavage of the peptide to release the drug in active, preferably free form. The conjugate is stable extracellularly in the absence of an enzyme capable of cleaving the linker. However, upon exposure to a suitable enzyme, the linker is cleaved initiating a spontaneous self-immolative reaction resulting in the cleavage of the bond covalently linking the self-immolative moiety to the drug, to thereby effect release of the drug in its underivatized or pharmacologically active form. In these embodiments, the self-immolative linker is coupled to the binding moiety through an enzymatically cleavable peptide sequence that provides a substrate for an enzyme to cleave the amide bond to initiate the self-immolative reaction. Suitably, the drug moiety is connected to the self-immolative moiety of the linker via a chemically reactive functional group pending from the drug such as a primary or secondary amine, hydroxyl, sulfhydryl or carboxyl group.

[0111] Examples of self-immolative linkers are PABC or PAB (para-aminobenzyloxycarbonyl), attaching the drug moiety to the binding moiety in the conjugate (Carl et al. (1981) J. Med. Chem. 24: 479-480; Chakravarty et al. (1983) J. Med. Chem. 26: 638-644). The amide bond linking the carboxy terminus of a peptide unit and the para-aminobenzyl of PAB may be a substrate and cleavable by certain proteases. The aromatic amine becomes electron-donating and initiates an electronic cascade that leads to the expulsion of the leaving group, which releases the free drug after elimination of carbon dioxide (de Groot, et al. (2001) Journal of Organic Chemistry 66 (26): 8815-8830). Further self-immolating linkers are described in W02005 / 082023.

[0112] In cases where C is a cleavable linker moiety, it is particularly preferred that it comprises a cleavable peptide unit, (e.g., a dipeptide unit as detailed above), is directly bound to a self-immolative moiety D (e.g., PABC or PAB), which, in turn, is bound to a drug moiety (e.g., a therapeutic effector, in particular: the TLR 7 agonist payload moiety E), e.g., as shown below:

[0113]

[0114] In yet other embodiments, the linker comprises a glucuronyl group that is cleavable by glucoronidase present on the cell surface or the extracellular region of the target tissue. It has been shown that lysosomal betaglucuronidase is liberated extracellularly in high local concentrations in necrotic areas in human cancers, and that this provides a route to targeted chemotherapy (Bosslet, K. et al. Cancer Res. 58, 1195-1201 (1998)). In any of the above embodiments, the linking moiety suitably further comprises a spacer unit. A spacer unit can be the unit B§, which may be linked to the binding moiety A, for example via an amide, amine or thioether bond. The spacer unit is of a length that enables e.g., the cleavable peptide sequence to be contacted by the cleaving enzyme (e. g. cathepsin B) and suitably also the hydrolysis of the amide bond coupling the cleavable peptide to the self-immolative moiety D. Spacer units may for example comprise a divalent radical such as alkylene, arylene, a heteroarylene, repeating units of alkyloxy (e.g., polyethylenoxy, PEG, polymethyleneoxy) and alkylamino (e.g., polyethyleneamino), or diacid ester and amides including succinate, succinamide, diglycolate, malonate, and caproamide.

[0115] In any of the embodiments described therein, * represents a point of attachment to moiety A or a point of attachment for which the shortest path to moiety A comprises less atoms than that for •, as the case may be; and • represents a point of attachment a point of attachment to moiety C or a point of attachment to moiety E for which the shortest path to moiety E comprises less atoms than that for *, as the case may be. The following notations and all have the meaning of a point of attachment of a certain group or atom (e.g., R) to a further moiety:

[0116] R

[0117]

[0118] -^- R-p R—

[0119] As used herein, and unless specified otherwise the groups and fragments described herein may be combined in either orientation, but it is preferred that they are combined in the orientation as drawn herein, reading from left to right, for example:

[0120] R

[0121] Fragment (a):

[0122]

[0123] 1

[0124] ; fragment (b):

[0125]

[0126] ; preferred combination of fragments (a) + (b):

[0127] R1- R2- R3- R4- 1

[0128] If the structure of relevance is a peptide mono- or oligomer, each * represents a point of attachment for which the shortest path to moiety A comprises less atoms than that for •; and each • represents a point of attachmentfor which the shortest path to moiety C comprises less atoms than that for *, with the proviso that when n is > 1 and a respective point of attachment is indicated on any one of Ra, R^ and Rc, then it can be independently present in one or more of the peptide monomeric units, preferably in one peptide monomeric unit most distant from the other point of attachment indicated in the respective structure.

[0129] In any of the embodiments described herein, the terms “peptide”, “dipeptide”, “tripeptide”, “tetrapeptide” etc. refer to peptide mono- or oligomers having a backbone formed by proteinogenic and / or a non-proteinogenic amino acids. As used herein, the terms “aminoacyl” or “aminoacid” generally refer to any proteinogenic or a non-proteinogenic amino acid. Preferably, in any of the embodiments disclosed therein, the side-chain residues of a proteinogenic or a non-proteinogenic amino acid are represented by any of Ra,

[0130]

[0131] and Rc, each of which is selected from the following list:

[0132]

[0133] wherein each of R, R1, R2 and R3 is independently selected from H, OH, SH, NH2, halogen, cyano, carboxy, alkyl, cycloalkyl, aryl and heteroaryl, each of which is substituted or unsubstituted;

[0134] each X is independently selected from NH, NR, S, O and CH2, preferably NH; and

[0135] each n and m is independently an integer preferably selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20.wherein the definitions of R, R1, R2, R3, X, m, and n here are independent from the definitions of R1, R2 and R3, X, m, and n used elsewhere in the present specification.

[0136] Preferably, in any of the embodiments disclosed therein, side-chain residues of a proteinogenic or a non-proteinogenic amino acid are represented by any of Ra, Rb, Rc, Rd and Re,

[0137] each of which may be part of a 3-, 4-, 5-, 6- or 7-membered ring. For instance, the side chain alpha, beta and / or gamma position of said proteinogenic or non-proteinogenic amino acid can be part of a cyclic structure selected from an azetidine ring, pyrrolidine ring and a piperidine ring, such as in the following aminoacids (proline and hydroxyproline):

[0138]

[0139] each of which may independently be part of an unsaturated structure (i.e. wherein the H atom geminal to the respective group Ra, R^ and Rcis absent), e.g.:

[0140] X

[0141] As used herein, the following notation of peptide sequences refers to a sequence from N to C terminus, and attachment of group through a horizontal bond (here: moiety C) means covalent attachment to the peptide backbone via amide bond to the respective terminal amino acid (here: AA3):

[0142] -

[0143]

[0144] ^-AA1-AA2-AA3-C

[0145] As used herein, the following notation of peptide sequences refers to a sequence from N to C terminus, and attachment of group through a vertical bond (here: moiety C) means covalent attachment via the sidechain of the respective amino acid (here: AA3):

[0146] AA-] AA2AA3

[0147] C

[0148] Further preferable non-proteinogenic amino acids can be selected from the following list:

[0149]

[0150] Payload moiety E (TLR7 agonist)In Formula I, E represents a TLR7 agonist moiety. In the present disclosure, E can be more specifically defined in related structures as defined in the following sections. For example, in Formula I' below:

[0151] A - B - f-C-W-D-l - E'

[0152]

[0153] E, denoted as E', is or comprises a structure derived by removing at least one hydrogen atom or R group in the following general formula:

[0154] N(R)R

[0155]

[0156] wherein:

[0157] Z is selected from C2-5 alkynyl, C1-5 alkenyl, C1-5 alkyl, and (C1-2 alkyl)C6-10aryl;

[0158] U is selected from O, NH, N(C1-3 alkyl), S, CH2, and CH(C1-3 alkyl);

[0159] W is selected from C1-10 alkyl, C2-10 alkenyl, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl), (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)O, (C2-10 alkyl)O, (C2-10 alkenyl)O, (C2-6alkyl)O(C2-6alkyl), (C2-6alkyl)O(C2-6alkyl)O, (C2-10alkyl)NH, (C2-10 alkenyl)NH, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)NH, and (C2-6 alkyl)O(Ci-6 alkyl)NH; each optionally substituted with one or more substituents preferably selected from C1-3 alkyl and (C1-3 alkyl)O.

[0160] X is selected from CH, N, and S;

[0161] Y is selected from CH and N, or is absent;

[0162] R is selected from H, C1-3 alkyl, C1-3 haloalkyl, and C1-3 heteroalkyl;

[0163] R1 is selected from C1-8 alkyl, C2-8 cycloalkyl, (C3-6 cycloalkyl)C1-3 alkyl, C1-7 heteroalkyl, C2-7 cycloheteroalkyl, -C(=O)NH(C1-3 alkyl), -C1-3 alkyl(C=O)OMe, -C(=O)NH(C2-8 cycloalkyl), (C2-7 cycloheteroaryl)C1-3 alkyl and (C6-10 aryl)C1-3 alkyl; each optionally substituted with one or more substituent(s) preferably selected from OH, CH3, OMe, CN, -C(=O)Me, F2CH, SO2Me, and halogen.

[0164] It is noted that N(C1-3 alkyl) refers to a nitrogen atom that is bonded to other two structural elements of E' while bearing a C1-3 alkyl substituent. Similarly, CH(C1-3 alkyl) refers to a carbon atom that is bonded to two other parts of the molecule and carries a C1-3 alkyl group as a substituent.

[0165] Surprisingly, the inventors have found that the TLR7 agonists of the invention show superior potency in conjugated form (e.g., as payload moiety E' in the conjugates of Formula I'), with stronger immune activation and better in vivo efficacy, e.g., compared to imidazoquinoline or purine-like reference compounds (in unconjugated and / or conjugated form), particularly in terms of tumor regression and immune cell activation.Surprisingly, the inventors have also found that the conjugates of Formula I result in remarkably high complete remission rates (up to 100% in the CT-26 tumor model), outperforming both free payloads and the conjugates of the reference compounds. Furthermore, a dose-response relationship was also observed, with higher doses (e.g., 250 nmol / kg) leading to improved therapeutic outcomes (tumor clearance in all mice) while maintaining a good tolerability and low toxicity.

[0166] More specifically, E may be further represented as E-a and / or as E-c. These variations share the same core structure but differ in their points of attachment to the other components of the conjugate, the advantageous properties described herein are substantially maintained.

[0167] Accordingly, the compound of Formula I', can be represented by one or more of Formulae I-a and I-c: the corresponding structures of Formula I-a and I-c are independently disclosed below:

[0168] A - B - t-C-W-D-)— E-a

[0169] I-a

[0170] A - B - (-C-4— (-D-) - E-c

[0171] I-c

[0172] wherein, each of E-a and E-c is or comprises, respectively, a structure of Formula E-a, or E-c:

[0173]

[0174] E-a E-c

[0175] wherein:

[0176] In E-a and E-c, Zais selected from C2-5 alkynyl, C2-5 alkenyl, and C2-5 alkyl. The remaining variables are as defined in compound of Formula I'. R is preferably H.

[0177] Preferably, the compound structure of Formula I' can be represented by one or more of Formulae I-al and I-cl provided below:

[0178] A - B - (-C-)— (-D-) - E-a1Lal

[0179] — E-d

[0180]

[0181] Lcl

[0182] wherein each of E-al and E-cl is or comprises, respectively, a structure of Formula E-al, or Formula E-cl:

[0183]

[0184] E-al E-cl

[0185] wherein:

[0186] Zal is C3 alkynyl; U1-W1 is selected from:

[0187]

[0188] the remaining variables are as defined in the compound of Formula I'. R is preferably H.

[0189] Preferably, the compound of Formula I' can be represented by one or more of Formulae I-al', I-al", I-al'"", I-cl', I-cl", and I-cl'":

[0190] E-a1

[0191] I-al'A - B (-C-)— (-D-) E-a1"

[0192]

[0193] I-al"A - B (-C-)- (-D-) E-a1I-al"'

[0194] A - B (■C-)— (-D-) - E-C1 ■

[0195] I-cl'

[0196] A - B - (-C-J— (-D-) - E-C1 "

[0197] I-cl"

[0198] A - B - - E-C1 "■

[0199]

[0200] I-cl'"

[0201] wherein each ofE-al', E-al", E-al'", E-cl', E-cl", and E-cl'" is or comprises, respectively, a structure of Formula E-al', E-al", E-al'", E-cl', E-cl", or E-cl'":

[0202]

[0203] wherein, R1, X and Y are as defined in compound of Formula I'.

[0204] In an alternative preferred embodiment, the structure of Formula I' can be represented by one or more of Formulae I-a2 and I-c2:

[0205] A - B - f-C-W-D-) - E-a2

[0206] I-a2

[0207] A - B - - E-c2

[0208]

[0209] wherein, each of E-a2 and E-c2 is or comprises, respectively, a structure of Formula E-a2 or E-c2:

[0210]

[0211] E-c2

[0212] wherein Za2 is C4-5 alkyl; U2-W1 is selected from:

[0213]

[0214] the remaining variables are as defined in compound of Formula I'. R is preferably H.

[0215] Preferably, the compound of Formula I' is represented by one or more of Formulae I-a2', I-a2", I-a2"', I-c2', I-c2", and I-c2'" provided below:

[0216] A - B (-C-)- (-D-) - E-a2’

[0217] I-a2'

[0218] E-a2"

[0219] A - B - (-C-)- (-D-) - E-c2’

[0220] I-c2'

[0221] A - B - (-C-)- (-D-) - E-c2"

[0222]

[0223] A - B - (-C-W-D-) - E-c2"’I-c2"""wherein each of E-a2', E-a2", E-a2'"", E-c2', E-c2", and E-c2'"" is or comprises, respectively, a structure of Formula E-a2', E-a2", E-a2'", E-c2', E-c2", or E-c2'":

[0224]

[0225] wherein, R1, X and Y are as defined in compound of Formula I'.

[0226] In any of the above embodiments of Formulae I', I-a, I-c, I-al, I-cl, I-al', I-al", I-al'", I-cl', I-cl", and I-cl'", I-a2, I-c2, I-a2', I-a2", I-a2'", I-c2', I-c2", and I-c2'", X is preferably selected from CH and N, and Y is preferably selected from CH and N, or is absent.

[0227] Particularly preferred are the combinations of X and Y reported below. As noted above, these combinations are preferred and can be applied to any of the above-described embodiments.

[0228] X = CH and Y = CH,

[0229] X = N andY = CH,

[0230] X = CH andY = N,

[0231] X = N andY = N, or

[0232] X = S and Y is absent

[0233] Most preferably, X = CH and Y = CH.

[0234] R1in the conjugates described herein can preferably be selected from the group consisting of:

[0235]

[0236] In any of the above embodiments of Formulae I', I-a, I-c, I-al, I-cl, I-al', I-al", I-al'", I-cl', I-cl", and I-cl'", I-a2, 1-c2, 1-a2', I-a2", I-a2'", I-c2', I-c2", and I-c2'", c and d are preferably 1.

[0237] The present disclosure also refers to the following compound having a structure represented by the following F ormula I-MB 357:

[0238] A - B - (-C-W-D-) - MB357

[0239] I-MB357

[0240] wherein MB357 is or comprise a compound derived by removing at least one H atom in the following formula:

[0241]

[0242] Preferably, Formula I-MB357 is represented by one or more of Formulae I-(MB357') and I-(MB357") provided below:

[0243] {-C-)- (-D-) — MB357'

[0244] c d

[0245] l-(MB357‘)

[0246] A - B — (-C^“ (-D-) — MB357"

[0247]

[0248] c d

[0249] l-(MB357")

[0250] wherein MB357' and MB357" represent, respectively, a structure of the following Formula MB357', orMB357":

[0251]

[0252] In any of the above embodiments of Formulae I-(MB357), I-(MB357'), and I-(MB357"), c and d are preferably 1.

[0253] In the present disclosure, the compound of Formula I' can be represented by one or more of Formulae I-b and I-d. These variations share the same core structure but differ in their points of attachment to the other components of the conjugate, the advantageous properties described herein are substantially maintained. Accordingly, the corresponding structures of Formula I-b and I-d are disclosed below:

[0254] A - B - (-C-W-D^ - E-b

[0255] I-b

[0256] A - B

[0257]

[0258] I-d

[0259] wherein, each of E-b and E-d is or comprises, respectively, a structure of Formula E-b, and of Formula E-d:

[0260]

[0261] wherein Zbis (C1-2alkyl)C6aryl. The remaining variables are as defined in the compound of Formula I'. Surprisingly, the inventors have found that the conjugates of Formula I-b and I-d show a remarkably good therapeutic response in terms of in vivo efficacy, and tumor regression. In particular, better results were obtained in comparison with TLR7 agonists with an imidazoquinolinic structure, both in conjugated and unconjugated form. Surprisingly, it was also found that conjugates of Formula I-b and I-d show an improvedanticancer effect even in comparison to the respective free payloads (unconjugated purine-like compounds of Formula II), underlining the beneficial effect of the conjugate-mediate pharmacodelivery.

[0262] Preferably, the compound of Formula I' is represented by one or more of Formula I-bl and I-dl provided below:

[0263] A - B - (-C-)— (-D-) - E-b1

[0264] I-bl

[0265] A - B - - E-d1

[0266]

[0267] I-dl

[0268] wherein, each of E-bl and E-dl is or comprises, respectively, a structure of Formula E-bl, or E-dl:

[0269] N(R)R

[0270]

[0271] E-bl E-dl

[0272] wherein Zblis (C1alkyl)C6aryl; U1-W1is selected from:

[0273]

[0274] the remaining variables are as defined in compound of Formula I'.

[0275] Preferably, the compound of Formula I' is represented by one or more of Formulae I-bl', I-bl", I-bl'", I-dl', I-dl", and I-dl'":

[0276] A - B - f-C-)- (-D-) - E-b1 'I-bl'

[0277] A - B - (-C-)— (-D-) - E-b1 "

[0278] I-bl"

[0279] A - B - f-C-W-D-) - E-b1

[0280] I-bl'"

[0281] A - B (-C-)- (-D-) - E-d 1 '

[0282] I-dl'

[0283] A - B— (-C-W-D-) - E-d 1 "

[0284] I-dl"

[0285] A - B - f-C-W-D-) - E-d1 ■"

[0286]

[0287] I-dl'"

[0288] wherein, each of E-bl', E-bl", E-bl'", E-dl', E-dl", and E-dl'" is or comprises, respectively, a structure of Formula E-bl', E-bl", E-bl'" E-dl', E-dl"or E-dl'":

[0289]

[0290] wherein, R1, X and Y are as defined in the compound of Formula I'.

[0291] In any of the above embodiments of Formulae I-b, I-d, I-bl, I-dl, I-bl', I-bl", I-bl'", I-dl', I-dl", and I-dl'", X is preferably selected from CH and N, and Y is preferably selected from CH and N, or is absent.

[0292] Particularly preferred are the combinations of X and Y reported below. As noted above, these combinations are preferred and can be applied to any of the above-described embodiments.

[0293] X = CH and Y = CH,X = N andY = CH,

[0294] X = CH andY = N,

[0295] X = N andY = N, or

[0296] X = S and Y is absent

[0297] Most preferably, X = CH and Y = CH.

[0298] R1in the conjugates described herein can preferably be selected from the group consisting of:

[0299]

[0300] In any of the above embodiments of Formulae I-b, I-d, I-bl, I-dl, I-bl', I-bl", I-bl'", I-dl', I-dl", and I-dl'", c and d are preferably 1.

[0301] The present disclosure also refers to a compound having a structure represented by the following Formula I-(IIb-19):

[0302] A - B - f-C-J-f-D-) - llb-19

[0303] I-(IIb-19)

[0304] wherein, IIb-19 is or comprises a structure derived by removing at least one H atom in the following formula:

[0305]

[0306] IIb-19Preferably, the compound of Formula I-(IIb-19) can be represented by one or more of Formulae I-(IIb-19'), and I-(IIb-19") provided below:

[0307] A - B (-C-)— (-D-)— — llb-19'

[0308] I-(IIb-19')

[0309] A - B - (-c4— (-D-) - llb-19"

[0310]

[0311] I-(IIb-19")

[0312] wherein, each of llb-19' and llb-19" is or comprises, respectively, a structure of Formula llb-19' or llb-19":

[0313]

[0314] In any of the above embodiments of Formulae I-(IIb- 19), I-(IIb- 19'), I-(IIb- 19"), c and d are preferably 1.

[0315] Compounds

[0316] The present invention also provides a compound of Formula II, its individual diastereoisomers, its hydrates, its solvates, its crystal forms, its individual tautomers or a pharmaceutically acceptable salt thereof, wherein the compound the following structure:

[0317]

[0318] Z is selected from C2-5alkynyl, C1-5alkenyl, C1-5alkyl, and (C1-2alkyl)C6-10aryl;

[0319] U is selected from O, NH, N(C1-3 alkyl), S, CH2, and CH(C1-3 alkyl);

[0320] W is selected from C1-10 alkyl, C2-10 alkenyl, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl), (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)O, (C2-10 alkyl)O, (C2-10 alkenyl)O, (C2-6alkyl)O(C2-6alkyl), (C2-6alkyl)O(C2-6alkyl)O, (C2-10alkyl)NH,(C2-10 alkenyl)NH, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)NH, and (C2-6 alkyl)O(Ci-6 alkyl)NH; each optionally substituted with one or more substituents preferably selected from C1-3 alkyl and (C1-3 alkyl)O;

[0321] X is selected from CH, N, and S;

[0322] Y is selected from CH and N, or is absent;

[0323] R is selected from H, C1-3 alkyl, C1-3 haloalkyl, and C1-3 heteroalkyl;

[0324] R1is selected from C1-8alkyl, C2-8cycloalkyl, (C3-6cycloalkyl)C1-3alkyl, C1-7heteroalkyl, C2-7cycloheteroalkyl, -C(=O)NH(C1-3alkyl), -C1-3alkyl(C=O)OMe, -C(=O)NH(C2-8cycloalkyl), (C2-7cycloheteroaryl)C1-3alkyl and (C6-10aryl)C1-3alkyl; each optionally substituted with one or more substituent(s) preferably selected from OH, CH3, OMe, CN, -C(=O)Me, F2CH, SO2Me, and halogen;

[0325] R2and R3are each independently selected from H and a substituent, preferably a substituent selected from C1-3haloalkyl, C1-3heteroalkyl, and A-B-(C)c-(D)d—* as defined in any one of the preceding embodiments. It is noted that N(C1-3 alkyl) refers to a nitrogen atom that is bonded to other two structural elements of E' while bearing a C1-3 alkyl substituent. Similarly, CH(C1-3 alkyl) refers to a carbon atom that is bonded to two other parts of the molecule and carries a C1-3 alkyl group as a substituent.

[0326] The TLR7 agonists of the invention are highly effective and selective compounds that stimulate TLR7. In particular, it has been surprisingly found that compounds of Formula II outperform other TLR7 agonists, such as compounds with an imidazoquinoline structure (e.g., A78, or resiquimod). The compounds of Formula II, have also an improved effect in comparison with reference compounds, both in terms of TLR7 activation and cytokine release (e.g., hIL6, hTNFa) from immune cells. Furthermore, the compounds of the invention, and in particular those of Formula Il-a, can upregulate co-receptors like CD86 in dendritic cells, indicating a strong immune modulatory potential, in comparison to both imidazoquinoline s and other purine-like reference compounds (e.g., IIb-19). This can be beneficial in cancer immunotherapy where immune cell activation is crucial for inducing an effective anti-tumor immune response. Compound MB357 is particularly effective in this regard.

[0327] The compounds of Formula II as described herein, can be used as precursors or intermediates for the preparation of the conjugate of Formula I, which in turn have multiple surprising and advantageous effects, as described herein. In particular, the inventors have surprisingly found that the inclusion of the compound of Formula II as payload can result in an improved anticancer effect of the conjugate. Therefore, the compounds of Formula II can be used as useful precursors, which can also be included in conjugates other than the ones disclosed herewith.

[0328] It is noted that N(C1-3alkyl) refer to a nitrogen atom that is bonded to another structural element while bearing a C1-3alkyl substituent. Similarly, CH(C1-3alkyl) refers to a carbon atom that is bonded to another part of themolecule and carries a C1-3 alkyl group as a substituent.

[0329] Preferably in the compound of Formula II,

[0330] a) at least one of R2and R3is independently selected from C1-3 haloalkyl, C1-3 heteroalkyl,

[0331] and A-B-(C)c-(D)dis defined as in any one of the preceding embodiments;

[0332] b) R2is H, and R3is independently selected from H and A-B-(C)c-(D)d—* as defined in any one of the preceding embodiments;

[0333] c) R3is H, and R2is independently selected from H and A-B-(C)c-(D)d—* as defined in any one of the preceding embodiments; or

[0334] d) R2and R3are each H.

[0335] Preferably, the compound of Formula II corresponds to a structure of Formula Il-a below:

[0336]

[0337] Il-a

[0338] wherein Zais selected from C2-5alkynyl, C2-5alkenyl, and C2-5alkyl. The remaining variables are as defined in Formula II.

[0339] A preferred aspect of compound of Formula I-a corresponds to a compound of Formula Il-al:

[0340]

[0341] Il-al

[0342] wherein, Zalis C3alkynyl; U1-W1is selected from:

[0343]

[0344]

[0345] the remaining variables are as defined in compound of Formula II.

[0346] Preferably, compound of Formula Il-al can be selected from compounds of Formulae II-al', II-al" and II-al'" below:

[0347]

[0348] An alternative preferred aspect of the compound of Formula Il-a corresponds to the compound of Formula II-a2:

[0349]

[0350] II-a2

[0351] wherein Za2 is C4-5 alkyl; U2-W1 is selected from:

[0352]

[0353]

[0354] the remaining variables are as defined in compound of Formula II.

[0355] Preferably, compound of Formula II -a2 can be represented by one or more of Formulae II-a2', II-a2" and II-a2'" below:

[0356]

[0357] In any of the above embodiments of Formula II, II-a, II-al, II-al', II-al", II-al'", II-a2, II-a2', II-a2", II-a2'", X is preferably selected from CH and N, and Y is preferably selected from CH and N, or is absent.

[0358] Particularly preferred are the combinations X and Y reported below. As noted above, these combinations are preferred and can be applied to any of the above-described embodiments.

[0359] X = CH and Y = CH,

[0360] X = N andY = CH,

[0361] X = CH and Y = N,

[0362] X = N andY = N, or

[0363] X = S and Y is absent.

[0364] Most preferably, X = CH and Y = CH.

[0365] R1in the compounds described herein can preferably be selected from the group consisting of:

[0366]

[0367] A particularly preferred aspect of compound of Formula II corresponds to compound MB357 below:

[0368]

[0369] MB357

[0370] Combination Therapies and Dual-Mode Conjugates

[0371] In certain embodiments, combination strategies are contemplated, wherein the compounds of the present invention, comprising TLR7 conjugates, are used alone or in combination with other therapeutic agents. These approaches may enhance therapeutic efficacy by using TLR7-mediated immune activation alongside complementary mechanisms, such as direct cytotoxicity, radiotherapy, or immune modulation.

[0372] Additionally, the inventors have surprisingly found that a combination of the conjugate of the invention with other therapeutic agents (e.g., SMDCs and RLTs) can be advantageous in terms of tumor growth inhibition. This is particularly prominent when the combination partner is a cytotoxic or radioactive anticancer agent (radiotherapeutic), e.g., a conjugate, preferably SMDC, comprising an auristatin moiety (e.g., MMAE) a chelator moiety complexed with a radioactive nuclide, e.g.,177Lu; or an immunocytokine.

[0373] In some embodiments, the conjugates themselves may incorporate two distinct payloads, exploiting a dual mode of action within a single therapeutic agent. Such dual-payload conjugates may combine a TLR7 agonist with a radioactive moiety, allowing for both immune activation and targeted radiotherapy, or with a cytotoxic payload, integrating tumor-killing activity with immune stimulation. Alternatively, a TLR7 agonist may be combined with an immune checkpoint inhibitor within the same molecule, promoting both immune activation and checkpoint blockade. These dual-payload conjugates offer several advantages, including synergistic anti-tumor effects that simultaneously stimulate the immune response while directly eliminating cancer cells. Beyond single-molecule dual-payload designs, TLR7 conjugates may also be co-administered with radioligand therapeutics (RLTs) to enhance both tumor-targeted immune activation and radiotherapeutic efficacy.

[0374] In the context of immune checkpoint blockade, TLR7 activation may promote immune cell recruitment and counteract resistance to checkpoint inhibitors targeting PD-1, PD-L1, or CTLA-4, making their combination a promising strategy for improving treatment outcomes. Moreover, combination with immunocytokines (e.g., L19IL2, L19TNF, or similar) can be beneficial in boosting the immune response with different or complementary mechanisms of action.

[0375] Combinations with an immunocytokine

[0376] Provided is a pharmaceutical combination comprising a compound or pharmaceutical composition as disclosed herein and an immunocytokine.

[0377] Herein, the term “immunocytokine” refers to a conjugate protein or fusion protein comprising a cytokine and an antibody, antibody fragment or antibody derivative. A fusion protein is a polypeptide that is a translation product resulting from the fusion of two or more genes or nucleic acid coding sequences into one open reading frame (ORF). The fused expression products of the two genes or ORFs may be conjugated by a linker. Herein, the terms conjugate protein or fusion protein are generally used interchangeably. The fusion protein may further comprise a signal peptide sequence, normally located upstream (5’) of the specific binding member and subunit.

[0378] Taken together, these combination approaches—whether through the development of dual-payload conjugates or co-administration with other therapies—are an advantageous strategy to further enhance the anti-tumor effect of the compound of the invention.

[0379] Immunocytokine comprising IL2

[0380] Preferably, the immunocytokine comprises a sequence having IL2 activity, i.e., an IL2 polypeptide, i.e., the cytokine IL2 or a functional fragment thereof. Preferably, the immunocytokine comprises only one (i.e., a single) IL2 polypeptide per polypeptide chain. Herein the terms “IL2” and “IL2 polypeptide” are used interchangeably.

[0381] The IL2 may be derived from any animal, e.g., human, rodent (e.g., rat, mouse), horse, cow, pig, sheep, dog, etc. Human IL2 is preferred in conjugates for administration to humans. The amino acid sequence of human IL2 is set out below:

[0382] APTSSSTKKT QLQLEHLLLD LQMILNGINN YKNPKLTRML TFKFYMPKKA TELKHLQCLE 60 EELKPLEEVL NLAQSKNFHL RPRDLISNIN VIVLELKGSE TTFMCEYADE TATIVEFLNR 120WITFCQSIIS TLT (SEQ ID NO: 1)

[0383] The immunocytokine conjugate preferably comprises a single IL2 polypeptide. An IL2 polypeptide in an immunocytokine of the invention retains a biological activity of IL2, e.g., an ability to promote proliferation and / or differentiation of activated T and B lymphocytes and natural killer (NK) cells, and / or to induce cytotoxic T cell (CTL) activity, and / or to induce NK / lymphokine -activated killer (LAK) cell antitumor cytotoxicity.

[0384] Antibodies, fragments or derivatives thereof comprised in the immunocytokine or the conjugates of the invention

[0385] Besides a cytokine (e.g., IL2), the immunocytokine or conjugate may comprise an antibody or an antibody fragment or an antibody derivative. The antibody derivative may, e.g., comprise a single-chain variable fragment (scFv), a diabody or a single chain diabody (scDb) or a Fab or a Fab2 or a nanobody or an “SIP” (W02003 / 076469) or a “Crab” (Neri et al., (1995) J Mol Biol, 246, 367-73). The immunocytokine may comprise an IgG antibody or an IgG derivative.

[0386] Preferably the antibody derivate comprises an scFv. As is known in the art, an scFv comprises a VH domain and a VL domain, wherein the domains are linked by a linker that allows association of VH and VL domains to form an antigen binding site. The scFv may be stabilized by the incorporation of disulphide bridges linking the VH and VL domains.

[0387] Single chain Fv (scFv) antibody polypeptide sequences are particularly preferred for incorporation in the immunocytokine (e.g., with a further polypeptide sequence having IL2 activity), owing to their small size of the scFv format, which provides physiological and therapeutic advantages for in vivo use of the immunocytokine conjugates. In addition, scFv lacks an Fc region, potentially reducing anti-idiotypic reactions and also minimizing undesirable properties relating to activation of complement and interaction with Fc receptors that may hinder tumor targeting and cause non-specific cell activation.

[0388] The linker joining the VH and VL domains within an scFv chain may be a peptide linker sequence that is not long enough to allow pairing of the VH and VL domains within the same scFv polypeptide chain. Thus, a homodimer of scFvs may form instead, in which the VH of one scFv chain pairs with the VL of the other scFv chain (and vice versa). This general format may be referred to as an “scFv2” format, or, alternatively, in some cases, as a “diabody”. Examples of suitable short linker sequences are GSSGG (SEQ ID NO: 2) and GGSGG (SEQ ID NO: 3).

[0389] Preferably, the linker is a 12-residue linker, such as the one set out below:

[0390] GDGSSGGSGGAS (SEQ ID NO: 4)

[0391] In a so-called single-chain diabody (“scDb”), the two sets of VH and VL domains (i.e., the two polypeptides that pair to form a dimer in a diabody or scFv2) are connected as a single-chain by a peptide linker (“scDb linker”) as follows:(VH-VL)-linker-(VH-VL), wherein “(VH-VL)” indicates an scFv unit consisting of a set of a VH and a VL domain connected by a short linker, as described above.

[0392] The scDb linker sequence is sufficiently long and / or flexible to allow pairing of the VH domain of one scFv unit (i.e., the first VH and VL-containing polypeptide) with the VL domain of the other, complementary scFv unit (i.e., the second VH and VL-containing polypeptide), and vice versa, within a single polypeptide chain. Generally, a long and / or flexible linker that allows two complementary VH and VL-containing polypeptides to dimerize within a single polypeptide chain in this manner is 10 to 20 amino acids in length.

[0393] Antigen binding specificity of the immunocytokine

[0394] The antibody, antibody fragment or antibody derivative suitably binds specifically to an extra-cellular matrix (ECM) component associated with neoplastic growth and / or angiogenesis. The antibody, fragment or derivative thereof (e.g., scFv, diabody or single-chain diabody) comprises an antigen-binding site having the complementarity determining regions (CDRs), or the VH and / or VL domains of an antibody capable of specifically binding to an antigen of interest. In particular, it may comprise one or more CDRs or VH and / or VL domains of an antibody capable of specifically binding to an antigen of the ECM.

[0395] The antigen-binding sites of the antibody, antibody fragment or antibody derivative (e.g., an scFv, a diabody or scFv2 or single -chain diabody) may be identical or different, but preferably are identical. Each of the antigen-binding sites may bind the same antigen or epitope. This can be achieved by providing two identical antigen-binding sites such as two identical VH-VL domain pairs, or by providing two different antigen-binding sites, for example comprising different VH and VL domains, which nevertheless both bind the same antigen or epitope. Alternatively, the antibody, antibody fragment or antibody derivative may be bispecific. By “bispecific” it is meant that each of the antigen-binding sites binds a different antigen. Optionally, two antigenbinding sites may bind two different antigens mentioned herein, e.g., two different antigens of the extracellular matrix, or two different domains of a particular antigen.

[0396] The antigen may be an antigen preferentially expressed by cells of a tumor or tumor neovasculature or associated with the ECM.

[0397] Herein, the term "specific binding" means that one member of a specific binding pair will not show any significant binding to molecules other than its specific binding partner(s). The term is also applicable where, e.g., an antigen-binding site is specific for a particular epitope that is present on a number of different antigens, in which case the antibody, antibody fragment or antibody derivative carrying the antigen-binding site will be able to bind to the various antigens carrying the epitope.

[0398] Further definitions and techniques relating to the immunocytokine or antibody moieties

[0399] Sequence identity is commonly defined with reference to the algorithm GAP (Wisconsin GCG package, Accelerys Inc, San Diego USA). GAP uses the Needleman and Wunsch algorithm to align two completesequences that maximizes the number of matches and minimizes the number of gaps. Generally, default parameters are used, with a gap creation penalty = 12 and gap extension penalty = 4. Use of GAP may be preferred but other algorithms may be used, e.g., BLAST (which uses the method of Altschul et al. (1990) J. Mol. Biol. 215: 405-410), FASTA (which uses the method of Pearson and Lipman (1988) PNAS USA 85: 2444-2448), or the Smith-Waterman algorithm (Smith and Waterman (1981) J. Mol Biol. 147: 195-197), or the TBLASTN program, of Altschul et al. (1990) supra, generally employing default parameters. In particular, the psi-Blast algorithm (Nucl. Acids Res. (1997) 25 3389-3402) may be used.

[0400] Variants of these VH and VL domains and CDRs may also be employed in antibody moieties for use in conjugates as described herein. Suitable variants can be obtained by means of methods of sequence alteration, or mutation, and screening. Preferred variants may be derived by conservative substitution of one or more amino acids in the VH and VL domains and CDRs.

[0401] Particular variants for use as described herein may include one or more amino acid sequence alterations (addition, deletion, substitution and / or insertion of an amino acid residue), maybe less than about 20 alterations, less than about 15 alterations, less than about 10 alterations or less than about 5 alterations, 4, 3, 2 or 1. With regard to group A, especially when it is an antibody, antibody derivative or an antigen-biding fragment thereof, any reactive groups on A can serve as a conjugation site, including s-amino groups in lysine residues, pendant carbohydrate moieties, carboxylic acid groups on aspartic or glutamic acid side chains, cysteinecysteine disulfide groups, and cysteine thiol groups. For reviews on antibody reactive groups suitable for conjugation, see, e.g., Garnett, Adv. Drug Delivery Rev. 2001, 53, 171-216 and Dubowchik and Walker, Pharmacology & Therapeutics 1999, 83, 67-123, the disclosures of which are incorporated herein by reference. Most antibodies have multiple lysine residues, which can be conjugated via their s-amino groups via amide, urea, thiourea, or carbamate bonds. A thiol (-SH) group in the side chain of a cysteine can be used to form a conjugate by several methods. It can be used to form a disulfide bond between it and a thiol group on the linker. Another method is via its Michael addition to a maleimide group on the linker. Typically, although antibodies have cysteine residues, they lack free thiol groups because all their cysteines are engaged in intra-or inter-chain disulfide bonds. To generate a free thiol group, a native disulfide group can be reduced. See, e.g., Packard et al., Biochemistry 1986, 25, 3548; King et al., Cancer Res. 1994, 54, 6176; and Doronina et al., Nature Biotechnol. 2003, 21, 778. Alternatively, a cysteine having a free -SH group can be introduced by mutating the antibody, substituting a cysteine for another amino acid or inserting one into the polypeptide chain. See, for example, Eigenbrot et al., US 7,521,541 B2 (2009); Chilkoti et al., Bioconjugate Chem. 1994, 5, 504; Umovitz et al., US 4,698,420 (1987); Stimmel et al., J. Biol. Chem. 2000, 275, 30445; Bam et al., US 7,311,902 B2 (2007); Kuan etal., J. Biol. Chem. 1994, 269, 7610; Poon etal., J. Biol. Chem. 1995, 270, 8571; Junutula et al., Nature Biotechnology 2008, 26, 925 and Rajpal et al., US 2018 / 0362619 (2018). In yet another approach, a cysteine is added to the C-terminus of the heavy of light chain. See, e.g., Liu et al., US 8,865,875 B2 (2014); Cumber et al., J. Immunol. 1992, 149, 120; King et al, Cancer Res. 1994, 54, 6176; Li et al., Bioconjugate Chem. 2002, 13, 985; Yang et al., Protein Engineering 2003, 16, 761; and Olafson et al., ProteinEngineering Design & Selection 2004, 17, 21. The disclosures of the documents cited in this paragraph are incorporated herein by reference.

[0402] Treatment

[0403] The compounds described herein may be used for the treatment of diseases. The treatment may be therapeutic and / or prophylactic treatment, with the aim being to prevent, reduce or stop an undesired physiological change or disorder. The treatment may prolong survival as compared to expected survival if not receiving treatment. The disease that is treated by the compound may be any disease that might benefit from treatment. This includes chronic and acute disorders or diseases including those pathological conditions which predispose to the disorder.

[0404] The term "cancer" and "cancerous" is used in its broadest sense as meaning the physiological condition in mammals that is typically characterized by unregulated cell growth. A tumor comprises one or more cancerous cells.

[0405] When treating cancer, the therapeutically effect that is observed may be a reduction in the number of cancer cells; a reduction in tumor size; inhibition or retardation of cancer cell infiltration into peripheral organs; inhibition of tumor growth; and / or relief of one or more of the symptoms associated with the cancer.

[0406] In animal models, efficacy may be assessed by physical measurements of the tumor during the treatment, and / or by determining partial and complete remission of the cancer. For cancer therapy, efficacy can, for example, be measured by assessing the time to disease progression (TTP) and / or determining the response rate (RR).

[0407] Particularly preferred embodiments for the methods of treatment related to the present invention are shown in the appended claims.

[0408] Herein disclosed are also methods for treatment of the human or animal body, e.g., by surgery or therapy practised on the human or animal body, the methods involving a step of administering a therapeutically effective amount of a compound or a pharmaceutical composition as described herein to a subject in need thereof. More specifically, herein disclosed are methods for treatment, e.g., by therapy or prophylaxis, of a subject suffering from or having risk for a disease or disorder; or by guided surgery practised on a subject suffering from or having risk for a disease or disorder; method for targeted delivery of a therapeutic agent to a subject suffering from or having risk for a disease or disorder. In the aforementioned methods, said disease or disorder may be independently selected from cancer, inflammation, atherosclerosis, fibrosis, tissue remodelling and keloid disorder, preferably wherein the cancer is selected from the group consisting of breast cancer, pancreatic cancer, small intestine cancer, colon cancer, multi -drug resistant colon cancer, rectal cancer, colorectal cancer, metastatic colorectal cancer, lung cancer, non-small cell lung cancer, head and neck cancer, ovarian cancer, hepatocellular cancer, oesophageal cancer, hypopharynx cancer, nasopharynx cancer, larynxcancer, myeloma cells, bladder cancer, cholangiocarcinoma, clear cell renal carcinoma, neuroendocrine tumor, oncogenic osteomalacia, sarcoma, CUP (carcinoma of unknown primary), thymus cancer, desmoid tumors, glioma, astrocytoma, cervix cancer, skin cancer, kidney cancer and prostate cancer. When used in the methods disclosed herein, the compound has a prolonged residence at the disease site at a therapeutically relevant level. The present disclosure also relates to the use of the compounds as disclosed herein (conjugated and unconjugated) in the treatment of a disease, wherein the disease is preferably cancer.

[0409] Preferably, the compounds of the invention are for use in the treatment of a disease characterized by overexpression of ACP3.

[0410] In a particular embodiment, the compounds of the invention are for use in the treatment of cancer characterized by overexpression of ACP3, preferably the disease is prostate cancer. More preferably the disease is selected from prostate adenocarcinoma, ductal prostate cancer, ductal adenocarcinoma, clear cell adenocarcinoma, acinar adenocarcinoma, urothelial cancer, neuroendocrine prostate cancer, small cell prostate cancer, multiple myeloma.

[0411] Pharmaceutical compositions

[0412] The compounds described herein may be in the form of pharmaceutical compositions which may be for human or animal usage in human and veterinary medicine and will typically comprise any one or more of a pharmaceutically acceptable diluent, carrier, or excipient. Acceptable carriers or diluents for therapeutic use are well known in the pharmaceutical art, and are described, for example, in Remington's Pharmaceutical Sciences, Mack Publishing Co. (A. R. Gennaro edit. 1985). The choice of pharmaceutical carrier, excipient or diluent can be selected with regard to the intended route of administration and standard pharmaceutical practice. The pharmaceutical compositions may comprise as - or in addition to - the carrier, excipient or diluent any suitable binder(s), lubricant(s), suspending agent(s), coating agent(s), solubilising agent(s).

[0413] Preservatives, stabilisers, dyes and even flavouring agents may be provided in the pharmaceutical composition. Examples of preservatives include sodium benzoate, sorbic acid and esters of p-hydroxybenzoic acid. Antioxidants and suspending agents may be also used.

[0414] There may be different composition / formulation requirements dependent on the different delivery systems. By way of example, the pharmaceutical composition may be formulated to be administered using a mini-pump or by a mucosal route, for example, as a nasal spray or aerosol for inhalation or ingestable solution, or parenterally in which the composition is formulated by an injectable form, for delivery, by, for example, an intravenous, intramuscular or subcutaneous route. Alternatively, the formulation may be designed to be administered by a number of routes.

[0415] If the agent is to be administered mucosally through the gastrointestinal mucosa, it should be able to remain stable during transit though the gastrointestinal tract; for example, it should be resistant to proteolyticdegradation, stable at acid pH and resistant to the detergent effects of bile.

[0416] Where appropriate, the pharmaceutical compositions may be administered by inhalation, in the form of a suppository or pessary, topically in the form of a lotion, solution, cream, ointment or dusting powder, by use of a skin patch, orally in the form of tablets containing excipients such as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs, solutions or suspensions containing flavouring or colouring agents, or the pharmaceutical compositions can be injected parenterally, for example, intravenously, intramuscularly or subcutaneously. For parenteral administration, the compositions may be best used in the form of a hydroalcoholic solution, cyclodextrins, surfactants, liposome or a sterile aqueous solution which may contain other substances, for example, enough salts or monosaccharides to make the solution isotonic with blood. For buccal or sublingual administration, the compositions may be administered in the form of tablets or lozenges which can be formulated in a conventional manner.

[0417] The compound of the present invention may be administered in the form of a pharmaceutically acceptable or active salt. Pharmaceutically-acceptable salts are well known to those skilled in the art, and for example, include those mentioned by Berge et al., in J. Pharm. Sci., 66, 1-19 (1977). Salts include, but are not limited, to sulfate, citrate, acetate, oxalate, chloride, bromide, iodide, nitrate, bisulfate, phosphate, acid phosphate, isonicotinate, lactate, salicylate, acid citrate, tartrate, oleate, tannate, pantothenate, bitartrate, ascorbate, succinate, maleate, gentisinate, fumarate, gluconate, glucaronate, saccharate, formate, benzoate, glutamate, methanesulfonate, ethanesulfonate, benzenesulfonate, p-toluenesulfonate, and pamoate (e.g., l,l'-methylene-bis-(2-hydroxy-3-naphthoate)) salts.

[0418] The routes for administration (delivery) may include, but are not limited to, one or more of oral (e.g., as a tablet, capsule, or as an ingestable solution), topical, mucosal (e.g., as a nasal spray or aerosol for inhalation), nasal, parenteral (e.g., by an injectable form), gastrointestinal, intraspinal, intraperitoneal, intramuscular, intravenous, intrauterine, intraocular, intradermal, intracranial, intratracheal, intravaginal, intracerebroventricular, intracerebral, subcutaneous, ophthalmic (including intravitreal or intracameral), transdermal, rectal, buccal, vaginal, epidural, sublingual.

[0419] Typically, a physician will determine the actual dosage which will be most suitable for an individual subject. The specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific compound employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the individual undergoing therapy.

[0420] The formulations may be packaged in unit-dose or multi-dose containers, for example sealed ampoules and vials, and may be stored in a freeze-dried (lyophilized) condition requiring only the addition of the sterile liquid carrier, for example water, for administration. Extemporaneous injection solutions and suspensions are prepared from sterile powders, granules and tablets of the kind previously described. Exemplary unit dosageformulations contain a daily dose or unit daily sub-dose, or an appropriate fraction thereof, of the active ingredient.

[0421] Definitions

[0422] Unless otherwise specified, all scientific, chemical names, and technical terms used herein have the same meaning as commonly understood by the skilled person. A dash (-; 'nnn / ) at the front or end of a chemical group is a matter of convenience to indicate the point of attachment. However, chemical groups may be depicted with or without one or more dashes without losing their ordinary meaning. If not otherwise specified, each linking substituent include both the forward and backward forms of the linking substituent. For example, Ci-2 alkylCg-io aryl- includes both -Cg-io aryl-Ci-2 alkyl- and -C1-2 alkyl-Cg-10 aryl- and is intended to disclose each of the forms individually and can be attached on one side only (e.g., C1-2 alkyl or Cg-10 aryl-) or on both sides.

[0423] Antibody. The term "antibody" is used in its broadest sense and covers monoclonal antibodies, polyclonal antibodies, dimers, multimers, multispecific antibodies (e.g., bispecific antibodies), veneered antibodies, antibody fragments and small immune proteins (SIPs) (see Int. J. Cancer (2002) 102, 75-85). An antibody is a protein generated by the immune system that is capable of recognizing and binding to a specific antigen. A target antigen generally has numerous binding sites, also called epitopes, recognized by CDRs on multiple antibodies. Each antibody that specifically binds to a different epitope has a different structure. Thus, one antigen may have more than one corresponding antibody. An antibody includes a full-length immunoglobulin molecule or an immunologically active fragment of a full-length immunoglobulin molecule, i.e., a molecule that contains an antigen binding site that immunospecifically binds an antigen of a target of interest or part thereof. The antibodies may be of any type - such as IgG, IgE, IgM, IgD, and IgA - any class - such as IgGl, IgG2, IgG3, IgG4, IgAl and IgA2 - or subclass thereof. The antibody may be or may be derived from murine, human, rabbit or from other species. The antibody can be chimeric, humanized, or, preferably, human.

[0424] Antibody fragments. The term "antibody fragment" refers to a fragment of a full-length antibody, generally the antigen binding or variable region thereof. Examples of antibody fragments include, but are not limited to, Fab, Fab', F(ab')2, and Fv fragments; scFv’s, diabodies; single chain diabodies; linear antibodies; single domain antibodies, including dAbs, camelid VHH antibodies and the IgNAR antibodies of cartilaginous fish. Antibodies and their fragments may be replaced by binding molecules based on alternative nonimmunoglobulin scaffolds, peptide aptamers, nucleic acid aptamers, structured polypeptides comprising polypeptide loops subtended on a non-peptide backbone, natural receptors or domains thereof.

[0425] Analog. This term encompasses any enantiomers, racemates and stereoisomers, as well as all pharmaceutically acceptable salts and hydrates of such compounds.

[0426] Unless otherwise stated, the following definitions apply to chemical terms used in connection of compounds of the invention and compositions containing such compounds.Alkyl refers to a branched or unbranched saturated hydrocarbyl radical. Suitably, the alkyl group comprises from 1 to 100, preferably 3 to 30, carbon atoms, more preferably from 5 to 25 carbon atoms. Preferably, alkyl refers to methyl, ethyl, propyl, butyl, pentyl, or hexyl.

[0427] Alkenyl refers to a branched or unbranched hydrocarbyl radical containing one or more carbon-carbon double bonds. Suitably, the alkenyl group comprises from 2 to 30 carbon atoms, preferably from 5 to about 25 carbon atoms.

[0428] Alkynyl refers to a branched or unbranched hydrocarbyl radical containing one or more carbon-carbon triple bonds. Suitably, the alkynyl group comprises from about 3 to about 30 carbon atoms, for example from about 5 to about 25 carbon atoms.

[0429] Halogen refers to fluorine, chlorine, bromine or iodine, preferably fluorine or chlorine.

[0430] Cycloalkyl refers to an alicyclic moiety, suitably having 3, 4, 5, 6, 7 or 8 carbon atoms. The group may be a bridged or polycyclic ring system. More often cycloalkyl groups are monocyclic. This term includes reference to groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbomyl, bicyclo[2.2.2]octyl and the like.

[0431] Aryl refers to an aromatic carbocyclic ring system, suitably comprising 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 ring carbon atoms. Aryl may be a polycyclic ring system, having two or more rings, at least one of which is aromatic. This term includes reference to groups such as phenyl, naphthyl fluorenyl, azulenyl, indenyl, anthryl and the like.

[0432] Carbamoyl: The term "carbamoyl," as used herein refers to a group of formula -C(O)NH2, -NH2C(O), RmNHC(=O)Rn, C(O)NHRn. Non limiting examples are: (C2-6 alkyl)NHC(=O)(Ci-6 alkyl), and (C2-6 alkyl)NHC(=O). Rmand Rnrepresent alkyl or alkenyl groups as defined above, m and n represent the number of carbon atoms in the chain.

[0433] Carbonyl: The term "carbonyl," as used herein refers to a -C(=O)- group, which also may be written as -C(O)-, or -CO-.

[0434] Amino: The term "amino," as used herein refers to a group of formula -NH2. The term -(Cn-CmAlkyl)NHRnrefers to an amino group linked to an alkyl group defined as above, wherein additionally one hydrogen atom is substituted with an atom or a group of atoms. In the definition -(Cn-CmAlkyl)NH- (with or without dash), both the alkyl group and the NH group are bonded to another structural element, such as in a cyclic system represented by -U-W-, wherein -(Cn-CmAlkyl)NH is the W. Cn-Cmrefers to the number of carbon atoms. Derivative. A derivative includes the chemical modification of a compound. Examples of such modifications include the replacement of a hydrogen by a halo group, an alkyl group, an acyl group or an amino group and the like. The modification may increase or decrease one or more hydrogen bonding interactions, charge interactions, hydrophobic interactions, van der Waals interactions and / or dipole interactions.Diastereomers or diastereoisomers, unless specified otherwise, preferably refer to stereoisomers of a compound having different configurations at one or more stereocenters in parts of the molecule other than the tumor-targeting moiety A. That is, unless specified otherwise, the stereochemical configuration of moiety A is as represented in the respective structure, and the individual diastereomers may differ in their stereochemical configuration in parts of the molecule other than moiety A.

[0435] The prefix (hetero) herein signifies that one or more of the carbon atoms of the group may be substituted by nitrogen, oxygen, phosphorus, silicon or sulfur. Heteroalkyl groups include for example, alkyloxy groups and alkythio groups. Heterocycloalkyl or heteroaryl groups herein may have from 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 or 16 ring atoms, at least one of which is selected from nitrogen, oxygen, phosphorus, silicon and sulfur. In particular, a 3- to 10-membered ring or ring system and more particularly a 5- or 6-membered ring, which may be saturated or unsaturated. For example, selected from oxiranyl, azirinyl, 1,2-oxathiolanyl, imidazolyl, thienyl, furyl, tetrahydrofuryl, pyranyl, thiopyranyl, thianthrenyl, isobenzofuranyl, benzofuranyl, chromenyl, 2H-pyrrolyl, pyrrolyl, pyrrolinyl, pyrrolidinyl, imidazolyl, imidazolidinyl, benzimidazolyl, pyrazolyl, pyrazinyl, pyrazolidinyl, thiazolyl, isothiazolyl, dithiazolyl, oxazolyl, isoxazolyl, pyridyl, pyrazinyl, pyrimidinyl, piperidyl, piperazinyl, pyridazinyl, morpholinyl, thiomorpholinyl, especially thiomorpholino, indolizinyl, l,3-Dioxo-l,3-dihydro-isoindolyl, 3H-indolyl, indolyl, benzimidazolyl, cumaryl, indazolyl, triazolyl, tetrazolyl, purinyl, 4H-quinolizinyl, isoquinolyl, quinolyl, tetrahydroquinolyl, tetrahydroisoquinolyl, decahydroquinolyl, octahydroisoquinolyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, phthalazinyl, naphthyridinyl, quinoxalyl, quinazolinyl, quinazolinyl, cinnolinyl, pteridinyl, carbazolyl, [beta] -carbolinyl, phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, furazanyl, phenazinyl, phenothiazinyl, phenoxazinyl, chromenyl, isochromanyl, chromanyl, 3,4-dihydro-2H-isoquinolin-l-one, 3,4-dihydro-2H-isoquinolinyl, and the like.

[0436] “Substituted” signifies that one or more, especially up to 5, more especially 1, 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of substituents. The term "optionally substituted" as used herein includes substituted or unsubstituted. It will, of course, be understood that substituents are only at positions where they are chemically possible, the person skilled in the art being able to decide (either experimentally or theoretically) without inappropriate effort whether a particular substitution is possible. For example, amino or hydroxy groups with free hydrogen may be unstable if bound to carbon atoms with unsaturated (e.g., olefinic) bonds. Preferably, the term “substituted” signifies one or more, especially up to 5, more especially 1, 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of substituents selected from OH, SH, NH2, halogen, cyano, carboxy, alkyl, cycloalkyl, aryl and heteroaryl. Additionally, the substituents described herein may themselves be substituted by any substituent, subject to the aforementioned restriction to appropriate substitutions as recognised by the skilled person. Preferably, any of the aforementioned substituents may be further substituted by any of the aforementioned substituents, each of which may be further substituted by any of the aforementioned substituents.Preferably, the term “substituted” used herein means any of the above groups (e.g., alkyl, alkylene, alkylcycloalkyl, alkoxy, alkoxyalkyl, alkoxycarbonyl, aryloxy, alkylaminyl, alkylcarbonylaminyl, alkylaminylalkyl, aminylcarbonyl, alkylaminylcarbonyl, aminylcarbonylalkyl, aminylcarbonycycloalkylalkyl, thioalkyl, aryl, aralkyl, carboxyalkyl, cyanoalkyl, cycloalkyl, cyanocycloalkyl, cycloalkylaminylcarbonyl, cycloalkylalkyl, haloalkyl, haloalkoxy, heterocyclyl, -heterocyclyl. heterocyclylalkyl, heteroaryl, N-heteroaryl, phosphoalkoxy and / or heteroarylalkyl) wherein at least one hydrogen atom (e.g., 1, 2, 3 or all hydrogen atoms) is replaced by a bond to a non-hydrogen atom such as, but not limited to: a halogen atom such as F, Cl, Br, and I; an oxygen atom in groups such as hydroxyl groups, alkoxy groups, and ester groups; a sulfur atom in groups such as thiol groups, thioalkyl groups, sulfone groups, sulfonyl groups, and sulfoxide groups; a nitrogen atom in groups such as amines, amides, alkylamines, dialkylamines, arylamines, alkylarylamines, diarylamines, N-oxides, imides, and enamines; a silicon atom in groups such as trialkylsilyl groups, dialkylarylsilyl groups, alkyldiarylsilyl groups, and triarylsilyl groups; and other heteroatoms in various other groups. “Substituted” also means any of the above groups in which one or more hydrogen atoms are replaced by a higher-order bond (e.g., a double- or triple-bond) to a heteroatom such as oxygen in oxo, carbonyl, carboxyl, and ester groups; and nitrogen in groups such as imines, oximes, hydrazones, and nitriles. For example, “substituted” includes any of the above groups in which one or more hydrogen atoms are replaced with -NRgRh, -NRgC(=O)Rh, -NRgC(=O)NRgRh, -NRgC(=O)ORh, -NRgSO2Rh, -OC(=O)NRgRh, -ORg, -SRg, -SORg, -SO2Rg, -OSO2Rg, -SO2ORg, =NSC>2Rg, and -SO2NRgRh. “Substituted” also means any of the above groups in which one or more hydrogen atoms are replaced with -C(=O)Rg, -C(=O)ORg, -C(=O)NRgRh, -CH2SO2Rg, -CH2SO2NRgRh. In the foregoing, Rgand Rh are the same or different and independently hydrogen, alkyl, alkoxy, alkylaminyl, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, -heterocyclyl. heterocyclylalkyl, heteroaryl, A-heteroaryl and / or heteroarylalkyl. “Substituted” further means any of the above groups in which one or more hydrogen atoms are replaced by a bond to an aminyl, cyano, hydroxyl, imino, nitro, oxo, thioxo, halo, alkyl, alkoxy, alkylaminyl, thioalkyl, aryl, aralkyl, cycloalkyl, cycloalkylalkyl, haloalkyl, heterocyclyl, / V-heterocyclyl, heterocyclylalkyl, heteroaryl, -heteroaryl and / or heteroarylalkyl group. In addition, each of the foregoing substituents may also be optionally substituted with one or more of the above substituents.

[0437] More preferably, substituents suitably include halogen atoms and halomethyl groups such as CF3 and CCl3; oxygen containing groups such as oxo, hydroxy, carboxy, carboxyalkyl, alkoxy, alkoyl, alkoyloxy, aryloxy, aryloyl and aryloyloxy; nitrogen containing groups such as amino, alkylamino, dialkylamino, cyano, azide and nitro; sulfur containing groups such as thiol, alkylthiol, sulfonyl and sulfoxide; heterocyclic groups which may themselves be substituted; alkyl groups, which may themselves be substituted; and aryl groups, which may themselves be substituted, such as phenyl and substituted phenyl. Alkyl includes substituted and unsubstituted benzyl.

[0438] Where two or more moieties are described as being "each independently" selected from a list of atoms or groups, this means that the moieties may be the same or different. The identity of each moiety is thereforeindependent of the identities of the one or more other moieties.

[0439] Molecular weight. This term is used to refer to the mass of a given molecule and is expressed herein as “weight average molecular weight” or Mw. In the present disclosure, the molecular weight may be determined by mass spectrometry, preferably by an ESI quadrupole or Orbitrap instrument, more preferably with an Agilent 6100 Series Single Quadrupole MS instrument.

[0440] Specific binding. As used herein, and unless specified otherwise, "specific binding” to a certain target or antigen refers to better binding expressed by Kd as compared to binding to other proteins found in mammals, preferably humans, primates and / or rodents, e.g., albumin (e.g., HSA or MSA).

[0441] The term "pharmaceutically acceptable" herewith is intended to those compounds and materials, which are generally safe, non-toxic, and neither biologically nor otherwise undesirable and includes that which is acceptable for veterinary use as well as human pharmaceutical use.

[0442] The terms "subject" or "patient," or “recipient” used interchangeably, refer to any mammal, preferably mice, rats, other rodents, rabbits, dogs, cats, swine, or primates, and most preferably humans.

[0443] The phrase "therapeutically effective amount" refers to the amount of active compound or pharmaceutical agent that elicits the biological or medicinal response in a tissue, system, animal, individual or human.

[0444] As used herein, the term "treating" or "treatment" refers to the inhibition of the disease; condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder; and / or to ameliorating the disease; e.g., ameliorating a disease, condition or disorder in an individual who is experiencing or displaying the pathology or symptomatology of the disease, condition or disorder (i.e., reversing the pathology and / or symptomatology) such as decreasing the severity of disease.EXAMPLES

[0445] Example 1: Synthesis of the compounds

[0446]

[0447] Schematic synthesis of MB 357.

[0448] While the above schematic synthesis exemplifies the preparation of one regioisomer, other regioisomers (e.g., wherein the attachment of R to the rest of the molecule takes place via the amino group on the purine moiety) may also be prepared by the same or analogous methods.

[0449] Synthesis of Compound 1

[0450] To a solution of 3-hydroxy-4-iodobenzoic acid in THF was added dropwise Borane-tetrahydrofuran complex at 0 °C under nitrogen atmosphere. The mixture was stirred at 25 °C for 16 hours. The reaction was quenched with MeOH carefully and diluted with saturated NaHCO3and extracted with EtOAc. The organic phases were combined and washed with brine, dried over Na2SO4and concentrated under vacuum. The residue was purified by direct liquid chromatography (Petroleum ether / EtOAc) to afford compound 1.Synthesis of Compound 2

[0451] Tert-butyl cyclobutylcarbamate was dissolved in DMF under nitrogen and the mixture was cooled down to 0 °C. NaH was added in portions and the mixture was stirred at 0 °C. After 30 minutes, propargyl bromide was added dropwise. The mixture was stirred at 25 °C for 3 hours. The reaction was quenched with saturated NH4CI and extracted with EtOAc. The organic layers were combined and washed with brine, dried over Na2SO4and concentrated under vacuum. The residue was purified by direct liquid chromatography (Petroleum ether / EtOAc) to afford compound 2.

[0452] Synthesis of Compound 3

[0453] To a solution of 4,6-dichloro-2-(methylthio)-5-nitropyrimidine and TEA in dioxane was added NH3 in dioxane dropwise at -20 °C under nitrogen. The mixture was stirred at 0 °C for 16 hours. The reaction was concentrated under vacuum and the residue was diluted with water and extracted with EtOAc. The organic layers were combined and dried over Na2SO4. concentrated under vacuum to compound 3.

[0454] Synthesis of Compound 4

[0455] Compound 3 and TEA were dissolved in THF, ethyl chloroformate was added dropwise at 0 °C under nitrogen. The mixture was stirred at 25 °C for 16 hours. The reaction was quenched with water and extracted with EtOAc. The organic layers were combined and dried over Na2SO4. concentrated under vacuum. The residue was purified by silica gel chromatography (Petroleum ether / EtOAc) to afford compound 4.

[0456] Synthesis of Compound 5

[0457] Compound 4 and compound 1 were dissolved in THF, followed by the dropwise addition of PPh3and DIAD at 0 °C under nitrogen atmosphere. The mixture was stirred at 25 °C for 6 hours. The reaction was quenched with water and extracted with EtOAc. The organic layers were combined and dried over Na2SO4. concentrated under vacuum. The residue was purified by silica gel chromatography (Petroleum ether / EtOAc) to afford compound 5.

[0458] Synthesis of Compound 6

[0459] Compound 5 was solubilized in THF and NH3 H2O was added. The mixture was stirred at 25 °C for 6 hours. The reaction crude was purified by silica gel chromatography (Petroleum ether / EtOAc) to afford compound 6.

[0460] Synthesis of Compound 7

[0461] To a solution of compound 6 in DMF were added Cs2CO3and allyl bromide. The mixture was stirred at 25 °C for 16 hours. The reaction was quenched with water (and extracted with EtOAc). The organic layers were combined and washed with brine, dried over Na2SO4 and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to afford compound 7.

[0462] Synthesis of Compound 8To a solution of compound 7 in DCM was added m-CPBA and the mixture was stirred at 25 °C for 16 hours. The reaction was quenched with saturated sodium thiosulfate and extracted with DCM. The organic layers were combined and washed with brine, dried over Na2SO4 and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to afford compound 8.

[0463] Synthesis of Compound 9

[0464] To a solution of compound 8 in allyl alcohol was added TEA and the reaction was stirred at 25 °C for 16 hours. The mixture was quenched with water and extracted with EtOAc. The organic layers were combined and washed with brine, dried over Na2SO4and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to obtain compound 9.

[0465] Synthesis of Compound 10

[0466] To a solution of compound 9 in DCE was added Hoveyda Grubbs catalyst(II) and the mixture was stirred at 80 °C for 4 hours. Imidazole was added to the mixture which was left stirring at 80 °C for an additional 1 hour. The mixture was cooled to room temperature and washed with HC1 and brine. The organic layer was dried over Na2SO4and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to afford compound 10.

[0467] Synthesis of Compound 11

[0468] To a solution of compound 10 in THF and MeOH was added Tris(triphenylphosphine)rhodium(I) chloride and the mixture was stirred at 40 °C for 16 hours under H2(0.35 MPa). After this time, the mixture was diluted with water and extracted with EtOAc. The organic layers were combined and washed with brine, dried over Na2SO4and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to afford compound 11.

[0469] Synthesis of Compound 12

[0470] To a solution of compound 11 in DMF was added Cui, TEA, Pd(dppf)C12 and compound 2. The mixture was stirred at 50 °C under nitrogen for 16 hours. The mixture was then filtered and the filtrate was quenched with water and extracted with EtOAc. The organic layers were combined and washed with brine, dried over Na2SO4and concentrated under vacuum. The residue was purified by column chromatography (Petroleum ether / EtOAc) to afford compound 12.

[0471] Synthesis of MB357

[0472] To a solution of intermediate 12 in AcOH and water was added iron. The mixture was stirred at 100 °C for 16 hours and then concentrated under vacuum. The residue was purified by reverse phase column chromatography and followed by prep-HPLC to afford MB357.

[0473] Example 2: In vitro activation of human TLR7 and murine TLR7 expressed on NF-KB-SEAP reporter HEK293 cellsNF-KB-SEAP reporter HEK293 cells expressing human or murine TLR7 were cultured in 96-well plates at a density of 200000 cells / mL (200 pL / well) at 37 °C for 24 hours. After 24 hours the media was removed from the wells and substituted with 200 pL of medium containing serial dilutions of MB357, A78, or Resiquimod. After an incubation of 24 hours, 20 pL from each well of the cell culture supernatants were collected and transferred to another 96-well plate. Each well was treated with 200 pL of QUANTI-Blue solution and incubated at 37 °C for 30 min. The optical density was measured using a plate reader at an absorbance of 655 nm. EC50 values were determined by fitting data to the four-parameter logistic equation using Prism 9 software (GraphPad Software) for data analysis.

[0474] The activity of MB357 on TLR7 was measured on two different HEK293 cell lines expressing the human or murine isoform of the receptor, and compared to reference compounds based on an imidazoquinoliamine scaffold: resiquimod (l-(4-amino-2-(ethoxymethyl)-lH-imidazo[4,5-c]quinolin-l-yl)-2-methylpropan-2-ol or R848) or A78 (l-(4-(aminomethyl)benzyl)-2-butyl-lH-imidazo[4,5-c]quinoline-4-amine) or compound 7d of US 8,728,486 B2)). The data shown in FIG. 1 represent the EC50 for each compound on HEK cells expressing hTLR7 or mTLR7. MB357 exhibited advantageous activity on both isoforms with a single digit nanomolar EC50 (2.4 and 8.8 nM for human and murine TLR7, respectively).

[0475] Example 3: Expression of cytokines after incubation with TLR agonists

[0476] Quantification of cytokines released by human Peripheral Blood Mononuclear Cells (PBMCs) Human PBMCs were seeded in a 96-well plate at a density of 2.5 × 105cells per well with 100 pL of medium (RPMI supplemented with 10% FBS, 1% pen / strep). 100 pL of medium containing serial dilutions of MB357 or A78 were added. Cells were incubated for 24 hours at 37 °C in a 5% CO2 humidified incubator. The cell culture supernatants were collected and the levels of cytokines (hIL6 and hTNFoc) were determined using commercially available ELISA kits.

[0477] After incubation, the media were collected, and cytokines were measured by ELISA. The data shown in FIG. 2 indicate that MB357 was able to stimulate the expression and release of hIL6 (A) and hTNFoc (B) at very low concentrations, and exhibited a higher potency compared to A78. This is expected to result in a superior in vivo activity for MB357.

[0478] Quantification of cytokines released by murine Bone Marrow derived Dendritic Cells (BMDCs) and by murine Splenocytes

[0479] To collect the bone marrow, naive Balb / C mice were euthanized, and the two tibias and two femurs were collected. The bones were cut and flushed with sterile PBS to afford the bone marrow. The cells were seeded in a 6-well plate and the promotion of their differentiation to dendritic cells was obtained with the use of 20 ng / mL of GM-CSF every other day for 6 days. Cells were collected and stimulated with serial dilutions of MB357 or A78 for 24 hours.Splenocytes were obtained from the spleen of naive Balb / C mice. The mice were euthanized, and the spleen was removed and smashed on a 70 pm cell strainer to obtain the splenocytes. The cells were counted and treated with serial dilution of the compounds for 24 hours. The supernatants of both splenocytes and dendritic cells were collected and the levels of cytokines (mIL6 and mTNFoc) were determined using commercially available ELISA kits (Biolegend).

[0480] As shown in FIG. 3A and B, MB357 showed the ability to promote cytokine release (mIL6 and mTNFoc) from bone marrow-derived dendritic cells (BMDCs) at least as good as or better than A78. As shown in FIG. 3C and D, MB357 was a much more potent agonist in the stimulation of cytokine expression and release from splenocytes than A78.

[0481] Example 4: Activation of murine Bone Marrow derived Dendritic Cells (BMDCs) and splenocytes after incubation with TLR agonists measured by Flow Cytometry

[0482] Activation of murine BMDCs and splenocytes

[0483] Bone marrow dendritic cells (BMDCs) and Splenocytes were obtained as described in Example 3. Cells were incubated with compound MB357, A78 or IIb-19 (compound IIb-19 from W02019 / 209811A1) for 24 hours at 37 °C in a 5% CO2 humidified incubator. The media was removed and the cells were washed twice with PBS. Following the washing steps, the cells were incubated with fluorophore-labeled antibodies for 30 minutes (APC-Cy7-ocI-A / I-E, PE-ocCD40, FITC-aCD86, Alexa647-ocCDllc for BMDCs, Alexa647-ocB220 for Splenocytes). The cells were washed again with PBS and analyzed by flow cytometry (CytoFLEX S). CD11c positive or I-A / I-E positive cells were gated as Dendritic Cells or Antigen Presenting Cells (APCs), respectively. B220 positive cells were gated as B cells. CD86 and CD40 expression levels were plotted as relative MFI values.

[0484] As shown in FIG. 4A, B and D, MB357 was able to induce the upregulation of CD86 in dendritic cells (CD11c positive), of CD40 in dendritic cells (CD 11c positive), and of CD86 in B cells (B220 positive), at lower concentrations than A78.

[0485] As shown in FIG. 4C, MB357 was able to induce the upregulation of CD86 in dendritic cells (CD11c positive) at lower concentrations than IIb-19.The present disclosure further provides the following embodiments of the invention.

[0486] Embodiment 1. A compound having the following structure:

[0487] A - B— E

[0488]

[0489] c d

[0490] I

[0491] or a pharmaceutically acceptable salt, solvate, hydrate, crystal form, tautomer, or diastereoisomer thereof,

[0492] wherein:

[0493] A is a tumor-targeting moiety, preferably an PSMA-binding moiety;

[0494] B is a spacer;

[0495] C is a cleavable or non-cleavable linker;

[0496] D is a self-immolative spacer;

[0497] E is a TLR7 agonist moiety; and

[0498] c and d may each be 0 or an integer of 1 or more; preferably 0, 1, 2 or 3;

[0499] wherein optionally each occurrence of B, C, and D may be in any order.

[0500] Embodiment!. The compound according to embodiment 1, wherein the compound structure is represented by the following Formula I':

[0501] A - B (-C-)- (-D-) E’

[0502] r

[0503] wherein E' is or comprises a structure derived by removing at least one H atom or R group in the following general formula:

[0504] N(R)R

[0505]

[0506] wherein:

[0507] Z is selected from C2-5 alkynyl, C1-5 alkenyl, C1-5 alkyl, and (C1-2 alkyl)C6-ioaryl;

[0508] U is selected from O, NH, N(CI-3 alkyl), S, CEE, and CH(CI-3 alkyl);

[0509] W is selected from C1-10 alkyl, C2-10 alkenyl, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl), (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)O, (C2-10 alkyl)O, (C2-10 alkenyl)O, (C2-6 alkyl)O(C2-6 alkyl), (C2-6alkyl)O(C2-6 alkyl)O, (C2-10 alkyl)NH, (C2-10 alkenyl)NH, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)NH, and (C2-6 alkyl)O(C2-6 alkyl)NH;each optionally substituted with one or more substituents, preferably selected from C1-3 alkyl and (C1-3 alkyl)O;

[0510] X is selected from CH, N, and S;

[0511] Y is selected from CH and N, or is absent;

[0512] R is selected from H, C1-3 alkyl, C1-3 haloalkyl, and C1-3 heteroalkyl;

[0513] R1is selected from Ci-s alkyl, C2-8 cycloalkyl, (C3-ecycloalkyl)Ci-3 alkyl, C1-7 heteroalkyl, C2-7 cycloheteroalkyl, -C(=O)NH(Ci-3 alkyl), -C1-3 alkyl(C=O)OMe, -C(=O)NH(C2-8 cycloalkyl), (C2-7 cycloheteroaryl)Ci-3 alkyl and (Cg-io aryl)Ci-3 alkyl; each optionally substituted with one or more substituent(s) preferably selected from OH, CH3, OMe, CN, -C(=O)Me, F2CH, SO2Me, and halogen. Embodiment 3. The compound according to embodiment 2, wherein the compound structure is represented by one or more of Formulae I-a and I-c:

[0514]

[0515] I-a

[0516] A - B - (-C ) ( D-) - E-c

[0517] I-c

[0518] wherein each of E-a and E-c is or comprises, respectively, a structure of Formula E-a or E-c:

[0519]

[0520] wherein Zais selected from C2-5alkynyl, C2-5alkenyl, and C2-5alkyl.

[0521] Embodiment 4. The compound according to embodiment 2 or 3, wherein the compound structure is represented by one or more of Formulae I-al and I-cl:

[0522] A - B - (-C-)- (-D-)— E-a1

[0523] I-alI-cl

[0524] wherein each of E-al and E-cl is or comprises, respectively, a structure of Formula E-al or E-cl:

[0525]

[0526] E-al E-cl

[0527] wherein Zal is C3 alkynyl; U1-W1 is selected from:

[0528]

[0529] Embodiment 5. The compound according to any of the preceding embodiments, wherein the compound structure is represented by one or more of Formulae I-al', I-al", I-al'", I-cl', I-cl", and I- cl'":

[0530] A - B— (-C-)— (-D-) - E-a1 '

[0531] I-al'

[0532] A - B (-C-)— (-D-)^E-a1 "

[0533] I-al"

[0534] A - B - (-C-)— (-D-) - E-a1

[0535]

[0536] I-al'"

[0537] A - B— f-C-)— (-D-) - E-C1 '

[0538] I-cl'

[0539] A - B (-C-)- (-D-) - E-c1 ”

[0540] I-cl"A - B - f-C-W-D-) - E-C1 ■"

[0541] I-cl"'

[0542] wherein each of E-al', E-al", E-al'", E-cl', E-cl", and E-cl'" is or comprises, respectively, a structure of Formula E-al', E-al", E-al'", E-cl', E-cl", or E-cl'":

[0543]

[0544] Embodiment 6. The compound according to embodiments 1 to 3, wherein the compound structure is represented by one or more of Formulae I-a2 and I-c2:

[0545] A - B (-C-)- (-D-)— E-a2

[0546] I-a2

[0547] E-C2

[0548]

[0549] I-c2

[0550] wherein each of E-a2 and E-c2 is or comprises, respectively, a structure of Formula E-a2 or E-c2:

[0551]

[0552] wherein Za2is C4-5alkyl; U1-W1is selected from:

[0553]

[0554] Embodiment 7. The compound according to embodiment 6, wherein the compound structure is represented by one or more of Formulae I-a2', I-a2", I-a2'", I-c2', I-c2", and I-c2'":

[0555] A - B - (-C-)- (-D-) - E-a2"

[0556] c d

[0557] I-a2'

[0558] A - B - (-C-)- (-D-) - E-a2"

[0559] I-a2"

[0560] A - B (-C-4— f-D-) - E-a2"’

[0561] I-a2'"

[0562] A - B - f-C-)— (-D-) - E-c2'

[0563] I-c2'

[0564] A - B - £-c4- (-D-) - E-c2"

[0565] I-c2"

[0566] A - B - (-C-J-i-D-) - E-c2'"

[0567]

[0568] I-c2'"

[0569] wherein each of E-a2', E-a2", E-a2'", E-c2', E-c2", and E-c2'" is or comprises, respectively, a structure of Formula E-a2', E-a2", E-a2'", E-c2', E-c2", or E-c2'":

[0570]

[0571]

[0572] Embodiment 8. The compound according to any of the preceding embodiments, wherein:

[0573] X = CH and Y = CH,

[0574] X = N andY = CH,

[0575] X = CH and Y = N,

[0576] X = N andY = N, or

[0577] X = S and Y is absent.

[0578] Embodiment 9. The compound according to any of the preceding embodiments, wherein: R1is selected from the group consisting of:

[0579]

[0580] Embodiment 10. The compound according to any of embodiments 1 to 9 having a structure represented by the following formula:

[0581]

[0582] I-MB357

[0583] wherein MB357 is or comprises a structure derived by removing at least one H atom in the following formula:

[0584]

[0585] MB357

[0586] Embodiment 11. The compound according to embodiment 10, wherein the compound structure is represented by one or more of Formulae I-(MB357') and I-(MB357"):

[0587] A - B — (-C-)- (-D-) — MB357’

[0588] c d

[0589] l-(MB357’)

[0590]

[0591] c d

[0592] l-(MB357")

[0593] wherein each of MB357' and MB357" represent, respectively, a structure of the following Formula MB357' or MB357":

[0594]

[0595] Embodiment 12. The compound according to embodiment 2, wherein the compound structure is represented by one or more of Formulae I-b and I-d:

[0596] Lb

[0597]

[0598] I-d

[0599] wherein each of E-b and E-d is or comprises, respectively, a structure of Formula E-b or E-d:

[0600]

[0601] wherein Zbis (C1-2alkyl)C6aryl.

[0602] Embodiment 13. The compound according to embodiment 12, wherein the compound structure is represented by one or more of Formulae I-bl and I-dl:

[0603] A - B - f-C-4- (-D-) - E-b1

[0604] I-bl

[0605] A - B f-c4— f-D-) E-d 1

[0606]

[0607] I-dl

[0608] wherein each of E-bl and E-dl is or comprises, respectively, a structure of Formula E-bl or E-dl:

[0609]

[0610] wherein Zb1is (C1alkyl)C6aryl; U1-W1is selected from:

[0611]

[0612] Embodiment 14. The compound according to embodiment 13, wherein the compound structure is represented by one or more of Formulae I-bl', I-bl", I-bl'", I-dl', I-dl", and I-dl'":

[0613] A - B - (-C-)- f-D-J - E-b1 '

[0614] I-bl'

[0615] A - B - E-b1 "

[0616] I-bl"

[0617] A - B - (-cA-t-oA - E-b1 ■"

[0618] I-bl'"

[0619] A - B f-C A- t-oA^E-d 1 ’

[0620] I-dl'

[0621] A - B - (" C-)— (-D-) - E-d 1 "

[0622] I-dl"

[0623] A - B - f-cA-f-DA - E-d1 ■"

[0624]

[0625] I-dl'"

[0626] wherein each of E-bl', E-bl", E-bl'", E-dl', E-dl", and E-dl'" is or comprises, respectively, a structure of Formula E-b 1 ', E-bl", E-bl'", E-dl', E-dl" or E-dl'":

[0627]

[0628] Embodiment 15. The compound according to any of embodiments 12-14, wherein X and Y are defined as in embodiment 8.

[0629] Embodiment 16. The compound according to any of embodiments 12-14, wherein R1is defined as in embodiment 9.

[0630] Embodiment 17. The compound according to any of embodiments 12 to 14 having a structurerepresented by the following formula:

[0631] A - B - f-C-W-D-) - llb-19

[0632] I-(IIb-19)

[0633] wherein lib- 19 is or comprises a structure derived by the removing at least one H atom in the following formula:

[0634]

[0635] IIb-19

[0636] Embodiment 18. The compound according to embodiment 17, wherein the compound is represented by one or more of Formulae I-(IIb-19') and I-(IIb-19"):

[0637] A - B f-C-W-D-) llb-19’

[0638] I-(IIb-19')

[0639] A - B (-C-)- (-D-) - llb-19"

[0640] I-(IIb-19")

[0641] wherein each of IIb-19' and 11-19" represents, respectively, a structure of Formula IIb-19' or IIb-19":

[0642]

[0643] Embodiment 19. The compound according to any one of the preceding embodiments, having a structure selected from:

[0644] 2-8.

[0645] A

[0646]

[0647] - B - C - D - E A - B - C ’E; and A B E

[0648] Embodiment 20. The compound according to any one of the preceding embodiments, wherein A is asmall molecule moiety having a molecular weight of 3000 Da or less, preferably 2500 Da or less, more preferably 2000 Da or less, even more preferably from 250 to 2000 Da.

[0649] Embodiment 21. The compound according to any one of embodiments 1 to 20, wherein A is an ACP3- binding moiety.

[0650] Embodiment 22. The compound according to any one of embodiments 1-21, wherein A is an ACP3- binding moiety comprising the structure:

[0651]

[0652] Embodiment 23. The compound according to embodiment 22, wherein A is an ACP3-binding moiety comprising the structure:

[0653]

[0654] Embodiment 24. The compound according to any one of embodiments 1-21, wherein A is an ACP3- binding moiety having the structure:

[0655]

[0656] Embodiment 25. The compound according to any one of embodiments 1-19, wherein A is an antibody, an antibody derivative, or an antigen-binding fragment thereof.

[0657] Embodiment 26. The compound according to any one of embodiments 1-19, wherein A is a tumortargeting antibody or antigen binding fragment thereof that binds to

[0658] ACP3.

[0659] Embodiment 27. The compound according to any one of the preceding embodiments, wherein B is:

[0660] (a) a single bond or an optionally substituted C1-58aliphatic group, in which optionally one or more carbon atoms can be replaced by heteroatom, a C3-12carbocyclic or a C3-12heterocyclic group, and which can be saturated or optionally contain one or more double or triple bonds;

[0661] (b) represented by any of the following general Formulae III- VI:

[0662] III IV

[0663]

[0664] V VI

[0665] wherein

[0666] each x is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;

[0667] each y is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;

[0668] each z is 0, 1, 2, 3 or 4; preferably 1;

[0669] preferably with the proviso that at least one of x and y is not 0;

[0670] * represents a point of attachment to a moiety i -Y- or R1-;

[0671] • represents a point of attachment to a moiety C; and

[0672] each of Bg and BL is independently selected from alkylene, cycloalkylene, arylalkylene, heteroarylalkylene, heteroalkylene, heterocycloalkylene, alkenylene, cycloalkenylene, arylalkenylene, heteroarylalkenylene, heteroalkenylene, heterocycloalenkylene, alkynylene, heteroalkynylene, arylene, heteroarylene, aminoacyl, oxyalkylene, aminoalkylene, diacidester, dialkylsiloxane, amide, thioamide, thioether, thioester, ester, carbamate, hydrazone, thiazolidine, methylene alkoxy carbamate, disulfide, vinylene, imine, imidamide, phosphoramide, saccharide, phosphate ester, phosphoramide, carbamate, dipeptide, tripeptide, tetrapeptide, each of which is optionally substituted; or

[0673] (c) represented by (Bs)xwherein:

[0674] each x is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10;

[0675] each Bs is independently selected from the group consisting of alkylene, cycloalkylene, arylalkylene, heteroarylalkylene, heteroalkylene, heterocycloalkylene, alkenylene, cycloalkenylene, arylalkenylene, heteroarylalkenylene, heteroalkenylene, heterocycloalenkylene, alkynylene, heteroalkynylene, arylene, heteroarylene, aminoacyl, oxyalkylene, aminoalkylene, diacid ester, dialkylsiloxane, amide, thioamide, thioether, thioester, ester, carbamate, hydrazone, thiazolidine, methylene alkoxy carbamate, disulfide, vinylene, imine, imidamide, phosphoramide, saccharide, phosphate ester, phosphoramide, carbamate, dipeptide, tripeptide, tetrapeptide.

[0676]

[0677] 

[0678]

[0679]

[0680] wherein in each of the above structures:

[0681] each n is independently 0, 1, 2, 3, 4, 5, 6, 7, or 8;

[0682] each m is independently 0, 1, 2, 3, or 4;

[0683] each Rc, R^, and Reis independently selected from H, optionally substituted Cj.g alkyl, (C3 1 ) carbocyclyl)C _6 alkyl, (C^ ) () aryl)C _6 alkyl, ( ] ]() hctcrocyclyl)C|_ alkyl, C’2-6 alkenyl, C’2-6 alkynyl, and C’6- 1 ()ar> '- in cac'q°f which optionally one or more of the carbon atoms can be replaced by heteroatoms; preferably selected from side-chain residues of proteinogenic or a non-proteinogenic amino acids;

[0684] each occurrence of R and R’ is independently H or selected from Cj.g-alkyl, O(C j.g alkyl), S(C j.g-alkyl), C3.10 cycloalkyl, O(C'3_ 10 cycloalkyl), S(C’3_|() cycloalkyl), C2-6 alkenyl, C2-6 alkynyl, Gj. g heteroalkenyl,

[0685]

[0686] heteroalkynyl, €3.10 cycloalkenyl, C | > 10 cycloheteroalkenyl, Cg.^o aryl, Cj.

[0687] 10 heteroaryl, (Cg.jo aryl)C j.g alkyl and (C |_ | Q heteroary^Cj.g alkyl, each of which can be optionally substituted with from 1 to 3 substituents selected from Cj.g-alkyl, OH, oxo and halogen, or from OH, oxo and halogen.

[0688] each * represents a point of attachment for which the shortest path to a moiety R'-Y- or R1- comprises less atoms than that for •; and each • represents a point of attachment for which the shortest path to a moiety C comprises less atoms than that for *, with the proviso that when n is > 1 and a respective point of attachment is indicated on any one of Rc, R^ and Re, then it can be independently present in one or more of the peptide monomeric units; preferably in one peptide monomeric unit most distant from the other point of attachment indicated in the respective structure.(e) represented by a structure selected from:

[0689] single bond, (B$)x.

[0690]

[0691] , and,

[0692] each n is independently 0, 1, 2, 3, 4, 5, 6, 7, or 8;

[0693] each m is independently 0, 1, 2, 3, or 4;

[0694] each Rc, Rd, and Reis independently selected from H, optionally substituted

[0695]

[0696] alkyl, (C3-10 carbocyclyl)C _6 alkyl, (C^ l () aryl)C|_ alkyl, ( ] ]() hctcrocyclyl)C|_ alkyl, C’2-6 alkenyl, C’2-6 alkynyl, and C’6- 1 ()ar> '- in cac'q°f which optionally one or more of the carbon atoms can be replaced by heteroatoms; preferably selected from side-chain residues of proteinogenic or a non-proteinogenicamino acids;

[0697] each occurrence of R and R’ is independently H or selected from C ^.g-alkyl, O(C |~o alkyl), S(C _g- alkyl), C3.10 cycloalkyl, O(C’3_|() cycloalkyl), S(C’3_|() cycloalkyl), C2-6 alkenyl, C2-6 alkynyl, Cj_ g heteroalkenyl, C _g heteroalkynyl, €3.10 cycloalkenyl, C | > 10 cycloheteroalkenyl, C’o-|oar\'- Cl- 10 heteroaryl, (Cg.io aryl)C |_o alkyl and (C ]_ ] Q hctcroaryl)C |~o alkyl, each of which can be optionally substituted with from 1 to 3 substituents selected from Cj.g-alkyl, OH, oxo and halogen, or from OH, oxo and halogen;

[0698] wherein each of AA3, AA4, AA5, AAg, AA7, and AAg represents a proteinogenic or non- proteinogenic amino acid, or is absent;

[0699] wherein preferably:

[0700] each proteinogenic or non-proteinogenic amino acid is preferably independently represented by one of the following structures:

[0701] RcR' RcReRc

[0702]

[0703] and / or AA4 is an amino acid with a charged sidechain, and AA7 is an amino acid with an aliphatic sidechain;

[0704] wherein more preferably:

[0705] AA3 is selected from Asp, Glu, and Lys, or is absent; preferably Asp;

[0706] AA4 is selected from Arg, HomoArg, Lys, Asp, and Glu, or is absent; preferably Lys or Arg;

[0707] AA5 is selected from Asp, Glu, and Lys; preferably Asp;

[0708] AAg is selected from Cys, Lys, Gly and Vai; preferably Cys or Lys;

[0709] AA7 is selected from Gly, Ala, Vai, Arg, He, Pro; preferably Gly or Vai; and

[0710] AAg is selected from Pro and citrulline (Cit); preferably Pro

[0711] even more preferably according to one of the sequences shown in the below table:

[0712] AA3 AA4 AA5 AAg AA7 AA3 AA3 AA4 AA5 AAg AA7 AA3

[0713] Lys —

[0714] Asp Arg Asp Cys Asp Lys Asp Cys Ala Pro Asp Arg Asp Gly Asp Lys Asp Cys Ala Vai Asp Lys Asp Lys Asp Lys Asp Cys Arg Pro Asp Lys Asp Vai - Asp Lys Asp Cys Gly Pro Asp Arg Asp Cys Vai Ala Asp Lys Asp Cys lie Pro

[0715]

[0716] Asp Arg Asp Cys Vai Cit Asp Lys Asp Cys Pro ProAsp Homo Arg Asp Cys Vai Cit Asp Lys Asp Cys Vai Cit Asp Lys Asp Cys any AA Pro Asp Lys Asp Cys Vai Pro any AA Pro — any AA Cit Gly Pro Vai Cit

[0717]

[0718] Vai Pro

[0719] Embodiment 28. The compound according to any one of the preceding embodiments, wherein B is selected from:

[0720] a. bond

[0721] b. Asp-Lys-Asp-Cys-MaleimidoCaproyl

[0722]

[0723] NH2

[0724] c. Asp-Arg-Asp-Lys-Succinic

[0725]

[0726] d. PEG

[0727]

[0728] o

[0729] Embodiment 29. The compound according to any one of the preceding embodiments, wherein one or more C is independently:

[0730] a. a cleavable linker selected from:

[0731] i

[0732]

[0733] . GlyPro:ii. ValCit:

[0734] v. Disulfide:

[0735] v. Disulfide:

[0736]

[0737] v

[0738]

[0739] iii. AlaAlaAsn:

[0740] b. a non-cleavable linker selected from:

[0741] n = 1 to 8, preferably 2 to 6

[0742]

[0743] xiii. MCC (maleimidomethyl cyclohexane- 1 -carboxylate):

[0744]

[0745]

[0746] Embodiment 30. The compound according to any one of the preceding embodiments, wherein one ormore D is a self-immolative spacer independently selected from:

[0747]

[0748] Embodiment 31. The compound according to any one of the preceding embodiments, wherein the fragment -B-C-D- has a structure selected from those below, wherein all variables are as defined hereinabove:

[0749]

[0750]

[0751] 

[0752]

[0753]

[0754] Embodiment 32. A compound having the following structure II:

[0755]

[0756] its individual diastereoisomers, its hydrates, its solvates, its crystal forms, its individual tautomers or a pharmaceutically acceptable salt thereof, wherein:

[0757] Z is selected from C2-5alkynyl, C1-5alkenyl, C1-5alkyl, and (C1-2alkyl)C6-10aryl;

[0758] U is selected from O, NH, N(C1-3 alkyl), S, CH2, and CH(C1-3 alkyl);

[0759] W is selected from C1-10 alkyl, C2-10 alkenyl, (C2-6alkyl)NHC(=O)(Ci-6 alkyl), (C2-6alkyl)NHC(=O)(Ci- 6 alkyl)O, (C2-10 alkyl)O, (C2-10 alkenyl)O, (C2-6 alkyl)O(C2-6 alkyl), (C2-6alkyl)O(C2-6 alkyl)O, (C2- 10 alkyl)NH, (C2-10 alkenyl)NH, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)NH and (C2-6alkyl)O(C2-6 alkyl)NH; each optionally substituted with one or more substituents preferably selected from C1-3 alkyl and (C1-3 alkyl)O;

[0760] X is selected from CH, N, and S;

[0761] Y is selected from CH and N, or is absent;

[0762] R is selected from H, C1-3 alkyl, C1-3 haloalkyl, and C1-3 heteroalkyl;

[0763] R1is selected from C1-8 alkyl, C2-8 cycloalkyl, (C3-6 cycloalkyl)C1-3 alkyl, C1-7 heteroalkyl, C2-7 cycloheteroalkyl, -C(=O)NH(C1-3 alkyl), -C1-3 alkyl(C=O)OMe, -C(=O)NH(C2-8 cycloalkyl), (C2-7cycloheteroaryl)Ci-3 alkyl and (Cg-io aryl)Ci-3 alkyl; each optionally substituted with one or more substituent(s) preferably selected from OH, CH3, OMe, CN, -C(=O)Me, F2CH, SO2Me, and halogen; R2and R3are each independently selected from H and a substituent, preferably a substituent selected from C1-3 haloalkyl, C1-3 heteroalkyl, and A-B-(C)c-(D)d^ as defined in any one of the preceding embodiments.

[0764] Embodiment 33. The compound according to embodiment 32, wherein the compound structure is represented by the following Formula Il-a:

[0765]

[0766] Il-a

[0767] wherein Zais selected from C2-5alkynyl, C2-5alkenyl, and C2-5alkyl.

[0768] Embodiment 34. The compound according to embodiment 32 or 33, wherein the compound structure is represented by the following Formula Il-al:

[0769]

[0770] wherein, Zalis C3alkynyl; U1-W1is selected from:

[0771] O'

[0772]

[0773] Embodiment 35. The compound according to any of embodiments 32 to 34, wherein the compound structure is represented by one or more of Formulae II -al', II -al" and II-al'" below:

[0774]

[0775] Embodiment 36. The compound according to embodiment 32 or 33, wherein the compound structure is represented by the following Formula II-a2:

[0776]

[0777] wherein Za2 is C4-5 alkyl; U2-W1 is selected from:

[0778]

[0779] Embodiment 37. The compound according to embodiment 36, wherein the compound structure is represented by one or more of Formulae II-a2', II-a2" and II-a2'" below:

[0780]

[0781] Embodiment 38. The compound according to any of embodiments 32-37, wherein X and Y are defined as in embodiment 8.

[0782] Embodiment 39. The compound according to any of embodiments 32-37, wherein R1is defined as in embodiment 9.

[0783] Embodiment 40. The compound according to any one of the preceding embodiments for use in the treatment of a disease.

[0784] Embodiment 41. The compound according to any one of embodiments 1-41 for use in the treatment of a disease characterized by overexpression of ACP3.

[0785] Embodiment 42. The compound for use according to embodiment 40 or 41, wherein the disease is cancer.

[0786] Embodiment 43. The compound for use according to any one of embodiment 42, wherein the cancer is characterized by ACP3 overexpression; preferably prostate cancer; more preferably a cancer selected from prostate adenocarcinoma, ductal prostate cancer, ductal adenocarcinoma, clear cell adenocarcinoma, acinar adenocarcinoma, urothelial cancer, neuroendocrine prostate cancer, small cell prostate cancer, or multiple myeloma.

Claims

CLAIMS1. A compound having the following structure:A - B — (-C-)- (-D-) — Ec dIor a pharmaceutically acceptable salt, solvate, hydrate, crystal form, tautomer, or diastereoisomer thereof,wherein:A is a tumor-targeting moiety having a molecular weight of 3000 Da or less, and is an PSMA-binding moiety;B is a spacer;C is a cleavable or non-cleavable linker;D is a self-immolative spacer;E is a TLR7 agonist moiety; andc and d may each be 0 or an integer of 1 or more; preferably 0, 1, 2 or 3;wherein optionally each occurrence of B, C, and D may be in any order.

2. The compound according to claim 1, wherein the compound structure is represented by the following Formula I':A - B — (-C-)- (-D-) — E'c drwherein E' is or comprises a structure derived by removing at least one H atom or R group in the following general formula:wherein:Z is selected from C2-5 alkynyl, C1-5 alkenyl, C1-5 alkyl, and (C1-2 alkyl)C6-ioaryl;U is selected from O, NH, N(C1-3 alkyl), S, CH2, and CH(C1-3 alkyl);W is selected from C1-10 alkyl, C2-10 alkenyl, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl), (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)O, (C2-10 alkyl)O, (C2-10 alkenyl)O, (C2-6 alkyl)O(C2-6 alkyl), (C2-6alkyl)O(C2-6 alkyl)O,(C2-10 alkyl)NH, (C2-10 alkenyl)NH, (C2-6 alkyl)NHC(=O)(Ci-6 alkyl)NH, and (C2-6 alkyl)O(C2-6 alkyl)NH; each optionally substituted with one or more substituents, preferably selected from C1-3 alkyl and (C1-3 alkyl)O;X is selected from CH, N, and S;Y is selected from CH and N, or is absent;R is selected from H, C1-3 alkyl, C1-3 haloalkyl, and C1-3 heteroalkyl;R1is selected from C1-8 alkyl, C2-8 cycloalkyl, (C3-6cycloalkyl)C1-3 alkyl, C1-7 heteroalkyl, C2-7 cycloheteroalkyl, -C(=O)NH(C1-3 alkyl), -C1-3 alkyl(C=O)OMe, -C(=O)NH(C2-8 cycloalkyl), (C2-7 cycloheteroaryl)Ci-3 alkyl and (Cg-io aryl)Ci-3 alkyl; each optionally substituted with one or more substituent(s) preferably selected from OH, CH3, OMe, CN, -C(=O)Me, F2CH, SO2Me, and halogen. The compound according to claim 1 or 2, wherein the compound structure is represented by one or more of Formulae I-al and I-cl:A - B - (-C-W-D-) - E-a1I-alA - B - f-c — (-D-) - E-c1I-clwherein each of E-al and E-cl is or comprises, respectively, a structure of Formula E-al or E-cl:E-al E-clwherein Zal is C3 alkynyl; U1-W1 is selected from:

4. The compound according to any of the preceding claims, wherein the compound structure is represented by one or more of Formulae Lal', Lal", Lal'", Lcl', I-cl", and I-cl'":A - B (-C-)- (-D-) - E-a11Lal'A - B - - E-a1 "Lal"A - B - - E-a1 ■"Lal'"A - B (-C-)- (-D-) - E-c11Lcl'A - B (-C-)- (-D-) E-c1 ”Lcl"E-cT"Lcl'"wherein each of E-al', E-al", E-al'", E-cl', E-cl", and E-cl'" is or comprises, respectively, a structure of Formula E-al', E-al", E-al'", E-cl', E-cl", or E-cl'":E-aTE-a1" E-a15. The compound according to any one of claims 2 to 4, wherein:X = CH and Y = CH, or X = N and Y = CH, or X = CH and Y = N, or X = N and Y =N, or X = S and Y is absent; andR1is selected from the group consisting of:

6. The compound according to any of claims 1 to 5 having a structure represented by the following formula:A - B — (-C-)- (-D-) — M B357c dI-MB357wherein MB357 is or comprises a structure derived by removing at least one H atom in the following formula:

7. The compound according to any one of the preceding claims, wherein A is:- an ACP3-binding moiety comprising the structure:

8. The compound according to any one of the preceding claims, wherein:- B is:a. a single bond or an optionally substituted C1-50 aliphatic group, in which optionally one or more carbon atoms can be replaced by heteroatom, a C3-42 carbocyclic or a heterocyclic group, and which can be saturated or optionally contain one or more double or triple bonds;- one or more C is independently:a. a cleavable linker selected from:i. GlyPro:orb. a non-cleavable linker selected from:- one or more D is a self-immolative spacer independently selected from:

9. The compound for use according to any one of the preceding claims for use in the treatment of cancer.

10. The compound for use according to claim 9, wherein the cancer is characterized by ACP3 overexpression; preferably prostate cancer; more preferably a cancer selected from prostate adenocarcinoma, ductal prostate cancer, ductal adenocarcinoma, clear cell adenocarcinoma, acinar adenocarcinoma, urothelial cancer, neuroendocrine prostate cancer, small cell prostate cancer, or multiple myeloma.

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