EP4694941A1 - Radiotherapeutic conjugates for treating cancer - Google Patents

Abstract

The present disclosure relates to methods for treating cancer, comprising administering to the patient a agent comprising a targeting component coupled to a cancer therapeutic component.

Description

RADIOTHERAPEUTIC CONJUGATES FOR TREATING CANCER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Patent Application Serial No. 63/495,642, filed April 12, 2023, the contents of which are incorporated herein by reference in its entirety.

REFERENCE TO SEQUENCE LISTING

[0002] The contents of the electronic sequence listing (Filename: CNTH_007_01WO_SeqList_ST26.xml; Size: 38,665 bytes; and Date of Creation: April 9, 2024) are herein incorporated by reference in its entirety.

BACKGROUND

[0003] Prostate cancer (PC) is a significant health burden, with 180,890 new diagnoses and 26,120 deaths in the United States in 2016. Despite advances in diagnostic technology and treatment strategies, up to 40% of patients treated with primary therapy with curative intent will experience disease progression. PC deaths are typically the result of metastatic castration-resistant prostate cancer (mCRPC), and historically the median survival for men with mCRPC has been less than two years. Metastatic castration-resistant prostate cancer (mCRPC) poses a particular clinical challenge in need of additional therapeutic approaches beyond classic androgen deprivation therapies. Chemotherapy compounds docetaxel and cabazitaxel, the androgen receptor signaling inhibitor enzalutamide, CYP-17-inhibitor abiraterone, autologous cellular immunotherapy with sipuleucel-T, and the bone-seeking a-emitter ²²³Ra have shown improved overall survival (OS) and most have demonstrated quality of life advantages as well. However, these agents have been tested in multiple disease states of CRPC to determine if or when patients might benefit from each treatment, and in all cases, however, these now established therapies become ineffective in controlling tumor progression over time.

[0004] Prostate-specific membrane antigen (PSMA) is a cell surface marker which can be over-expressed in malignant prostate tissues when compared to other organs in the human body such as kidney, proximal small intestine, and salivary glands, and is present and enriched in 75-95% of metastatic castration-resistant prostate cancer (mCRPC). PSMA is also expressed on the neovasculature within many non-prostate solid tumors, including lung cancer, colon cancer, breast cancer, renal cancer, liver cancer, pancreatic cancer, thyroid cancer, transitional cell carcinoma of the bladder, neuroendocrine carcinoma, glioblastoma multiforme, melanoma, and non-soft tissue sarcoma, but not on normal vasculature.

[0005] New therapies are urgently needed in order to treat cancers, including PSMA expressing cancers such as prostate cancer.

[0006] The present invention is directed to overcoming these and other deficiencies in the art.

SUMMARY

[0007] In an aspect, the present disclosure relates to methods of treating cancer by administering an agent comprising a targeting component coupled to a cancer therapeutic component, to a subject having cancer, to treat the cancer.

[0008] In embodiments, provided herein are methods of treating cancer by administering an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the patient received prior treatment with a PSMA radioligand, such as PSMA I&T- Lu¹⁷⁷ or PSMA 617-Lu¹⁷⁷. In another specific embodiment, the cancer is relapsed and/or refractory or resistant to a PSMA radioligand, such as PSMA I&T-Lu¹⁷⁷ or PSMA 617-Lu¹⁷⁷. In embodiments, provided herein are methods of of treating or ameliorating prostate cancer in a patient in need thereof, comprising administering to the patient an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the patient has not received, or does not require, a PSMA PET scan prior to treatment.

[0009] In embodiments, the present disclosure provides methods of treating cancer in a patient in need thereof, comprising administering to the patient: an initial dose and a subsequent dose of an agent comprising a targeting component coupled to a cancer therapeutic component; wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the cumulative amount of the agent administered in the initial dose and the subsequent dose is in the range of about 90 KBq/Kg to about 130 KBq/Kg. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 shows the best PSA response (Best % change in PSA) per subject after a fractional dose regimen at 45 KBq/Kg does level, a 50 KBq/Kg dose level, a 55 KBq/Kg dose level, a 60 KBq/Kg dose level, or a 65 KBq/Kg dose level.

[0011] FIG. 2 shows the best PSA response (Best % change in PSA) per subject after a multiple dose regimen at 45 KBq/Kg dose level, a 55 KBq/Kg dose level, or a 65 KBq/Kg dose level.

DEFINITIONS

[0012] Listed below are definitions of various terms used in the specification and claims to describe the present disclosure. Unless defined otherwise, all technical and scientific terms used in this disclosure have the same meanings as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0013] Throughout the present specification, the terms “about” and/or “approximately” may be used in conjunction with numerical values and/or ranges. The term “about” is understood to mean those values near to a recited value. Furthermore, the phrases “less than about [a value]” or “greater than about [a value]” should be understood in view of the definition of the term “about” provided herein. The terms “about” and “approximately” may be used interchangeably.

[0014] Throughout the present specification, numerical ranges are provided for certain quantities. It is to be understood that these ranges comprise all subranges therein. Thus, the range “from 50 to 80” includes all possible ranges therein (e.g., 51-79, 52-78, 53-77, 54-76, 55-75, 60- 70, etc.). Furthermore, all values within a given range may be an endpoint for the range encompassed thereby (e.g., the range 50-80 includes the ranges with endpoints such as 55-80, 50-75, etc.).

[0015] As used herein, the verb “comprise” as is used in this description and in the claims and its conjugations are used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. The present invention may suitably “comprise”, “consist of’, or “consist essentially of’, the steps, elements, and/or reagents described in the claims.

[0016] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely", "only" and the like in connection with the recitation of claim elements, or the use of a "negative" limitation.

[0017] As used herein, the term “treating” means one or more of relieving, alleviating, delaying, reducing, improving, or managing at least one symptom of a condition in a subject. The term "treating" may also mean one or more of arresting, delaying the onset (i.e., the period prior to clinical manifestation of the condition) or reducing the risk of developing or worsening a condition.

[0018] An “effective amount” means the amount of a formulation according to the invention that, when administered to a patient for treating a state, disorder or condition is sufficient to affect such treatment. The “effective amount” will vary depending on the active ingredient, the state, disorder, or condition to be treated and its severity, and the age, weight, physical condition, and responsiveness of the mammal to be treated.

[0019] The term “therapeutically effective” applied to dose or amount refers to that quantity of a compound or pharmaceutical formulation that is sufficient to result in a desired clinical benefit after administration to a patient in need thereof.

[0020] The term “relapsed” refers to a situation where, after therapy, patients who have had a remission of cancer have a return of cancer cells.

[0021] The term “refractory or resistant” refers to a circumstance where patients, even after treatment, have residual cancer cells in their body.

[0022] As used herein, the term “cancer” includes all types of cancerous growths or oncogenic processes, metastatic tissues or malignantly transformed cells, tissues, or organs, irrespective of histopathologic type or stage of invasiveness.

[0023] As used herein, the “targeting component” is a component that is able to bind to or otherwise associate with a molecular target, for example, a membrane component, a cell surface receptor, prostate specific membrane antigen (PSMA, which is also known as folate hydrolase 1, glutamate carboxypeptidase II, and NAALADase), or the like. A agent comprising the targeting component may become localized at a particular targeted site, for instance, a tumor, a disease site, a tissue, an organ, a type of cell, etc. As such the agent may be “target-specific”. In some cases, the therapeutic agent may exert its anti -cancer effect without the need for release from the targeting component. In other cases, the therapeutic component may be released from the agent and allowed to interact locally with the particular targeting site. [0024] As used herein, the “cancer therapeutic component” is an agent, or combination of agents, that treats a cell, tissue, or subject having a condition requiring therapy, when contacted with the cell, tissue or subject. The first and second cancer therapeutic components may be the same or different, and may be, for example, therapeutic radionuclides, chemotherapeutic agents, hormones, hormone antagonists, receptor antagonists, enzymes or proenzymes activated by another agent, biologies, autocrines or cytokines. Toxins also can be used in the methods of the present invention. Other therapeutic agents useful in the present invention include anti-DNA, anti-RNA, radiolabeled oligonucleotides, such as anti-sense oligodeoxy ribonucleotides, anti-protein and anti -chromatin cytotoxic or antimicrobial agents. Other therapeutic agents are known to those skilled in the art, and the use of such other therapeutic agents in accordance with the present invention is specifically contemplated.

[0025] As used herein, “PSMA” or "prostate-specific membrane antigen" protein refers to mammalian PSMA, preferably human PSMA protein. The long transcript of PSMA encodes a protein product of about 100-120 kDa molecular weight characterized as a type II transmembrane receptor having sequence homology with the transferrin receptor and having NAALADase activity (Carter et al., "Prostate-Specific Membrane Antigen is a Hydrolase With Substrate and Pharmacologic Characteristics of a Neuropeptidase," Proc. Natl. Acad Sci. USA 93:749-753 (1996), which is hereby incorporated by reference in its entirety). (UniProtKB- Q04609 (FOLH1 HUMAN), Isoform I, set forth in SEQ ID NO: 1).

[0026] As used herein, “Radioligand” is a radioactive chemical or biochemical species such as a ligand that is radiolabeled (for example, with ¹⁷⁷Lutetium), and can be used for diagnostics or therapeutic purposes. Radioligand can bind to a specific target or antigen. For example, a “PSMA radioligand” refers to a radiolabeled ligand that binds to or has a high affinity for PSMA. The ligand can be radiolabeled by methods known in the art, including the use of various linkers and chelators that bind to a specific radioisotope.

[0027] The term “antibody” is intended to refer to an immunoglobulin molecule, a fragment of an immunoglobulin molecule, or a derivative of either thereof, which has the ability to specifically bind to an antigen under typical physiological conditions. As used herein, the term encompasses intact polyclonal or monoclonal antibodies and antigen-binding fragments thereof.

[0028] The term “subject” or “patient” as used herein refers to humans and other primates, including non-human primates such as chimpanzees and other apes and monkey species. [0029] The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed inventions, or that any publication specifically or implicitly referenced is prior art.

DETAILED DESCRIPTION

[0030] Throughout this disclosure, various patents, patent applications and publications are referenced. The disclosures of these patents, patent applications and publications in their entireties are incorporated into this disclosure by reference for all purposes in order to more fully describe the state of the art as known to those skilled therein as of the date of this disclosure.

This disclosure will govern in the instance that there is any inconsistency between the patents, patent applications and publications cited and this disclosure.

Therapeutic Agent

[0031] In embodiments, the agent used in the methods disclosed herein, is an agent comprising a targeting component (e.g., as described herein) coupled to a cancer therapeutic component (e.g., as described herein). In one embodiment, the agent is an antibody conjugated to a radionuclide. In one embodiment, the antibody is a PSMA-targeted antibody. In a specific embodiment, the PSMA-targeted antibody is huJ591 comprising SEQ ID NOs: 38 and 39. In embodiments, the radionuclide is ¹⁷⁷Lu or ²²⁵ Ac. In one embodiment, the agent is ²²⁵Ac-DOTA-huJ591 mAb. In a specific embodiment, huJ591 is as described in U.S. Patent No. 7,045,605, and PCT application publication WO2018/204477, which are hereby incorporated by reference in its entirety.

Targeting Component

[0032] In embodiments, the targeting component is independently selected from the group consisting of an antibody or binding fragment thereof.

[0033] Antibodies against molecular targets on tumors are known. For example, antibodies and antibody fragments which specifically bind markers produced by or associated with tumors have been disclosed, inter alia, in U.S. Patent No. 3,927,193 to Hansen, and U.S. Patent Nos. 4,331,647, 4,348,376, 4,361,544, 4,468,457, 4,444,744, 4,818,709 and 4,624,846 to Goldenberg, the contents of all of which are incorporated herein by reference in their entirety. In particular, antibodies against an antigen, e.g., a gastrointestinal, lung, breast, prostate, ovarian, testicular, brain or lymphatic tumor, a sarcoma or a melanoma, are advantageously used. Antibodies to cancer-related antigens are well known to those in the art.

[0034] The antibodies of the present invention may exist in a variety of forms including, for example, polyclonal antibodies, monoclonal antibodies, intracellular antibodies ("intrabodies"), antibody fragments (e.g. Fv, Fab and F(ab )2), half-antibodies, hybrid derivatives, as well as single chain antibodies (scFv), chimeric antibodies and humanized antibodies (Ed Harlow and David Lane, USING ANTIBODIES: A LABORATORY MANUAL (Cold Spring Harbor Laboratory Press, 1999); Houston et al., "Protein Engineering of Antibody Binding Sites: Recovery of Specific Activity in an Anti-Digoxin Single-Chain Fv Analogue Produced in Escherichia coli," Proc. Natl. Acad Sci. USA 85:5879-5883 (1988); Bird et al, "Single-Chain Antigen-Binding Proteins," Science 242:423-426 (1988), each of which is hereby incorporated by reference in its entirety).

[0035] Antibodies of the present invention may also be synthetic antibodies. A synthetic antibody is an antibody which is generated using recombinant DNA technology, such as, for example, an antibody expressed by a bacteriophage. Alternatively, the synthetic antibody is generated by the synthesis of a DNA molecule encoding and expressing the antibody of the present invention or the synthesis of an amino acid sequence specifying the antibody, where the DNA or amino acid sequence has been obtained using synthetic DNA or amino acid sequence technology which is available and well known in the art.

[0036] Methods for monoclonal antibody production may be carried out using the techniques described herein or are well-known in the art (MONOCLONAL ANTIBODIES PRODUCTION, ENGINEERING AND CLINICAL APPLICATIONS (Mary A Ritter and Heather M. Ladyman eds., 1995), which is hereby incorporated by reference in its entirety). Generally, the process involves obtaining immune cells (lymphocytes) from the spleen of a mammal which has been previously immunized with the antigen of interest either in vivo or in vitro.

[0037] Alternatively monoclonal antibodies can be made using recombinant DNA methods as described in U.S. Patent No. 4,816,567 to Cabilly et al., which is hereby incorporated by reference in its entirety. The polynucleotides encoding a monoclonal antibody are isolated from mature B-cells or hybridoma cells, for example, by RT-PCR using oligonucleotide primers that specifically amplify the genes encoding the heavy and light chains of the antibody. The isolated polynucleotides encoding the heavy and light chains are then cloned into suitable expression vectors, which when transfected into host cells such as E. coli cells, simian COS cells, Chinese hamster ovary (CHO) cells, or myeloma cells that do not otherwise produce immunoglobulin protein, monoclonal antibodies are generated by the host cells. Also, recombinant monoclonal antibodies or fragments thereof of the desired species can be isolated from phage display libraries (McCafferty et al., "Phage Antibodies: Filamentous Phage Displaying Antibody Variable Domains," Nature 348:552-554 (1990); Clackson et al., "Making Antibody Fragments using Phage Display Libraries," Nature 352:624-628 (1991); and Marks et al., "By-Passing Immunization. Human Antibodies from V-Gene Libraries Displayed on Phage," J Mai. Biol. 222:581-597 (1991), which are hereby incorporated by reference in their entirety).

[0038] The polynucleotide(s) encoding a monoclonal antibody can further be modified using recombinant DNA technology to generate alternative antibodies. For example, the constant domains of the light and heavy chains of a mouse monoclonal antibody can be substituted for those regions of a human antibody to generate a chimeric antibody. Alternatively, the constant domains of the light and heavy chains of a mouse monoclonal antibody can be substituted for non-immunoglobulin polypeptide to generate a fusion antibody. In other embodiments, the constant regions are truncated or removed to generate the desired antibody fragment of a monoclonal antibody. Furthermore, site-directed or high-density mutagenesis of the variable region can be used to optimize specificity and affinity of a monoclonal antibody.

[0039] The monoclonal antibody of the present invention can be a humanized antibody. Humanized antibodies are antibodies that contain minimal sequences from non-human (e.g., murine) antibodies within the variable regions. Such antibodies are used therapeutically to reduce antigenicity and human anti-mouse antibody responses when administered to a human subject. In practice, humanized antibodies are typically human antibodies with minimal to no non-human sequences. A human antibody is an antibody produced by a human or an antibody having an amino acid sequence corresponding to an antibody produced by a human.

[0040] In addition to whole antibodies, the present invention encompasses binding portions of such antibodies. Such binding portions include the monovalent Fab fragments, Fv fragments (e.g., single-chain antibody, scFv), and single variable VH and VL domains, and the bivalent F(ab')2 fragments, Bis-scFv, diabodies, triabodies, minibodies, etc. These antibody fragments can be made by conventional procedures, such as proteolytic fragmentation procedures, as described in James Goding, MONOCLONAL ANTIBODIES PRINCIPLES AND PRACTICE 98-118 (Academic Press, 1983) and Ed Harlow and David Lane, ANTIBODIES: A LABORATORY MANUAL (Cold Spring Harbor Laboratory, 1988), which are hereby incorporated by reference in their entirety, or other methods known in the art. [0041] It may further be desirable, especially in the case of antibody fragments, to modify the antibody in order to increase its serum half-life. This can be achieved, for example, by incorporation of a salvage receptor binding epitope into the antibody fragment by mutation of the appropriate region in the antibody fragment or by incorporating the epitope into a peptide tag that is then fused to the antibody fragment at either end or in the middle (e.g., by DNA or peptide synthesis).

[0042] Antibody mimics are also suitable for use in accordance with the present invention. A number of antibody mimics are known in the art including, without limitation, those known as monobodies, which are derived from the tenth human fibronectin type III domain (10Fn3) (Koide et al., "The Fibronectin Type III Domain as a Scaffold for Novel Binding Proteins," J Mai. Biol. 284: 1141-1151 (1998); Koide et al., "Probing Protein Conformational Changes in Living Cells by Using Designer Binding Proteins: Application to the Estrogen Receptor," Proc. Natl. Acad Sci. USA 99: 1253-1258 (2002), each of which is hereby incorporated by reference in its entirety); and those known as affibodies, which are derived from the stable alpha-helical bacterial receptor domain Z of staphylococcal protein A (Nord et al., "Binding Proteins Selected from Combinatorial Libraries of an alpha-helical Bacterial Receptor Domain," Nature Biotechnol. 15(8):772-777 (1997), which is hereby incorporated by reference in its entirety).

[0043] In embodiments, the targeting component is a PSMA receptor antibody.

[0044] In embodiments, the targeting components may bind to a receptor (e.g. PSMA). A

PSMA receptor antibody is an antibody that interacts with (e.g., binds to) PSMA, preferably human PSMA protein. Preferably, the PSMA receptor antibody interacts with, e.g., binds to, the extracellular domain of PSMA, e.g., the extracellular domain of human PSMA located at about amino acids 44-750 of human PSMA (amino acid residues correspond to the human PSMA sequence disclosed in U.S. Patent No. 5,538,866, which is hereby incorporated by reference in its entirety). PSMA receptor antibodies are known in the art (Goldsmith et al., "Targeted Radionuclide Therapy for Prostate Cancer," in Therapeutic Nuclear Medicine 617-628 (R. Baum ed. 2014), which is hereby incorporated by reference in its entirety). Exemplary PSMA receptor antibodies include, but are not limited to, J591, J415, J533, and E99 (SEQ ID NOs: 2-13).

[0045] In some embodiments, PSMA receptor antibody comprises the CDRs in any of the disclosed antibodies. In some embodiments, the CDRs are delineated by any numbering system known in the art, including AbM, Kabat, Chothia, and IMGT. In some embodiments, the PSMA receptor antibody comprises the CDRs disclosed in SEQ ID NOs: 14-37. In some embodiments, the PSMA receptor antibody comprises the CDRs disclosed in SEQ ID NOs: 14- 19. In some embodiments, the PSMA receptor antibody comprises the CDRs disclosed in SEQ ID NOs: 20-25. In some embodiments, the PSMA receptor antibody comprises the CDRs disclosed in SEQ ID NOs: 26-31. In some embodiments, the PSMA receptor antibody comprises the CDRs disclosed in SEQ ID NOs: 32-37.

[0046] In some embodiments, the PSMA receptor antibody comprises a variable heavy chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 2 or 10 and consists of CDR1 comprising SEQ ID NO: 14, CDR2 comprising SEQ ID NO: 15, and CDR3 comprising SEQ ID NO: 16. In some embodiments the PSMA receptor antibody variable heavy chain consists of SEQ ID NO: 2 or 10. In some embodiments, the PSMA receptor antibody comprises a variable light chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 3 or 11 and consists of CDR1 comprising SEQ ID NO: 17, CDR2 comprising SEQ ID NO: 18, and CDR3 comprising SEQ ID NO: 19. In some embodiments the PSMA receptor antibody variable light chain consists of SEQ ID NO: 3 or 11.

[0047] In some embodiments, the PSMA receptor antibody comprises a variable heavy chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 4 or 12 and consists of CDR1 comprising SEQ ID NO: 20, CDR2 comprising SEQ ID NO: 21, and CDR3 comprising SEQ ID NO: 22. In some embodiments the PSMA receptor antibody variable heavy chain consists of SEQ ID NO: 4 or 12. In some embodiments, the PSMA receptor antibody comprises a variable light chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 5 or 13 and consists of CDR1 comprising SEQ ID NO: 23, CDR2 comprising SEQ ID NO: 24, and CDR3 comprising SEQ ID NO: 25. In some embodiments the PSMA receptor antibody variable light chain consists of SEQ ID NO: 5 or 13.

[0048] In some embodiments, the PSMA receptor antibody comprises a variable heavy chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 6 and consists of CDR1 comprising SEQ ID NO: 26, CDR2 comprising SEQ ID NO: 27, and CDR3 comprising SEQ ID NO: 28. In some embodiments the PSMA receptor antibody variable heavy chain consists of SEQ ID NO: 6. In some embodiments, the PSMA receptor antibody comprises a variable light chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 7 and consists of CDR1 comprising SEQ ID NO: 29, CDR2 comprising SEQ ID NO: 30, and CDR3 comprising SEQ ID NO: 31. In some embodiments the PSMA receptor antibody variable light chain consists of SEQ ID NO: 7.

[0049] In some embodiments, the PSMA receptor antibody comprises a variable heavy chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 8 and consists of CDR1 comprising SEQ ID NO: 32, CDR2 comprising SEQ ID NO: 33, and CDR3 comprising SEQ ID NO: 34. In some embodiments the PSMA receptor antibody variable heavy chain consists of SEQ ID NO: 8. In some embodiments, the PSMA receptor antibody comprises a variable light chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 9 and consists of CDR1 comprising SEQ ID NO: 35, CDR2 comprising SEQ ID NO: 36, and CDR3 comprising SEQ ID NO: 37. In some embodiments the PSMA receptor antibody light chain consists of SEQ ID NO: 9.

[0050] In one embodiment, the PSMA receptor antibody is selected from the group consisting of J591, J415, J533, and E99.

[0051] In one embodiment, the PSMA receptor antibody variable chains comprise sequences selected from the group consisting of J591 (SEQ ID NOs: 2 and 3), deimmunized J591 (also referred to herein as “huJ591”) ( SEQ ID NOs: 10 and 11), J415 (SEQ ID NOs: 4 and 5), deimmunized J415 (SEQ ID NOs: 12 and 13), J533 (SEQ ID NOs: 6 and 7), and E99 (SEQ ID NOs: 8 and 9).

[0052] In one embodiment, the PSMA receptor antibody is J591, which comprises SEQ ID NOs: 2 and 3. In one embodiment, the PSMA receptor antibody is J415, which comprises SEQ ID NOs: 4 and 5. In one embodiment, the PSMA receptor antibody is J533, which comprises SEQ ID NOs: 6 and 7. In one embodiment, the PSMA receptor antibody is E99, which comprises SEQ ID NOs: 8 and 9. In one embodiment, the PSMA receptor antibody is deimmunized J591, which comprises SEQ ID NOs: 10 and 11. In one embodiment, the PSMA receptor antibody is deimmunized J451, which comprises SEQ ID NOs: 12 and 13. In some embodiments, the PSMA receptor antibody is disclosed in US 2010/0278726, which is herein incorporated it its entirety.

[0053] In some embodiments, the PSMA receptor antibody comprises a heavy chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 38. In some embodiments the PSMA receptor antibody heavy chain consists of SEQ ID NO: 38. In some embodiments, the PSMA receptor antibody comprises a light chain sequence that is at least 90%, at least 92%, at least 94%, at least 96%, at least 98%, or 100% similar to SEQ ID NO: 39. In some embodiments the PSMA receptor antibody light chain consists of SEQ ID NO: 39. In some embodiments the PSMA receptor antibody comprises or consists of SEQ ID NOs: 38 and 39. In some embodiments the PSMA receptor antibody comprises or consists of SEQ ID NO: 39.

[0054] EVQLVQSGPEVKKPGATVKISCKTSGYTFTEYTIHWVKQAPGKGLEWIGN INPNNGGTTYNQKFEDKATLTVDKSTDTAYMELSSLRSEDTAVYYCAAGWNFDYWGQ GTLLTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHT FPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPC PAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAK TKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQ VYTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLY SKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK (SEQ ID NO: 38).

[0055] By way of example, the PSMA receptor antibodies can be radiolabeled with l l llndium, 90Yttrium, or ¹⁷⁷Lutetium by coupling with 1,4,7, 10-tetraazacyclododecane- N,N’,N”,N”’-tetraacetic acid (DOTA) as described in U.S. Patent No. 7,045,605 to Bander, which is hereby incorporated by reference in its entirety.

Cancer Therapeutic component

[0056] In embodiments, the cancer therapeutic component may comprise a chemotherapeutic agent or a radionuclide. In embodiments, the cancer therapeutic component may comprise a chemotherapeutic agent. In embodiments, the cancer therapeutic component may comprise a radionuclide.

[0057] In embodiments, the cancer therapeutic component is a radionuclide independently selected from the group consisting of ¹⁸⁶Re, ⁹⁰Y, ⁶⁷ Cu, ¹⁶⁹Er, ¹²¹ Sn, ¹²⁷Te, ¹⁴²Pr, ¹⁹⁸Au, ¹⁹⁹ AU, ¹⁶¹Tb, ¹⁰⁹Pd, ¹⁸⁸Rh, ¹⁶⁶Dy, ¹⁶⁶Ho, ¹⁴⁹Pm, ¹⁵¹Pm, ¹⁵³Sm, ¹⁵⁹Gd, ¹⁷²Tm, ¹⁶⁹Yb, ¹⁷⁵Yb, ¹⁷⁷LU, ¹⁰⁵Rh, ^{n i}Ag, ¹³¹I, ^117mSn, ²²⁵ Ac, ²²⁷Th, ²¹¹At, ²¹²Pb and combinations thereof.

[0058] Procedures for labeling agents with radioactive isotopes are generally known in the art. For example, there are a wide range of moi eties which can serve as chelating ligands, and which can be derivatized to the targeting component of the invention. For instance, the chelating ligand can be a derivative of 1,4,7, 10-tetraazacyclododecanetetraacetic acid (DOTA), ethylenediaminetetraacetic acid (EDTA), di ethylenetriaminepentaacetic acid (DTP A), and 1- plsothiocyanato-benzyl-methyl-diethylenetriaminepentaacetic acid (ITC-MX). These chelators typically have groups on the side chain by which the chelator can be used for attachment to a targeting component of the present invention. Such groups include, e.g., benzylisothiocyanate, by which the DOTA, DTP A, or EDTA can be coupled to, e.g., an amine group of the targeting component. Procedures for iodinating biological agents, such as antibodies, binding portions thereof, probes, or ligands, are described by Hunter and Greenwood, “Preparation of Iodine-131 Labelled Human Growth Hormone of High Specific Activity,” Nature 144:496-496 (1962), David et al., “Protein Iodination With Solid State Lactoperoxidase,” Biochemistry 13: 1014- 1021 (1974), and U.S. Patent Nos. 3,867,517 to Ling and 4,376,110 to David, which are hereby incorporated by reference in their entirety. Other procedures for iodinating biological agents are described by Greenwood et al., “The Preparation ofl-131-Labelled Human Growth Hormone of High Specific Radioactivity,” Biochem. J 89: 114-123 (1963); Marchalonis, “An Enzymic Method for the Trace Iodination of Immunoglobulins and Other Proteins,” Biochem. J. 113 :299- 305 (1969); and Morrison et al., “Use of Lactoperoxidase Catalyzed Iodination in Immunochemical Studies,” Immunochemistry 8:289-297 (1971), which are hereby incorporated by reference in their entirety. Procedures for 99mTc-labeling are described by Rhodes, B. et al. in Burchiel, S. et al. (eds.), Tumor Imaging: The Radioimmunochemical Detection of Cancer, New York: Masson 111-123 (1982) and the references cited therein, which are hereby incorporated by reference in their entirety. Procedures suitable for 11 Hn-labeling biological agents are described by Hnatowich et al., “The Preparation of DTPA-coupled Antibodies Radiolabeled With Metallic Radionuclides: an Improved Method,” J Immul. Methods 65: 147- 157 (1983), Hnatowich et al., “Coupling Antibody With DTPA-an Alternative to the Cyclic Anhydride,” Int. J Applied Radiation 35:554-557 (1984), and Buckley et al., “An Efficient Method For Labelling Antibodies With 11 Hn,” F.E.B.S. 166:202-204 (1984), which are hereby incorporated by reference in their entirety.

[0059] In another embodiment, the cancer therapeutic component is a chemotherapeutic agent independently selected from the group consisting of busulfan, cisplatin, carboplatin, chlorambucil, cyclophosphamide, ifosfamide, dacarbazine (DTIC),mechlorethamine (nitrogen mustard), melphalan carmustine (BCNU), lomustine (CCNU), 5- fluorouracil (5-FU), capecitabine, methotrexate, gemcitabine, cytarabine (ara-C), fludarabine dactinomycin, daunorubicin, doxorubicin (Adriamycin), idarubicin, mitoxantrone, paclitaxel, docetaxel, etoposide (VP- 16), vinblastine, vincristine, vinorelbine prednisone, dexamethasone, tamoxifen, fulvestrant, anastrozole, letrozole, megestrol acetate, bicalutamide, flutamide, leuprolide, goserelin, L-asparaginase, tretinoin, maytansines, auristatins, pyrrolobenzodiazepines, duocarmycins, and combinations thereof. [0060] Procedures for conjugating biological agents with chemotherapeutic agents are well known in the art. Most of the chemotherapeutic agents currently in use in treating cancer possess functional groups that are amenable to chemical crosslinking directly with an amine or carboxyl group of a targeting component of the present invention. For example, free amino groups are available on methotrexate, doxorubicin, daunorubicin, cytosinarabinoside, cisplatin, vindesine, mitomycin, and bleomycin while free carboxylic acid groups are available on methotrexate, melphalan, and chlorambucil. These functional groups, that is free amino and carboxylic acids, are targets for a variety of homo-bifunctional and hetero-bifunctional chemical crosslinking agents which can crosslink these drugs directly to a free amino group of a targeting component. Specific procedures for conjugating targeting components with chemotherapeutic agents have been described and are known in the art. By way of example, conjugation of chlorambucil with antibodies is described by Flechner, “The Cure and Concomitant.

[0061] Immunization of Mice Bearing Ehrlich Ascites Tumors by Treatment With an Antibody — Alkylating Agent Complex,” European Journal of Cancer 9:741-745 (1973); Ghose et al., “Immunochemotherapy of Cancer with Chlorambucil-Carrying Antibody,” British Medical Journal 3 :495-499 (1972); and Szekerke et al., “The Use of Macromolecules as Carriers of Cytotoxic Groups (part II) Nitrogen Mustard — Protein Complexes,” Neoplasma 19:211-215 (1972), which are hereby incorporated by reference in their entirety. Procedures for conjugating daunomycin and adriamycin to antibodies are described by Hurwitz et al., “The Covalent Binding of Daunomycin and Adriamycin to Antibodies, With Retention of Both Drug and Antibody Activities,” Cancer Research 35: 1175-1181 (1975) and Arnon et al. Cancer Surveys 1 :429-449 (1982), which are hereby incorporated by reference in their entirety. Coupling procedures as also described in EP 86309516.2, which is hereby incorporated by reference in its entirety.

[0062] Pharmaceutical compositions containing agents for use in the methods of the present invention can include a pharmaceutically acceptable carrier as described infra, one or more active agents, and a suitable delivery vehicle.

[0063] The agents of the present invention may be orally administered, for example, with an inert diluent, or with an assimilable edible carrier, or it may be enclosed in hard or soft shell capsules, or it may be compressed into tablets, or they may be incorporated directly with the food of the diet. Agents of the present invention may also be administered in a time release manner incorporated within such devices as time-release capsules or nanotubes. Such devices afford flexibility relative to time and dosage. For oral therapeutic administration, the agents of the present invention may be incorporated with excipients and used in the form of tablets, capsules, elixirs, suspensions, syrups, and the like. Such compositions and preparations should contain at least 0.1 % of the agent, although lower concentrations may be effective and indeed optimal. The percentage of the agent in these compositions may, of course, be varied and may conveniently be between about 2% to about 60% of the weight of the unit. The amount of an agent of the present invention in such therapeutically useful compositions is such that a suitable dosage will be obtained.

[0064] When the agents of the present invention are administered parenterally, solutions or suspensions of the agent can be prepared in water and, in some cases, may be suitably mixed with a surfactant such as hydroxypropylcellulose. Dispersions can also be prepared in glycerol, liquid polyethylene glycols, and mixtures thereof in oils. Illustrative oils are those of petroleum, animal, vegetable, or synthetic origin, for example, peanut oil, soybean oil, or mineral oil. In general, water, saline, aqueous dextrose and related sugar solution, and glycols, such as propylene glycol or polyethylene glycol, are preferred liquid carriers, particularly for injectable solutions. Under ordinary conditions of storage and use, these preparations may contain a preservative to prevent the growth of microorganisms.

[0065] Pharmaceutical formulations suitable for injectable use include sterile aqueous solutions or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersions. In all cases, the form must be sterile and must be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms, such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (e.g., glycerol, propylene glycol, and liquid polyethylene glycol), suitable mixtures thereof, and vegetable oils.

[0066] When it is desirable to deliver the agents of the present invention systemically, they may be formulated for parenteral administration by injection, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain agents such as suspending, stabilizing and/or dispersing agents.

[0067] Intraperitoneal or intrathecal administration of the agents of the present invention can also be achieved using infusion pump devices. Such devices allow continuous infusion of desired compounds avoiding multiple injections and multiple manipulations. [0068] In addition to the formulations described previously, the agents may also be formulated as a depot preparation. Such long acting formulations may be formulated with suitable polymeric or hydrophobic materials (for example as an emulsion in an acceptable oil) or ion exchange resins, or as sparingly soluble derivatives, for example, as a sparingly soluble salt.

Therapeutic Use

[0069] In one embodiment, provided herein are methods of treating cancer by administering an agent comprising a targeting component (e.g., as described herein) coupled to a cancer therapeutic component (e.g., as described herein).

[0070] In embodiments, provided herein are methods of treating cancer in a patient in need thereof, comprising administering to the patient an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591 and the cancer therapeutic component is a radionuclide; and wherein the patient received prior treatment with at least one PSMA radioligand. In a specific embodiment, the PSMA radioligand is PSMA I&T-Lu¹⁷⁷ and/or PSMA 617-Lu¹⁷⁷. In a specific embodiment, the cancer is relapsed and/or refractory or resistant to at least one PSMA radioligand. In a specific embodiment, the PSMA radioligand is PSMA 617- Lu¹⁷⁷ and/or PSMA I&T-Lu¹⁷⁷.

[0071] In embodiments, provided herein are methods of treating cancer in a patient in need thereof, comprising administering to the patient an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the cancer is relapsed and/or refractory or resistant to at least one PSMA radioligand. In a specific embodiment, the PSMA radioligand is PSMA I&T-Lu¹⁷⁷ and/or PSMA 617-Lu¹⁷⁷.

[0072] In embodiments, the present disclosure provides methods of treating or ameliorating prostate cancer in a patient in need thereof, comprising administering to the patient a agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591 and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the patient has not received, or does not require, a PSMA PET scan prior to treatment.

[0073] In embodiments, the present disclosure provides methods of treating cancer in a patient in need thereof, comprising administering to the patient: an initial dose and at least one subsequent dose of an agent comprising a targeting component coupled to a cancer therapeutic component; wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the cumulative amount of the agent administered in the initial dose and the subsequent dose is in the range of about 90 KBq/Kg to about 130 KBq/Kg or about 180 KBq/Kg to about 340 KBq/Kg.

[0074] In certain embodiments, the cancer is prostate cancer, neuroendocrine cancer, breast cancer, or non-Hodgkin's lymphoma. In some embodiments, the cancer is a primary tumor, while in other embodiments, the cancer is a secondary or metastatic tumor. In embodiments of the present disclosure, the cancer is prostate cancer.

[0075] In embodiments, the cancer is a PSMA expressing cancer.

[0076] In embodiments, the cancer is breast cancer, prostate cancer, neuroendocrine cancer, non-Hodgkin's Lymphoma, colorectal cancer, lung cancer, endometrial and ovarian cancer, gastric cancer, renal cell cancer, urothelial cancer, hepatocellular, oral squamous cell cancer, thyroid cancer, glioblastoma, or adenoid cystic carcinoma.

[0077] In embodiments, the cancer is prostate cancer. In embodiments, when the cancer is prostate cancer, the targeting component targets the PSMA receptor. In embodiments, when the cancer is prostate cancer, the targeting component is an antibody to the PSMA receptor.

[0078] In embodiments, the prostate cancer is metastatic prostate cancer. In embodiments, when the cancer is metastatic prostate cancer, the targeting component targets the PSMA receptor. In embodiments, when the cancer is metastatic prostate cancer, the targeting component is a PSMA receptor antibody.

[0079] In embodiments, the prostate cancer is metastatic castration-resistant prostate cancer (mCRPC). In some embodiment, the prostate cancer is castration-sensitive prostate cancer. In embodiments, when the cancer is mCRPC, the targeting component targets the PSMA receptor. In embodiments, when the cancer is mCRPC, the targeting component is a PSMA receptor antibody. [0080] In some embodiments, the cancer is prostate-specific membrane antigen (PSMA)- positive metastatic castration-resistant prostate cancer (mCRPC) who have been treated with prior therapies e.g., androgen receptor (AR) pathway inhibition and/or taxane-based chemotherapy and/or anti-PSMA therapy. In another embodiment, the prostate cancer is castration-sensitive prostate cancer.

[0081] In some embodiments, the cancer is relapsed and/or refractory to prior treatment with a therapeutic agent comprising a second targeting component coupled to a second cancer therapeutic component (e.g., a cancer therapeutic component as described herein). In embodiments, the second targeting component is a PSMA receptor binding peptide or PSMA receptor inhibitor. The PSMA receptor inhibitor may include any lipids, carbohydrates, polynucleotides, peptides, polypeptides, or any other biologic, organic or inorganic molecules which bind the enzyme active site and inhibit the function of the PSMA receptor. Exemplary PSMA receptor inhibitor are known in the art include, but are not limited to, PSMA 617, PSMA I&T, ¹⁷⁷LU-J591, DCFBC, DCFPyL, glutamate-urea-lysine analogs, phosphoramidate analogs, and 2-(phosphinylmethyl) pentanedioic acid analogs (Lutje et al., “PSMA Ligands for Radionuclide Imaging and Therapy of Prostate Cancer: Clinical Status,” Theranostics 5(12): 1388-1401 (2015); Haberkom et al., “New Strategies in Prostate Cancer: Prostate-Specific Membrane Antigen (PSMA) Ligands for Diagnosis and Therapy,” Clin. Cancer Res. 22(1):9-15 (2016), which are hereby incorporated by reference in their entirety). In embodiments, the second targeting component is a peptide selected from the group consisting of PSMA 617, PSMA I&T, DCFBC, DCFPyL, glutamate urea-lysine analogs, phosphoramidate analogs, 2- (phosphinylmethyl) pentanedioic acid analogs, and other PSMA ligands/inhibitors. In embodiments, the cancer is relapsed and/or refractory to prior treatment with PSMA 617-¹⁷⁷Lu or PSMA I&T-¹⁷⁷LU. In embodiments, the cancer is relapsed and/or refractory to prior treatment with PSMA 617-¹⁷⁷LU.

[0082] In some embodiments, the methods include prior treatment with a therapeutic agent comprising a second targeting component coupled to a second cancer therapeutic component such as a PSMA radioligand, including PSMA radioligands such as PSMA 617-¹⁷⁷Lu and/or PSMA I&T-¹⁷⁷Lu. In embodiments, the therapeutic agent used in the prior treatment is a small molecule conjugated to a radionuclide and is administered at a dose of about 200 to 1,000 mCi total in a 2 week cycle, or about 300 to 800 mCi total in a 2 week cycle, or about 400 to 700 mCi total in a 2 week cycle, or about or about 500 to 600 mCi total in a 2 week cycle. A specific dose could include a dose of 200, 225, 250, 300, 325, 350, 375, 400, 425, 450, 475, 500. 525, 550, 575, 600, 625, 650, 675, 700, 725, 750, 775, 800, 825, 850, 875, 900, 925, 950, 975, 1,000 mCi total. In a specific embodiment, these amounts are the total dose in a 2 week cycle.

[0083] In embodiments, the additional therapeutic agent is a PSMA radioligand. In a specific embodiment, the prior treatment is with PSMA 617-¹⁷⁷Lu or PSMA I&T-¹⁷⁷Lu and comprises administering about 1 GBq to about 12 GBq, or about 2 GBq to about 20 GBq, or about about 3 GBq to about 9 GBq, or about 4 GBq to about 8 GBq, or any ranges therebetween. In another embodiment, the prior treatment is with PSMA 617-¹⁷⁷Lu or PSMA I&T-¹⁷⁷Lu at one of the disclosed doses described herein, and administered, once every week, every 2 weeks, every 3 weeks, every 4 weeks, every 5 weeks, every 6 weeks, every 7 weeks, every 8 weeks, every 9 weeks, every 10 weeks, every 11 weeks or every 12 weeks. In a specific embodiment, the overall number of cycles or doses are 1 dose or cycle, 2 doses or cycles, 3 doses of cycles, 4 doses or cycles, 5 doses or cycles, 6 doses or cycles, 7 doses or cycles, or 8 doses or cycles. In embodiments, the therapeutic agent comprising a second targeting component coupled to a second cancer therapeutic component is intravenously administered.

[0084] In specific embodiments, the prior treatment is with a therapeutic agent that is a PSMA radioligand. In a specific embodiment, the PSMA radioligand is PSMA 617-¹⁷⁷Lu and comprises administering about 5.9 GBq (160 mCi) to about 7.4 GBq (200 mCi) every 6-10 weeks. In embodiments, the prior treatment with a therapeutic agent, PSMA 617-¹⁷⁷Lu comprises administering about 1 GBq to about 12 GBq, or about 2 GBq to about 20 GBq, or about about 3 GBq to about 9 GBq, or about 4 GBq to about 8 GBq, or any ranges therebetween. In a specific embodiment, PSMA 617-¹⁷⁷Lu is administered once every week, every 2 weeks, every 3 weeks, every 4 weeks, every 5 weeks, every 6 weeks, every 7 weeks, every 8 weeks, every 9 weeks, every 10 weeks, every 11 weeks or every 12 weeks. In a specific embodiment, the overall number of cycles or doses are 1 dose or cycle, 2 doses or cycles, 3 doses of cycles, 4 doses or cycles, 5 doses or cycles, 6 doses or cycles, 7 doses or cycles, or 8 doses or cycles. In embodiments, the prior treatment with a therapeutic agent PSMA 617-¹⁷⁷Lu comprises administering about 7.4 GBq (200 mCi) every 6 weeks for up to 6 doses. In another specific embodiment, the PSMA 617-¹⁷⁷Lu is administered at a dose of 8.5 GBq. In another specific embodiment, the subsequent doses are decreased. In a specific embodiment, the subsequent dose can be administered at about 8.5 GBq. In another embodiment, the next dose is at about 8.0 GBq to 8.5 GBq. In another embodiment, the next dose is at about 7.5 GBq to 8.0 GBq. In another embodiment, the next dose is at about 7.0 GBq to 7.5 GBq. In another embodiment, the next dose is at about 6.5 GBq to 7.0 GBq. [0085] In embodiments, the prior treatment with a therapeutic agent PSMA I&T-¹⁷⁷Lu comprises administering about 1 GBq to about 12 GBq, or about 2 GBq to about 20 GBq, or about about 3 GBq to about 9 GBq, or about 4 GBq to about 8 GBq, or any ranges therebetween. In a specific embodiment, PSMA I&T-¹⁷⁷Lu is administered once every week, every 2 weeks, every 3 weeks, every 4 weeks, every 5 weeks, every 6 weeks, every 7 weeks, every 8 weeks, every 9 weeks, every 10 weeks, every 11 weeks or every 12 weeks. In a specific embodiment, the overall number of cycles or doses are 1 dose or cycle, 2 doses or cycles, 3 doses of cycles, 4 doses or cycles, 5 doses or cycles, 6 doses or cycles, 7 doses or cycles, or 8 doses or cycles.

Dosing of²²⁵Ac-huJ591

[0086] In embodiments, the total daily dose of the agent comprising a targeting component coupled to a cancer therapeutic component, z.e., ²²⁵Ac-huJ591, administered in the methods provided herein may range, e.g., between about 10 KBq/Kg and about 130 KBq/Kg, including between about 10 KBq/Kg, about 15 KBq/Kg, about 20 KBq/Kg, about 25 KBq/Kg, about 30 KBq/Kg, about 35 KBq/Kg, about 40 KBq/Kg, about 45 KBq/Kg, about 50 KBq/Kg, about 55 KBq/Kg, about 60 KBq/Kg, about 65 KBq/Kg, about 70 KBq/Kg, about 75 KBq/Kg, about 80 KBq/Kg, about 85 KBq/Kg, about 90 KBq/Kg, about 95 KBq/Kg, about 100 KBq/Kg, about 105 KBq/Kg, about 110 KBq/Kg, about 115 KBq/Kg, about 120 KBq/Kg, about 125 KBq/Kg, and about 130 KBq/Kg including all values and subranges therebetween. In embodiments, the total daily dose of the agent administered in the methods provided herein may range, between about 13.3 KBq/Kg to about 93.3 KBq/Kg. In embodiments, the total daily dose of the agent administered in the methods provided herein may range, between about dose of about 45 KBq/Kg to about 65 KBq/Kg. In embodiments, the total daily dose of the agent administered in the methods provided herein may be a dose of about 40 KBq/Kg, 45 KBq/Kg, about 55 KBq/Kg, about 60 KBq/Kg, about 65 KBq/Kg, about 70 KBq/Kg, about 75 KBq/Kg, about 80 KBq/Kg, or about 85 KBq/Kg of the agent is administered. In embodiments, the total daily dose is about 45 KBq/Kg. In embodiments, the total daily dose is about 55 KBq/Kg. In embodiments, the total daily dose is about 60 KBq/Kg. In embodiments, the total daily dose is about 65 KBq/Kg. In embodiments, the total daily dose is about 70 KBq/Kg. In embodiments, the total daily dose is about 75 KBq/Kg. In embodiments, the total daily dose is about 85 KBq/Kg. In embodiments, the total daily dose is about 90 KBq/Kg.

[0087] In embodiments, the methods of the present disclosure comprise administering to the patient an initial dose and a subsequent dose of the agent comprising a targeting component coupled to a cancer therapeutic component. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose may range, e.g., between about 70 KBq/Kg and about 140 KBq/Kg, about 80 KBq/Kg and about 130 KBq/Kg, or about 90 KBq/Kg and about 130 KBq/Kg, including about 70 KBq/Kg, about 80 KBq/Kg, about 90 KBq/Kg, about 95 KBq/Kg, about 100 KBq/Kg, about 105 KBq/Kg, about 110 KBq/Kg, about 115 KBq/Kg, about 120 KBq/Kg, about 125 KBq/Kg, and about 130 KBq/Kg, including all values and subranges therebetween. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 70 KBq/Kg, about 80 KBq/Kg, about 90 KBq/Kg, about 110 KBq/Kg, about 120 KBq/Kg, or about 130 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 90 KBq/Kg. In embodiments, the initial dose of the agent is about 45 KBq/Kg, and the subsequent dose of the agent is about 45 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 110 KBq/Kg. In embodiments, the initial dose of the agent is about 55 KBq/Kg, and the subsequent dose of the agent is about 55 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is a about 120 KBq/Kg. In embodiments, the initial dose of the agent is about 60 KBq/Kg, and the subsequent doses of the agent are about 60 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 130 KBq/Kg. the initial dose of the agent is about 65 KBq/Kg, and the subsequent dose of the agent is about 65 KBq/Kg.

[0088] In embodiments, the methods of the present disclosure comprise administering to the patient an initial dose and a least one subsequent dose of the agent comprising a targeting component coupled to a cancer therapeutic component. In embodiments, there is one subsequent dose. In embodiments, there are two subsequent doses. In embodiments, there are three subsequent doses. In embodiments, there are four subsequent doses. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose may range, e.g., between about 70 KBq/Kg and about 500 KBq/Kg, about 80 KBq/Kg and about 400 KBq/Kg, or about 90 KBq/Kg and about 340 KBq/Kg, including about 70 KBq/Kg, about 80 KBq/Kg, about 90 KBq/Kg, about 95 KBq/Kg, about 100 KBq/Kg, about 105 KBq/Kg, about 110 KBq/Kg, about 115 KBq/Kg, about 120 KBq/Kg, about 125 KBq/Kg, about 130 KBq/Kg, about 140 KBq/Kg, about 150 KBq/Kg, about 160 KBq/Kg, about 170 KBq/Kg, about 180 KBq/Kg, about 190 KBq/Kg, about 200 KBq/Kg, about 210 KBq/Kg, about 220 KBq/Kg, about 230 KBq/Kg, about 240 KBq/Kg, about 250 KBq/Kg, about 260 KBq/Kg, about 270 KBq/Kg, about 280 KBq/Kg, about 290 KBq/Kg, about 300 KBq/Kg, about 310 KBq/Kg, about 320 KBq/Kg, about 330 KBq/Kg, about 340 KBq/Kg, about 350 KBq/Kg, about 360 KBq/Kg, about 370 KBq/Kg, about 380 KBq/Kg, and about 390 KBq/Kg, including all values and subranges therebetween. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 70 KBq/Kg, about 80 KBq/Kg, 90 KBq/Kg, about 110 KBq/Kg, about 120 KBq/Kg, about 130 KBq/Kg, 140 KBq/Kg, about 150 KBq/Kg, 160 KBq/Kg, about 170 KBq/Kg, about 180 KBq/Kg, about 190 KBq/Kg, about 200 KBq/Kg, about 210 KBq/Kg, about 220 KBq/Kg, 230 KBq/Kg, about 240 KBq/Kg, 250 KBq/Kg, about 260 KBq/Kg, about 270 KBq/Kg, about 280 KBq/Kg, 290 KBq/Kg, about 300 KBq/Kg, 310 KBq/Kg, about 320 KBq/Kg, about 330 KBq/Kg, or about 340 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent doses is about 180 KBq/Kg. In embodiments, the initial dose of the agent is about 45 KBq/Kg, and the subsequent doses of the agent are about 45 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent doses is about 220 KBq/Kg. In embodiments, the initial dose of the agent is about 55 KBq/Kg, and the subsequent doses of the agent are about 55 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent doses is about 260 KBq/Kg. In embodiments, the initial dose of the agent is about 65 KBq/Kg, and the subsequent doses of the agent are about 60 KBq/Kg. In embodiments, the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 130 KBq/Kg. the initial dose of the agent is about 65 KBq/Kg, and the subsequent dose of the agent is about 65 KBq/Kg.

[0089] In embodiments, the methods of the present disclosure comprise administering to the patient an initial dose and a series of subsequent doses, such as 2, 3, 4, 5, or 6 cycles of the agent comprising a targeting component coupled to a cancer therapeutic component. In a specific embodiment, the agent is administered in 4 separate doses, i.e., 1 dose in 4 separate cycles. In embodiments, the cumulative amount of the agent administered in the 4 cycles may range, e.g., between about 60 KBq/Kg and about 500 KBq/Kg, between about 150 KBq/Kg and about 400 KBq/Kg, between about 180 KBq/Kg and about 340 KBq/Kg, and between about 220 KBq/Kg and about 300 KBq/Kg and any range therebetween. In a specific embodiment, the cumulative amount over 4 cycles may be about 60 KBq/Kg, about 70 KBq/Kg, about 80 KBq/Kg, 100 KBq/Kg, about 150 KBq/Kg, about 180 KBq/Kg, about 200 KBq/Kg, about 220 KBq/Kg, about 260 KBq/Kg, about 300 KBq/Kg, about 340 KBq/Kg, and about 400 KBq/Kg, including all values and subranges therebetween.

[0090] In embodiments, the subsequent dose administered in the methods provided herein is administered at least about two weeks after the initial dose. In embodiments, the subsequent dose is administered about two weeks after the initial dose. In embodiments, the subsequent dose is administered about 14-20 days after the initial dose. In embodiments, the subsequent dose is administered about 14 days after the initial dose. In embodiments, the subsequent dose is administered about 3 weeks after the initial dose. In embodiments, the subsequent dose is administered about 4 weeks after the initial dose. In embodiments, the subsequent dose is administered about 5 weeks after the initial dose. In embodiments, the subsequent dose is administered about 6 weeks after the initial dose. In embodiments, the subsequent dose is administered about 7 weeks after the initial dose. In embodiments, the subsequent dose is administered about 8 weeks after the initial dose. In embodiments, the subsequent dose is administered about 9 weeks after the initial dose. In embodiments, the subsequent dose is administered about 9 weeks after the initial dose.

[0091] When more than one dose or cycle is involved, the additional cycles will be delivered about 1 week apart, 2 weeks apart, 3 weeks apart, 4 weeks apart, 5 weeks apart, 6 weeks apart, 7 weeks apart, 8 weeks apart, 9 weeks apart, 10 weeks apart, 11 weeks apart or 12 weeks apart.

[0092] In embodiments, the agent comprising a targeting component coupled to a cancer therapeutic component administered in the methods provided herein may be administered as a single dose in a 6-week cycle (q6w). In embodiments, the agent comprising a targeting component coupled to a cancer therapeutic component administered in the methods provided herein may be administered as a single dose in a 8-week cycle. In another embodiment, there may be 1 cycle, 2 cycles, 3 cycles, 4 cycles, 5 cycles or 6 cycles.

[0093] In some embodiments, after initiating treatment with the dosing and dosing schedule as described herein, the subject demonstrates a bPFS of at least 50 days, at least 100 days, at least 150 days, at least 200 days, at least 250 days, at least 300 days, or at least 1 year. In another embodiment, after initiating treatment, the subject demonstrates a bPFS range of about 50 days to 500 days, about 100 days to about 400 days, or about 200 to about 300 days.

[0094] In one embodiment, the agent comprising a targeting component coupled to a cancer therapeutic component administered in the methods provided herein can be delivered as a single dose such as, e.g., a single bolus injection, or oral tablets or pills; or over time such as, e.g., continuous infusion over time or divided bolus doses over time. In one embodiment, the agent can be administered repetitively, if necessary, e.g., until the patient experiences stable disease or regression, or until the patient experiences disease progression or unacceptable toxicity. Stable disease or lack thereof is determined by methods known in the art such as evaluation of patient's symptoms, physical examination, visualization of the tumor that has been imaged using X-ray, CAT, PET, bone scan, or MRI scan and other commonly accepted evaluation modalities. In one embodiment, the agent can be administered repetitively, if necessary, e.g., until the patient experiences PSA progression e.g., a rise of at least about 25% above the pretreatment level or the nadir PSA level.

[0095] In some embodiments, a dose limiting toxicity (DLT) is: a. Grade 4 neutropenia or any occurrence of febrile neutropenia b. Grade 4 thrombocytopenia or Grade 3 thrombocytopenia associated with major bleeding c. Any Grade > 2 non-hematologic toxicity deemed to be at least possibly related to 2²⁵Ac-huJ591 will be termed as dose-limiting toxicity.

[0096] In some embodiments, the maximum tolerated dose (MTD) is the dose level at which no more than one subject out of six experiences a DLT during the DLT evaluation period.

[0097] In embodiments, the patient is treated in the methods provided herein for at least about 8 weeks, at least about 10 weeks, at least about 12 weeks, at least about 14 weeks, at least about 16 weeks, at least about 18 weeks, at least about 20 weeks, at least about 22 weeks, at least about 24 weeks or at least about 26 weeks.

[0098] In certain embodiments, the agent comprising a targeting component coupled to a cancer therapeutic component is administered to a patient in the methods provided herein in cycles (e.g., a single administration, then a rest period with no administration for up to 6 weeks (e.g., about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, or about 6 weeks). Cycling therapy involves the administration of an active agent for a period of time, followed by a rest for a period of time, and repeating this sequential administration. In embodiments, cycling therapy can reduce the development of resistance, avoid or reduce the side effects, and/or improves the efficacy of the treatment.

[0099] In embodiments, a method provided herein comprises administering the agent comprising a targeting component coupled to a cancer therapeutic component in 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, or greater than 40 cycles. In embodiments, the agent is administered for at least one cycle. In embodiments, the agent is administered for up to 4 cycles. In embodiments, the agent is administered for at least one cycle. In embodiments, the agent is administered for up 1-4 cycles. In embodiments, the median number of cycles administered in a group of patients is about 1. In one embodiment, the median number of cycles administered in a group of patients is about 2. In one embodiment, the median number of cycles administered in a group of patients is about 3. In one embodiment, the median number of cycles administered in a group of patients is about 4.

[0100] In certain embodiments, treatment cycles comprise multiple doses of the agent comprising a targeting component coupled to a cancer therapeutic component administered to a patient in need thereof over one or multiple days (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or greater than 14 days), optionally followed by treatment dosing holidays (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, or greater than 28 days).

[0101] In practicing the methods of the present disclosure, the administering step is carried out to treat cancer in a subject. In one embodiment, a subject having cancer is selected prior to the administering step. Such administration can be carried out systemically or via direct or local administration to the tumor site. By way of example, suitable modes of systemic administration include, without limitation orally, topically, transdermally, parenterally, intradermally, intramuscularly, intraperitoneally, intravenously, subcutaneously, or by intranasal instillation, by intracavitary or intravesical instillation, intraocularly, intraarterialy, intralesionally, or by application to mucous membranes. Suitable modes of local administration include, without limitation, catheterization, implantation, direct injection, dermal/transdermal application, or portal vein administration to relevant tissues, or by any other local administration technique, method or procedure generally known in the art. The mode of affecting delivery of agent will vary depending on the type of therapeutic agent and the disease to be treated.

[0102] In some embodiments, after the treatment the patient experiences a decline in circulating tumor cell (CTC) count e.g., compared to baseline prior to treating. In embodiments, the patient experiences a decline in CTC count of at least about 10% of at least about 20%, at least about 30%, of at least about 40%, at least about 50%, at least about 55%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or more compared to baseline prior to treatment. In embodiments, the patient experiences a decline in CTC count of at least about 50% compared to baseline prior to treatment.

[0103] In embodiments, after treatment according to the methods disclosed herein, the patient has a CTC count of less than about 5, less than about 4, less than about 3, less than about 2, or less than about 1.

[0104] In embodiments, after treatment according to the methods disclosed herein, the patient has an undetectable CTC count. In embodiments, CTC counts are evaluated using CTC assay system. CTC counts via the CellSearch platform were demonstrated to be prognostic in men with advanced PCa prior to systemic therapy and a “conversion” from an unfavorable count (>5 CTCs/7.5 mL) was associated with a median similar to those starting with favorable counts (<5 CTCs/7.5 mL), leading to clearance of this particular test by the FDA (de Bono et al. 2008). The combination of CellSearch CTC enumeration and serum LDH have been demonstrated to have prognostic value, meeting Prentice criteria for survival surrogacy in the setting of abiraterone/prednisone treatment in men with mCRPC previously treated with docetaxel (Scher et al. 2015). Most recently, conversion from unfavorable to favorable and detectable to undetectable CTC counts in 5 pooled phase III studies has been demonstrated to be associated with survival (Heller et al. 2018). Blood for CellSearch CTC enumeration will be collected prior to treatment and at 3 -months.

[0105] In embodiments, after treatment according to the methods disclosed herein, the patient has normal LDL levels.

[0106] In embodiments, after treatment according to the methods disclosed herein, the patient experiences a PSA decline compared to baseline prior to treatment. In embodiments, after said treating the patient experiences a PSA decline of at least about 10% of at least about 20%, at least about 30%, of at least about 40%, at least about 50%, at least about 55%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or more compared to baseline prior to treatment. In embodiments, after said treating the patient experiences a PSA decline of at least about 30% compared to baseline prior to treatment. In embodiments, after said treating the patient experiences a PSA decline of at least about 50% compared to baseline prior to treatment. In embodiments, PSA response is determined by comparing the PSA levels after therapy to the baseline, pre-treatment PSA.

[0107] In embodiments, after treatment according to the methods disclosed herein, the patient experiences a complete response, partial response, or stable disease. In embodiments, the patient’s response is calculated using Response Evaluation Criteria in Solid Tumors (RECIST Version 1.1) with PCWG3 modifications. In embodiments, after treatment according to the methods disclosed herein, he patient experiences a 30% or greater reduction in the sum longest uni-dimensional diameter of all measurable lesions. In embodiments, after treatment according to the methods disclosed herein, the patient has complete disappearance of all measurable and evaluable lesions by physical examination or imaging studies. In embodiments, after treatment according to the methods disclosed herein, the patient has no signs of progressive disease for at least 1 month. [0108] In embodiments, after treatment according to the methods disclosed herein, the patient has complete disappearance of all measurable and evaluable lesions and normalization of PSA with no appearance of new lesions e.g., for about 1 month or more.

[0109] In some embodiments, a treated subject has biochemical progression-free survival (bPFS). Biochemical (PSA) progression is defined as a rise of >25% above the nadir PSA level (lowest PSA value reached; this can be the baseline value if PSA never decreases on treatment). PSA may also increase by at least 2 ng/mL above the nadir to be considered progression. Confirmation requires a second consecutive rising PSA at least two weeks later.bPFS is the interval between initiating protocol treatment (C1D1) until biochemical progression or death, whichever comes first, or censored at last PSA measurement for subjects alive without PSA progression at the time of data cut or subjects who started a new systemic cancer therapy before biochemical progression.

[0110] In some embodiments, after initiating treatment, the subject demonstrates a bPFS of at least 50 days, at least 100 days, at least 150 days, at least 200 days, at least 250 days, at least 300 days, or at least 1 year. In another embodiment, after initiating treatment, the subject demonstrates a bPFS range of about 50 days to 500 days, about 100 days to about 400 days, or about 200 to about 300 days.

[oni] In some embodiments, the main criteria for being treated by the cancer therapeutic disclosed herein includes:

[0112] Adult male subjects of >18 years old with: a. Histologically or cytologically confirmed adenocarcinoma of prostate origin b. Documented progressive mCRPC based on PCWG3 criteria, which includes at least one of the following criteria: i. PSA progression ii. Objective radiographic progression in soft tissue iii. New bone lesions c. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 d. Have serum testosterone <50 ng/dL. Subjects must continue primary androgen deprivation with a luteinizing hormone-releasing hormone (LHRH)/gonadotropin releasing hormone (GnRH) analogue (agonist/antagonist) if they have not undergone an orchiectomy. e. Have previously been treated with at least one of the following in any disease state: i. Androgen receptor signaling inhibitor (ARSI) (such as enzalutamide) ii. Cytochrome P450 17alpha-hydroxylase/17,20-lyase (CYP 17) inhibitor (such as abiraterone acetate) f. Have previously received taxane chemotherapy (in any disease state), been determined to be ineligible for taxane chemotherapy by their physician, or refused taxane chemotherapy.

[0113] Those refusing chemotherapy will be informed that it is possible that toxicity from 225Ac-huJ591 may preclude the ability to receive future chemotherapy.

[0114] Must have normal organ and marrow function as defined below: a. Absolute neutrophil count >2,000 cells/mm³ b. Hemoglobin >9 g/dL c. Platelet count >150 x 103/uL d. Serum creatinine <1.5 x upper limit of normal (ULN) or calculated creatinine clearance >60 mL/min/1.73 m2 by Cockcroft-Gault e. Serum total bilirubin <1.5 x ULN (unless due to Gilbert’s syndrome in which case direct bilirubin must be normal f. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT)<3 x ULN in absence of liver metastases; <5x ULN if due to liver metastases (in both circumstances bilirubin must meet entry criteria) g. Ability to understand and the willingness to sign a written informed consent document h. For subjects enrolled in the post-¹⁷⁷Lu-PSMA cohort in the fractionated dose regimen: must have previously received either ¹⁷⁷Lu-PSMA-617 or ¹⁷⁷Lu-PSMA-I&T

[0115] In some embodiments, exclusion criteria for being treated with the cancer therapeutic disclosed herein includes: a. Implantation of investigational medical device <4 weeks of Treatment Visit 1 (C1D1) or current enrollment in oncologic investigational drug or device study b. Use of investigational drugs <4 weeks or <5 half-lives of C1D1 or current enrollment in investigational oncology drug or device study c. Prior systemic beta-emitting bone-seeking radioisotopes (e.g., samarium-153, strontium-89) d. For subjects enrolled in the post-177Lu-PSMA-RLcohort: Prior 223Ra. e. Untreated hydronephrosis f. Known active brain metastases or leptomeningeal disease g. History of deep vein thrombosis and/or pulmonary embolus within one month of C1D1 h. Other serious illness(es) involving the cardiac, respiratory, central nervous system (CNS), renal, hepatic or hematological organ systems which might preclude completion of this study or interfere with determination of causality of any adverse effects experienced in this study i. Radiation therapy for treatment of PC <4 weeks of C1D1 j . Chemotherapy for treatment of PC <4 weeks of C ID 1 k. Patients on stable dose of bisphosphonates or denosumab, which have been started no less than four weeks prior to treatment start, may continue on this medication, however subjects were not allowed to initiate bisphosphonate/denosumab therapy during the DLT-assessment period of the study l. Having partners of childbearing potential and not willing to use a method of birth control deemed acceptable by the Principal Investigator and chairperson during the study and for one month after last study drug administration m. Currently active other malignancy other than non-melanoma skin cancer. Patients are considered not to have “currently active” malignancy if they have completed any necessary therapy and are considered by their physician to be at less than 30% risk of relapse n. Known history of known myelodysplastic syndrome o. Bone scan with confluent lesions and lack of urinary tracer consistent with a “superscan” as determined by the investigator

EXAMPLES

[0116] The examples below are intended to exemplify the practice of embodiments of the disclosure but are by no means intended to limit the scope thereof.

Example 1: Dose-Escalation Study of PSMA-Targeted Alpha Emitter ²²⁵Ac-huJ591 in Men with Metastatic Castration-Resistant Prostate Cancer (mCRPC)

[0117] Men with progressive mCRPC following at least 1 potent Androgen Receptor signaling inhibitor (ARSI) and chemo (or unfit/refuse) without limit of the number of prior therapies (Ra-223 and PSMA-617-Lu¹⁷⁷ allowed) with ECOG PS 0-2 and adequate organ function were eligible. Baseline ⁶⁸Ga-PSMAl 1 PET was performed, but not used for eligibility. Initially 1 -subject cohorts were treated until transition to 3+3 cohorts at dose level 5 (predicted by dosimetry to have moderate toxicity) with a single infusion of ²²⁵Ac-huJ591 (13.3 KBq/kg with planned escalation up to 93.3 KBq/kg). Dose-limiting toxicity (DLT) was defined as attributable grade (Gr) 4 heme toxicity or Gr 3/4 non-heme tox. Imaging, genomic, patient- reported outcomes (PRO), and immune correlates were embedded in the trial design.

Table 1: Treatment Plan with ²²⁵Ac-J591

[0118] ²²⁵Hc-huJ591

[0119] ²²⁵ Ac nitrate residue, 37 MBq (1.0 mCi) is supplied in a 2mL glass vial, a radiochemical grade preparation. 225Ac-DOTA-huJ591 mAb injection is manufactured by reacting ²²⁵ Ac chloride with DOTA-huJ591 (3.0 mg) aseptically withdrawn from the packaged drug substance vial and allowing the DOTA chelator to chelate ²²⁵ Ac in tetramethylammonium acetate buffer (TMAA). Following the reaction, the ²²⁵Ac-DOTA-huJ591 is challenged with an excess of the chelator DTPA to remove any free or loosely bound ²²⁵ Ac. ²²⁵ Ac-DOT A-huJ591 is then separated from ²²⁵Ac-DTPA by gel filtration (Biogel P-6 column, Biorad, CA) using sterile saline solution containing 2% Human Serum Albumin as an eluent. The eluent fraction (4-8 mL) containing 225Ac-DOTA-huJ591 is then sterilized by membrane filtration into a final drug product vial. QC Samples are removed for Quality Control. The specific activity of the 225Ac-DOTA-huJ591 injection is estimated based on dose calibrator measurement of total 225Ac activity (50 - 300pCi) and the total DOTA-huJ591 (3 mg) precursor used. Expected SA is 16.6 - 100 pCi/mg.

Results

[0120] 32 patients with advanced prostate cancer were treated intravenously with a single dose of ²²⁵Ac-huJ591 on 7 dose levels. No PSMA imaging pre-selection was used and the patients were heavily pre-treated with prior therapies e.g., Androgen Receptor signaling inhibitors (ARSI), chemotherapy, Ra-223, and PSMA-617-Lu¹⁷⁷. Seventy-eight percent (25/32) of the patients had received at least two prior ARSIs 63% (20/32) had previously received chemotherapy, and 46.9% (15/32) had previously been treated with PSMA-617-Lu¹⁷⁷.

[0121] 28 of the patients treated and with a PSMA PET all had at least 1 tumor with

PSMA SUVmax > liver SUVmean, with 21 of 28 (75%) having the brightest lesion > 5x liver. Nine (28.1%) patients had PSA rise as best response, with PSA decline in the remainder, including 15 (46.9%) with >50% PSA decline at any time during follow up.

[0122] A confirmed >50% PSA (PSA50) response was observed in 11/32 (34.4%) patients. Of 11 patients with measurable disease at baseline and any follow up imaging results, 2 (18.2%) had partial response, 7 (63.6%) had stable disease, and 2 (18.2%) had progression of disease. Circulating tumor cell (CTC) response in patients with paired pre/post-therapy counts, defined per protocol as a drop from >5 CTCs (per 7.5 ml of blood) to <4 CTCs, or count remaining at <4 CTCs at 12 weeks, occurred in 13 of 22 (59.1%). Twelve of 16 (75%) with initially detectable CTC count declined and 6 (37.5%) became undetectable. Of 13 with baseline unfavorable count, 5 (41.7%) converted to favorable. Of 6 with initially undetectable CTC count, 5 remained undetectable and 1 (16.7%) increased.

[0123] Median progression-free survival was 5.6 months (95% CI 3.7-7.9) and median overall survival was 10.7 months (95% CI 6.5-17.2). On multivariable analysis, only CALGB prognostic grouping was associated with survival (HR 0.68, p=0.07).

[0124] 225Ac-huJ591 was also well tolerated. Only one patient experienced DLT during dose-escalation (dose level 6, 80 KBq/kg, grade 4 anemia and thrombocytopenia), and no patients (0/6) at the seventh dose level experienced DLT. Maximum tolerated dose was not achieved as only a single patient experienced DLT. The majority of high-grade adverse events were hematologic. In addition to the DLT, three patients had grade 3 anemia, two had grade 3 thrombocytopenia, two had grade 4 thrombocytopenia, two had grade 3 neutropenia, and one had grade 4 neutropenia. All were transient. The non-hematologic AEs were generally grade 1 or 2, with no grade 3 AEs occurring in more than 1 patient. Higher administered radioactivity was associated with higher grade hematologic AEs.

Example 2: Phase I/II Trial ²²⁵Ac-huJ591 in Patients with Metastatic Castration Resistant Prostate Cancer (mCRPC)

[0125] This study is a Phase Eli parallel dose-escalation studies of fractionated (DI, D15) single cycle & multiple (q6w) dose regimens of ²²⁵Ac-huJ591in patients with mCRPC. Fractionated Dose Regimen.

[0126] The study is designed as a Phase I dose escalation study with ²²⁵Ac-huJ591 using two different regimens for men with progressive mCRPC with and without prior ¹⁷⁷Lu PSMA Radioligand (¹⁷⁷Lu-PSMA-RL) treatment. Dose fractionation regimen is a single cycle of study drug administered on DI and D15. The multiple dose regimen is a single dose of ²²⁵Ac-huJ591 per cycle, with each cycle administered every 6 weeks X 4. Following determination of RP2D, each cohort will transition to phase II.

[0127] This study will enroll up to 130 subjects who receive treatment. Adult male patients of >18 years of age with documented progressive metastatic CRPC are eligible. About 6-130 eligible/evaluable patients will be enrolled into a 3+3 study design with up to 5 doseescalation cohorts in each regimen (q2 week regimen and q6 week regimen). For patients without prior ¹⁷⁷Lu-PSMA-RL (such as PSMA 617-Lu¹⁷⁷ or PSMA I&T-Lu+) treatment, up to 30 patients will be enrolled in the q2 week regimen and up to 18 in the q6 week regimen in phase I and an additional 24-27 PSMA+ patients will be enrolled in phase II (up to 30 each including phase I cohort). For patients who received prior ¹⁷⁷Lu-PSMA-RL (such as PSMA 617-Lu¹⁷⁷ or PSMA I&T-Lu¹⁷⁷) treatment, up to 18 patients will be enrolled in phase I and an additional 16- 19 patients will be enrolled in phase II (up to 22 patients including the phase I cohort); additional PSMA-low subjects may be enrolled (approx, additional 10%).

[0128] Phase I dose limiting toxicity assessment phase is 8 weeks for the fractionated dose regimen and up to 9 weeks past the 2nd dose of ²²⁵Ac-huJ591 for the multiple dose regimen (for subjects receiving 4 cycles, 26 weeks is expected in the treatment portion of the study). Following treatment, short-term follow up is planned until radiographic progression, expected to be 6 months.

[0129] ²²⁵Ac-huJ591 will be administered as a single fractionated cycle DI and DI 5 in the fractionated dose regimen and as a single dose per cycle repeated every 6 weeks in the multiple dose regimen. 68Ga-PSMA-HBED-CC is comprised of gallium-68, which is a PET emitting radionuclide linked to PSMA-HBED-CC (aka PSMA-11), which is a small molecule targeting PSMA. 68Ga-PSMA-HBED-CC will be administered intravenously prior to PET/CT at screening and at follow up imaging x2. In lieu of 68Ga-PSMA-HBED-CC, patients may receive 18F-DCFPyL, which is comprised of PET emitting radionuclide fluorine-18 linked to PSMA- targeting small molecule DCFPyL.

[0130] The phase I primary objective is the determination of dose-limiting toxicity (DLT) & recommended phase II dose (RP2D). DLT was defined as within 8 weeks of first dose: neutropenia (Gr 4 or febrile neutropenia), thrombocytopenia (TCP) (Gr 4, or Gr 3 with clinically significant bleeding), any Gr >2 non-hematologic toxicity deemed to be at least possibly related to ²²⁵Ac-huJ591, or any attributable toxicity precluding or delaying the second dose by >2 weeks. Secondary objectives include efficacy measures (e.g., PSA decline, radiographic RR, biochemical/radiographic PFS, OS, CTCs) & safety (CTCAE v5).

Study Design (2 dose Fractionated ²²⁵ Ac-huJ591)

[0131] This is an open-label, multicenter Phase I/II dose escalation trial designed to determine the cumulative MTD in a dose fractionation regimen in which ²²⁵Ac-huJ591 will be given in a single cycle of 2 doses on DI and DI 5. Two populations of patients will be evaluated with the dose fractionation regimen: patients without prior ¹⁷⁷Lu-PSMA-RL exposure (Table 2) and patients who were previously treated with ¹⁷⁷Lu-PSMA-RL (such as PSMA 617-Lu¹⁷⁷ or PSMA I&T-Lu¹⁷⁷) (Table 3). The initial planned dose level for both populations is 45 KBq/Kg per dose with the dose escalation plan depicted in Tables 2 and 3 below. Should dose level 1 be determined to be intolerable (more than 2 DLT’s within 6 subjects), a lower dose level group will be enrolled.

Table 2: Dose-Escalation Plan with Fractionated ²²⁵Ac-huJ591 for Subjects Without prior 1⁷⁷Lu-PSMA-RL

Results for subjects without prior ¹⁷⁷Lu-PSMA-RL:

[0132] 24 patients were enrolled in the phase I. Median age 73.5 (57-91), PSA 25.78

(3.39-2133.41); 53% (n=13) >1 prior ARSI, 58% (n=14) taxane chemo, 8% (n=2) anti-PSMA therapy. CALGB prognostic groups: Good 4 (16%), Intermediate 8 (33%), Poor 12 (50%).

[0133] Two subjects withdrew before the second dose (intercurrent illness). Most common low grade non-hematologic AEs: fatigue (95%), xerostomia (69%), & nausea (57%). Among evaluable patients for PSA change (n=21), 18 (86%) experienced PSA decline with 14 (67%) with decline of 50%. 13/21 patients had CTCs samples collected at baseline & 12 weeks;

5 were unfavorable at baseline (>5/7.5 mL); 10/13 (77%) remained favorable or converted from unfavorable to favorable; 6/12 (50%) had 50% decline in CTC count; and 5/13 (38%) converted from detectable to undetectable.

[0134] Regarding tolerability and toxicity, no DLTs were observed in Cohort 1 (n=3). No DLTs were observed in Cohort 2 (n=6). For Cohort 2.5, 8 patients were enrolled in an intermediate dose cohort (2.5) with 1 DLT (Gr 4 TCP). In Cohort 3, 2/6 subjects experienced DLTs (Gr 3 weakness, Gr 2 TCP with >2 week delay in second fraction). A single fractionated cycle of dose-dense ²²⁵Ac-huJ591 at a total dose of 120 KBg/kg was thus delivered with acceptable toxicity and with evidence of preliminary efficacy across all dose levels by PSA and CTC changes.

Table 3: Dose-Escalation Plan with Fractionated ²²⁵Ac-huJ591 for Subjects with prior 1⁷⁷Lu-PSMA-RL

[0135] Upon meeting the inclusion and exclusion criteria and signing the informed consent and HIPAA form, subjects will undergo the screening. As part of the screening, subjects will undergo a ¹⁸F-DCFPyL / ⁶⁸Ga-PSMA-HBED-CC PET/CT or PET/MR.

Study Design (Multiple dose ²²⁵Ac-huJ591)

[0136] This is an open-label, multicenter Phase Eli dose escalation trial designed to determine the cumulative maximum tolerated dose (MTD) of 225Ac-huJ591 administered in up to 4 cycles delivered 6 weeks apart. The initial dose level per cycle will be 65 KBq/Kg with dose escalation plan depicted in Table 4 below. Table 4: Dose-Escalation Plan with Multiple Dose ²²⁵Ac-huJ591

[0137] Upon meeting the inclusion and exclusion criteria and signing the informed consent and HIPAA form, subjects will undergo the screening. As part of the screening, subjects will undergo a ¹⁸F-DCFPyL / ⁶⁸Ga-PSMA-HBED-CC PET/CT or PET/MR.

Example 3: Phase I/II Trial of ²²⁵Ac-huJ591- in Patients with Metastatic Castration Resistant Prostate Cancer (mCRPC) Fractionated Dose with and without prior Treatment with Prostate-Specific Membrane Antigen (PSMA)-Directed Lutetium-177 Radioligand (¹⁷⁷Lu-PSMA-RL ) and Patients Treated with Multiple Doses of ²²⁵Ac-huJ591

[0138] This study is an ongoing dose-escalation study with ²²⁵Ac-huJ591 evaluating two different regimens in subjects with mCRPC with and without prior ¹⁷⁷Lu-PSMA-RL (such as PSMA 617-Lu¹⁷⁷ or PSMA I&T-Lu¹⁷⁷) treatment. The fractionated dose regimen is a single cycle of ²²⁵Ac-huJ591 administered on Cycle (C) 1, Day (D) 1 and C1D15. The multiple dose regimen is a single dose of ²²⁵Ac-huJ591 per cycle, with each cycle administered every six weeks (Q6W) for up to four cycles. Five escalating dose levels were planned in each regimen. The aim of the Phase 1 portion of the study is to determine the cumulative maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of fractionated dose ²²⁵Ac-huJ591 and multiple dose ²²⁵Ac-huJ591.

[0139] Diagnosis and main criteria for inclusion:

[0140] Adult male subjects of >18 years old with: a. Histologically or cytologically confirmed adenocarcinoma of prostate origin b. Documented progressive mCRPC based on PCWG3 criteria, which includes at least one of the following criteria: i. PSA progression ii. Objective radiographic progression in soft tissue iii. New bone lesions c. Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 d. Have serum testosterone <50 ng/dL. Subjects must continue primary androgen deprivation with a luteinizing hormone-releasing hormone (LHRH)/gonadotropin releasing hormone (GnRH) analogue (agonist/antagonist) if they have not undergone an orchiectomy. e. Have previously been treated with at least one of the following in any disease state: i. Androgen receptor signaling inhibitor (ARSI) (such as enzalutamide) ii. Cytochrome P450 17alpha-hydroxylase/17,20-lyase (CYP 17) inhibitor (such as abiraterone acetate) f. Have previously received taxane chemotherapy (in any disease state), been determined to be ineligible for taxane chemotherapy by their physician, or refused taxane chemotherapy.

[0141] Those refusing chemotherapy will be informed that it is possible that toxicity from 225Ac-huJ591 may preclude the ability to receive future chemotherapy.

[0142] Must have normal organ and marrow function as defined below: a. Absolute neutrophil count >2,000 cells/mm³ b. Hemoglobin >9 g/dL c. Platelet count >150 x 103/uL d. Serum creatinine <1.5 x upper limit of normal (ULN) or calculated creatinine clearance >60 mL/min/1.73 m2 by Cockcroft-Gault e. Serum total bilirubin <1.5 x ULN (unless due to Gilbert’s syndrome in which case direct bilirubin must be normal f. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT)<3 x ULN in absence of liver metastases; <5x ULN if due to liver metastases (in both circumstances bilirubin must meet entry criteria) g. Ability to understand and the willingness to sign a written informed consent document h. For subjects enrolled in the post-¹⁷⁷Lu-PSMA-RL cohort in the fractionated dose regimen: must have previously received either ¹⁷⁷Lu-PSMA-617 or ¹⁷⁷Lu-PSMA-I&T

[0143] Exclusion Criteria: a. Implantation of investigational medical device <4 weeks of Treatment Visit 1 (C1D1) or current enrollment in oncologic investigational drug or device study b. Use of investigational drugs <4 weeks or <5 half-lives of C1D1 or current enrollment in investigational oncology drug or device study c. Prior systemic beta-emitting bone-seeking radioisotopes (e.g., samarium-153, strontium-89) d. For subjects enrolled in the post-177Lu-PSMA-RL cohort: Prior 223Ra e. Untreated hydronephrosis f. Known active brain metastases or leptomeningeal disease g. History of deep vein thrombosis and/or pulmonary embolus within one month of C1D1 h. Other serious illness(es) involving the cardiac, respiratory, central nervous system (CNS), renal, hepatic or hematological organ systems which might preclude completion of this study or interfere with determination of causality of any adverse effects experienced in this study i. Radiation therapy for treatment of PC <4 weeks of C1D1 j . Chemotherapy for treatment of PC <4 weeks of C ID 1 k. Patients on stable dose of bisphosphonates or denosumab, which have been started no less than four weeks prior to treatment start, may continue on this medication, however subjects were not allowed to initiate bisphosphonate/denosumab therapy during the DLT-assessment period of the study l. Having partners of childbearing potential and not willing to use a method of birth control deemed acceptable by the Principal Investigator and chairperson during the study and for one month after last study drug administration m. Currently active other malignancy other than non-melanoma skin cancer. Patients are considered not to have “currently active” malignancy if they have completed any necessary therapy and are considered by their physician to be at less than 30% risk of relapse n. Known history of known myelodysplastic syndrome o. Bone scan with confluent lesions and lack of urinary tracer consistent with a “superscan” as determined by the investigator The Study:

[0144] The study utilized a modified 3+3 dose-escalation study design, with the planned initial and subsequent escalating dose levels described in Table 5, Table 6, and Table 7. NCI CTCAE version 5.0 was used to grade all adverse events (AEs). Table 5: Dose-Escalation Plan with Fractionated ²²⁵Ac-huJ591 for Subjects not Required to have prior ¹⁷⁷Lu-PSMA-RL (pre/post-¹⁷⁷Lu-PSMA-RL )

Table 6: Dose-Escalation Plan with Fractionated ²²⁵Ac-huJ591 for Subjects Required to have prior ¹⁷⁷Lu-PSMA-RL (Post-¹⁷⁷Lu-PSMA-RL )

Table 7: Dose-Escalation Plan with Multiple Dose ²²⁵Ac-huJ591

[0145] For the fractionated dose regimen, the DLT evaluation period begins with treatment on CID 1 and continues for a period of 8 weeks. [0146] For the multiple dose regimen, the DLT evaluation period begins with treatment on C1D1 (cycle 1, day one) through treatment on C3D1 (cycle 3, day one). For subjects not receiving C3 therapy, the DLT evaluation period is for six weeks after C2.

[0147] As per the DLT definition, for those that are without DLT after six weeks, but ineligible for C3 treatment due to possibly related adverse event, an additional three-week DLT assessment period will be observed (nine weeks after C2). All fractionated dose regimen and multiple dose regimen subjects were followed-up for radiographic progression (up to 6 months).

[0148] A DLT for dose-escalation cohorts is defined as: a. Grade 4 neutropenia or any occurrence of febrile neutropenia b. Grade 4 thrombocytopenia or Grade 3 thrombocytopenia associated with major bleeding c. Any Grade > 2 non-hematologic toxicity deemed to be at least possibly related to 2²⁵Ac-huJ591 will be termed as dose-limiting toxicity.

[0149] Additionally, any grade toxicity attributed to study drug that precludes treatment with DI 5 therapy by more than two weeks in the fractionated dose regimen is considered a DLT. Any grade toxicity attributed to study drug that precludes treatment with C2 or C3 of therapy by more than three weeks in the multiple dose regimen is considered a DLT. However, delays in subsequent doses of therapy due to issues such as scheduling or availability of radionuclide are not considered a DLT.

[0150] All toxi cities as described above are considered DLTs if they are at least possibly related to ²²⁵Ac-huJ591 as judged by the investigator. Attribution is reviewed by the study chair and discussed with the medical monitor if there are questions about severity or attribution.

[0151] The MTD is defined as the dose level at which no more than one subject out of six experiences DLT during the DLT evaluation period.

[0152] Duration of treatment: Duration of treatment for the fractionated dose regimen was 15 days, with doses administered on CID 1 and C1D15.

[0153] Disposition and Exposure: Subjects with mCPRC were enrolled into the fractionated dose regimen in four dose levels consisting of subjects pre/post-¹⁷⁷Lu-PSMA-RL therapy and in one dose level of subjects post-¹⁷⁷Lu-PSMA-RL . All 28 subjects enrolled received at least one dose of ²²⁵Ac-huJ591, and 25 received the full two dose regimen and completed the study, (see Table 8). Table 8: Dose Level for the Fractionated Dose Regimen

[0154] The study initially enrolled subjects in the fractionated dose regimen with and without or prior ¹⁷⁷Lu-PSMA-RL therapy (pre/post-¹⁷⁷Lu-PSMA-RL therapy) at three increasing dose levels (45 KBq/kg, 55 KBq/kg, and 65 KBq/kg). The 65 KBq/kg level has since been reduced to 60 KBq/kg. Four subjects that were previously dosed with ¹⁷⁷Lu-PSMA therapy were enrolled into the 50 KBq/kg dose level.

[0155] Duration of treatment: Duration of treatment for the multiple dose regimen was up to 24 weeks, with doses administered Q6W for up to four cycles.

[0156] 18 subjects with mCPRC were enrolled into the multiple dose regimen in three

225 dose levels. All 18 subjects enrolled received at least one dose of Ac-huJ591, 17 subjects 225 225 received two doses of Ac-huJ591, eight subjects received three doses of Ac-huJ591, and four subjects received the full four dose regimen and completed the study. See Table 9.

Table 9: Disposition by Dose Level for the Multiple Dose Regimen

[0157] Demographics and Baseline Characteristics for the Fractionated Dose Regimen: The median age at enrollment was 74 years (range 57-91 years) and the median PSA at C1D1 was 30 ng/mL. The majority of subjects were Caucasian and non-Hispanic/Latino. Most subjects had a performance status of ECOG PS 1. 75% of subjects (21/28) previously received chemotherapy, 18% of subjects (5/28) received prior ¹⁷⁷Lu-PSMA-RL therapy. 11% of subjects (3/28) received prior radium-223 (Ra-223), and 4% of subjects (1/28) received prior ¹⁷⁷Lu- PSMA-RL . 46% of subjects (13/28) received one prior androgen receptor signaling inhibitor (ARSI), 43% of subjects (12/28) received two prior ARSIs, and 11% of subjects (3/28) received three prior ARSIs. 43% of subjects (12/28) had bone only metastatic disease at baseline, while 32% of subjects (9/28) had bone and soft tissue involvement, and 14% of subjects (4/28) had soft tissue only disease. Disease location was not reported for three subjects. The median circulating tumor cell (CTC) enumeration at baseline was 12 cells.

[0158] Demographics and Baseline Characteristics for the Multiple Dose Regimen: The median age at enrollment was 71 years (range 51-95 years) and the median PSA at CID 1 was 122 ng/mL. The majority of subjects were Caucasian and non-Hispanic/Latino. Most subjects had a performance status of ECOG PS 1. 89% of subjects (16/18) previously received chemotherapy, 6% (1/18) received prior ¹⁷⁷Lu-PSMA-RL therapy. 39% of subjects (7/18) received one prior ARSI, 44% of subjects (8/18) received two prior ARSIs, and 17% of subjects (3/18) received three prior ARSIs. 89% of subjects (16/18) had bone and soft tissue involvement, and 11% of subjects (2/18) had soft tissue only disease. The median circulating tumor cell (CTC) enumeration at baseline was 12 cells.

[0159] Safety Results:

[0160] In the fractionated dose regimen, no dose limiting toxicities (DLT) were observed in the 45 or 55 KBq/kg dose levels in the pre/post-¹⁷⁷Lu-PSMA-RL cohort. At the 65 KBq/kg dose level in the pre/post-¹⁷⁷Lu-PSMA cohort, two DLTs were observed (Grade 2 platelet count decreased leading to a >2 -week treatment delay and Grade 4 platelet count decreased). These DLTs resulted in dose reduction to the 60 KBq/kg dose level, where another Grade 4 platelet count decreased DLT was observed and the dose level was expanded to six subjects. One DLT, Grade 4 platelet count decreased, was observed so far in the ongoing 50 KBq/kg dose level in the post-¹⁷⁷Lu-PSMA-RL cohort. The RP2D for the fractionated dose regimen for subjects who received prior chemotherapy for mCRPC with and without prior ¹⁷⁷Lu-PSMA-RL treatment is 120 KBq/kg given over two fractions of 60 KBq/kg.

[0161] All subjects (28/28) in the fractionated dose regimen experienced at least one treatment-emergent adverse event (TAEA) and at least one treatment-related adverse event (TRAE). Grade 3 or higher TAEAs were reported in 93% of subjects (26/28) in the fractionated dose regimen, of which 89% of subjects (25/28) experienced at least one Grade 3 or higher TRAE. 18% of subjects (5/28) in the fractionated dose regimen experienced at least one serious TAEA of which one event was considered related to the study drug (Grade 4 platelet count decreased). No subjects died as a result of a TAEA in the fractionated dose regimen. [0162] In the multiple dose regimen, two DLTs were observed at the 65 KBq/kg dose level (Grade 3 platelet count decreased and Grade 1 platelet count decreased that precluded treatment with C3). These DLTs resulted in dose reduction to the 55 KBq/kg dose level, where three additional DLTs were observed (Grade 3 platelet count decreased and two instances of Grade 4 platelet count decreased). These DLTs resulted in a subsequent dose reduction to the 45 KBq/kg dose level, where two DLTs were observed (Grade 1 platelet count decreased that precluded treatment with C3 and Grade 2 platelet count decreased that precluded treatment with C3).

[0163] All subjects (18/18) in the multiple dose regimen experienced at least one TEAE and at least one TRAE. Grade 3 or higher TEAEs were reported in 89% of subjects (16/18) in the multiple dose regimen, all of whom experienced at least one Grade 3 or higher TRAE. 50% of subjects (9/18) in the multiple dose regimen experienced at least one serious TEAE.

[0164] As expected, thrombocytopenia (platelet count decreased), lymphopenia (lymphocyte count decreased), and neutropenia (neutrophil count decreased) were the most common TRAEs, experienced by 89% (25/28), 89% (25/28), and 68% (19/28) of subjects, respectively, in the fractionated dose regimen, and 83% (15/18), 83% (15/18) and 50% (9/18) of subjects, respectively, in the multiple dose regimen. In the multiple dose regimen, seven TRAEs led to treatment discontinuation in six subjects: neutrophil count decreased (1/18, 6% of subjects), anemia (1/18, 6% of subjects) and platelet count decreased (5/18, 28% of subjects), with anemia in combination with platelet count decreased being the cause for treatment discontinuation in one subject (seven TRAEs leading to treatment discontinuation in 6/18, 33% of subjects). Increased transaminases determined to be related to study drug were observed in 50% of subjects (14/28), in the fractionated dose regimen however, all events were Grade 1 and did not result in treatment delay or discontinuation. Other Grade 3 and higher TRAEs reported in three or more subjects in the fractionated dose regimen overall included lymphocyte count decreased (23/28, 82% of subjects), white blood cell count decreased (8/28, 29% of subjects), neutrophil count decreased (6/28, 21% of subjects), platelet count decreased (5/28, 18% of subjects), and anemia (3/28, 11% of subjects).

[0165] The most commonly reported TEAEs across all grades occurring in >50% of subjects in the fractionated dose regimen included platelet count decreased, lymphocyte count decreased, neutrophil count decreased, white blood cell count decreased, fatigue, dry mouth, and increased transaminases. There were no Grade 5 TEAEs observed in the fractionated dose regimen. [0166] In the multiple dose regimen, other Grade 3 and higher TRAEs reported in three or more subjects overall included lymphocyte count decreased (15/18, 83% of subjects), platelet count decreased (8/18, 44% of subjects), white blood cell count decreased (5/18, 28% of subjects), and anemia (5/18, 28% of subjects).

[0167] The most commonly reported TEAEs across all grades occurring in >50% of subjects in the multiple dose regimen included anemia, nausea, decreased appetite, fatigue, platelet count decreased, lymphocyte count decreased, white blood cell count decreased, increased transaminases, and dry mouth. Platelet count decreased and neutrophil count decreased events were transient in both regimens, lasting a median of 34 and 22 days, respectively, from worst grade to resolution in the fractionated dose regimen and a median of 28 and 13 days, respectively, in the multiple dose regimen. There was only one Grade 5 TEAE observed in the multiple dose regimen (Grade 5 pneumonia).

[0168] Efficacy Results:

[0169] Within the fractionated dose regimen, the majority of the subjects (24/27, 89%) exhibited a decline in PSA levels, with the exception of three subjects who showed PSA elevations as best PSA response (one subject each in the 45 KBq/kg, 50 KBq/kg, and 60 KBq/kg dose levels, see FIG. 1). 67% of subjects (18/27) over all, 67%(2/3) in the 45 KBq/kg dose level, 50% of subjects (2/4) in the 50 KBq/kg dose level, 57% of subjects (4/7) in the 55 KBq/kg dose level, 71% of subjects (5/7) in the 60 KBq/kg dose level, and 83% of subjects (5/6) in the 65 KBq/kg dose level had a >50% decline in PSA. Among the 18 subjects in the fractionated dose regimen with a >25% PSA decline and follow-up PSA measurements, the median duration of PSA response was 49 days following the first >25% decline, with median duration of response the longest at the 65 KBq/kg dose level (98 days). See Table 10. subjects that are not included in the PSA response duration calculations, as noted in the table, and were excluded either because they did not have a >25% PSA decline or because PSA measurements following their initial decline were not available. Table 10: Duration of PSA Response of the Fractionated Dose Regimen (N=18)

PSA = prostate-specific antigen; IQR = interquartile range

*Ten subjects in the Efficacy analysis set are not included in the Duration of PSA Response analysis: seven subjects did not have a >25% PSA Response, one subject did not have follow-up PSA measurements post baseline, and two subjects had a >25% PSA Response but did not have subsequent follow-up PSA measurements (Overall N=18).

[0170] In the multiple dose regimen, the majority of the subjects (13/18, 72%) exhibited a decline in PSA levels, with the exception of five subjects who showed PSA elevations as best PSA response, two subjects in the 65 KBq/kg dose level and three subjects in the 55 KBq/kg dose level (see FIG. 2). 28% of subjects (5/18) overall, 33% of subjects (2/6) in the 65 KBg/kg dose level, 17% of subjects (1/6) in the 55 KBq/kg dose level, and 33% of subjects (2/6) in the 45 KBq/kg dose level had a >50% decline in PSA. Among the 7 subjects in the multiple dose regimen with a >25% PSA decline and follow-up PSA measurements, the median duration of PSA response was 49 days following the first >25% decline, with median duration of response the longest at the 55 KBq/kg dose level (77 days). See Table 11.

Table 11: Duration of PSA Response of the Multiple Dose Regimen (N=7)

PSA = prostate-specific antigen; IQR = interquartile range *Eleven subjects in the Efficacy analysis set are not included in the Duration of PSA Response analysis: eight subjects did not have a >25% PSA Response and three subjects had a >25% PSA Response but did not have subsequent follow-up PSA measurements (Overall N=7).

[0171] bPFS for the fractionated dose regimen is summarized in Table 12. Table 12: bPFS by Dose Level of the Fractionated Dose Regimen

[0172] bPFS for the multiple dose regimen is summarized in Table 13.

Table 13: bPFS by Dose Level of the Multiple Dose Regime [0173] Subjects in the fractionated dose regimen treated at the 65 KBq/kg dose level demonstrated the best response in biochemical progression-free survival (bPFS) (243 days), and a trend toward bPFS dose-response was observed as dose level increased, with the exception of the 60 KBq/kg dose level where median bPFS was 105 days, versus 112 days in the 45 KBq/kg dose level and 138 days in the 55 KBq/kg dose level. [0174] In the multiple dose regimen, subjects in the 45 KBq/kg dose level demonstrated the best improvement in bPFS where median bPFS was 198 days, followed by 65 KBq/kg with a median bPFS of 152 days, and 55 KBq/kg with a median bPFS of 113 days. [0175] Conclusion:

[0176] This ongoing study evaluating dose escalation of a fractionated and multiple dose regimen of ²²⁵Ac-huJ591 in men with heavily pretreated progressive mCRPC demonstrated a satisfactory safety profile in the fractionated dose regimen. Evaluation of the safety profile in the multiple dose regimen remains ongoing, but preliminary results show that this regimen may be less efficacious and not as well tolerated as the fractionated dose regimen. A majority of subjects experienced declines in PSA levels, with 64% of subjects in the fractionated dose regimen and 28% of subjects in the multiple dose regimen experiencing a PSA response of >50% PSA. There were four DLTs in the fractionated dose regimen with no DLTs experienced in the lower dose levels (45 and 55 KB/kg), leading to determination of a cumulative MTD and RP2D of 120 KBq/kg. There were seven DLTs in the multiple dose regimen with DLTs at every dose level. It is important to note that the platelet count decreased, neutrophil count decreased and dry mouth were transient in both regimens, lasting a median of 34, 22 days and 76 days, respectively, from worst grade to resolution in the fractionated dose regimen, and a median of 28, 13 and 7 days, respectively, in the multiple dose regimen.

[0177] Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow.

Claims

WHAT IS CLAIMED IS:

1. A method of treating cancer in a patient in need thereof, comprising administering to the patient an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591,and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the patient received prior treatment with a PSMA radioligand.

2. The method of claim 1, wherein the PSMA radioligand is PSMA 617-Lu¹⁷⁷ and/or PSMA I&T- Lu¹⁷⁷.

3. The method of claim 1 or 2, wherein the cancer is prostate cancer.

4. The method of claim 1 or 2, wherein the cancer is a PSMA expressing cancer.

5. The method of claim 3, wherein the prostate cancer is metastatic castration-resistant prostate cancer (mCRPC).

6. The method of claim 3, wherein the prostate cancer is castration-sensitive prostate cancer.

7. The method of any one of claims 1-6, wherein the cancer is relapsed cancer.

8. The method of any one of claims 1-6, wherein the cancer is refractory cancer.

9. A method of treating or ameliorating prostate cancer in a patient in need thereof, comprising administering to the patient an agent comprising a targeting component coupled to a cancer therapeutic component, wherein the targeting component is huJ591 and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the patient has not received, or does not require, a PSMA PET scan prior to treatment.

10. The method of any one of claims 1-9, wherein the agent is huJ591-DOTA-Ac²²⁵.

11. The method of any one of claims 1-10, wherein a dose of about 10 KBq/Kg to about 130 KBq/Kg of the agent is administered to the patient.

12. The method of claim 11, wherein a dose of about 13.3 KBq/Kg to about 93.3 KBq/Kg of the agent is administered to the patient.

13. The method of claim 12, wherein a dose of about 40 KBq/Kg to about 65 KBq/Kg of the agent is administered to the patient.

14. The method of claim 13, wherein a dose of about 40 KBq/Kg, 45 KBq/Kg, about 55 KBq/Kg, about 60 KBq/Kg, about 65 KBq/Kg of the agent is administered to the patient.

15. The method of claim 14, wherein a dose of about 45 KBq/Kg of the agent is administered to the patient.

16. The method of claim 14, wherein a dose of about 55 KBq/Kg of the agent is administered to the patient.

17. The method of claim 14, wherein a dose of about 60 KBq/Kg of the agent is administered to the patient.

18. The method of claim 14, wherein a dose of about 65 KBq/Kg of the agent is administered to the patient.

19. The method of any one of claims 1-18, comprising administering an initial dose and at least one subsequent dose of the agent to the patient.

20. The method of claim 19, wherein the wherein the cumulative amount of the agent administered in the initial dose and the subsequent dose or subsequent doses is between about 60 KBq/Kg and about 130 KBq/Kg or between about 60 KBq/Kg and about 340 KBq/Kg.

21. The method of claim 19 or 20, wherein the cumulative amount of the agent administered in the initial dose and the subsequent dose is about 80 KBq/Kg, about 90 KBq/Kg, about 90 KBq/Kg, about 110 KBq/Kg, about 120 KBq/Kg, or about 130 KBq/Kg.

22. The method of any one of claims 19-21, wherein the initial dose of the agent is about 45 KBq/Kg, and the subsequent dose of the agent is about 45 KBq/Kg.

23. The method of any one of claims 19-21, wherein the initial dose of the agent is about 55 KBq/Kg, and the subsequent dose of the agent is about 55 KBq/Kg.

24. The method of any one of claims 19-21, wherein the initial dose of the agent is about 60 KBq/Kg, and the subsequent dose of the agent is about 60 KBq/Kg.

25. The method of any one of claims 19-21, wherein the initial dose of the agent is about 65 KBq/Kg, and the subsequent dose of the agent is about 65 KBq/Kg.

26. The method of any one of claims 19-25, wherein the subsequent dose is administered at least about two weeks after the initial dose.

27. The method of claim 26, wherein the subsequent dose is administered two to three weeks after the initial dose.

28. The method of claim 26, wherein the subsequent dose is administered 14 days after the initial dose.

29. The method of any one of claims 1-18, wherein the agent is administered as a single dose repeated in a 6-week cycle (q6w).

30. The method of claim 29, wherein the agent is administered for at least one cycle.

31. The method of claim 30, wherein the agent is administered for up to 4 cycles.

32. The method of any one of claims 1-31, wherein the patient is treated for at least about 8 weeks, at least about 10 weeks, at least about 12 weeks, at least about 14 weeks, at least about 16 weeks, at least about 18 weeks, at least about 20 weeks, at least about 22 weeks, at least about 24 weeks or at least about 26 weeks.

33. A method of treating cancer in a patient in need thereof, comprising administering to the patient: an initial dose and a subsequent dose of an agent comprising a targeting component coupled to a cancer therapeutic component; wherein the targeting component is huJ591,and the cancer therapeutic component is a ²²⁵ Ac radionuclide; and wherein the cumulative amount of the agent administered in the initial dose and the subsequent dose is in the range of about 90 KBq/Kg to about 130 KBq/Kg or the range of about 90 KBq/Kg to about 340 KBq/Kg.

34. The method of claim 33, wherein the cumulative amount of the agent is about 90 KBq/Kg, about 110 KBq/Kg, about 120 KBq/Kg, or about 130 KBq/Kg.

35. The method of claim 33 or 34, wherein the initial dose of the agent is about 45 KBq/Kg, and the subsequent dose of the agent is about 45 KBq/Kg.

36. The method of claim 33 or 34, wherein the initial dose of the agent is about 55 KBq/Kg, and the subsequent dose of the agent is about 55 KBq/Kg.

37. The method of claim 33 or 34, wherein the initial dose of the agent is about 60 KBq/Kg, and the subsequent dose of the agent is about 60 KBq/Kg.

38. The method of claim 33 or 34, wherein the initial dose of the agent is about 65 KBq/Kg, and the subsequent dose of the agent is about 65 KBq/Kg.

39. The method of any one of claims 33-38, wherein the subsequent dose is administered at least about two weeks after the initial dose.

40. The method of claim 39, wherein the subsequent dose is administered about 14 days after the initial dose.

41. The method of any one of claims 33-40, wherein the cancer is a PSMA expressing cancer.

42. The method of any one of claims 33-41, wherein the cancer is prostate cancer.

43. The method of claim 42, wherein the prostate cancer is metastatic castration-resistant prostate cancer (mCRPC).

44. The method of claim 42, wherein the prostate cancer is castration-sensitive prostate cancer.

45. The method of any one of claims 1-18, comprising administering an initial dose and an additional 3 cycles of the agent to the patient.

46. The method of claim 45, wherein the cumulative amount of the agent administered in four cycles is between about 100 KBq/Kg and about 500 KBq/Kg.

47. The method of claim 45, wherein the cumulative amount of the agent administered in four cycles is between about 150 KBq/Kg and about 400 KBq/Kg.

48. The method of claim 45, wherein the cumulative amount of the agent administered in four cycles is between about 180 KBq/Kg and about 340 KBq/Kg.

49. The method of any one of claims 45-48, wherein the cumulative amount of the agent administered is about 180 KBq/Kg, about 220 KBq/Kg, about 260 KBq/Kg, about 300 KBq/Kg or about 340 KBq/Kg.

50. The method of any one of claims 45-49, wherein each dose of the agent per cycle is about 30 KBq/Kg to about 100 KBq/Kg.

51. The method of any one of claims 45-49, wherein each dose of the agent per cycle is about 40 KBq/Kg to about 90 KBq/Kg.

52. The method of any one of claims 45-49, wherein each dose of the agent per cycle is about 45 KBq/Kg to about 85 KBq/Kg.

53. A method of treating cancer in a patient in need thereof, comprising administering to the patient: a initial dose and three subsequent doses in total of 4 cycles of an agent comprising a targeting component coupled to a cancer therapeutic component; wherein the targeting component is huJ591, and the cancer therapeutic component is a Ac²²⁵ radionuclide; and wherein the cumulative amount of the agent administered in the cumulative dose is in the range of about 100 KBq/Kg and about 500 KBq/Kg.

54. The method of claim 53, wherein the cumulative amount of the agent administered in four cycles is between about 150 KBq/Kg and about 400 KBq/Kg.

55. The method of claim 53, wherein the cumulative amount of the agent administered in four cycles is between about 180 KBq/Kg and about 340 KBq/Kg.

56. The method of any one of claims 53-55 wherein the cumulative amount of the agent administered is about 180 KBq/Kg, about 220 KBq/Kg, about 260 KBq/Kg, about 300 KBq/Kg or about 340 KBq/Kg.

57. The method of any one of claims 53-55, wherein each dose of the agent per cycle is about 30 KBq/Kg to about 100 KBq/Kg.

58. The method of any one of claims 53-55, wherein each dose of the agent per cycle is about 40 KBq/Kg to about 90 KBq/Kg.

59. The method of any one of claims 53-55, wherein each dose of the agent per cycle is about 45 KBq/Kg to about 85 KBq/Kg.

60. The method of any one of claims 45-59, wherein each dose is administered at least 2 weeks apart, 3 weeks apart, 4 weeks apart, 5 weeks about 6 weeks apart, 7 weeks apart, or 8 weeks apart.

61. The method of any one of claims 1-60, wherein the agent is huJ591-DOTA-Ac²²⁵.

62. The method of any one of claims 1-61, wherein any non-cumulative dose amount is a daily dose amount.

63. The method of any one of claims 1-62, wherein after said treating the patient experiences a PSA decline compared to baseline prior to treatment.

64. The method of claim 63, wherein after said treating the patient experiences a PSA decline of at least about 50% compared to baseline prior to treatment.

65. The method of any one of claims 1-64, wherein after said treating the patient experiences a decline in CTC count.

66. The method of claim 65, wherein after said treating, the patient has undetectable CTC count.

67. The method of any one of claims 1-66, wherein the agent is administered intravenously.

68. The method of any one of claims 1-67, wherein the patient is human.