Compositions and methods for treating prostate cancer

Abstract

The present invention provides compositions and methods for the treatment of cancer, particularly prostate cancer. According to certain embodiments, a method for treating cancer in a patient comprises administering to the patient a therapeutically effective amount of a radioconjugate, the radioconjugate comprising an antibody or antigen-binding domain with binding specificity for hK2. A pharmaceutical composition comprising a radiolabeled antibody with binding specificity for hK2 is also provided herein.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 193,704, filed May 27, 2021, and U.S. Provisional Patent Application No. 63 / 335,761, filed April 28, 2022, which are incorporated by reference herein in their entireties for all purposes.

[0002] FIELD OF THEINVENTION FIELD OF THEINVENTION Embodiments of the present invention relate to compositions and methods for the treatment of prostate cancer. In particular, embodiments of the present invention relate to radioconjugate compositions for hK2 targeted therapy.

[0003] (Reference to electronically submitted sequence listing) This application contains a Sequence Listing that has been submitted electronically via EFS-Web as an ASCII formatted Sequence Listing with the filename "JBI6423WOPCT1_SeqListing.txt", created on May 12, 2022, and having a size of 17kb. The Sequence Listing submitted via EFS-Web is a part of the present specification and is incorporated by reference in its entirety herein. [Background technology]

[0004] Prostate cancer is one of the most common forms of cancer. Tumor growth is a process that usually occurs over a long period of time. Prostate cancer is often a mild form of cancer. In fact, the majority of people diagnosed with prostate cancer survive and recover. A small number of people encounter a more aggressive form of prostate cancer that metastasizes early. This aggressive form of prostate cancer can only be cured if it is diagnosed early, before the cancer spreads to extracapsular tissue.

[0005] The landscape for the management of patients with metastatic castration-resistant prostate cancer (mCRPC) has changed with the approval of several new agents, including androgen receptor (AR)-directed therapies (e.g., enzalutamide and abiraterone acetate plus prednisone), chemotherapy (e.g., docetaxel and cabazitaxel), and cellular immunotherapy (e.g., sipuleucel-T). With these agents, overall survival has improved from previously reported 6-10 months to a range of 18-24 months. However, most prostate cancer patients experience disease progression within 13-20 months of antiandrogen or androgen synthesis inhibitor treatment. Summary of the Invention

[0006] New therapeutic agents and methods for treating and diagnosing prostate cancer remain needed, and in particular, therapies with mechanisms of action that overcome resistance pathways are crucial in developing alternative strategies for the treatment of mCRPC.

[0007] The present invention relates to pharmaceutical compositions, methods of making pharmaceutical compositions, and methods of treating cancer in patients in need of such treatment.

[0008] According to one embodiment of the invention, a method for treating cancer in a patient comprises administering to the patient a therapeutically effective amount of a pharmaceutical composition comprising a radioconjugate and one or more pharma- ceutically acceptable excipients, wherein the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2, the radiometal complex comprising a radioactive metal, which upon administration provides a target radioactivity of about 50 μCi to about 350 μCi per dose of the pharmaceutical composition.

[0009] According to one embodiment of the invention, a method for treating cancer in a patient comprises administering to the patient a therapeutically effective amount of a pharmaceutical composition comprising a radioconjugate and one or more pharma- ceutical acceptable excipients, the radioconjugate comprising at least one radiometal complex conjugated to an antibody having binding specificity for hK2, the radiometal complex comprising: 225 Ac, which upon administration provides a target radioactivity of about 50 μCi to about 350 μCi per dose of the pharmaceutical composition.

[0010] According to one embodiment, the radioconjugate comprises at least one radioactive metal complex conjugated to an antibody having binding specificity for hK2, the antibody comprising a heavy chain variable region comprising the amino acid sequences of SEQ ID NO:1, SEQ ID NO:2 and SEQ ID NO:3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO:4, SEQ ID NO:5 and SEQ ID NO:6.

[0011] According to one embodiment, the radiometal complex comprises a chelating agent that is DOTA.

[0012] According to one embodiment, the radioconjugate has the formula (a)

[0013] [ka] (In the formula, R1 is hydrogen and R2 is -L1-R4; Alternatively, R1 is -L1-R4 and R2 is hydrogen; R3 is hydrogen; or R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, the 5- or 6-membered cycloalkyl being optionally substituted with -L1-R4; L1 is absent or is a linker, R4 is an antibody, or a pharma- ceutically acceptable salt thereof; or

[0014] (b) Formula (V)

[0015] [ka] (In the formula, L1 is absent or is a linker, R4 is an antibody, or a pharma- ceutical acceptable salt thereof; For example, the chelating agent may have the formula:

[0016] [ka] or a pharma- ceutically acceptable salt thereof.

[0017] According to one embodiment, the radiometal is 225 Ac, and the radiometal provides a target specific activity of about 25 μCi to about 350 μCi per about 2 mg of total antibody, or about 50 μCi to about 350 μCi per about 2 mg of total antibody.

[0018] According to one embodiment, the method comprises administering the pharmaceutical composition intravenously to the patient.

[0019] The embodiments of the present invention are particularly useful in treating patients who have been diagnosed with prostate cancer, for example, patients with late-stage prostate cancer. According to one embodiment, the cancer is non-localized prostate cancer. According to another embodiment, the cancer is metastatic prostate cancer. According to another embodiment, the cancer is castration-resistant prostate cancer (CRPC). According to another embodiment, the cancer is metastatic castration-resistant prostate cancer (mCRPC). According to another embodiment, the cancer is mCRPC with adenocarcinoma.

[0020] Another embodiment of the present invention provides a pharmaceutical composition comprising a radioconjugate and one or more pharma- ceutically acceptable excipients, wherein the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2, and the radiometal complex comprises a radiometal.

[0021] According to one embodiment, the pharmaceutical composition comprises a radioconjugate and one or more pharma- ceutically acceptable excipients, the radioconjugate comprising at least one radiometal complex conjugated to an antibody having binding specificity for hK2, the radiometal complex comprising: 225 The antibody comprises a heavy chain variable region comprising the amino acid sequences of SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6.

[0022] According to one embodiment, the one or more pharma- ceutically acceptable excipients include one or more radioprotectants such as sodium ascorbate, gentisic acid, or a combination thereof (e.g., in an amount of about 0.1 to about 5 w / v%, or about 0.1 to about 4 w / v%, or about 0.1 to about 3 w / v%, about 0.1 to about 2 w / v%, or about 0.1 to about 1 w / v%, or about 0.25 to about 0.75 w / v%, or about 0.5 w / v%).

[0023] According to one embodiment, the one or more pharma- ceutical acceptable excipients include one or more surfactants, such as polysorbate 20.

[0024] According to one embodiment, the pharmaceutical composition comprises a radioconjugate, sodium ascorbate, polysorbate 20, acetate buffer, and water.

[0025] According to one embodiment, the pharmaceutical composition comprises a radioconjugate, about 24-28 mM acetic acid, about 0.25-0.75 w / v % sodium ascorbate, and about 0.01-0.15 w / v % polysorbate 20 in water.

[0026] According to one embodiment, the pharmaceutical composition has a pH of about 5 to about 6 (eg, about 5.5).

[0027] According to one embodiment, the pharmaceutical composition does not contain any cryoprotectants, such as sugars or sugar alcohols.

[0028] According to one embodiment, the radiometal is 225 Ac, the radiometal provides a specific radioactivity of about 50 μCi to about 350 μCi per about 2 mg of total antibody upon dosing.

[0029] According to one embodiment, the pharmaceutical composition comprises a total amount of the conjugate intermediate and the radioconjugate in an amount of about 0.1-1.0 mg / mL, for example, about 0.5 mg / mL.

[0030] Another embodiment of the present invention provides a method of making a pharmaceutical composition comprising combining a first intermediate composition and a second intermediate composition to form the pharmaceutical composition, wherein the first intermediate composition comprises a radioconjugate and the second intermediate composition comprises a conjugate intermediate and does not contain any radioconjugate. [Brief description of the drawings]

[0031] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the invention. The invention may be better understood by reference to one or more of these drawings in combination with the description of specific embodiments presented herein. [Figure 1A] 1 is a high performance liquid chromatograph of a drug product composition. [Figure 1B] This is a high-performance liquid chromatograph of 111In-DOTA-h11B6. [Figure 2A] 2A-2C are high performance liquid chromatographs of 225Ac-DOTA-h11B6 drug product containing sucrose and lacking ascorbic acid at T=0 (FIG. 2A) and T=96 hours (FIG. 2A). [Figure 2B] 2A-2C are high performance liquid chromatographs of 225Ac-DOTA-h11B6 drug product containing sucrose and lacking ascorbic acid at T=0 (FIG. 2A) and T=96 hours (FIG. 2A). [Figure 3A] 3A and 3B are high performance liquid chromatographs of the drug product. The composition contains about 50 μCi of 225Ac-DOTA-h11B6 per 4 mL of drug product (FIGS. 3A and 3B). The compositions of FIGS. 3A and 3C further contain sodium ascorbate. [Figure 3B] 3A and 3B are high performance liquid chromatographs of the drug product. The composition contains about 50 μCi of 225Ac-DOTA-h11B6 per 4 mL of drug product (FIGS. 3A and 3B). The compositions of FIGS. 3A and 3C further contain sodium ascorbate. [Figure 3C] 3B and 3D are high performance liquid chromatographs of the drug product. The composition contains 200 μCi of 225Ac-DOTA-h11B6 per 4 mL of drug product (FIGS. 3C and 3D). The compositions of FIG. 3B and 3D further contain sucrose. [Figure 3D] 3B and 3D are high performance liquid chromatographs of the drug product. The composition contains 200 μCi of 225Ac-DOTA-h11B6 per 4 mL of drug product (FIGS. 3C and 3D). The compositions of FIG. 3B and 3D further contain sucrose. [Figure 4A] Illustrates an example of a radioconjugate of the present invention (the bond between Ac-225 and the chelator not shown). [Figure 4B] Illustrates an example of a radioconjugate of the present invention (the bond between Ac-225 and the chelator not shown). [Figure 5A] 1 illustrates an example of a conjugate intermediate of the present invention. An illustration of a conjugate intermediate containing DOTA (lysine moiety not shown) is provided. [Figure 5B] 1 illustrates an example of a conjugate intermediate of the present invention.

[0023] FIG. 1 provides an illustration of a conjugate intermediate containing DOTA (representing a lysine moiety). [Figure 5C]1 illustrates an example of a conjugate intermediate of the present invention.

[0023] FIG. 1 provides an illustration of the conjugation process of a conjugate intermediate containing DOTA. [Figure 6A] 1 illustrates an example of a conjugate intermediate (TOPA-h11B6) of the present invention.

[0023] FIG. 1 provides an illustration of a conjugate intermediate (lysine moiety not shown) that includes a TOPA chelator (TOPA-h11B6). [Figure 6B] 6A-6C illustrate an example of a conjugate intermediate (TOPA-h11B6) of the present invention.FIG. 6A provides an illustration of the conjugate intermediate (representing the lysine moiety) shown in FIG. [Figure 6C] 1 illustrates an example of a conjugate intermediate (TOPA-h11B6) of the present invention. 2 provides an illustration of the conjugation process of the conjugate intermediate. [Figure 7] 1 shows the amino acid sequences of the bulk heavy and light chains of the h11B6 antibody. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The compounds, compositions and methods described herein are useful for treating cancer in patients who need such treatment.Embodiments of the compounds, compositions and methods are effective in treating advanced stage prostate cancer, particularly prostate cancer including castration-resistant prostate cancer (CRPC), thus resulting in longer survival rates for patients.These compounds are particularly useful in patients who are considered to have failed existing treatments for advanced stage prostate cancer.

[0033] Human kallikrein 2 (hK2) is a trypsin-like antigen produced by columnar prostate epithelial cells and driven by androgen receptor (AR) signaling in a manner identical to the closely related prostate-specific antigen (PSA) human glandular kallikrein 3, which shares 80% homology genetically with the PSA gene. However, unlike PSA, circulating levels of hK2 are found at exceptionally low levels, where they can be bound by multiple protease inhibitor complexes. hK2 is thought to be primarily secreted, but there is evidence that it can induce internalization via antigen-antibody complexes, and thus it is thought to be present on the cell surface as well. hK2 expression is highly specific for prostate adenocarcinoma and increases over disease progression, making hK2-targeted therapy attractive.

[0034] An exemplary hK2 sequence is set forth as transcript:KLK2-201 (ENST00000325321), provided herein as SEQ ID NO:7, and is the product of gene ENSG00000167751, as provided in the Ensemble database.

[0035] Certain terms "Antigen-binding fragment" or "antigen-binding domain" refers to a portion of an isolated protein that binds to an antigen. Antigen-binding fragments may be synthetic, enzymatically obtainable, or genetically engineered polypeptides, including antigen-binding immunoglobulin portions (such as VH, VL, VH, and VL), Fab, Fab', F(ab')2, Fd, and Fv fragments, domain antibodies (dAbs) consisting of one VH domain or one VL domain, shark variable IgNAR domains, camelized VH domains, VHH domains, minimal recognition units consisting of amino acid residues mimicking the CDRs of an antibody such as the FR3-CDR3-FR4 portion, HCDR1, HCDR2, and / or HCDR3, and LCDR1, LCDR2, and / or LCDR3, alternative scaffolds that bind antigen, and multispecific proteins comprising antigen-binding fragments. Antigen-binding fragments (such as VH and VL) can be linked together via synthetic linkers to form various types of single chain antibody designs in which, when the VH and VL domains are expressed as separate single chains, the VH / VL domains can pair intramolecularly or intermolecularly to form monovalent antigen-binding domains, such as single chain Fvs (scFvs) or diabodies.

[0036] "Antibody" has a broad meaning and includes immunoglobulin molecules, including monoclonal antibodies, including murine, human, humanized, and chimeric monoclonal antibodies, multispecific antibodies (such as antigen-binding fragments, bispecific, trispecific, tetraspecific, dimeric, tetrameric, or multimeric antibodies), single-chain antibodies, domain antibodies, and any other modified configuration of an immunoglobulin molecule that contains an antigen-binding site of the required specificity. A "full-length antibody" is composed of two heavy chains (HC) and two light chains (LC), and multimers thereof (e.g., IgM), interconnected by disulfide bonds. Each heavy chain is composed of a heavy chain variable region (VH) and a heavy chain constant region (composed of domains CH1, hinge, CH2, and CH3). Each light chain is composed of a light chain variable region (VL) and a light chain constant region (CL). The VH and VL regions are interspersed with framework regions (FR) and may be further subdivided into regions of hypervariability called complementarity determining regions (CDRs). Each VH and VL is composed of three CDR and four FR segments arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4. Depending on the amino acid sequence of the heavy-chain constant domain, immunoglobulins can be assigned to five major classes, namely IgA, IgD, IgE, IgG, and IgM. IgA and IgG are further subdivided into isotypes IgA1, IgA2, IgG1, IgG2, IgG3, and IgG4. Antibody light chains of any vertebrate species can be assigned to one of two clearly distinct types, namely kappa (κ) and lambda (λ), based on the amino acid sequence of their constant domain.

[0037] The term "variant" when used with respect to an antigen or antibody can refer to a peptide or polypeptide that contains one or more (e.g., about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5, etc.) amino acid sequence substitutions, deletions, and / or additions compared to a native or unmodified sequence. For example, an hK2 variant can result from one or more (e.g., about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5, etc.) modifications to the amino acid sequence of native hK2. Also, by way of example, a variant of an anti-hK2 antibody, such as h11B6, can result from one or more (e.g., about 1 to about 25, about 1 to about 20, about 1 to about 15, about 1 to about 10, or about 1 to about 5, etc.) modifications to the amino acid sequence of a native or previously unmodified anti-hK2 antibody. The variants may be naturally occurring (such as allelic variants or splice variants) or artificially constructed. Polypeptide variants may be prepared from corresponding nucleic acid molecules encoding the variants. In certain embodiments, the hK2 variants or anti-hK2 antibody variants retain at least the functional activity of hK2 or anti-hK2 antibody, respectively. In certain embodiments, the anti-hK2 antibody variants bind to hK2 and / or are antagonistic to hK2 activity. In certain embodiments, the variants are encoded by single nucleotide polymorphism (SNP) variants of a nucleic acid molecule encoding the VH or VL region or subregion (such as one or more CDRs) of hK2 or an anti-hK2 antibody.

[0038] A non-limiting example of a variant, when used in reference to an antibody, is an "Fc variant," which is an antibody having a variant Fc region. A "variant Fc region" comprises an amino acid sequence that differs from the amino acid sequence of a native sequence Fc region by at least one amino acid modification (e.g., substitution, addition, or deletion). In certain embodiments, the variant Fc region has at least one amino acid substitution compared to a native sequence Fc region or the Fc region of a parent polypeptide, e.g., about 1 to about 10 amino acid substitutions, or about 1 to about 5 amino acid substitutions in the native sequence Fc region or the Fc region of a parent polypeptide. The variant Fc region herein can have at least about 80% homology to the native sequence Fc region and / or the Fc region of the parent polypeptide, or at least about 90% homology thereto, e.g., at least about 95% homology thereto.

[0039] The term "identity" refers to the relationship between the sequences of two or more polypeptide molecules or two or more nucleic acid molecules, as determined by aligning and comparing the sequences. "Percent sequence identity (%)" to a reference polypeptide sequence is defined as the percentage of amino acid residues in a candidate sequence that are identical to the amino acid residues in the reference polypeptide sequence, after aligning the sequences and introducing gaps as necessary to achieve the maximum percent sequence identity, and without considering any conservative substitutions as part of the sequence identity. Alignment for the purpose of determining percent amino acid sequence identity can be achieved using a variety of methods within the skill of the art, for example, publicly available computer software such as BLAST, BLAST-2, ALIGN, or MEGALIGN (DNAStar, Inc.) software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms required to achieve maximum alignment over the entire length of the sequences being compared.

[0040] "Specifically binds," "specific binding," "specifically binding," or "binds" refers to a proteinaceous molecule binding to an antigen or an epitope within an antigen with higher affinity than its affinity for other antigens. Typically, a proteinaceous molecule binds to an antigen with an affinity of about 1×10 -7 M or less, e.g., about 5 × 10 -8 M or less, approximately 1×10 -8 M or less, approximately 1×10 -9 M or less, approximately 1×10 -10 M or less, approximately 1×10 -11 M or less, or about 1 x 10 -12 The equilibrium dissociation constant (K D ) binds to an antigen or an epitope within an antigen, typically D is its K for binding to non-specific antigens (e.g., BSA, casein) D As used herein, an antibody or antigen-binding domain "having binding specificity for hK2" refers to an antibody or antigen-binding domain, respectively, that specifically binds to hK2.

[0041] As used herein, in certain embodiments, the term "subject" refers to a mammal, such as a non-primate (e.g., cows, pigs, horses, cats, dogs, rats, etc.) or a primate (e.g., monkeys and humans). In certain embodiments, the subject is a human. In one embodiment, the subject is a mammal, e.g., a human, who has been diagnosed with a condition or disorder. In another embodiment, the subject is a mammal, e.g., a human, who is at risk of developing a condition or disorder. As used herein, the term "patient" refers to a human.

[0042] "Administering" or "administration" refers to the act of physically delivering a substance present outside the body to a patient by injection or other means, such as by mucosal, intradermal, intravenous, intramuscular, subcutaneous delivery, and / or any other physical delivery method described herein or known in the art.

[0043] As used herein, the terms "treat", "treatment", and "treating" refer to the reduction or amelioration of the progression, severity, and / or duration of a disease or condition resulting from the administration of one or more therapies. Treatment may be determined by assessing whether there has been a reduction, alleviation, and / or mitigation of one or more symptoms associated with the underlying disease such that an improvement is observed in the patient, even though the patient may still be suffering from the underlying disease. The term "treat" includes both management and amelioration of the disease. The terms "manage", "managing", and "management" refer to the beneficial effects that a subject derives from a therapy, and do not necessarily result in a cure of the disease.

[0044] As used herein, the term "effective amount" or "therapeutically effective amount" refers to the amount of a radioconjugate or pharmaceutical composition provided herein that is sufficient to provide the desired therapeutic effect for a given condition and administration regimen.

[0045] The terms drug, pharmaceutical, active agent, active pharmaceutical ingredient (API), drug, agent, and activity are used interchangeably herein to refer to a pharma- ceutical active compound in a pharmaceutical composition. One example of an API suitable for use according to the present invention is a radioconjugate with binding specificity for hK2. A pharmaceutical composition may include one or more APIs and one or more additional components, referred to herein as "excipients." Preferably, the excipients are substantially or completely pharma- ceutical inert.

[0046] The term "dose" refers to the total amount of a particular pharmaceutical composition administered to a patient at a particular time. Preferably, the dose is delivered as a single administration of a unit dose of the pharmaceutical composition (e.g., via intravenous administration). Alternatively, there may be multiple administrations of a unit dose that is subdivided into multiple partial doses (a partial dose refers to a portion of a unit dose).

[0047] As used herein, the term "pharmaceutical acceptable" means non-toxic and preferably approved by, e.g., a European or U.S. federal or state regulatory agency or listed in the U.S. Pharmacopeia or other generally recognized pharmacopoeias for use in animals, and more specifically in humans.

[0048] Radioactive decay refers to the process by which unstable atomic nuclei lose energy through radiation to produce at least one daughter nuclide. Half-life refers to the time required for half of the atomic nuclei in a radioactive sample to decay into their daughter nuclei. The non-SI unit of measure of a substance's radioactivity is the curie (Ci). One curie is the number of atoms decaying per second of 37 billion (3.7 × 10 10 ) of a radioactive substance. An alternative unit of measurement for the radioactivity of a substance is the SI unit of becquerel (Bq). A becquerel is equal to the amount of radioactive substance that will decay into one atomic nucleus per second. Specific activity refers to the amount of radioactivity per unit mole or mass in a sample and may be expressed, for example, as Ci / mmol or Ci / mg. Radioactivity concentration, also known as specific concentration (expressed, for example, as mCi / mL or μCi / mL), refers to the total amount of radioactivity per unit volume.

[0049] With respect to immunoconjugates and radioconjugates, the term "conjugated" means "linked." Molecules (such as antibodies and chelators) can be linked to one another, for example, by covalent bonds.

[0050] "Cancer" refers to a broad group of different diseases characterized by the uncontrolled growth of abnormal cells in the body. Uncontrolled cell division and growth can lead to the formation of malignant tumors that invade adjacent tissues and may also metastasize to distant parts of the body via the lymphatic system or bloodstream. "Cancer" or "cancerous tissue" can include tumors.

[0051] The transitional term "comprising" is intended to connote its generally accepted meaning in patent language. "Comprising" is synonymous with "including" or "containing" and is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.

[0052] The term "between" when used in phrases such as "between A and B" or "between A and B" refers to a range that includes both A and B. The term "from" when used in phrases such as "from A to B" or "A to B" refers to a range that includes both A and B.

[0053] When values ​​are expressed as approximations by use of the descriptor "about," it is understood that the particular value forms another embodiment. In general, the use of the term "about" indicates an approximation that may vary depending on the desired properties sought to be obtained by the inventive subject matter of the present disclosure and should be interpreted in the particular context in which it is used based on its function. In some cases, the number of significant figures used for a particular value may be one non-limiting way of determining the extent of the term "about." In other cases, the gradations used in a series of values ​​may be used to determine the intended range available to the term "about" for each value. When present, all ranges are inclusive and combinable. That is, reference to values ​​described in ranges includes all values ​​within that range. In certain embodiments, the term "about" refers to a variation of ±10% of the associated value, but in additional embodiments, the variation may be ±5%, ±15%, ±20%, ±25%, or ±50%.

[0054] It is understood that certain features of the invention that are described herein for clarity in the context of separate embodiments may also be provided in combination within a single embodiment. That is, unless expressly incompatible or specifically excluded, each individual embodiment is considered combinable with any other embodiment, and such combination is considered to be another embodiment. Conversely, various features of the invention that are described for brevity in the context of a single embodiment may also be provided separately or in any subcombination. Finally, while an embodiment may be described as part of a series of steps or as part of a more general structure, each such step is considered to be an independent embodiment in itself and may be combinable with the others.

[0055] When lists are presented, unless otherwise stated, it is to be understood that each individual member of that list, and every combination of that list, is a separate embodiment. For example, a list of embodiments presented as "A, B, or C" should be interpreted to include the embodiments "A," "B," "C," "A or B," "A or C," "B or C," or "A, B, or C."

[0056] Abbreviations utilized throughout this disclosure include the following:

[0057] [Table 1-1]

[0058] [Table 1-2]

[0059] The present invention may be more readily understood by reference to the following description taken in conjunction with the accompanying figures and examples, all of which form part of this disclosure. It should be understood that the present invention is not limited to the specific compounds, methods, conditions, or parameters described or shown herein, and that the terminology used herein is for the purpose of describing specific embodiments by way of examples only, and is not intended to limit any claimed invention. Similarly, unless specifically stated otherwise, any explanation of possible mechanisms or modes of action or reasons for improvement is intended to be merely illustrative, and the present invention is not bound by the accuracy or inaccuracy of any such proposed mechanisms or modes of action or reasons for improvement.

[0060] Radioconjugates of the Invention The present invention relates to compositions and methods for targeting hK2 with radioconjugates to achieve effective cancer cell death (e.g., tumor cell death) in prostate cancer patients. As used herein, "immunoconjugate" refers to an antibody or antigen-binding domain conjugated (linked, e.g., bound via a covalent bond) to a second molecule, such as a toxin, a drug, a radioactive metal ion, a chelator, or a radioactive metal complex. "Radioconjugate" (also referred to herein as "radioimmunoconjugate") refers specifically to an antibody or antigen-binding domain conjugated (linked, e.g., bound via a covalent bond) to at least one radioactive metal complex. In other words, a radioconjugate refers to at least one radioactive metal complex linked, e.g., bound via a covalent bond, to an antibody or antigen-binding domain. A radioconjugate may include at least one radioactive metal complex comprising a linker, where the radioactive metal complex is linked to the antibody or antigen-binding domain via a linker.

[0061] As used herein, "antibody-chelator conjugate" or "conjugate intermediate" or "drug substance intermediate" refers to a precursor of a radioconjugate that includes an antibody or antigen-binding domain conjugated (linked, e.g., bound via a covalent bond) to a chelator that does not contain a radioactive metal. The conjugate intermediate may include a linker, and the chelator is linked to the antibody or antigen-binding domain via the linker. After the radioactive metal is chelated to the chelator of the conjugate intermediate, it becomes a radioactive conjugate. For example, "DOTA-mAb" refers to a conjugate intermediate that includes DOTA conjugated to an antibody. One example of a conjugate intermediate is DOTA-h11B6. As used herein, "DOTA-h11B6" is a conjugate intermediate that includes DOTA conjugated to h11B6, optionally via a linker. A non-limiting example of a DOTA-mAb is illustrated in Figures 5A-5C. Another example of a conjugate intermediate is TOPA-h11B6. As used herein, "TOPA-h11B6" is a conjugate intermediate that includes TOPA conjugated to h11B6, optionally via a linker. A non-limiting example of TOPA-mAb is illustrated in Figure 6A-6C.

[0062] The chelator may be conjugated to the antibody according to methods known in the art, for example, the chelator may be conjugated to the antibody via a linker. Thus, the radioconjugates and conjugate intermediates of the present invention may include a chelator linked to the antibody by a linker. As used herein, the term "linker" generally refers to a chemical moiety that links a chelator to an antibody or an antigen-binding domain. In view of the present disclosure, any suitable linker known to those of skill in the art may be used in the present invention. The linker may contain, for example, a substituted or unsubstituted alkyl, a substituted or unsubstituted heteroalkyl moiety, a substituted or unsubstituted aryl or heteroaryl, a polyethylene glycol (PEG) linker, a peptide linker, a sugar-based linker, or a cleavable linker, such as a disulfide bond or a protease cleavage site, for example, valine-citrulline-p-aminobenzyl (PAB).

[0063] According to certain embodiments, the chelator or chelator-linker comprises a nucleophilic or electrophilic moiety as described herein. Reaction of the nucleophilic or electrophilic group of the chelator or chelator-linker with an antibody or antigen-binding domain that comprises a corresponding reaction partner allows the antibody or antigen-binding domain to be covalently attached to the chelator-linker. As used herein with respect to compounds of formulas (I), (II), (III), (IV), (V), and (VI), the linker (L1) comprises an electrophilic or nucleophilic moiety (R 11 ) is connected to -L1-R 11can be formed. Examples of nucleophilic groups include, but are not limited to, azides, amines, and thiols. Examples of electrophilic groups include, but are not limited to, amine-reactive groups, thiol-reactive groups, alkynyls, and cycloalkynyls. Amine-reactive groups preferably react with primary amines, including those present at the N-terminus of each polypeptide chain and in the side chains of lysine residues. Examples of amine-reactive groups include, but are not limited to, N-hydroxy succinimide (NHS), substituted NHS (such as sulfo-NHS), isothiocyanates (-NCS), isocyanates (-NCO), esters, carboxylic acids, acyl halides, amides, alkylamides, and tetrafluorophenyl esters and perfluorophenyl esters. Thiol-reactive groups react with thiols or sulfhydryls, preferably with thiols present in the side chains of cysteine ​​residues of polypeptides. Examples of thiol-reactive groups include, but are not limited to, Michael acceptors (eg, maleimides), haloacetyls, acyl halides, activated disulfides, and phenyloxadiazole sulfones.

[0064] According to certain embodiments, the conjugation reaction results in the addition of one or more chelator molecules (e.g., DOTA molecules) to the epsilon amino groups of the lysine side chains of the antibody (e.g., h11B6 mAb). For example, 1, 2, 3, 4, or 5 DOTA molecules can be conjugated to the antibody. According to certain embodiments, p-SCN-Bn-DOTA can be reacted with the antibody to form a conjugate intermediate comprising DOTA, as illustrated in FIG. 5. FIG. 5A provides an illustration of a conjugate intermediate comprising DOTA (lysine moiety not shown). FIG. 5B provides an illustration of a conjugate intermediate comprising DOTA (lysine moiety depicted). FIG. 6B and FIG. 6C provide an illustration of a conjugate intermediate comprising an alternative chelator according to the present invention.

[0065] The chelator-to-antibody ratio (CAR), which indicates the number of chelator-linker molecules per antibody molecule, can be measured by intact mass analysis using RP-HPLC with on-line mass spectrometry. According to certain embodiments, the average CAR of the conjugate intermediate of the invention (e.g., DOTA-mAb such as DOTA-h11B6) is about 1 to about 8, about 1 to about 7, or about 1 to about 6, or about 1 to about 5, or about 1 to about 4, or about 1 to about 3, or about 2 to about 4, or about 2 to about 3.

[0066] According to certain embodiments, the radioconjugates described herein comprise a radioactive metal complex conjugated to an antibody or antigen-binding domain having binding specificity for kallikrein-related peptidase 2 (hK2). According to certain embodiments, the radioconjugate is a radiolabeled antibody comprising an antibody conjugated (linked) to a radioactive metal complex. According to certain embodiments, the radioconjugate comprises an antibody, such as h11B6, conjugated to a radioactive metal complex comprising a chelator and a radioactive metal. In some embodiments, the antibody is covalently bound to the chelator. As described herein, the radioactive metal complex optionally comprises a linker.

[0067] As used herein, a "radiometal complex" refers to a complex that includes a radioactive metal ion associated with a chelator that is a macrocyclic compound. Typically, the radioactive metal ion is bound or coordinated to the macrocyclic compound through a coordinate bond. The heteroatoms of the macrocyclic ring may participate in the coordinate bond of the radioactive metal ion to the macrocyclic compound. The macrocyclic compound may be substituted with one or more substituents that may also participate in the coordinate bond of the radioactive metal ion to the macrocyclic compound in addition to or instead of the heteroatoms of the macrocyclic ring. Other examples of possible bonds between the chelator and the radioisotope include guest-host bonds, such as ionic bonds, hydrogen bonds, van der Waals forces, or hydrophobic interactions. The radiometal complex may optionally include a linker, which is a chemical moiety that links the chelator to an antibody or antigen-binding domain.

[0068] As used herein, the terms "radioisotope", "radioactive metal ion", or "radioactive metal ion" are used interchangeably and refer to one or more isotopes of an element that emit particles and / or photons. Non-limiting examples of radioisotopes that may be used for therapeutic applications according to the present invention include, for example: 225 Ac, 177 Lu, 32 P, 47 Sc, 67 Cu, 77 As, 89 Sr, 90 Y, 99 Tc, 105 Rh, 109 Pd, 111 Ag, 131 I, 134 Ce, 149 Tb, 152 Tb, 155 Tb, 153 Sm, 159 Gd, 165 Dy, 166 Ho, 169 Er, 186 Re, 188 Re, 194 Ir, 198 Au, 199 Au, 211 At, 212 Pb, 212 Bi, 213 Bi, 223 Ra, 255 Fm, and 227 Other non-limiting examples of radioisotopes that may be used as imaging agents according to the present invention include, for example, beta-emitters or alpha-emitters, such as Th. 177 Lu, 62 Cu, 64 Cu, 67 Ga, 68 Ga, 86 Y, 89 Zr, and 111In certain embodiments, the radioactive metal ion is a "therapeutic emitter," which refers to a radioactive metal ion that is useful for therapeutic applications. Examples of therapeutic emitters include: 132 La, 135 La, 134 Ce, 144 Nd, 149 Tb, 152 Tb, 155 Tb, 153 Sm, 159 Gd, 165 Dy, 166 Ho, 169 Er, 177 Lu, 186 Re, 188 Re, 194 Ir, 198 Au, 199 Au, 211 At, 212 Pb, 212 Bi, 213 Bi, 223 Ra, 225 Ac, 255 Fm, and 227 Th, 226 Th, 230 The radioactive metal ions used in the present invention include, but are not limited to, beta emitters or alpha emitters such as U. Preferably, the radioactive metal ions used in the present invention are actinium 225 ( 225 Ac).

[0069] Certain radiometals can be used as therapeutic agents, e.g. 225 Ac) and / or contrast agents (e.g. 111 It should be noted that radiometals may be used as radioactive metals (HK2+, In). Suitable radiometals for use as therapeutic agents are those that can reduce or inhibit the growth of, or in particular kill, cancer cells, such as prostate cancer cells. In certain embodiments, the radioconjugates of the present invention can deliver a cytotoxic payload capable of releasing alpha and / or beta particles in the vicinity of the tumor by binding to surface antigens of cancer cells and initiating cell death. In certain embodiments, the radioconjugates of the present invention are internalized in hk2-expressing cancer cells.

[0070] As used herein, "225Ac," 225 The term "Ac" or "Ac-225" refers to the alpha-emitting radiometal Actinium-225. According to certain embodiments, 225 The half-life of Ac of approximately 10 days (about 9.9 days) is long enough to prepare the compounds described herein, yet short enough to match the circulating pharmacokinetics of antibodies conjugated to radioactive metal complexes such as h11B6. 225 Ac is a stable isotope 209 It decays in a series of steps emitting four alpha particles before finally reaching Bi, thereby providing an increase in the potency of the compound.

[0071] Antibodies of the Invention According to a particular embodiment, the radioconjugate of the present invention comprises an antibody that is an h11B6 antibody. An embodiment of the h11B6 antibody is described in U.S. Patent No. 10,100,125, which is incorporated herein by reference. As used herein, "h11B6 antibody" or "h11B6 mAb" or "h11B6" or "hu11B6" refers to an antibody having binding specificity for human kallikrein-2 (hK2), the antibody comprising (a) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO:1 and SEQ ID NO:2 and SEQ ID NO:3, and / or (b) a light chain variable region comprising the amino acid sequence of SEQ ID NO:4 and SEQ ID NO:5 and SEQ ID NO:6, wherein the heavy chain variable region and the light chain variable region comprise framework amino acid sequences derived from one or more human antibodies.

[0072] According to a particular embodiment, the radioconjugate of the present invention comprises the h11B6 antibody, which comprises (a) a heavy chain variable region (VH) comprising a VH CDR1 having the amino acid sequence of SEQ ID NO: 1 (SDYAWN), a VH CDR2 having the amino acid sequence of SEQ ID NO: 2 (YISYSGSTTYNPSLKS), and a VH CDR3 having the amino acid sequence of SEQ ID NO: 3 (GYYYGSGF), and (b) a light chain variable region (VL) comprising a VL CDR1 having the amino acid sequence of SEQ ID NO: 4 (KASESVEYFGTSLMH), a VL CDR2 having the amino acid sequence of SEQ ID NO: 5 (AASNRES), and a VL CDR3 having the amino acid sequence of SEQ ID NO: 6 (QQTRKVPYT).

[0073] The above six amino acid sequences represent the complementarity determining regions (CDRs) as defined according to Kabat et al., (1991) Sequences of Immunological Interest, 5th edition, NIH, Bethesda, Md., the disclosure of which is incorporated herein by reference. The Kabat numbering scheme (Kabat et al., 1991) is used throughout this description.

[0074] According to a particular embodiment, the radioconjugate of the present invention comprises the h11B6 antibody, which comprises a heavy chain variable region (VH) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:8, and / or a light chain variable region (VL) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:9.

[0075] According to a particular embodiment, the radioconjugate of the present invention comprises the h11B6 antibody, which comprises a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO:8 and / or a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO:9.

[0076] SEQ ID NO:8 is as follows: QVQLQESGPGLVKPSDTLSLTCAVSGNSITSDYAWNWIRQPPGKG LEWIGYISYSSGSTTYNPSLKSRVTMSRDTSKNQFSLKLSSVTAVD TAVYYCATGYYYGSGFWGQGTLVTVSS

[0077] SEQ ID NO:9 is as follows: DIVLTQSPDSLAVSLGERATINCKASESVEYFGTSLMHWYQQKP GQPPKLLIYAASNRESGVPDRFSGSGSGTDFTLTISSLQAEDVAV YYCQQTRKVPYTFGQGTKLEIK

[0078] According to certain embodiments, the radioconjugate of the present invention comprises an h11B6 antibody, which comprises a heavy chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:10, and / or a light chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:11.

[0079] According to a particular embodiment, the radioconjugate of the present invention comprises the h11B6 antibody, which comprises a heavy chain constant region comprising the amino acid sequence of SEQ ID NO:10 and / or a light chain constant region comprising the amino acid sequence of SEQ ID NO:11.

[0080] SEQ ID NO:10 is as follows: ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGV EVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

[0081] SEQ ID NO:11 is as follows: RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC

[0082] According to certain embodiments, the radioconjugate of the present invention comprises an h11B6 antibody, which comprises a heavy chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:12, and / or a light chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:13.

[0083] According to a particular embodiment, the radioconjugate of the present invention comprises the h11B6 antibody, which comprises a heavy chain having the amino acid sequence of SEQ ID NO:12 and / or a light chain having the amino acid sequence of SEQ ID NO:13.

[0084] The amino acid sequences of the h11B6 heavy and light chains are also shown in FIG.

[0085] According to certain embodiments, the antibodies of the invention (eg, h11B6) comprise or consist of an intact (ie, complete) antibody, such as an IgA, IgD, IgE, IgG, or IgM molecule.

[0086] According to certain embodiments, the antibodies of the invention (e.g., h11B6) comprise or consist of an intact IgG molecule, or a variant thereof. The IgG molecule can be of any known subtype, e.g., IgG1, IgG2, IgG3, or IgG4.

[0087] According to a particular embodiment, the radioconjugate of the present invention comprises an h11B6 antibody that is an IgG1 antibody. According to a particular embodiment, the radioconjugate of the present invention comprises an h11B6 antibody that is an IgG1 kappa isotype. According to a particular embodiment, the radioconjugate of the present invention comprises an h11B6 antibody that is an IgG1 antibody or a variant thereof (such as an Fc variant).

[0088] According to one embodiment, the radioconjugate of the present invention comprises an antibody conjugated to DOTA, optionally via a linker. For example, the h11B6 antibody can be conjugated to DOTA to produce a DOTA-h11B6 conjugate intermediate, which can then be mixed with DOTA-h11B6. 225 Chelated to Ac to form radioactive conjugates 225 Generate Ac-DOTA-h11B6.

[0089] According to certain embodiments, DOTA-h11B6 is formed by chemically conjugating h11B6 to the DOTA derivative p-SCN-Bn-DOTA (CAS Registry Number: 127985-74-4, chemical name: 2-S-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) according to known methods, resulting in the addition of multiple DOTA molecules to the epsilon amino groups of the lysine side chains of the h11B6 mAb. DOTA-h11B6 is then 225 Chelated to Ac to form radioactive conjugates 225Ac-DOTA-h11B6 can be generated. When administered to a patient, the radioactive conjugate 225 Ac-DOTA-h11B6 can bind to and be internalized in hK2-expressing cells.

[0090] According to one embodiment, the radioconjugate of the present invention comprises an antibody conjugated to TOPA, optionally via a linker. For example, the h11B6 antibody can be conjugated to TOPA to produce a TOPA-h11B6 conjugate intermediate, which can then be mixed with TOPA-h11B6. 225 Chelated to Ac to form radioactive conjugates 225 Generate Ac-TOPA-h11B6.

[0091] According to certain embodiments, TOPA-h11B6 is formed as described in International Publication No. WO 2020 / 229974 or International Application No. PCT / IB2021 / 060350. TOPA-h11B6 is then 225 Chelated to Ac to form radioactive conjugates 225 Ac-TOPA-h11B6 can be generated. When administered to a patient, the radioconjugate 225 Ac-TOPA-h11B6 can bind to and be internalized in hK2-expressing cells.

[0092] According to one embodiment, the antibodies of the invention, such as h11B6 antibodies, can be prepared as described in U.S. Patent Nos. 10,100,125 and 9,873,891, both of which are incorporated herein by reference. In some embodiments, the antibodies of the invention, such as h11B6, are prepared using CHO-DG44 cells.

[0093] Methods for the production of antibodies are well known in the art. For example, suitable methods for the production of recombinant polypeptides are known in the art, such as expression in prokaryotic or eukaryotic host cells (see, e.g., Sambrook & Russell, 2000, Molecular Cloning, A Laboratory Manual, Third Edition, Cold Spring Harbor, NY, the relevant disclosures of which are hereby incorporated by reference herein).

[0094] One aspect of the invention provides an isolated nucleic acid molecule encoding an antibody of the invention or a component polypeptide chain thereof. A "nucleic acid molecule" includes DNA (e.g., genomic DNA or complementary DNA) and mRNA molecules, which may be single-stranded or double-stranded. In one embodiment, the nucleic acid molecule is a cDNA molecule. It will be understood by those skilled in the art that a nucleic acid molecule may be codon-optimized for expression of an antibody polypeptide in a particular host cell, e.g., for expression in a human cell (see, e.g., Angov, 2011, Biotechnol. J. 6(6):650-659).

[0095] In certain embodiments, a nucleic acid molecule of the invention comprises (a) the nucleotide sequence of SEQ ID NO:14, and / or (b) the nucleotide sequence of SEQ ID NO:15.

[0096] Antibody variants of the invention In some embodiments, modifications of the amino acid sequence of the antibodies provided herein are contemplated. For example, it may be desirable to improve the binding affinity and / or other biological properties of the antibody, including but not limited to specificity, thermal stability, expression level, effector function, glycosylation (e.g., fucosylation), reduced immunogenicity, or solubility. Thus, in addition to the antibodies described herein, it is contemplated that antibody variants may also be prepared. For example, antibody variants can be prepared by introducing appropriate nucleotide changes into the encoding DNA and / or by synthesizing the desired antibody or polypeptide. Those skilled in the art will appreciate that amino acid changes may alter post-translational processes of the antibody, such as changing the number or position of glycosylation sites, or altering the membrane anchoring properties.

[0097] In some embodiments, the antibodies provided herein are chemically modified, for example, by covalently attaching any type of molecule to the antibody. Antibody derivatives can include antibodies that have been chemically modified, for example, by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization with known protecting / blocking groups, proteolytic cleavage, conjugation to cellular ligands or other proteins, and the like. Any of a number of chemical modifications can be performed by known techniques, including, but not limited to, specific chemical cleavage, acetylation, formulation, metabolic synthesis of tunicamycin, and the like. In addition, the antibody can contain one or more non-classical amino acids.

[0098] Mutations may be substitutions, deletions, or insertions of one or more codons encoding the antibody or polypeptide, resulting in a change in the amino acid sequence compared to the native sequence antibody or polypeptide. Amino acid substitutions may be the result of replacing one amino acid with another amino acid having similar structural and / or chemical properties, such as replacement of a leucine with a serine, e.g., a conservative amino acid replacement. Standard techniques known to those of skill in the art can be used to introduce mutations into the nucleotide sequences encoding the molecules provided herein, including, for example, site-directed mutagenesis and PCR-mediated mutagenesis resulting in amino acid substitutions. Insertions or deletions can optionally range from about 1 to 5 amino acids. In certain embodiments, the substitutions, deletions, or insertions include fewer than 25 amino acid substitutions, fewer than 20 amino acid substitutions, fewer than 15 amino acid substitutions, fewer than 10 amino acid substitutions, fewer than 5 amino acid substitutions, fewer than 4 amino acid substitutions, fewer than 3 amino acid substitutions, or fewer than 2 amino acid substitutions compared to the original molecule. In certain embodiments, the substitutions are conservative amino acid substitutions made at one or more predicted non-essential amino acid residues. Permissible variations can be determined by systematically making amino acid insertions, deletions, or substitutions in the sequence and testing the resulting variants for activity exhibited by the full-length or mature native sequence.

[0099] Amino acid sequence insertions include amino- and / or carboxyl-terminal fusions ranging in length from one residue to polypeptides containing 100 or more residues, as well as intrasequence insertions of single or multiple amino acid residues. An example of a terminal insertion is an antibody with an N-terminal methionyl residue. Other insertional variants of the antibody molecule include the fusion to the N- or C-terminus of the antibody to an enzyme (e.g., antibody-directed enzyme prodrug therapy) or a polypeptide which extends the serum half-life of the antibody.

[0100] A "conservative amino acid substitution" is one in which an amino acid residue is replaced with an amino acid residue having a side chain with a similar charge. Families of amino acid residues with similarly charged side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine), acidic side chains (e.g., aspartic acid, glutamic acid), uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine), nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan), beta-branched side chains (e.g., threonine, valine, isoleucine), and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine). Alternatively, mutations can be introduced randomly along all or part of a coding sequence, such as by saturation mutagenesis, and the resulting mutants screened for biological activity to identify mutants that retain activity. Following mutagenesis, the encoded protein can be expressed and the activity of the protein determined.

[0101] Substantial modifications in the biological properties of the antibody can be achieved by selecting substitutions that are significantly different in their effect on maintaining (a) the structural backbone of the polypeptide in the region of substitution, e.g., a sheet or helix conformation, (b) the charge or hydrophobicity of the molecule at the target site, or (c) the bulk of the side chains. Alternatively, conservative (e.g., within a group of amino acids with similar properties and / or side chains) substitutions can be made that maintain or do not significantly change properties. Amino acids can be grouped according to the similarity of their side chain properties (see, e.g., Lehninger, Biochemistry 73-75 (2d ed. 1975)): (1) nonpolar: Ala (A), Val (V), Leu (L), Ile (I), Pro (P), Phe (F), Trp (W), Met (M); (2) uncharged polar: Gly (G), Ser (S), Thr (T), Cys (C), Tyr (Y), Asn (N), Gln (Q); (3) acidic: Asp (D), Glu (E); and (4) basic: Lys (K), Arg (R), His (H).

[0102] Alternatively, naturally occurring residues may be differentiated into groups based on common side chain properties: (1) hydrophobic: norleucine, Met, Ala, Val, Leu, Ile; (2) neutral hydrophilic: Cys, Ser, Thr, Asn, Gln; (3) acidic: Asp, Glu; (4) basic: His, Lys, Arg; (5) residues that influence chain orientation: Gly, Pro; (6) aromatic: Trp, Tyr, Phe.

[0103] Non-conservative substitutions involve exchanging a member of one of these classes for a member of another class. Such substituted residues also may be introduced into the conservative substitution sites or into the remaining (non-conserved) sites.

[0104] Thus, in one embodiment, an antibody that binds to the hK2 epitope comprises an amino acid sequence that is at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical to the amino acid sequence of an antibody described herein, e.g., the amino acid sequence of the h11B6 antibody described herein.

[0105] Chelating Agent of the Present Invention According to a particular embodiment, the chelating agent of the present invention refers to a chelating agent that can complex a metal, preferably a radioactive metal, to form a radioactive metal complex.Preferably, the chelating agent is a macrocyclic compound.In a particular embodiment, the chelating agent comprises a macrocycle or a macrocyclic ring that contains one or more heteroatoms, such as oxygen and / or nitrogen, as ring atoms.

[0106] According to certain embodiments, the chelator comprises a macrocyclic chelating moiety. Examples of macrocyclic chelating moieties include 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,8,11-tetraazacyclodocedan-1,4,8,11-tetraacetic acid (TETA), Examples of chelating agents include, but are not limited to, 3,6,9,15-tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13-triene-4-(S)-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (PCTA), 5-S-(4-aminobenzyl)-1-oxa-4,7,10-triazacyclododecane-4,7,10-tris(acetic acid) (DO3A), or derivatives thereof. In some embodiments, the chelating agent is 1,4,7,10 tetraazacyclododecane-1,4,7,10,tetraacetic acid (DOTA). In other embodiments, the chelating agent is S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA). In further embodiments, the chelator is 1,4,8,11-tetraazacyclodocedan-1,4,8,11-tetraacetic acid (TETA). In yet other embodiments, the chelator is 3,6,9,15-tetraazabicyclo[9.3.1]-pentadeca-1(15),11,13-triene-4-(S)-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (PCTA). In still further embodiments, the chelator is 5-S-(4-aminobenzyl)-1-oxa-4,7,10-triazacyclododecane-4,7,10-tris(acetic acid) (DO3A). In other embodiments, the chelator is DOTA, DFO, DTPA, NOTA, or TETA.

[0107] In an alternative embodiment, the chelator comprises a macrocycle that is a derivative of 4,13-diaza-18-crown-6. 4,13-diaza-18-crown-6 can be prepared in a variety of ways (see, for example, Gatto et al., Org. Synth. 1990, 68, 227; doi:10.15227 / orgsyn.068.0227). According to a further embodiment of the invention, the chelator is H2bp18c6 or an H2bp18c6 derivative, such as those described in WO 2020 / 229974. H2bp18c6 refers to N,N'-bis[(6-carboxy-2-pyridyl)methyl]-4,13-diaza-18-crown-6 as described herein. H2bp18c6 and H2bp18c6 derivatives are also described, for example, in Thiele et al., "An Eighteen-Membered Macrocyclic Ligand for Actinium-225 Targeted Alpha Therapy" Angew.Chem.Int.Ed. (2017) 56, 14712-14717, and Roca-Sabio et al., "Macrocyclic Receptor Exhibiting Unprecedented Selectivity for Light Lanthanides" J.Am.Chem.Soc. (2009) 131, 3331-3341, which are incorporated herein by reference. Additional chelating agents suitable for use according to the present invention are described in WO 2018 / 183906 and WO 2020 / 106886, which are incorporated herein by reference.

[0108] As used herein, the term "TOPA" refers to the macrocycle known in the art as H2bp18c6, which may alternatively be referred to as N,N'-bis[(6-carboxy-2-pyridyl)methyl]-4,13-diaza-18-crown-6, or 6,6'-((1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)bis(methylene))dipicolinic acid. See, e.g., Roca-Sabio et al.

[0109] Chelating agents of formula (I), (II), and (III) Additional chelating agents suitable for use according to the present invention are described in WO 2020 / 229974, which is incorporated herein by reference. According to certain embodiments, for example as described in WO 2020 / 229974, the chelating agent has the structure of formula (I):

[0110] [ka] (In the formula, Each of ring A and ring B is independently 6- to 10-membered aryl or 5- to 10-membered heteroaryl, and each of ring A and ring B is optionally halo, alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl, -OR 13 , -SR 13 , -(CH2) p COOR 13 , -OC(O)R 13 , -N(R 13 )2, -CON(R 13 )2, -NO2, -CN-OC(O)N(R 13 ) 2, and X, Each of Z1 and Z2 is independently (C(R 12 )2) m - or -(CH2) n -C(R 12 )(X)-(CH2) n - and Each X is independently -L1-R 11 and each n is independently 0, 1, 2, 3, 4, or 5; each m is independently 1, 2, 3, 4, or 5; each p is independently 0 or 1; L1 is absent or is a linker, R 11 is a nucleophilic or electrophilic moiety, or R 11comprises an antibody or antigen binding domain, Each R 12 is independently hydrogen, alkyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; Each R 13 are independently hydrogen or alkyl; R 14 , R 15 , R 16 , and R 17 each is independently hydrogen, alkyl, or X; Or, R 14 and R 15 and / or R 16 and R 17 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl ring, optionally substituted by X; provided that the chelating agent contains at least one X, and when X is present on ring A or ring B, L1 is a linker or R 12 and R 14 ~R 17 is not hydrogen).

[0111] According to an embodiment of the invention, the chelating agent comprises at least one X group, where X is -L-R 11 L1 is absent or a linker; R 11 is an electrophilic or nucleophilic moiety, or R 11 includes an antibody or antigen-binding domain). 11 When R is a nucleophilic or electrophilic moiety, such a moiety can be used to attach a chelator to an antibody or antigen-binding domain, either directly or indirectly via a linker. 11 includes antibodies that have binding specificity for hK2, such as h11B6.

[0112] In certain embodiments, the chelator comprises a single X group, preferably where L1 of the X group is a linker.

[0113] The chelating agents of the invention can be substituted with X at any one of the carbon atoms of the macrocyclic ring, at the Z or Z positions, or on ring A or ring B, with the proviso that when ring A or ring B contains an X group, L is a linker or R 12 and R 14 ~R 17- is not hydrogen (i.e., at least one of the carbon atoms of Z1, Z2 and / or the carbons of the macrocycle is substituted with an alkyl group such as, for example, methyl or ethyl). Preferably, substitution at such positions is to provide a radioactive metal ion, especially 225 The substitution does not affect the chelating efficiency of the chelator towards Ac, and in some embodiments, the substitution can increase the chelation efficiency.

[0114] In some embodiments, L is absent. When L is absent, R 11 is directly attached to the chelator (eg, via a covalent bond).

[0115] In some embodiments, L1 is a linker. As used herein with respect to compounds of formula (I), (II), (III), (IV), (V), and (VI), L1 refers to a chemical moiety that links the chelator to a nucleophilic moiety, an electrophilic moiety, an antibody, or an antigen-binding domain. Any suitable linker known to one of skill in the art in light of the present disclosure can be used in the present invention. The linker can contain, for example, a substituted or unsubstituted alkyl, a substituted or unsubstituted heteroalkyl moiety, a substituted or unsubstituted aryl or heteroaryl, a polyethylene glycol (PEG) linker, a peptide linker, a sugar-based linker, or a cleavable linker, such as a disulfide bond or a protease cleavage site (such as valine-citrulline-p-aminobenzyl (PAB)). Exemplary linker structures suitable for use include:

[0116] [ka] (wherein n is an integer of 0 to 10, preferably an integer of 1 to 4, and m is an integer of 0 to 12, preferably an integer of 0 to 6).

[0117] In some embodiments, R 11 is a nucleophilic or electrophilic moiety. A "nucleophilic moiety" or "nucleophilic group" refers to a functional group that donates an electron pair to form a covalent bond in a chemical reaction. An "electrophilic moiety" or "electrophilic group" refers to a functional group that accepts an electron pair to form a covalent bond in a chemical reaction. A nucleophilic group reacts with an electrophilic group to form a new covalent bond in a chemical reaction, and vice versa. Reaction of a nucleophilic or electrophilic group of a chelating agent of the invention with an antibody or antigen binding domain or other chemical moiety (e.g., a linker) that includes a corresponding reaction partner allows for the covalent attachment of the antibody or antigen binding domain or chemical moiety to the chelating agent of the invention.

[0118] Illustrative examples of nucleophilic groups include, but are not limited to, azides, amines, and thiols. Illustrative examples of electrophilic groups include, but are not limited to, amine-reactive groups, thiol-reactive groups, alkynyls, and cycloalkynyls. Amine-reactive groups preferably react with primary amines, including those present at the N-terminus of each polypeptide chain and in the side chains of lysine residues. Examples of amine-reactive groups suitable for use in the present invention include, but are not limited to, N-hydroxy succinimide (NHS), substituted NHS (such as sulfo-NHS), isothiocyanate (-NCS), isocyanate (-NCO), esters, carboxylic acids, acyl halides, amides, alkylamides, and tetrafluorophenyl esters and perfluorophenyl esters. Thiol-reactive groups react with thiols or sulfhydryls, preferably with thiols present in the side chains of cysteine ​​residues of polypeptides. Examples of thiol-reactive groups suitable for use in the present invention include, but are not limited to, Michael acceptors (e.g., maleimides), haloacetyls, acyl halides, activated disulfides, and phenyloxadiazole sulfones.

[0119] In certain embodiments, R 11 is -NH2, -NCS (isothiocyanate), -NCO (isocyanate), -N3 (azide), alkynyl, cycloalkynyl, carboxylic acid, ester, amide, alkylamide, maleimide, acyl halide, tetrazine, or trans-cyclooctene, more specifically -NCS, -NCO, -N3, alkynyl, cycloalkynyl, -C(O)R 13 , -COOR 13 , -CON(R 13 )2, maleimide, acyl halide (e.g., —C(O)Cl, —C(O)Br), tetrazine, or trans-cyclooctene, where each R 13 is independently hydrogen or alkyl.

[0120] In some embodiments, R 11is an alkynyl, cycloalkynyl, or azido group, thus allowing for the attachment of the chelator to an antibody or antigen binding domain or other chemical moiety (e.g., a linker) using click chemistry. In such embodiments, a click chemistry reaction that can be performed is a Huisgen cycloaddition or a 1,3-dipolar cycloaddition between an azide (-N3) and an alkynyl or cycloalkynyl group to form a 1,2,4-triazole linker or moiety. In one embodiment, the chelator comprises an alkynyl or cycloalkynyl group and the antibody or antigen binding domain or other chemical moiety comprises an azide group. In another embodiment, the chelator comprises an azide group and the antibody or antigen binding domain or other chemical moiety comprises an alkynyl or cycloalkynyl group.

[0121] In certain embodiments, R 11is an alkynyl group, more preferably a terminal alkynyl group or a cycloalkynyl group that is particularly reactive with azide groups via strain-promoted azide-alkyne cycloaddition (SPAAC). Examples of cycloalkynyl groups that can react with azide groups via a SPAAC include, but are not limited to, cyclooctynyl or bicyclononynyl (BCN), difluorinated cyclooctynyl (DIFO), dibenzocyclooctynyl (DIBO), keto-DIBO, biarylazacyclooctynonyl (BARAC), dibenzoazacyclooctynyl (DIBAC, DBCO, ADIBO), dimethoxyazacyclooctynyl (DIMAC), difluorobenzocyclooctynyl (DIFBO), monobenzocyclooctynyl (MOBO), and tetramethoxy dibenzocyclooctynyl (TMDIBO).

[0122] In certain embodiments, R 11 is a dibenzoazacyclooctynyl (DIBAC, DBCO, ADIBO) having the following structure:

[0123] [ka] R 11 In such embodiments where is a DBCO, the DBCO can be covalently attached to the compound directly or indirectly via a linker, preferably indirectly via a linker.

[0124] In some embodiments, R 11comprises an antibody or antigen-binding domain. The antibody or antigen-binding domain can be linked to the chelator directly via a covalent bond or indirectly via a linker. According to a preferred embodiment, R 11 includes antibodies that have binding specificity for hK2, such as h11B6.

[0125] According to an embodiment of the present invention, each of rings A and B is independently 6-10 membered aryl or 5-10 membered heteroaryl. In an alternative embodiment, each of rings A and B is contemplated to be an optionally substituted heterocyclyl ring (such as oxazoline). Each of rings A and B can be halo, alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl, -OR 13 , -SR 13 , -(CH2) p COOR 13 , -OC(O)R 13 , -N(R 13 )2, -CON(R 13 )2, -NO2, -CN-OC(O)N(R 13 )2, and X. Examples of 6-10 membered aryl groups suitable for this purpose include, but are not limited to, phenyl and naphthyl. Examples of 5-10 membered heteroaryl groups suitable for this purpose include, but are not limited to, pyridinyl, thiazolyl, isothiazolyl, oxazolyl, isoxazolyl, and imidazolyl. Examples of suitable substituents for 5-10 membered heteroaryl and 6-10 membered aryl groups include, but are not limited to, -COOH, tetrazolyl, and -CH2COOH. In a preferred embodiment, the substituent is -COOH or tetrazolyl, which is an isostere of -COOH.

[0126] In certain embodiments, each of ring A and ring B is independently and optionally substituted with one or more carboxyl groups, including, but not limited to, -COOH and -CH2COOH.

[0127] In certain embodiments, each of ring A and ring B is independently and optionally substituted with tetrazolyl.

[0128] In one embodiment, ring A and ring B are the same, e.g., both ring A and ring B are pyridinyl. In another embodiment, ring A and ring B are different, e.g., one of ring A and ring B is pyridinyl and the other is phenyl.

[0129] In certain embodiments, both ring A and ring B are pyridinyl substituted with -COOH.

[0130] In certain embodiments, both ring A and ring B are pyridinyl substituted with tetrazolyl.

[0131] In another particular embodiment, both Ring A and Ring B are picolinic acid groups having the following structure:

[0132] [ka]

[0133] According to an embodiment of the present invention, each of Z1 and Z2 is independently -(C(R 12 )2) m or -(CH2) n -C(R 12 )(X)-(CH2) n and each X is independently -L1-R 11 And each R 12 is independently hydrogen, alkyl, cycloalkyl, aryl, heterocyclyl, or heteroaryl; each n is independently 0, 1, 2, 3, 4, or 5; and each m is independently 1, 2, 3, 4, or 5.

[0134] In some embodiments, each R 12 is independently hydrogen or alkyl, more preferably hydrogen, -CH3, or -CH2CH3.

[0135] In some embodiments, each R 12 is hydrogen.

[0136] In some embodiments, both Z1 and Z2 are -(CH2) m -, where each m is preferably 1. In such embodiments, a carbon atom of the macrocycle, ring A, or ring B is substituted with an X group.

[0137] In some embodiments, one of Z1 and Z2 is -(CH2) n -C(R 12 )(X)-(CH2) n - and the other is -(CH2) m -It is.

[0138] In some embodiments, Z and Z-(CH) n -C(R 12 )(X)-(CH2) n - and the other is -(CH2) m where each n is 0, m is 1, and X is -L1-R 11 and L1 is a linker.

[0139] In some embodiments, both Z1 and Z2 are -(CH2) m -, each m is independently 0, 1, 2, 3, 4, or 5, preferably each m is 1; R 14 , R 15 , R 16 , and R 17 One of them is X and the other is R 14 , R 15 , R 16 and R 17 The remainder of each is hydrogen.

[0140] In some embodiments, R 14 and R 15 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl ring (i.e., cyclopentyl or cyclohexyl). Such 5- or 6-membered cycloalkyl rings can be substituted with an X group.

[0141] In some embodiments, R 16 and R 17 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl ring (i.e., cyclopentyl or cyclohexyl). Such 5- or 6-membered cycloalkyl rings can be substituted with an X group.

[0142] In certain embodiments, the chelator has the structure of formula (II):

[0143] [ka] (In the formula, A1 is N, CR1 or absent; A2 is N or CR2; A3 is N or CR3; A4 is N or CR4; A5 is N or CR5; A6 is N, CR6 or absent; A7 is N or CR7; A8 is N or CR8; A9 is N or CR9, A 10 is N or CR 10 and However, three or less of A1, A2, A3, A4, and A5 are N, and A6, A7, A8, A9, and A 10 provided that not more than three of R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10 each independently represents hydrogen, halo, alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl, OR 13 , -SR 13 , -(CH2) p COOR 13 , -OC(O)R 13 , -N(R 13 )2, -CON(R13 )2, -NO2, -CN-OC(O)N(R 13 -X; Alternatively, any two immediately adjacent R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10 together with the atoms to which they are attached form a 5- or 6-membered substituted or unsubstituted carbocyclic or nitrogen-containing ring; Z1, Z2, X, n, m, p, L1, and R 11 ~R 17 is as described above for formula (I), provided that the chelating agent contains at least one X and R1, R2, R3, R4, R5, R6, R7, R8, R 9、 and R 10 is X, L1 is a linker or R 12 and R 14 ~R 17 provided that at least one of is not hydrogen.

[0144] In some embodiments, any two immediately adjacent R1, R2, R3, R4, R5, R6, R7, R8, R9, and R 10 together with the atom to which they are attached form a 5- or 6-membered substituted or unsubstituted carbocyclic ring or nitrogen-containing ring. Examples of such carbocyclic rings that can be formed include, but are not limited to, naphthyl. Examples of such nitrogen-containing rings that can be formed include, but are not limited to, quinolinyl. The carbocyclic or nitrogen-containing ring may be unsubstituted or substituted with one or more suitable substituents, such as -COOH, -CH2COOH, tetrazolyl, etc.

[0145] In some embodiments, L is absent. When L is absent, R 11 is directly attached to the chelator (eg, via a covalent bond).

[0146] In some embodiments, L1 is a linker. In light of the present disclosure, any suitable linker known to those of skill in the art, such as those described above, can be used in the present invention.

[0147] In some embodiments, one of A1, A2, A3, A4, and A5 is nitrogen, one of A1, A2, A3, A4, and A5 is a carbon substituted with -COOH, and the remainder are CH, i.e., forming a pyridinyl ring substituted with a carboxylic acid.

[0148] In some embodiments, A6, A7, A8, A9, and A 10 One of them is nitrogen, and A6, A7, A8, A9, and A 10 One of the carbons is substituted with -COOH and the remaining are CH, i.e., forming a pyridinyl ring substituted with a carboxylic acid.

[0149] In one embodiment, at least one of R1, R2, R3, R4, and R5 is -COOH. In one embodiment, at least one of R6, R7, R8, R9, and R 10 In another embodiment, at least one of R1, R2, R3, R4, and R5 is -COOH, and at least one of R6, R7, R8, R9, and R 10 At least one of the is -COOH.

[0150] In some embodiments, A and A 10 each of A3 to A8 is CR2, CR3, CR4, CR5, CR6, CR7, and CR8, respectively, and each of R3 to R8 is hydrogen.

[0151] In some embodiments, one of A1, A2, A3, A4, and A5 is nitrogen, one of A1, A2, A3, A4, and A5 is a carbon substituted with tetrazolyl, and the remainder are CH.

[0152] In some embodiments, A6, A7, A8, A9, and A 10 One of them is nitrogen, and A6, A7, A8, A9, and A 10 One of the carbons is substituted with tetrazolyl and the rest are CH.

[0153] In one embodiment, at least one of R1, R2, R3, R4, and R5 is tetrazolyl. In one embodiment, R6, R7, R8, R9, and R 10 In another embodiment, at least one of R1, R2, R3, R4, and R5 is tetrazolyl and R 6, R7, R8, R9, and R 10 At least one of is tetrazolyl.

[0154] In some embodiments, each R 12 is hydrogen.

[0155] In some embodiments, R 11 is an alkynyl or cycloalkynyl group, preferably cyclooctynyl or a cyclooctynyl derivative, such as DBCO.

[0156] In certain embodiments of the chelating agent of formula (II), A1 and A 10 each is nitrogen; A2 is CR2 and R2 is -COOH; A9 is CR9 and R9 is -COOH; A3 to A8 are CR2, CR3, CR4, CR5, CR6, CR7, and CR8, respectively; Each of R3 to R8 is hydrogen; One of Z1 and Z2 is -(CH2) m The other of Z1 and Z2 is -(CH2) n -C(R 12 )(X)-(CH2) n - and R 12 is hydrogen, m is 1, Each n is 0, X is -L1-R 11 L1 is a linker, -R 11 is an electrophilic group, for example, cyclooctynyl or a cyclooctynyl derivative such as DBCO; R 14 ~R 17 Each of R 16 and R 17 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl.

[0157] In certain embodiments, the chelator has the structure of formula (III):

[0158] [ka] (In the formula, Each A 11 are independently O, S, NMe, or NH; Each R 18 are independently hydrogen, halo, alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl, -OR 13 , -SR 13 , -COOR 13 , -OC(O)R 13 , -N(R 13 )2, -CON(R 13 )2, -NO2, -CN-OC(O)N(R 13 -X; Z1, Z2, X, n, m, L1, R 11 ~R 17 is as described above for formula (I), provided that the chelating agent contains at least one X and R 18 is X, L1 is a linker, or R 12 and R 14 ~R 17 is not hydrogen).

[0159] In some embodiments, each A 11 is the same, and each A 11 is O, S, NMe, or NH. For example, each A 11 can be S. In other embodiments, each A 11 are different and each is independently selected from O, S, NMe, and NH.

[0160] In some embodiments, each R 18 are independently -(CH 2p -COOR 13 or tetrazolyl, R 13 is hydrogen and each p is independently 0 or 1.

[0161] In some embodiments, each R 18 is -COOH.

[0162] In some embodiments, each R 18 is -CH2COOH.

[0163] In some embodiments, each R 18 is tetrazolyl.

[0164] In certain embodiments of the chelating agent of formula (III), Each R 18 is COOH, One of Z1 and Z2 is -(CH2) m The other of Z1 and Z2 is -(CH2) n -C(R 12 )(X)-(CH2) n - and R 12 is hydrogen, m is 1 and each n is 0; X is -L1-R 11 L1 is a linker, -R 11 is an electrophilic group, for example cyclooctynyl or a cyclooctynyl derivative such as DBCO or BCN; R 14~R 17 Each of R 16 and R 17 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl.

[0165] Particular embodiments of the present invention include the following:

[0166] [ka] (In the formula, L1 is absent or is a linker, R 11 is a nucleophilic or electrophilic moiety, or R 11 comprises an antigen-binding domain (e.g., h11B6), and Each R 12 are independently hydrogen, -CH3, or -CH2CH3, provided that at least one R 12 is a chelating agent selected from the group consisting of: -CH3 or -CH2CH3.

[0167] In some embodiments, R 11 are -NH2, -NCS, -NCO, -N3, alkynyl, cycloalkynyl, -C(O)R 13 , -COOR 13 , -CON(R 13 )2, maleimide, acyl halide, tetrazine, or trans-cyclooctene.

[0168] In certain embodiments, R 11is a cyclooctynyl or cyclooctynyl derivative selected from the group consisting of bicyclononynyl (BCN), difluorinated cyclooctynyl (DIFO), dibenzocyclooctynyl (DIBO), keto-DIBO, biarylazacyclooctynyl (BARAC), dibenzoazacyclooctynyl (DIBAC, DBCO, ADIBO), dimethoxyazacyclooctynyl (DIMAC), difluorobenzocyclooctynyl (DIFBO), monobenzocyclooctynyl (MOBO), and tetramethoxydibenzocyclooctynyl (TMDIBO).

[0169] Preferably, R 11 is an alkynyl group or a cycloalkynyl group, more preferably a cycloalkynyl group, such as DBCO or BCN.

[0170] Exemplary chelating agents of the present invention include:

[0171] [ka]

[0172] [ka] These include, but are not limited to:

[0173] Such chelators can be covalently attached to an antibody or antigen-binding domain by reacting the chelator with an azide-labeled antibody or antigen-binding domain via click chemistry to form a 1,2,3-triazole linker, as described in WO 2020 / 229974, to form an immunoconjugate or radioimmunoconjugate.

[0174] The chelating agents of the present invention can be prepared by any method known in the art in light of the present disclosure. For example, the pendant aromatic / heteroaromatic groups can be attached to the macrocyclic ring moiety by methods known in the art, such as those illustrated and described in WO 2020 / 229974.

[0175] Chelating agents of formula (IV), (V) and (VI) Additional chelating agents suitable for use according to the present invention are described in International Application No. PCT / IB2021 / 060350, which is incorporated herein by reference. According to certain embodiments, for example as described in International Application No. PCT / IB2021 / 060350, the chelating agent has the structure of formula (IV):

[0176] [ka] (In the formula, R1 is hydrogen and R2 is -L1-R4; Alternatively, R1 is -L1-R4 and R2 is hydrogen; R3 is hydrogen; or R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, the 5- or 6-membered cycloalkyl being optionally substituted with -L1-R4; L1 is absent or is a linker, R4 has a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen binding domain (eg, h11B6), or a pharma- ceutically acceptable salt thereof.

[0177] In some embodiments, L is absent. When L is absent, R is directly bonded to the compound (e.g., via a covalent bond).

[0178] In some embodiments, L1 is a linker. As used herein, the term "linker" refers to a chemical moiety that links the compounds of the invention to a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen-binding domain. Any suitable linker known to one of skill in the art in view of the present disclosure can be used in the present invention. The linker can have, for example, a substituted or unsubstituted alkyl, a substituted or unsubstituted heteroalkyl moiety, a substituted or unsubstituted aryl or heteroaryl, a polyethylene glycol (PEG) linker, a peptide linker, a sugar-based linker, or a cleavable linker (such as a disulfide bond or a protease cleavage site (such as valine-citrulline-p-aminobenzyl (PAB)). Exemplary linker structures suitable for use in the present invention include:

[0179] [ka] Examples include, but are not limited to, (wherein m is an integer of 0 to 12).

[0180] In some embodiments, R4 is a nucleophilic moiety or an electrophilic moiety. A "nucleophilic moiety" or "nucleophilic group" refers to a functional group that donates an electron pair to form a covalent bond in a chemical reaction. An "electrophilic moiety" or "electrophilic group" refers to a functional group that accepts an electron pair to form a covalent bond in a chemical reaction. A nucleophilic group reacts with an electrophilic group to form a new covalent bond in a chemical reaction, and vice versa. The reaction of a nucleophilic or electrophilic group of a compound of the invention with an antibody or antigen binding domain or other chemical moiety (e.g., a linker) containing a corresponding reaction partner allows the covalent attachment of the antibody or antigen binding domain or chemical moiety to the compound of the invention.

[0181] Examples of nucleophilic groups include, but are not limited to, azides, amines, and thiols. Examples of electrophilic groups include, but are not limited to, amine-reactive groups, thiol-reactive groups, alkynyls, and cycloalkynyls. Amine-reactive groups preferably react with primary amines, including those present at the N-terminus of each polypeptide chain and in the side chains of lysine residues. Examples of amine-reactive groups suitable for use in the present invention include, but are not limited to, N-hydroxy succinimide (NHS), substituted NHS (such as sulfo-NHS), isothiocyanate (-NCS), isocyanate (-NCO), esters, carboxylic acids, acyl halides, amides, alkylamides, and tetrafluorophenyl esters and perfluorophenyl esters. Thiol-reactive groups react with thiols or sulfhydryls, preferably with thiols present in the side chains of cysteine ​​residues of polypeptides. Examples of thiol-reactive groups suitable for use in the present invention include, but are not limited to, Michael acceptors (e.g., maleimides), haloacetyls, acyl halides, activated disulfides, and phenyloxadiazole sulfones.

[0182] In certain embodiments, R4 is -NH2, -NCS (isothiocyanate), -NCO (isocyanate), -N3 (azide), alkynyl, cycloalkynyl, carboxylic acid, ester, amide, alkylamide, maleimide, acyl halide, tetrazine, or trans-cyclooctene, more specifically, -NCS, -NCO, -N3, alkynyl, cycloalkynyl, -C(O)R 13 , -COOR 13 , -CON(R 13 ) 2, maleimide, acyl halide (e.g., —C(O)Cl, —C(O)Br), tetrazine, or trans-cyclooctene, where each R 13 are independently hydrogen or alkyl.

[0183] In some embodiments, R4 is an alkynyl, cycloalkynyl or azide group, thus allowing the attachment of the compounds of the invention to antibodies or antigen binding domains or other chemical moieties (e.g., linkers) using click chemistry. In such embodiments, the click chemistry reaction that can be performed is a Huisgen cycloaddition or 1,3-dipolar cycloaddition between azide (-N3) and an alkynyl or cycloalkynyl group to form a 1,2,4-triazole linker or moiety. In one embodiment, the compounds of the invention comprise an alkynyl or cycloalkynyl group and the antibody or antigen binding domain or other chemical moiety comprises an azide group. In another embodiment, the compounds of the invention comprise an azide group and the antibody or antigen binding domain or other chemical moiety comprises an alkynyl or cycloalkynyl group.

[0184] In certain embodiments, R4 is an alkynyl group, more preferably a terminal alkynyl group or a cycloalkynyl group that is particularly reactive with azide groups via strain-promoted azide-alkyne cyclocycloaddition (SPAAC). Examples of cycloalkynyl groups that can react with azide groups via SPAAC include, but are not limited to, cyclooctynyl or bicyclononyl (BCN), difluorinated cyclooctynyl (DIFO), dibenzocyclooctynyl (DIBO), keto-DIBO, biarylazacyclooctynyl (BARAC), dibenzoazacyclooctynyl (DIBAC, DBCO, ADIBO), dimethoxyazacyclooctynyl (DIMAC), difluorobenzocyclooctynyl (DIFBO), monobenzocyclooctynyl (MOBO), and tetramethoxydibenzocyclooctynyl (TMDIBO).

[0185] In certain embodiments, R4 is dibenzoazacyclooctynyl (DIBAC, DBCO, ADIBO) having the following structure:

[0186] [ka] In embodiments where R4 is DBCO, the DBCO can be covalently attached to the compound directly or indirectly via a linker, preferably indirectly attached to the compound via a linker.

[0187] In certain embodiments, R4 comprises an antibody or antigen-binding domain. The antibody or antigen-binding domain can be directly linked to the compound via a covalent bond or indirectly linked to the compound via a linker. In a preferred embodiment, the antibody or antigen-binding domain has binding specificity for hK2, such as h11B6.

[0188] In another embodiment, the chelating agent has the formula (V):

[0189] [ka] (In the formula, L1 is absent or is a linker, R4 is a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen-binding domain), or a pharma- ceutically acceptable salt thereof.

[0190] In another embodiment, the chelating agent has formula (VI):

[0191] [ka] (In the formula, L1 is absent or is a linker, R4 is a compound that is a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen binding domain (eg, h11B6), or a pharma- ceutically acceptable salt thereof.

[0192] In another embodiment, the chelator is the compound described above, wherein R1 is -L1-R4, R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, L1 is absent or is a linker, and R4 is a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen-binding domain, or a pharma- ceutically acceptable salt thereof.

[0193] In further embodiments, the chelator is the compound described above, where R1 is H, R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl substituted with -L1-R4, where L1 is absent or is a linker, and R4 is a nucleophilic moiety, an electrophilic moiety, or an antibody or antigen-binding domain, or a pharma- ceutically acceptable salt thereof.

[0194] Additional embodiments of the above chelators include those in which R4 is an antibody. According to a preferred embodiment, R4 comprises an antibody having binding specificity for hK2, such as h11B6.

[0195] In one embodiment, the chelating agent is any one or more independently selected from the group consisting of the following compounds and pharma- ceutically acceptable salts thereof:

[0196] [ka]

[0197] [ka] (wherein n is 1 to 10).

[0198] In one embodiment, the radioconjugate of the invention comprises a chelator of the following formula, or a pharma- ceutical acceptable salt thereof:

[0199] [ka]

[0200] The chelating agent can be covalently attached to an antibody or antigen-binding domain (e.g., h11B6) to form an immunoconjugate or radioimmunoconjugate, for example, by reacting the compound with an azide-labeled antibody or antigen-binding domain via click chemistry to form a 1,2,3-triazole linker, as described in WO 2020 / 229974 or PCT / IB2021 / 060350.

[0201] The chelators, radiometal complexes, and radioimmunoconjugates of the invention can be prepared by any method known in the art in light of the present disclosure. For example, the pendant aromatic / heteroaromatic groups can be attached to the macrocyclic ring moiety by methods known in the art, such as those illustrated and described in WO 2020 / 229974 and PCT / IB2021 / 060350.

[0202] chemical nomenclature Those skilled in the art will understand that compound structures can be named or identified using commonly recognized naming systems and symbols. For example, compounds can be named or identified by common name, systematic name, or non-systematic name. Commonly recognized naming systems and symbols in the field of chemistry include, but are not limited to, Chemical Abstract Service (CAS) and International Union of Pure and Applied Chemistry (IUPAC).

[0203] In general, a reference to a particular element, such as hydrogen or H, is meant to include all isotopes of that element. For example, if an R group is defined to include hydrogen or H, it also includes deuterium and tritium. Thus, tritium, C 14 , P 32 and S 35Compounds containing radioisotopes such as are within the scope of the present technology. Procedures for inserting such labels into the compounds of the present technology will be readily apparent to those of skill in the art based on the disclosure herein.

[0204] The term "substituted" means that at least one hydrogen atom has been replaced with a non-hydrogen group, provided that all normal valences are maintained and the replacement results in a stable compound. When a particular group is "substituted", the group can have one or more substituents, preferably 1-5 substituents, more preferably 1-3 substituents, and most preferably 1-2 substituents, independently selected from a list of substituents. For example, "substituted" refers to an organic group (e.g., an alkyl group) as defined below, in which one or more bonds to a hydrogen atom contained therein are replaced by a bond to a non-hydrogen or non-carbon atom. Substituted groups also include groups in which one or more bonds to a carbon or hydrogen atom are replaced by a heteroatom with one or more bonds, including double or triple bonds. Thus, unless otherwise specified, a substituted group is substituted with one or more substituents. In some embodiments, a substituted group is substituted with 1, 2, 3, 4, 5, or 6 substituents. Examples of substituents include halogens (i.e., F, Cl, Br, and I); hydroxyl; alkoxy, alkenoxy, aryloxy, aralkyloxy, heterocyclyl, heterocyclylalkyl, heterocyclyloxy, and heterocyclylalkoxy groups; carbonyl (oxo); carboxylates; esters; urethanes; oximes; hydroxylamines; alkoxyamines; aralkoxyamines; thiols; sulfides; sulfoxides; sulfones; sulfonyls; pentafluorosulfanyl (i.e., SF), sulfonamides; amines; N-oxides; hydrazines; hydrazides; hydrazones; azides; amides; ureas; amidines; guanidines; enamines; imides; isocyanates; isothiocyanates; cyanates; thiocyanates; imines; nitro groups; nitriles (i.e., CN), and the like. The term "independently," when used with reference to substituents, means that when two or more such substituents are possible, such substituents may be the same or different from one another.

[0205] Substituted ring groups, such as substituted cycloalkyl, aryl, heterocyclyl, and heteroaryl groups, also include rings and ring systems in which a bond to a hydrogen atom is replaced with a bond to a carbon atom. Thus, substituted cycloalkyl, aryl, heterocyclyl, and heteroaryl groups can also be substituted with substituted or unsubstituted alkyl, alkenyl, and alkynyl groups as defined below.

[0206] As used herein, C1-C 11 Cm-Cn, such as C1-C8 or C1-C6, when used before a group, refers to the group containing m to n carbon atoms.

[0207] Alkyl groups include straight and branched chain alkyl groups having 1 to 12 carbon atoms, typically 1 to 10 carbon atoms, or in some embodiments 1 to 8, 1 to 6, or 1 to 4 carbon atoms. For example, alkyl groups can be 1 to 12 carbon atoms (C 1~12 alkyl), or 1 to 8 carbon atoms (C 1~8 alkyl), or 1 to 6 carbon atoms (C 1~6 Examples of straight chain alkyl groups include groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, and n-octyl groups. Examples of branched chain alkyl groups include, but are not limited to, isopropyl, iso-butyl, sec-butyl, tert-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups. The alkyl groups can be substituted or unsubstituted. Representative substituted alkyl groups may be substituted one or more times with substituents such as those listed above, including, but not limited to, haloalkyl (e.g., trifluoromethyl), hydroxyalkyl, thioalkyl, aminoalkyl, alkylaminoalkyl, dialkylaminoalkyl, alkoxyalkyl, carboxyalkyl, and the like.

[0208] Cycloalkyl groups include monocyclic, bicyclic, or tricyclic alkyl groups having 3 to 12 carbon atoms in the ring, or in some embodiments, 3 to 10, 3 to 8, or 3 to 4, 5, or 6 carbon atoms. Exemplary monocyclic cycloalkyl groups include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. In some embodiments, cycloalkyl groups have 3 to 8 ring members, while in other embodiments, the number of ring carbon atoms ranges from 3 to 5, 3 to 6, or 3 to 7. Bicyclic and tricyclic ring systems include both bridged cycloalkyl groups and fused rings, such as, but are not limited to, bicyclo[2.1.1]hexane, adamantyl, decalinyl, and the like. Cycloalkyl groups can be substituted or unsubstituted. Substituted cycloalkyl groups can be substituted one or more times with non-hydrogen and non-carbon groups, as defined above. However, substituted cycloalkyl groups also include rings that are substituted with straight or branched chain alkyl groups as defined above. Representative substituted cycloalkyl groups may be mono-substituted or more than once substituted (such as, but not limited to, 2,2-, 2,3-, 2,4-2,5-, or 2,6-disubstituted cyclohexyl groups), which may be substituted with substituents such as those listed above.

[0209] Cycloalkylalkyl groups are alkyl groups as defined above where a hydrogen or carbon bond of the alkyl group is replaced with a bond to a cycloalkyl group as defined above. In some embodiments, cycloalkylalkyl groups have 4 to 16 carbon atoms, 4 to 12 carbon atoms, typically 4 to 10 carbon atoms. Cycloalkylalkyl groups can be substituted or unsubstituted. Substituted cycloalkylalkyl groups can be substituted at the alkyl portion, the cycloalkyl portion, or both the alkyl and cycloalkyl portions of the group. Representative substituted cycloalkylalkyl groups can be mono-substituted, substituted two or more times, and can be mono-, di-, or tri-substituted with substituents such as, but not limited to, those listed above.

[0210] Alkenyl groups include straight and branched chain alkyl groups as defined above, except that at least one double bond is present between two carbon atoms. Alkenyl groups have 2 to 12 carbon atoms, typically 2 to 10 carbon atoms, or in some embodiments, 2 to 8, 2 to 6, or 2 to 4 carbon atoms. In some embodiments, an alkenyl can have one carbon-carbon double bond, or multiple carbon-carbon double bonds, such as 2, 3, 4 or more carbon-carbon double bonds. Examples of alkenyl groups include, but are not limited to, methenyl, ethenyl, propenyl, butenyl, and the like. Alkenyl groups can be substituted or unsubstituted. Representative substituted alkenyl groups may be mono-substituted or substituted more than once, for example, mono-, di-, or tri-substituted with the substituents listed above, but are not limited thereto.

[0211] Cycloalkenyl groups include cycloalkyl groups as defined above, with at least one double bond between two carbon atoms. Cycloalkenyl groups can be monocyclic or polycyclic alkyl groups having 3 to 12, more preferably 3 to 8, carbon atoms in the ring and containing at least one double bond between two carbon atoms. Cycloalkenyl groups can be substituted or unsubstituted. In some embodiments, cycloalkenyl groups can have one, two, or three double bonds, or multiple carbon-carbon double bonds, such as two, three, four, or more carbon-carbon double bonds, but do not include aromatic compounds. Cycloalkenyl groups have 3 to 14 carbon atoms, or in some embodiments, 5 to 14 carbon atoms, 5 to 10 carbon atoms, or even 5, 6, 7, or 8 carbon atoms. Examples of cycloalkenyl groups include cyclohexenyl, cyclopentenyl, cyclohexadienyl, cyclobutadienyl, and cyclopentadienyl.

[0212] Cycloalkenylalkyl groups are alkyl groups as defined above, in which a hydrogen or carbon bond of the alkyl group is replaced with a bond to a cycloalkenyl group as defined above.Cycloalkenylalkyl groups can be substituted or unsubstituted.Substituted cycloalkenylalkyl groups can be substituted at the alkyl portion, the cycloalkenyl portion, or both the alkyl portion and the cycloalkenyl portion of the group.Representative substituted cycloalkenylalkyl groups can be substituted one or more times with a substituent such as those listed above.

[0213] Alkynyl groups include straight and branched chain alkyl groups as defined above, except that at least one triple bond is present between two carbon atoms. Alkynyl groups have 2 to 12 carbon atoms, typically 2 to 10 carbon atoms, or in some embodiments, 2 to 8, 2 to 6, or 2 to 4 carbon atoms. In some embodiments, alkynyl groups have one, two, or three carbon-carbon triple bonds. Examples include, but are not limited to, -C=CH, -C=CCH3, -CH2C=CCH3, -C=CCH2CH(CH2CH3)2, among others. Alkynyl groups can be substituted or unsubstituted. A terminal alkyne has at least one hydrogen atom bonded to a triple bonded carbon atom. Representative substituted alkynyl groups can be mono-substituted or substituted more than once, for example, mono-, di-, or tri-substituted with substituents such as those listed above, but are not limited thereto. A "cyclic alkyne" or "cycloalkynyl" is a cycloalkyl ring containing at least one triple bond between two carbon atoms. Examples of cyclic alkyne or cycloalkynyl groups include, but are not limited to, cyclooctyne, bicyclononyne (BCN), difluorinated cyclooctyne (DIFO), dibenzocyclooctyne (DIBO), keto-DIBO, biarylazacyclooctyne (BARAC), dibenzoazacyclooctyne (DIBAC), dimethoxyazacyclooctyne (DIMAC), difluorobenzocyclooctyne (DIFBO), monobenzocyclooctyne (MOBO), and tetramethoxyDIBO (TMDIBO).

[0214] An aryl group is a cyclic aromatic hydrocarbon that does not contain heteroatoms. Aryl groups herein include monocyclic, bicyclic, and tricyclic ring systems. Thus, aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, fluorenyl, phenanthrenyl, anthracenyl, indenyl, indanyl, pentalenyl, and naphthyl groups. In some embodiments, aryl groups contain 6-14 carbons, and in other cases, 6-12, or even 6-10 carbon atoms in the ring portion of the group. In some embodiments, an aryl group is phenyl or naphthyl. An aryl group can be substituted or unsubstituted. The phrase "aryl group" includes groups that contain fused rings, such as fused aromatic-aliphatic ring systems (e.g., indanyl, tetrahydronaphthyl, etc.). Representative substituted aryl groups may be mono-substituted or substituted more than once. For example, monosubstituted aryl groups include, but are not limited to, di-, tri-, tetra-, penta-, or hexasubstituted phenyl or naphthyl groups, which may be substituted with substituents such as those listed above. Aryl moieties are well known and are described, for example, in Lewis, RJ, ed., Hawley's Condensed Chemical Dictionary, 13 th Edition, John Wiley & Sons, Inc., New York (1997). Aryl groups can be a single ring structure (i.e., monocyclic) or can contain multiple ring structures (i.e., polycyclic) that are fused ring structures. Preferably, the aryl group is a monocyclic aryl group.

[0215] An alkoxy group is a hydroxyl group (-OH) in which the bond to the hydrogen atom is replaced by a bond to a carbon atom of a substituted or unsubstituted alkyl group as defined above. Examples of straight chain alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, and the like. Examples of branched chain alkoxy groups include, but are not limited to, isopropoxy, sec-butoxy, tert-butoxy, isopentoxy, isohexoxy, and the like. Examples of cycloalkoxy groups include, but are not limited to, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like. An alkoxy group may be substituted or unsubstituted. Representative substituted alkoxy groups may be substituted one or more times with a substituent such as those listed above.

[0216] Similarly, alkylthio or thioalkoxy refers to the group -SR, where R is an alkyl attached to the parent molecule via a sulfur bridge, e.g., -S-methyl, -S-ethyl, etc. Representative examples of alkylthio include, but are not limited to, -SCH, -SCHCH, and the like.

[0217] As used herein, the term "halogen" refers to bromine, chlorine, fluorine, or iodine. Correspondingly, the term "halo" means fluoro, chloro, bromo, or iodo. In some embodiments, the halogen is fluorine. In other embodiments, the halogen is chlorine or bromine.

[0218] The terms "hydroxy" and "hydroxyl" may be used interchangeably and refer to --OH.

[0219] The term "carboxy" refers to --COOH.

[0220] The term "cyano" refers to --CN.

[0221] The term "nitro" refers to --NO.

[0222] The term "isothiocyanate" refers to -N=C=S.

[0223] The term "isocyanate" refers to -N=C=O.

[0224] The term "azido" refers to -N3.

[0225] The term "amino" refers to -NH2. The term "alkylamino" refers to an amino group in which one or both of the hydrogen atoms attached to the nitrogen are replaced with an alkyl group. An alkylamine group can be represented as -NR2, where each R is independently hydrogen or an alkyl group. For example, alkylamines include methylamine (-NHCH3), dimethylamine (-N(CH3)2), -NHCH2CH3, and the like. As used herein, the term "aminoalkyl" is intended to include both branched and straight-chain saturated aliphatic hydrocarbon groups substituted with one or more amino groups. Representative examples of aminoalkyl groups include, but are not limited to, -CH2NH2, -CH2CH2NH2, and -CH2CH(NH2)CH3.

[0226] As used herein, "amide" refers to -C(O)N(R)2, where each R is independently an alkyl group or hydrogen. Examples of amides include, but are not limited to, -C(O)NH2, -C(O)NHCH3, and -C(O)N(CH3)2.

[0227] The terms "hydroxylalkyl" and "hydroxyalkyl" are used interchangeably and refer to an alkyl group substituted with one or more hydroxyl groups. The alkyl can be a branched or straight chain aliphatic hydrocarbon. Examples of hydroxylalkyl include, but are not limited to, hydroxylmethyl (-CHOH), hydroxylethyl (-CHCHOH), and the like.

[0228] As used herein, the term "heterocyclyl" includes stable monocyclic and polycyclic hydrocarbons containing at least one heteroatom ring member, such as sulfur, oxygen, or nitrogen. As used herein, the term "heteroaryl" includes stable monocyclic and polycyclic aromatic hydrocarbons containing at least one heteroatom ring member, such as sulfur, oxygen, or nitrogen. Heteroaryls can be monocyclic or polycyclic, e.g., bicyclic or tricyclic. Each ring of a heteroatom-containing heterocyclyl or heteroaryl group can contain one or two oxygen or sulfur atoms and / or one to four nitrogen atoms, provided that the total number of heteroatoms in each ring is four or less and each ring has at least one carbon atom. Heteroaryl groups that are polycyclic, e.g., bicyclic or tricyclic, must contain at least one fully aromatic ring, but other fused rings or rings can be aromatic or non-aromatic. The heterocyclyl or heteroaryl group can be attached to any available nitrogen or carbon atom of any ring of the heterocyclyl or heteroaryl group. Preferably, the term "heteroaryl" refers to 5- or 6-membered monocyclic and 9- or 10-membered bicyclic groups having at least one heteroatom (O, S, or N) in at least one of the rings, with the heteroatom-containing ring preferably having 1, 2, or 3 heteroatoms, more preferably having 1 or 2 heteroatoms selected from O, S, and / or N. The nitrogen heteroatom of a heteroaryl may be substituted or unsubstituted. In addition, the nitrogen and sulfur heteroatoms of a heteroaryl may be optionally oxidized (i.e., N→O and S(O)). r where r is 0, 1, or 2.

[0229] The term "ester" refers to -C(O)R, where R is alkyl.

[0230] The term "carbamate" refers to -OC(O)NR2, where each R is independently alkyl or hydrogen.

[0231] The term "aldehyde" refers to -C(O)H.

[0232] The term "carbonic acid" refers to -OC(O)OR, where R is alkyl.

[0233] The term "maleimide" refers to a group having the chemical formula H2C2(CO)2NH. The term "maleimide" refers to a maleimide group covalently bonded to another group or molecule. Preferably, the maleimide group is N-bonded, for example:

[0234] [ka]

[0235] The term "acyl halide" refers to -C(O)X, where X is halo (e.g., Br, Cl). Exemplary acyl halides include acyl chlorides (-C(O)Cl) and acyl bromides (-C(O)Br).

[0236] According to the convention used in the art,

[0237] [ka] is used in structural formulas herein to depict a bond that is the point of attachment of a moiety, functional group, or substituent to a core, parent, or scaffold structure, such as an antigen binding domain of the invention.

[0238] When any variable occurs more than one time in any constituent or formula for a compound, its definition at each occurrence is independent of its definition at every other occurrence. Thus, for example, if a group is shown to be substituted with 0 to 3 R groups, that group may be optionally substituted with up to 3 R groups, and each occurrence of R is independently selected from the definitions of R.

[0239] When a bond to a substituent is shown to cross a bond connecting two atoms in a ring, then such substituent may be bonded to any atom on the ring.

[0240] In certain embodiments, the radioconjugate is 225 Ac-DOTA-h11B6, also referred to as Actinium 225-1,4,7,10-tetraazacyclododecane-1,4,7,10,tetraacetic acid-h11B6. 225 Ac-DOTA-h11B6 is a compound chelated to DOTA. 225 A radioconjugate comprising Ac, wherein the DOTA is optionally conjugated to h11B6 via a linker. 111 In-DOTA-h11B6 is chelated to DOTA 111 A radioconjugate comprising In, said DOTA optionally being conjugated to h11B6 via a linker.

[0241] In certain embodiments, the radioconjugate can be represented by the following compound or a variant thereof:

[0242] [ka]

[0243] In certain embodiments, the radioconjugate is 225 Ac-TOPA-h11B6. 225 Ac-TOPA-h11B6 was chelated to TOPA. 225 Ac, wherein TOPA is conjugated to h11B6, optionally via a linker. 225 The Ac-TOPA-h11B6 radioconjugate can be represented by the following compound or a variant thereof, which may also be referred to as TOPA-[C7]-phenylthiourea-h11B6 antibody conjugate:

[0244] [ka]

[0245] In the TOPA-[C7]-phenylthiourea-h11B6 antibody conjugate shown above, the structure does not depict the lysine residue of h11b6 linked to the phenylthiourea moiety (depicted in Figures 6B and 6C).

[0246] Pharmaceutical Compositions and Methods of Use An embodiment of the present invention provides a method of treating cancer in a patient comprising administering to the patient a therapeutically effective amount of a radioconjugate. According to one embodiment, the method comprises administering to the patient a therapeutically effective amount of a pharmaceutical composition comprising the radioconjugate and one or more pharma- ceutically acceptable excipients.

[0247] The embodiments of the present invention are particularly useful in treating patients who have been diagnosed with prostate cancer, for example, patients with late-stage prostate cancer. According to one embodiment, the cancer is non-localized prostate cancer. According to another embodiment, the cancer is metastatic prostate cancer. According to another embodiment, the cancer is castration-resistant prostate cancer (CRPC). According to another embodiment, the cancer is metastatic castration-resistant prostate cancer (mCRPC). According to another embodiment, the cancer is mCRPC with adenocarcinoma. According to certain embodiments, the patient has a castrated testosterone level of about 50 ng / dL or less. According to additional embodiments, the patient has been previously exposed to at least one androgen receptor (AR) targeted therapy, such as abiraterone acetate, enzalutamide, apalutamide, darolutamide, or any combination of the foregoing. According to additional embodiments, the patient has been previously treated with chemotherapy, for example, the chemotherapy included administration of a taxane. According to another embodiment, the patient has been previously treated with orchiectomy or medical castration. According to another embodiment, the patient is undergoing ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH) agonist or antagonist.

[0248] According to embodiments of the methods of treatment described herein, the radioconjugate administered to the patient comprises at least one radioactive metal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2. Preferably, the radioconjugate comprises at least one radioactive metal complex conjugated to an antibody having binding specificity for hK2. In a preferred embodiment, the radioactive metal complex comprises 225 Contains Ac.

[0249] According to one embodiment, the radiometal in the pharmaceutical composition is 225 Ac, providing a target radioactivity of about 50 μCi to about 350 μCi per dose of the pharmaceutical composition. According to additional embodiments, the radiometal in the pharmaceutical composition is about 50 μCi to about 300 μCi, or about 50 μCi to about 250 μCi, or about 50 μCi to about 240 μCi, or about 50 μCi to about 230 μCi, or about 50 μCi to about 220 μCi, or about 50 μCi to about 210 μCi, or about 50 μCi to about 200 μCi, or about 50 μCi to about 175 μCi, or about 50 μCi to about 150 μCi, or about 50 μCi to about 125 μCi, or about 50 μCi to about 100 μCi, or A target radioactivity of about 100 μCi to about 300 μCi, or about 100 μCi to about 250 μCi, or about 100 μCi to about 240 μCi, or about 100 μCi to about 230 μCi, or about 100 μCi to about 220 μCi, or about 100 μCi to about 210 μCi, or about 100 μCi to about 200 μCi, or about 100 μCi to about 175 μCi, or about 100 μCi to about 150 μCi, or about 150 μCi to about 300 μCi, or about 150 μCi to about 250 μCi, or about 175 μCi to about 225 μCi is provided.

[0250] According to one embodiment, the radiometal in the pharmaceutical composition is 225Ac, providing a target radioactivity of about 50 μCi to about 500 μCi per dose of the pharmaceutical composition. According to additional embodiments, the radiometal in the pharmaceutical composition is about 50 μCi to about 450 μCi, or about 50 μCi to about 400 μCi, or about 50 μCi to about 350 μCi, or about 100 μCi to about 500 μCi, or about 100 μCi to about 450 μCi, or about 100 μCi to about 400 μCi, or about 100 μCi to about 350 μCi per dose of the pharmaceutical composition. i, or from about 150 μC to about 500 μCi, or from about 150 μC to about 450 μCi, or from about 150 μC to about 400 μCi, or from about 150 μC to about 350 μCi, or from about 200 μC to about 500 μCi, or from about 200 μC to about 450 μCi, or from about 200 μC to about 400 μCi, or from about 200 μC to about 350 μCi.

[0251] According to one embodiment, the radiometal in the pharmaceutical composition is 225Ac, providing a target specific radioactivity of about 50 μCi to about 350 μCi per about 2 mg of total antibody in the pharmaceutical composition. According to additional embodiments, the radiometal in the pharmaceutical composition is about 50 μCi to about 300 μCi, or about 50 μCi to about 250 μCi, or about 50 μCi to about 240 μCi, or about 50 μCi to about 230 μCi, or about 50 μCi to about 220 μCi, or about 50 μCi to about 210 μCi, or about 50 μCi to about 200 μCi, or about 50 μCi to about 175 μCi, or about 50 μCi to about 150 μCi, or about 50 μCi to about 125 μCi, or about 50 μCi to about 100 μCi, or provides a target specific activity of about 100 μCi to about 300 μCi, or about 100 μCi to about 250 μCi, or about 100 μCi to about 240 μCi, or about 100 μCi to about 230 μCi, or about 100 μCi to about 220 μCi, or about 100 μCi to about 210 μCi, or about 100 μCi to about 200 μCi, or about 100 μCi to about 175 μCi, or about 100 μCi to about 150 μCi, or about 150 μCi to about 300 μCi, or about 150 μCi to about 250 μCi, or about 175 μCi to about 225 μCi of radioactivity. According to additional embodiments, the radiometal in the pharmaceutical composition provides a target specific activity of about 50 μCi, or about 100 μCi, or about 150 μCi, or about 175 μCi, or about 200 μCi, or about 225 μCi, or about 250 μCi, or about 275 μCi, or about 300 μCi per about 2 mg of total antibody in the pharmaceutical composition. For example, it should be understood that an amount of 300 μCi per 2 mg of antibody is equivalent to 150 μCi / mg of antibody, 200 μCi per 2 mg of antibody is equivalent to 100 μCi / mg of antibody, etc.

[0252] According to another embodiment, the radiometal in the pharmaceutical composition is 225Ac and provides a target specific activity of about 50 μCi to about 350 μCi per about 2 mg to about 10 mg of total antibody in the pharmaceutical composition (e.g., per about 2 mg, or about 4 mg, or about 6 mg, or about 8 mg, or about 10 mg of total antibody in the pharmaceutical composition). According to additional embodiments, the radiometal in the pharmaceutical composition is about 50 μCi to about 300 μCi, or about 50 μCi to about 250 μCi, or about 50 μCi to about 240 μCi, or about 50 μCi to about 230 μCi, or about 50 μCi to about 220 μCi, or about 50 μCi to about 210 μCi, or about 50 μCi to about 200 μCi, or about 50 μCi to about 175 μCi, or about 50 μCi to about 15 ...50 μCi, or about 50 μCi to about 150 μCi, or about 50 μCi to about 150 μCi, or about 50 μCi to about 15 100 μCi to about 125 μCi, or about 50 μCi to about 100 μCi, or about 100 μCi to about 300 μCi, or about 100 μCi to about 250 μCi, or about 100 μCi to about 240 μCi, or about 100 μCi to about 230 μCi, or about 100 μCi to about 220 μCi, or about 100 μCi to about 210 μCi, or about 100 μCi to about 200 μCi, or about 100 μCi to about 175 μCi, or about 100 μCi to about 150 μCi, or about 150 μCi to about 300 μCi, or about 150 μCi to about 250 μCi, or about 175 μCi to about 225 μCi radioactivity. According to additional embodiments, the radiometal in the pharmaceutical composition provides a target specific activity of about 50 μCi, or about 100 μCi, or about 150 μCi, or about 175 μCi, or about 200 μCi, or about 225 μCi, or about 250 μCi, or about 275 μCi, or about 300 μCi, or about 350 μCi per about 2 mg to about 10 mg of total antibody in the pharmaceutical composition (e.g., per about 2 mg, or about 4 mg, or about 6 mg, or about 8 mg, or about 10 mg of total antibody in the pharmaceutical composition).

[0253] According to another embodiment, the radiometal in the pharmaceutical composition is 225Ac, providing a target specific radioactivity of about 50 μCi to about 500 μCi per about 2 mg to about 10 mg of total antibody in the pharmaceutical composition (e.g., per about 2 mg, or about 4 mg, or about 6 mg, or about 8 mg, or about 10 mg of total antibody in the pharmaceutical composition). According to additional embodiments, the radiometal in the pharmaceutical composition is about 50 μCi to about 450 μCi, or about 50 μCi to about 400 μCi, or about 50 μCi to about 350 μCi, or about 100 μCi to about 500 μCi, or about 100 μCi to about 450 μCi, or about A target specific radioactivity of 100 μCi to about 400 μCi, or about 100 μCi to about 350 μCi, or about 150 μCi to about 500 μCi, or about 150 μCi to about 450 μCi, or about 150 μCi to about 400 μCi, or about 150 μCi to about 350 μCi, or about 200 μCi to about 500 μCi, or about 200 μCi to about 450 μCi, or about 200 μCi to about 400 μCi, or about 200 μCi to about 350 μCi radioactivity is provided. According to additional embodiments, the radiometal in the pharmaceutical composition provides a target specific activity of about 350 μCi, or about 375 μCi, or about 400 μCi, or about 425 μCi, or about 450 μCi, or about 475 μCi, or about 500 μCi per about 2 mg to about 10 mg of total antibody in the pharmaceutical composition (e.g., per about 2 mg, or about 4 mg, or about 6 mg, or about 8 mg, or about 10 mg of total antibody in the pharmaceutical composition).

[0254] According to one embodiment, the radiometal in the pharmaceutical composition is 225 Ac, and the target radioactivity concentration of the pharmaceutical composition is about 1 μCi / mL to about 100 μCi / mL, or about 5 μCi / mL to about 75 μCi / mL, or about 10 μCi / mL to about 60 μCi / mL, or about 12.5 μCi / mL to about 50 μCi / mL, or about 12.5 μCi / mL, or about 25 μCi / mL, or about 37.5 μCi / mL, or about 50 μCi / mL.

[0255] As used herein, "at the time of dosing" refers to the time at which a patient is administered a dose of a pharmaceutical composition comprising a radioconjugate (e.g., as a single dose or in multiple administrations of two or more sub-doses). 225 Due to the breakdown of Ac, 225 The amount of radioactivity provided by Ac varies from the time of manufacture to the time of administration, i.e., during the manufacturing process. 225 The amount of Ac in the pharmaceutical composition is reduced from about the time that Ac is chelated to the conjugate intermediate to form the radioconjugate to the time that the radioconjugate is administered to a patient. 225 The radioactivity provided by Ac is 225 If Ac is about 264 μCi at the time that it is chelated to the conjugate intermediate to form the radioconjugate (e.g., after the radioconjugate is formed and purified), then the radioactivity about 96 hours after administration may be about 200 μCi. 225 The decay, and therefore the amount, of Ac is determined by the initial amount of activity measured at time zero, the elapsed time, and 225 It can be calculated based on the half-life of Ac.

[0256] As used herein, the "target" specific activity or "target" radioactivity or "target" radioactivity concentration of a radiometal refers to the amount of specific activity or activity or radioactivity concentration, respectively, that is calculated to be present in a dose of a pharmaceutical composition at the time of predicted administration to a patient, based, for example, on the amount of radiometal present in the composition at the time of manufacture and the amount of time (and associated radiometal decay) expected between manufacture and administration to a patient. It should be understood that the actual specific activity or activity or radioactivity concentration at the time of dosing may vary slightly from the target specific activity or activity or radioactivity concentration, respectively (e.g., if the actual administration time to a patient differs slightly from the predicted administration time).

[0257] According to certain embodiments, the pharmaceutical composition also contains a non-radiolabeled antibody. For example, a composition containing a non-radiolabeled antibody may be combined with a composition containing a radioconjugate to dilute the radioconjugate composition to the desired radioactive dose. As used herein, the term "non-radiolabeled antibody" refers to an antibody or antibody-chelator complex that is not conjugated to a radioactive metal. According to certain embodiments, the non-radiolabeled antibody present in the composition is a conjugate intermediate, such as DOTA-mAb (e.g., DOTA-h11B6). Preferably, the non-radiolabeled antibody comprises the same antibody as the radioconjugate contained in the composition, e.g., the pharmaceutical composition comprises an amount of 225 The pharmaceutical composition may comprise Ac-DOTA-h11B6 and an amount of DOTA-h11B6. Alternatively, the pharmaceutical composition may comprise an amount of 225 Ac-TOPA-h11B6 and an amount of TOPA-h11B6. As used herein, "total antibody" refers to the total amount of antibody in the pharmaceutical composition, for example, total antibody may include (a) the amount of antibody conjugated to a radioactive metal complex, and (b) the amount of non-radiolabeled antibody, such as a conjugate intermediate. Target total antibody refers to the amount of antibody calculated to be present in a dose of the pharmaceutical composition at the expected time of administration to a patient. According to certain embodiments, the total amount of antibody (radiolabeled and non-radiolabeled) does not exceed about 10 mg, or about 9 mg, or about 8 mg, or about 7 mg, or about 6 mg, or about 5 mg, or about 4 mg, or about 3 mg, or about 2 mg in the composition.

[0258] According to certain embodiments, a method of making a pharmaceutical composition of the present invention comprises combining a first intermediate composition and a second intermediate composition to form a pharmaceutical composition, where the first intermediate composition comprises a radioactive conjugate and the second intermediate composition comprises a conjugate intermediate and does not contain any radioactive conjugate. According to certain embodiments, the first intermediate composition and the second intermediate composition comprise the same pharma- ceutically acceptable excipient.

[0259] According to certain embodiments, the pharmaceutical composition comprises from about 0.1 mg to about 5 mg of total antibody, or from about 0.1 mg to about 4 mg of total antibody, or from about 0.1 mg to about 3 mg of total antibody, or from about 0.1 mg to about 4 mg of total antibody, or from about 0.1 mg to about 3 mg of total antibody, or from about 0.1 mg to about 2 mg of total antibody, or from about 0.5 mg to about 5 mg of total antibody, or from about 0.5 mg to about 4 mg of total antibody, or from about 0.5 mg to about 3 mg of total antibody, or from about 0.5 mg to about 3.5 mg of total antibody, or from about 0.5 mg to about 4 mg of total antibody, or from about 1 mg to about 10 mg of total antibody, or from about 1 mg to about 7 mg of total antibody, or from about 1 mg to about 5 mg of total antibody, or from about 1 mg to about 4 mg of total antibody. or about 1 mg to about 3 mg of total antibody, or about 1.5 to about 2.5 mg of total antibody, or about 1.1 or about 1.2 mg of total antibody, or about 1.3 mg of total antibody, or about 1.4 mg of total antibody, or about 1.5 mg of total antibody, or about 1.6 mg of total antibody, or about 1.7 mg of total antibody, or about 1.8 mg of total antibody, or about 1.9 mg of total antibody, or about 2 mg of total antibody, or about 2.1 mg of total antibody, or about 2.2 mg of total antibody, or about 2.3 mg of total antibody, or about 2.4 mg of total antibody, or about 2.5 mg of total antibody, or about 2.6 mg of total antibody, or about 2.7 mg of total antibody, or about 2.8 mg of total antibody, or about 2.9 mg of total antibody.

[0260] According to certain embodiments, the dose of the pharmaceutical composition has a volume of about 1 mL to about 20 mL, or about 1 mL to about 10 mL, or about 2 mL to about 6 mL, or about 3 mL to about 5 mL, or about 4 mL. According to one embodiment, the dose of the pharmaceutical composition contains about 2 mg of total antibody per about 4 mL dose (i.e., about 1 mg of total antibody per about 2 mL dose). As described herein, the dose may be administered as multiple partial doses. For example, an 8 mL dose may be administered as two 4 mL partial doses. In one embodiment, the subject is administered two 4 mL partial doses, each partial dose containing 2 mg of antibody, for a total of 4 mg of antibody per 8 mL dose.

[0261] According to certain embodiments, the pharmaceutical composition comprises the whole antibody in an amount of about 0.01-5.0 mg / mL, or about 0.01-4.0 mg / mL, or about 0.01-3.0 mg / mL, about 0.01-2.0 mg / mL, or about 0.01-1.0 mg / mL, about 0.1-5.0 mg / mL, or about 0.1-4.0 mg / mL, or about 0.1-3.0 mg / mL, about 0.1-2.0 mg / mL, or about 0.1-1.0 mg / mL, about 0.3-0.7 mg / mL, or about 0.4-0.6 mg / mL, or about 0.5 mg / mL.

[0262] According to one embodiment, in a vial containing a dose of the pharmaceutical composition, e.g. 225 The target total antibody concentration in the vial containing Ac-DOTA-h11B6 and DOTA-h11B6 is about 0.5±0.1 mg / mL. In one embodiment, when the dose contains about 4 mL of pharmaceutical composition, the target total antibody concentration in the dose is about 0.5 mg / mL, the target radioactivity of the dose is about 50 μCi, and the target radioactivity concentration is about 12.5 μCi / mL (e.g., 12.5 μCi / mL±10%). In another embodiment, when the dose contains about 4 mL of pharmaceutical composition, the target total antibody concentration in the dose is about 0.5 mg / mL, the target radioactivity of the dose is about 100 μCi, and the target radioactivity concentration is about 25 μCi / mL (e.g., 25 μCi / mL±10%). In another embodiment, when a dose contains about 4 mL of pharmaceutical composition, the target total antibody concentration in the dose is about 0.5 mg / mL, the target radioactivity in the dose is about 150 μCi, and the target radioactivity concentration is about 37.5 μCi / mL (e.g., 37.5 μCi / mL ± 10%). In another embodiment, when a dose contains about 4 mL of pharmaceutical composition, the target total antibody concentration in the dose is about 0.5 mg / mL (about 2 mg of total antibody), the target radioactivity in the dose is about 200 μCi, and the target radioactivity concentration is about 50 μCi / mL (e.g., 50 μCi / mL ± 10%). In another embodiment, where a dose contains about 8 mL of pharmaceutical composition, the target total antibody concentration in the dose is about 0.5 mg / mL (about 4 mg of total antibody), the target radioactivity of the dose is about 300 μCi, and the target radioactivity concentration is about 37.5 μCi / mL (e.g., 37.5 μCi / mL ± 10%).

[0263] According to further embodiments, the total antibody is present in the pharmaceutical composition at a concentration of about 0.1 mg / mL to about 1 mg / mL. In some embodiments, the concentration of the total antibody in the pharmaceutical composition is about 0.1 to about 0.9, about 0.1 to about 0.8, about 0.1 to about 0.7, about 0.1 to about 0.6, about 0.1 to about 0.5, about 0.1 to about 0.4, about 0.1 to about 0.3, about 0.1 to about 0.2, about 0.2 to about 1, about 0.2 to about 0.9, about 0.2 to about 0.8, about 0.2 to about 0.7, about 0.2 to about 0.6, about 0.2 to about 0.5, about 0.2 to about 0.4, about 0.2 to about 0.3, about 0.3 to about 1, about 0.3 to about 0.9, about 0.3 to about 0.8, about 0.3 to about 0.7, about 0.3 to about 0 In another embodiment, the pharmaceutical composition contains about 0.5 mg / mL of the total antibody. In a further embodiment, the pharmaceutical composition comprises a total of about 0.1 mg / mL to about 1 mg / mL 225 In a further embodiment, the pharmaceutical composition contains about 0.5 mg / mL of Ac-DOTA-h11B6 and DOTA-h11B6. 225 In a further embodiment, the pharmaceutical composition contains about 0.1 mg / mL to about 1 mg / mL of Ac-DOTA-h11B6 and DOTA-h11B6. 225 In a further embodiment, the pharmaceutical composition contains Ac-TOPA-h11B6 and TOPA-h11B6 in a total amount of about 0.5 mg / mL. 225 Contains Ac-TOPA-h11B6 and TOPA-h11B6.

[0264] The pharmaceutical composition of the present invention can be administered via any suitable route known to those skilled in the art. For example, the composition can be administered parenterally. Non-limiting examples of administration routes include intravenous (IV), intramuscular, or subcutaneous, or they can be administered by injection techniques. In certain aspects, the treatment method herein includes intravenous injection of the pharmaceutical composition.

[0265] According to one embodiment, the pharmaceutical compositions of the invention are provided in a single-use sterile injectable solution, which is preferably refrigerated until injection in a sealed vial, such as a cyclic olefin polymer vial closed with a latex-free stopper and an aluminum seal.

[0266] The pharmaceutical composition of the present invention may be administered to a patient by a medical professional. In some embodiments, the pharmaceutical composition is administered once every about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, about 14, about 15, or about 16 weeks. In some embodiments, the pharmaceutical composition is administered once every about 4 to about 12, about 4 to about 10, about 4 to about 8, about 4 to about 6, about 6 to about 12, about 6 to about 10, about 6 to about 8, about 8 to about 12, about 8 to about 10, or about 10 to about 12 weeks. In certain aspects, the pharmaceutical composition is administered to a patient once every about 4 weeks. In certain aspects, the pharmaceutical composition is administered to a patient once every about 6 weeks. In other aspects, the pharmaceutical composition is administered to a patient once every about 8 weeks. In certain aspects, the pharmaceutical composition is administered to a patient once every about 10 weeks. In a further aspect, the pharmaceutical composition is administered to the patient about once every 12 weeks. According to certain embodiments, the patient is administered about 2 to about 12 doses, or about 2 to about 10 doses, or about 2 to about 8 doses, or about 2 to about 6 doses, or about 2 to about 4 doses. According to one embodiment, the patient's dosing regimen comprises administering at least 2 doses, or at least 3 doses, or at least 4 doses, or at least 5 doses, or at least 6 doses, one dose being administered every 8 weeks. According to one embodiment, the patient's dosing regimen comprises administering 4 total doses, one dose being administered every 8 weeks. Alternatively, the patient's dosing regimen comprises administering 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 total doses, one dose being administered once every 8 weeks. In still further embodiments, the patient's dosing regimen may continue such that it comprises more than 12 total doses.

[0267] A dose of the pharmaceutical composition of the invention can be administered to a patient by a single dose, or by administering the dose in multiple doses of two or more subdoses (e.g., by administering the dose multiple times). Alternatively, the dose may be provided as a continuous infusion over an extended period of time.

[0268] It will be understood by those skilled in the art that the pharmaceutical composition of the present invention can be administered alone or in combination with one or more additional therapeutic or imaging agents or modalities as determined by the attending physician. The pharmaceutical composition of the present invention can be administered to a patient prior to or simultaneously with other therapeutic modalities for the treatment of prostate cancer.

[0269] Preferably, the pharmaceutical compositions of the present invention are in the form of a sterile aqueous solution, which may contain other substances to make the solution isotonic with blood and / or to provide a suitable pH. In some embodiments, the pH of the aqueous solution is about 4 to about 7, about 4.5 to about 6.5, about 5 to about 6, or about 5.5. In other embodiments, the pH of the aqueous solution is about 5, about 5.1, about 5.2, about 5.3, about 5.4, about 5.5, about 5.6, about 5.7, about 5.8, about 5.9, or about 6. In a further embodiment, the pH of the aqueous solution is about 5.5.

[0270] As described herein, 225 Due to the breakdown of Ac, 225 The amount of radioactivity provided by Ac is ( 225 The dose is decreased from approximately the time Ac is chelated to the conjugate intermediate to form the radioconjugate to the time the dose is administered to the patient. Preferably, the radioconjugate is estimated to form between the approximate time of chelation and the time of administration to the patient. 225 A sufficient amount of Ac should be added during production to take into account the decrease in the specific activity of Ac. 225 It is labeled with Ac. 225 It is also preferable to limit the time between formation of the radioconjugate (via chelation of Ac) and administration of the dose to the patient.

[0271] According to certain embodiments, the pharmaceutical composition of the present invention is administered to a patient within about 7 days (168 hours) of chelating the radiometal to the conjugate intermediate to form the radioconjugate, or within about 144 hours, or within about 120 hours, or within about 96 hours, or within about 72 hours, or within about 48 hours, or within about 24 hours of chelating the radiometal to the conjugate intermediate to form the radioconjugate. According to certain embodiments, the method of the present invention comprises administering the pharmaceutical composition to a patient (i.e., the dosing time occurs) within about 120 hours of chelating the radiometal to the conjugate intermediate to form the radioconjugate. According to certain embodiments, the method of the present invention comprises administering the pharmaceutical composition to a patient (i.e., the dosing time occurs) within about 96 hours of chelating the radiometal to the conjugate intermediate to form the radioconjugate. According to certain embodiments, the methods of the present invention include administering the pharmaceutical composition to a patient within about 72 hours of chelating the radiometal to a conjugate intermediate to form a radioconjugate (i.e., the dosing time occurs).

[0272] According to certain embodiments, the radioconjugates of the present invention are administered in admixture with one or more pharma- ceutical acceptable excipients. The terms "pharmaceutical composition" and "pharmaceutical formulation" are used interchangeably throughout this disclosure. The pharmaceutical compositions may be prepared using techniques known in the art. In certain embodiments, the pharmaceutical compositions are sufficiently storage stable and suitable for administration to humans.

[0273] The excipient may be selected by one skilled in the art and may take a variety of forms depending on the desired route of administration. For example, for parenteral administration, the excipient may comprise sterile water, and other ingredients may be added to increase the solubility and preservability of the composition. Injectable suspensions or solutions may also be prepared using an excipient that comprises an aqueous carrier and / or suitable additives, such as solubilizers and preservatives.

[0274] In some embodiments, the excipient comprises a buffer, which is preferably an aqueous solution containing an acid-base mixture for the purpose of stabilizing the pH of the solution. Examples of buffers include, but are not limited to, Trizma, Bicine, Tricine, MOPS, MOPSO, MOBS, Tris, Hepes, HEPBS, MES, phosphoric acid, carbonic acid, acetic acid, citric acid, glycolic acid, lactic acid, boric acid, ACES, ADA, tartaric acid, AMP, AMPD, AMPSO, BES, CABS, cacodylic acid, CHES, DIPSO, EPPS, ethanolamine, glycine, HEPPSO, imidazole, imidazole lactate, PIPES, SSC, SSPE, POPSO, TAPS, TABS, TAPSO, or TES. In some embodiments, the buffer is Trizma. In other embodiments, the buffer is Bicine. In further embodiments, the buffer is Tricine. In yet other embodiments, the buffer is MOPS. In yet further embodiments, the buffer is MOPSO. In other embodiments, the buffer is MOBS. In further embodiments, the buffer is Tris. In yet other embodiments, the buffer is Hepes. In yet further embodiments, the buffer is HEPBS. In other embodiments, the buffer is MES. In further embodiments, the buffer is phosphate. In yet other embodiments, the buffer is carbonate. In yet further embodiments, the buffer is acetate. In yet other embodiments, the buffer is citric acid. In yet further embodiments, the buffer is glycolic acid. In other embodiments, the buffer is lactic acid. In further embodiments, the buffer is boric acid. In yet other embodiments, the buffer is ACES. In yet further embodiments, the buffer is ADA. In other embodiments, the buffer is tartaric acid. In further embodiments, the buffer is AMP. In yet other embodiments, the buffer is AMPD. In yet further embodiments, the buffer is AMPSO. In other embodiments, the buffer is BES. In further embodiments, the buffer is CABS. In yet other embodiments, the buffer is cacodylic acid. In still further embodiments, the buffer is CHES. In other embodiments, the buffer is DIPSO. In a further embodiment, the buffer is EPPS.In yet another embodiment, the buffer is ethanolamine. In yet a further embodiment, the buffer is glycine. In another embodiment, the buffer is HEPPSO. In yet a further embodiment, the buffer is imidazole. In yet another embodiment, the buffer is imidazole lactate. In yet a further embodiment, the buffer is PIPES. In another embodiment, the buffer is SSC. In yet a further embodiment, the buffer is SSPE. In yet another embodiment, the buffer is POPSO. In yet a further embodiment, the buffer is TAPS. In another embodiment, the buffer is TABS. In yet a further embodiment, the buffer is TAPSO. In another embodiment, the buffer is TES. It is desirable that the buffer is provided at a concentration to obtain the desired pH. In some aspects, the concentration of the buffer is about 10 to about 50 mM. In another embodiment, the pH of the buffer is about 20 to about 50, about 25 to about 50, about 30 to about 50, about 35 to about 50, about 40 to about 50, about 45 to about 50, about 20 to about 45, about 25 to about 45, about 30 to about 45, about 35 to about 45, about 40 to about 45, about 20 to about 40, about 25 to about 40, about 30 to about 40, about 35 to about 40, about 20 to about 35, about 25 to about 35, about 30 to about 35, about 20 to about 30, about 25 to about 30, or about 20 to about 25 mM. In a further embodiment, the concentration of the buffer is about 24 to about 28, about 25 to about 28, about 25 to about 27, about 26 to about 28, or about 26 to about 27 mM. In yet another aspect, the concentration of the buffering agent is about 25 mM. In yet another aspect, the concentration of the buffering agent is about 26.75 mM. In one embodiment, the buffering agent comprises acetate.

[0275] In additional embodiments, the excipient comprises a diluent. The term "diluent" refers to an aqueous or non-aqueous solution intended for diluting the pharmaceutical composition. For example, the diluent may comprise one or more of saline, water, polyethylene glycol, propylene glycol, ethanol, or oil (such as safflower oil, corn oil, peanut oil, cottonseed oil, or sesame oil). In certain embodiments, the diluent is water. Additional non-limiting examples of diluents include sterile water, saline in various concentrations (NS / 0.9%, 1 / 2 NS / 0.45%), dextrose in various concentrations (D5W, D10W), or dextrose + saline (1 / 2 NSD5W).

[0276] The pharmaceutical compositions may be subjected to conventional formulation procedures, such as sterilization, and / or may contain conventional adjuvants. The pharmaceutical compositions may also contain aqueous and non-aqueous sterile injection solutions which may contain antioxidants, buffers, bacteriostats, and / or solutes which render the formulation isotonic with the blood of the intended recipient.

[0277] In yet other embodiments, the excipient may include one or more of binders, carbohydrates, coating agents, colorants, disintegrants, dispersants, emulsifiers, fillers, flavoring agents, granulating agents, lipids, lubricants, minerals, polymers, preservatives, radioprotectants, solubilizers, stabilizers, suspending agents, sweeteners, thickeners, wetting agents, or combinations thereof.

[0278] According to certain embodiments, the excipient comprises at least one radioprotectant. In certain embodiments, the pharmaceutical composition comprises a radioconjugate and one or more pharma- ceutically acceptable excipients, where the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2 (e.g., h11B6 or a variant thereof), and the one or more pharma-ceutically acceptable excipients comprise one or more radioprotectants.

[0279] Examples of radioprotectants include, but are not limited to, sodium ascorbate, gentisic acid, or a combination thereof. According to one embodiment, the composition comprises sodium ascorbate. According to an alternative embodiment, the composition comprises gentisic acid.

[0280] In other embodiments, the excipient comprises one or more surfactants. Non-limiting examples of surfactants include polysorbates and poloxamers, such as polysorbate 20, polysorbate 80, and poloxamer 188. According to one embodiment, the excipient comprises polysorbate 20. In further embodiments, the excipient comprises sodium ascorbate, polysorbate 20, or a combination thereof. In some embodiments, the pharmaceutical composition contains a radioconjugate and sodium ascorbate. In other embodiments, the pharmaceutical composition contains polysorbate 20. In further embodiments, the pharmaceutical composition contains sodium ascorbate and polysorbate 20. In some embodiments, the pharmaceutical composition contains a radioconjugate and gentisic acid. In further embodiments, the pharmaceutical composition contains gentisic acid and polysorbate 20.

[0281] The amount of excipient is selected based on the desired route of administration, the patient, and the particular excipient in the pharmaceutical composition. In a preferred embodiment, the amount of sodium ascorbate present in the pharmaceutical composition inhibits degradation of the radioconjugate. Desirably, sodium ascorbate inhibits degradation of the radioconjugate compared to a composition not containing sodium ascorbate, as measured, for example, by spectroscopic methods such as high performance liquid chromatography, nuclear magnetic resonance, mass spectrometry, or elemental analysis, among others. In other embodiments, the pharmaceutical composition contains about 0.05 to about 5.0 w / v % sodium ascorbate and / or gentisic acid. In a further embodiment, the pharmaceutical composition comprises about 0.1 to about 5, about 0.1 to about 4, about 0.1 to about 3, about 0.1 to about 2, about 0.1 to about 1, about 0.2 to about 1, about 0.3 to about 1, about 0.4 to about 1, about 0.5 to about 1, about 0.6 to about 1, about 0.7 to about 1, about 0.8 to about 1, about 0.9 to about 1, about 0.1 to about 0.9, about 0.2 to about 0.9, about 0.3 to about 0.9, about 0.4 to about 0.9, about 0.5 to about 0.9, about 0.6 to about 0.9, about 0.7 to about 0.9, about 0.8 to about 0.9, about 0.1 to about 0.8, about 0.2 to about 0.8, The composition contains 0.3 to about 0.8, about 0.4 to about 0.8, about 0.5 to about 0.8, about 0.6 to about 0.8, about 0.7 to about 0.8, about 0.1 to about 0.7, about 0.2 to about 0.7, about 0.3 to about 0.6, about 0.4 to about 0.6, about 0.5 to about 0.6, about 0.1 to about 0.5, about 0.2 to about 0.5, about 0.3 to about 0.5, about 0.4 to about 0.5, about 0.1 to about 0.4, about 0.2 to about 0.4, about 0.3 to about 0.4, about 0.1 to about 0.3, about 0.2 to about 0.3, or about 0.1 to about 0.2 w / v % sodium ascorbate. In yet other embodiments, the pharmaceutical composition contains about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or about 1% w / v sodium ascorbate. In yet further embodiments, the pharmaceutical composition contains about 0.5% w / v sodium ascorbate.

[0282] In other embodiments, the pharmaceutical composition contains about 0.005 to about 0.15 w / v%, or about 0.005 to about 0.12 w / v%, or about 0.005 to about 0.1 w / v%, or about 0.005 to about 0.08 w / v%, or about 0.005 to about 0.06 w / v%, or about 0.005 to about 0.12 w / v%, or about 0.005 to about 0.04 w / v% polysorbate 20. In certain embodiments, the pharmaceutical composition comprises a dilution of about 0.01 to about 0.12, about 0.02 to about 0.12, about 0.03 to about 0.12, about 0.04 to about 0.12, about 0.05 to about 0.12, about 0.06 to about 0.12, about 0.07 to about 0.12, about 0.08 to about 0.12, about 0.09 to about 0.12, about 0.01 to about 0.1, about 0.02 to about 0.1, about 0. 03 to about 0.1, about 0.04 to about 0.1, about 0.05 to about 0.1, about 0.06 to about 0.1, about 0.07 to about 0.1, about 0.08 to about 0.1, about 0.09 to about 0.1, about 0.01 to about 0.09, about 0.02 to about 0.09, about 0.03 to about 0.09, about 0.04 to about 0.09, about 0.05 to about 0.09, about 0.06 to about 0.09, about 0.07 to about 0.1 about 0.09, about 0.08 to about 0.09, about 0.01 to about 0.08, about 0.02 to about 0.08, about 0.03 to about 0.08, about 0.04 to about 0.08, about 0.05 to about 0.08, about 0.06 to about 0.08, about 0.07 to about 0.08, about 0.01 to about 0.07, about 0.02 to about 0.07, about 0.03 to about 0.06, about 0.04 to about 0.06, about Contains 0.05 to about 0.06, about 0.01 to about 0.05, about 0.02 to about 0.05, about 0.03 to about 0.05, about 0.04 to about 0.05, about 0.01 to about 0.04, about 0.02 to about 0.04, about 0.03 to about 0.04, about 0.01 to about 0.03, about 0.02 to about 0.03, or about 0.01 to about 0.02 w / v % polysorbate 20. In other embodiments, the pharmaceutical composition contains about 0.01, about 0.02, about 0.03, about 0.04, about 0.05, about 0.06, about 0.07, about 0.08, about 0.09, about 0.1, about 0.11, about 0.12, about 0.13, about 0.14, or about 0.15% w / v polysorbate 20. In further embodiments, the pharmaceutical composition contains about 0.04% w / v polysorbate 20.

[0283] According to certain embodiments, the pharmaceutical composition does not contain any preservatives.

[0284] According to certain embodiments, the pharmaceutical composition does not contain any sucrose, and in particular, 225 When Ac is, for example, the radioactive conjugate is 225 In the case of Ac-DOTA-h11B6, the pharmaceutical composition may not contain any sucrose. 225 The inclusion of sucrose in a composition containing Ac results in the formation of radiolytic decomposition products, as described herein. Thus, in certain embodiments, sucrose may be excluded or limited to small amounts, e.g., less than 1%, less than 0.5%, less than 0.1%, less than 0.05%, or less than 0.01%.

[0285] According to certain embodiments, the pharmaceutical composition does not contain any dextrins (eg, cyclodextrins), monosaccharides, disaccharides, oligosaccharides, or polysaccharides.

[0286] According to certain embodiments, the pharmaceutical composition does not contain any monosaccharides or disaccharides.

[0287] According to certain embodiments, the pharmaceutical composition does not contain any disaccharides.

[0288] According to certain embodiments, the pharmaceutical composition does not contain any sugar alcohol (eg, sorbitol).

[0289] According to certain embodiments, the pharmaceutical composition does not contain any cryoprotectants (e.g., sugars, sugar alcohols, glycerol, ethylene glycol, propylene glycol, dimethylsulfoxide, etc.).

[0290] In certain embodiments, the pharmaceutical composition contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, and about 0.5% w / v% sodium ascorbate. In other embodiments, the pharmaceutical composition contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, and about 0.04% w / v% polysorbate 20. In further embodiments, the pharmaceutical composition contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, and about 25-27 mM acetate buffer. In yet other embodiments, the pharmaceutical product contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, about 0.5% w / v% sodium ascorbate, and about 0.04% w / v% polysorbate 20. In yet a further embodiment, the pharmaceutical preparation contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, about 0.5 w / v% sodium ascorbate, and about 25-27 mM acetate buffer. In another embodiment, the pharmaceutical preparation contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, about 0.04 w / v% polysorbate 20, and about 25-27 mM acetate buffer. In a further embodiment, the pharmaceutical composition contains about 0.5 mg / mL of the radioactive conjugate and conjugate intermediate, about 0.5 w / v% sodium ascorbate, about 0.04 w / v% polysorbate 20, and about 25-27 mM acetate buffer.

[0291] In certain embodiments, the pharmaceutical composition comprises a radioconjugate and an acetate buffer. In other embodiments, the pharmaceutical composition comprises a radioconjugate, an acetate buffer, and sodium ascorbate. In a further embodiment, the pharmaceutical composition comprises a radioconjugate and polysorbate 20. In yet another embodiment, the pharmaceutical composition comprises a radioconjugate, sodium ascorbate, polysorbate 20, and an acetate buffer. In yet a further embodiment, the pharmaceutical composition comprises 225 In another embodiment, the pharmaceutical composition comprises: Ac-DOTA-h11B6; and an acetate buffer. 225In a further embodiment, the pharmaceutical composition comprises Ac-DOTA-h11B6, an acetate buffer, and sodium ascorbate. 225 Ac-DOTA-h11B6, polysorbate 20. In yet another embodiment, the pharmaceutical composition comprises: 225 In yet a further embodiment, the pharmaceutical composition comprises Ac-DOTA-h11B6, sodium ascorbate, polysorbate 20, and acetate buffer. 225 In another embodiment, the pharmaceutical composition comprises: Ac-TOPA-h11B6; acetate buffer. 225 In a further embodiment, the pharmaceutical composition comprises Ac-TOPA-h11B6, an acetate buffer, and sodium ascorbate. 225 Ac-TOPA-h11B6, polysorbate 20. In yet another embodiment, the pharmaceutical composition comprises: 225 Contains Ac-TOPA-h11B6, sodium ascorbate, polysorbate 20, and acetate buffer.

[0292] According to one embodiment, the pharmaceutical composition comprises 25 to 27 mM acetic acid (e.g., 25 mM or 26.75 mM). 225 Ac-DOTA-h11B6 and DOTA-h11B6 are at a total amount of about 0.5 mg / mL, containing 0.5% sodium ascorbate and 0.04% polysorbate 20 in sterile water (preferably at a pH of about 5.5). 225 Radioactivity of Ac-DOTA-h11B6 225 The Ac dose targets about 50, about 100, about 150, or about 200 μCi in 4 mL (about 2 mg of h11B6 mass) at the expected dosing time. 225 Radioactivity of Ac-DOTA-h11B6 225 Ac doses are targeted to greater than 200 μCi (e.g., about 250 μCi or about 300 μCi or about 350 μCi) at dosing, for example, a dose may contain about 250 μCi in about 8 mL, or about 300 μCi in about 8 mL, or about 350 μCi in about 8 mL (e.g., per about 2 mg of h11B6, or about 4 mg or about 6 mg or about 8 mg or about 10 mg mass per dose) at the expected dosing.

[0293] According to one embodiment, the pharmaceutical composition comprises a total amount of about 0.5 mg / mL in 25-27 mM acetic acid (e.g., 25 mM or 26.75 mM). 225 Ac-TOPA-h11B6 and TOPA-h11B6, 0.5% sodium ascorbate, and 0.04% polysorbate 20 in sterile water (preferably at a pH of about 5.5). 225 Radioactivity of Ac-TOPA-h11B6 225 The Ac dose targets about 50, about 100, about 150, or about 200 μCi in 4 mL (about 2 mg of h11B6 mass) at the expected dosing time. 225 Radioactivity of Ac-TOPA-h11B6 225 Ac doses are targeted to greater than 200 μCi (e.g., about 250 μCi or about 300 μCi or about 350 μCi) at dosing, for example, a dose may contain about 250 μCi in about 8 mL, or about 300 μCi in about 8 mL, or about 350 μCi in about 8 mL (e.g., per about 2 mg of h11B6, or about 4 mg or about 6 mg or about 8 mg or about 10 mg mass per dose) at the expected dosing.

[0294] Enumerated Embodiments Numbered exemplary embodiments of the present invention are provided below. 1. A method of treating cancer in a patient, comprising: administering to a patient a therapeutically effective amount of a pharmaceutical composition comprising a radioconjugate and one or more pharma- ceutical acceptable excipients; the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2; the radiometal complex comprises a radiometal; The method wherein the radiometal, upon administration, provides a target radioactivity of about 50 μCi to about 350 μCi per dose of the pharmaceutical composition. 1A. A method of treating cancer in a patient, comprising: administering to a patient a therapeutically effective amount of a pharmaceutical composition comprising a radioconjugate and one or more pharma- ceutical acceptable excipients; the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2; the radiometal complex comprises a radiometal; The method wherein the radiometal, upon administration, provides a target radioactivity of about 350 μCi to about 500 μCi per dose of the pharmaceutical composition. 2. The method of embodiment 1 or 1A, wherein the radioconjugate comprises at least one radiometal complex conjugated to an antibody having binding specificity for hK2. 3. The method of embodiment 2, wherein the antibody comprises a heavy chain variable region comprising the amino acid sequences of SEQ ID NO:1 and SEQ ID NO:2 and SEQ ID NO:3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO:4 and SEQ ID NO:5 and SEQ ID NO:6. 4. The method of embodiment 2 or 3, wherein the antibody comprises a heavy chain variable region (VH) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:8, and a light chain variable region (VL) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:9. 5. The method of embodiment 2 or 3, wherein the antibody comprises a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO:8, and a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO:9. 6. The method of any one of embodiments 2 to 5, wherein the antibody comprises a heavy chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 10, and a light chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 11. 7. The method of any one of embodiments 2 to 5, wherein the antibody comprises a heavy chain constant region comprising the amino acid sequence of SEQ ID NO:10, and a light chain constant region comprising the amino acid sequence of SEQ ID NO:11. 8. The method of any one of embodiments 2-7, wherein the antibody comprises a heavy chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a light chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 13. 9. The method of any one of embodiments 2 to 7, wherein the antibody comprises a heavy chain having the amino acid sequence of SEQ ID NO:12, and a light chain having the amino acid sequence of SEQ ID NO:13. 10. Radioactive metals, 225 Ac, 111 In, 177 Lu, 32 P, 47 Sc, 67 Cu, 77 As, 89 Sr, 90 Y, 99 Tc, 105 Rh, 109 Pd, 111 Ag, 131 I, 134 Ce, 149 Tb, 152 Tb, 155 Tb, 153 Sm, 159 Gd, 165 Dy, 166 Ho, 169 Er, 186 Re, 188 Re, 194 Ir, 198 Au, 199 Au, 211 At, 212 Pb, 212 Bi, 213 Bi, 223 Ra, 255 Fm, and 227 The method of any one of embodiments 1-9 or 1A, wherein the compound is selected from the group consisting of Th. 11. Radioactive metals, 225 The method of any one of embodiments 1-9 or 1A, wherein Ac is 12. Radioactive metal complexes include 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,8,11-tetraazacyclodocedan-1,4,8,11-tetraacetic acid (TETA), 3,6,9,15-tetraazabicyclo The method of any one of embodiments 1-11 or 1A, comprising a chelating agent selected from the group consisting of [9.3.1]-pentadeca-1(15),11,13-triene-4-(S)-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (PCTA), 5-S-(4-aminobenzyl)-1-oxa-4,7,10-triazacyclododecane-4,7,10-tris(acetic acid) (DO3A), and derivatives thereof. 13. The method of any one of embodiments 1-11 or 1A, wherein the radiometal complex comprises a chelating agent that is DOTA. 13A. The method of any one of embodiments 1-11 or 1A, wherein the radiometal complex comprises a chelating agent that is TOPA. 14. Radioactive metal complexes are chelated to DOTA. 225 The method of any one of embodiments 1-13 or 1A, comprising Ac. 14A. Radioactive metal complexes are chelated to TOPA. 225 The method of any one of embodiments 1-11 or 1A, comprising Ac. 15. The radioactive conjugate is represented by the formula (a)

[0295] [ka] (In the formula, R1 is hydrogen and R2 is -L1-R4; Alternatively, R1 is -L1-R4 and R2 is hydrogen; R3 is hydrogen; or R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, the 5- or 6-membered cycloalkyl being optionally substituted with -L1-R4; L1 is absent or is a linker, or a pharma- ceutically acceptable salt thereof; or (b) Formula (V)

[0296] [ka] (In the formula, L1 is absent or is a linker, R4 is an antibody, or a pharma- ceutical acceptable salt thereof; For example, the chelating agent used to form the radioconjugate may have the following formula:

[0297] [ka] or a pharma- ceutically acceptable salt thereof. 16. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 350 μCi per about 2 mg of total antibody, or about 50 μCi to about 350 μCi per about 2 mg of total antibody. 16A. Radioactive metals are 225 The method of any one of embodiments 2-15 or 13A or 14A, wherein the radiometal provides a target specific radioactivity of about 25 μCi to about 350 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody) or about 50 μCi to about 350 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody). 17. Radioactive metals are 225The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 300 μCi per about 2 mg of total antibody, or about 50 μCi to about 300 μCi per about 2 mg of total antibody. 17A. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal provides a target specific radioactivity of about 25 μCi to about 300 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody), or about 50 μCi to about 300 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody). 18. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 250 μCi per about 2 mg of total antibody, or about 50 μCi to about 250 μCi per about 2 mg of total antibody. 18A. Radioactive metals, 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal provides a target specific radioactivity of about 25 μCi to about 250 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody), or about 50 μCi to about 250 μCi per about 2 mg to about 10 mg of total antibody (e.g., per about 4 mg of total antibody). 19. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 200 μCi per about 2 mg of total antibody, or about 50 μCi to about 200 μCi per about 2 mg of total antibody. 20. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 150 μCi per about 2 mg of total antibody, or about 50 μCi to about 150 μCi per about 2 mg of total antibody. 21. Radioactive metals, 225The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific radioactivity of about 25 μCi to about 100 μCi per about 2 mg of total antibody, or about 50 μCi to about 100 μCi per about 2 mg of total antibody. 22. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific activity of about 150 μCi to about 250 μCi per about 2 mg of total antibody. 23. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific activity of about 50 μCi per about 2 mg of total antibody. 24. Radioactive metals, 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific activity of about 100 μCi per about 2 mg of total antibody. 25. Radioactive metals are 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific activity of about 150 μCi per about 2 mg of total antibody. 26. Radioactive metals, 225 The method of any one of embodiments 2-15, or 13A, or 14A, wherein the radiometal is Ac and provides a target specific activity of about 200 μCi per about 2 mg of total antibody. 27. The method of any one of embodiments 2-26 or 13A or 14A or 16A or 17A or 18A, wherein the pharmaceutical composition comprises a target radioactivity concentration of about 1 μCi / mL to about 100 μCi / mL, or about 5 μCi / mL to about 75 μCi / mL, or about 10 μCi / mL to about 60 μCi / mL, or about 12.5 μCi / mL to about 50 μCi / mL, or about 12.5 μCi / mL, or about 25 μCi / mL, or about 37.5 μCi / mL, or about 50 μCi / mL. 28. The method of any one of embodiments 2-26 or 13A or 14A or 16A or 17A or 18A, wherein the pharmaceutical composition comprises from about 1 mg to about 5 mg of total antibody, or from about 1 mg to about 4 mg of total antibody. 28A. The method of any one of embodiments 2-26 or 13A or 14A or 16A or 17A or 18A, wherein the pharmaceutical composition comprises from about 1 mg to about 10 mg of total antibody, or from about 2 mg to about 8 mg of total antibody. 29. The method of any one of embodiments 2-26, or 13A, or 14A, or 16A, or 17A, or 18A, wherein the pharmaceutical composition comprises from about 1 mg to about 4 mg of whole antibody. 30. The method of any one of embodiments 2-26, or 13A, or 14A, or 16A, or 17A, or 18A, wherein the pharmaceutical composition comprises from about 1 mg to about 3 mg of whole antibody. 31. The method of any one of embodiments 2-26, or 13A, or 14A, or 16A, or 17A, or 18A, wherein the pharmaceutical composition comprises about 1.5 to about 2.5 mg of total antibody. 32. The method of any one of embodiments 2-26, or 13A, or 14A, or 16A, or 17A, or 18A, wherein the pharmaceutical composition comprises about 2 mg of whole antibody. 32A. The method of any one of embodiments 2-26 or 13A or 14A or 16A or 17A or 18A, wherein the pharmaceutical composition comprises about 4 mg of total antibody or about 8 mg of total antibody. 33. The method of any one of embodiments 1-31 or 1A or 13A or 14A or 16A or 17A or 18A or 28A, wherein the one or more pharma- ceutically acceptable excipients comprise one or more radioprotectants. 34. The method of embodiment 32 or 32A, wherein the one or more radioprotectants comprise sodium ascorbate, gentisic acid, or a combination thereof. 35. The method of embodiment 32 or 32A, wherein the one or more radioprotectants comprises sodium ascorbate. 36. The method of embodiment 32 or 32A, wherein the one or more radioprotectants comprises gentisic acid. 37. The method of any one of embodiments 1-35 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the one or more pharma- ceutically acceptable excipients further comprise one or more surfactants. 38. The method of embodiment 36, wherein the one or more surfactants comprise polysorbate 20. 39. The method of any one of embodiments 1-37, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, wherein the one or more pharma- ceutically acceptable excipients further comprise an acetate buffer. 40. The method of any one of embodiments 1-38 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition comprises the radioconjugate, sodium ascorbate, polysorbate 20, acetate buffer, and water (acetic acid may optionally be added for pH adjustment). 41. The method of any one of embodiments 1-38 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition comprises the radioconjugate, about 24-28 mM acetic acid, about 0.25-0.75% sodium ascorbate, and about 0.01-0.15% polysorbate 20 in water. 42. The method of any one of embodiments 1-38 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition comprises the radioconjugate, about 25 mM acetic acid, about 0.5% sodium ascorbate, and about 0.04% polysorbate 20 in water. 43. The method of any one of embodiments 1-38 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition comprises the radioconjugate, about 26.75 mM acetic acid, about 0.5% sodium ascorbate, and about 0.04% polysorbate 20 in water. 44. The method of any one of embodiments 1-42, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, wherein the pharmaceutical composition has a pH of about 5 to about 6 (e.g., about 5.5). 45. The method according to any one of embodiments 1-43, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, wherein the pharmaceutical composition does not contain any preservatives. 46. ​​The method according to any one of embodiments 1-44 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition does not contain any sucrose. 47. The method according to any one of embodiments 1-44 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition does not contain any monosaccharides, disaccharides, oligosaccharides, or polysaccharides. 48. The method according to any one of embodiments 1-44 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition does not contain any monosaccharides or disaccharides. 49. The method according to any one of embodiments 1-44 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition does not contain any disaccharides. 50. The method of any one of embodiments 1-48 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition is stable at a temperature range of about 2-8° C. for at least about 72 hours, or at least about 96 hours, or at least about 120 hours. 51. The method of any one of embodiments 2 to 49 or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the dose of the pharmaceutical composition has a volume of about 1 mL to about 20 mL, or about 1 mL to about 10 mL, or about 2 mL to about 6 mL, or about 3 mL to about 5 mL, or about 4 mL. 52. The method of any one of embodiments 2-49 or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the dose of the pharmaceutical composition comprises about 2 mg of total antibody per about 4 mL dose. 53. The method of any one of embodiments 2-51 or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition comprises the whole antibody in an amount of about 0.1-1.0 mg / mL, or about 0.4-0.6 mg / mL, or about 0.5 mg / mL. 54. The method of any one of embodiments 2-52 or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the pharmaceutical composition further comprises a non-radiolabeled antibody (e.g., a conjugated intermediate such as a DOTA-mAb, e.g., DOTA-h11B6), and the non-radiolabeled antibody is the same antibody as the antibody conjugated to the radioactive metal complex. 55. The method of embodiment 53, wherein the total amount of conjugated antibody and non-radiolabeled antibody does not exceed about 10 mg, or about 9 mg, or about 8 mg, or about 7 mg, or about 6 mg, or about 5 mg, or about 4 mg, or about 3 mg, or about 2 mg. 56. The method according to any one of embodiments 1-54, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the pharmaceutical composition intravenously to the patient. 57. The method of any one of embodiments 1-55, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the pharmaceutical composition to the patient within about 168 hours, or within about 144 hours, or within about 120 hours, or within about 96 hours, or within about 72 hours, or within about 48 hours, or within about 24 hours of chelating the radiometal to the conjugate intermediate to form the radioconjugate. 58. The method according to any one of embodiments 1-56, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the pharmaceutical composition to the patient about once every four weeks. 59. The method according to any one of embodiments 1-56, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the pharmaceutical composition to the patient once every about 8 weeks. 60. The method of any one of embodiments 1-56, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the pharmaceutical composition to the patient once every about 12 weeks. 61. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is prostate cancer. 62. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is non-localized prostate cancer. 63. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is metastatic prostate cancer. 64. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is castration-resistant prostate cancer (CRPC). 65. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is metastatic castration-resistant prostate cancer (mCRPC). 66. The method of any one of embodiments 1-59 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the cancer is mCRPC with adenocarcinoma. 67. The method of any one of embodiments 1-65 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the patient's castrate testosterone level is about 50 ng / dL or less. 68. The method of any one of embodiments 1-66 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the patient has been previously exposed to at least one androgen receptor (AR) targeted therapy. 69. The method of embodiment 67, wherein the AR targeted therapy is abiraterone acetate, enzalutamide, apalutamide, darolutamide, or any combination of the foregoing. 70. The method of any one of embodiments 1-68 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the patient has previously undergone chemotherapy. 71. The method of embodiment 69, wherein the chemotherapy included administration of a taxane. 72. The method of any one of embodiments 1-70 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the patient has previously undergone orchiectomy or medical castration. 73. The method of any one of embodiments 1-71 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, wherein the patient is undergoing ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH) agonist or antagonist. 74. The method of any one of embodiments 1-72, or 1A, or 13A, or 14A, or 16A, or 17A, or 18A, or 28A, or 32A, comprising administering the dose to the patient in a single administration. 75. The method according to any one of embodiments 1-72 or 1A or 13A or 14A or 16A or 17A or 18A or 28A or 32A, comprising administering the dose in multiple administrations of two or more partial doses. 75A. The method of embodiment 75, comprising administering the dose in two sub-doses (e.g., two 4 mL sub-doses). 76. A pharmaceutical composition comprising: comprising a radioconjugate and one or more pharma- ceutically acceptable excipients, the radioconjugate comprises at least one radiometal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2; A pharmaceutical composition, wherein the radiometal complex comprises a radiometal. 77. The pharmaceutical composition according to embodiment 76, wherein the one or more pharma- ceutically acceptable excipients comprise one or more radioprotectants. 78. The pharmaceutical composition according to embodiment 76 or 77, wherein the radioconjugate comprises at least one radiometal complex conjugated to an antibody having binding specificity for hK2. 79. The pharmaceutical composition of embodiment 78, wherein the antibody comprises a heavy chain variable region comprising the amino acid sequences of SEQ ID NO:1 and SEQ ID NO:2 and SEQ ID NO:3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO:4 and SEQ ID NO:5 and SEQ ID NO:6. 80. The pharmaceutical composition of embodiment 78 or 79, wherein the antibody comprises a heavy chain variable region (VH) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 8, and a light chain variable region (VL) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 9. 81. The pharmaceutical composition according to embodiment 78 or 79, wherein the antibody comprises a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 8, and a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 9. 82. The pharmaceutical composition according to any one of embodiments 78 to 81, wherein the antibody comprises a heavy chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 10, and a light chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 11. 83. The pharmaceutical composition according to any one of embodiments 78 to 81, wherein the antibody comprises a heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 10, and a light chain constant region comprising the amino acid sequence of SEQ ID NO: 11. 84. The pharmaceutical composition according to any one of embodiments 78 to 83, wherein the antibody comprises a heavy chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a light chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 13. 85. The pharmaceutical composition according to any one of embodiments 78 to 83, wherein the antibody comprises a heavy chain having the amino acid sequence of SEQ ID NO: 12, and a light chain having the amino acid sequence of SEQ ID NO: 13. 86. Radioactive metals, 225 Ac, 111 In, 177 Lu, 32 P, 47 Sc,67 Cu, 77 As, 89 Sr, 90 Y, 99 Tc, 105 Rh, 109 Pd, 111 Ag, 131 I, 134 Ce, 149 Tb, 152 Tb, 155 Tb, 153 Sm, 159 Gd, 165 Dy, 166 Ho, 169 Er, 186 Re, 188 Re, 194 Ir, 198 Au, 199 Au, 211 At, 212 Pb, 212 Bi, 213 Bi, 223 Ra, 255 Fm, and 227 The pharmaceutical composition according to any one of embodiments 76 to 85, wherein the pharmaceutical composition is selected from the group consisting of Th. 87. Radioactive metals, 225 The pharmaceutical composition according to any one of embodiments 76 to 85, wherein Ac is 88. Radioactive metal complexes include 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,8,11-tetraazacyclodocedan-1,4,8,11-tetraacetic acid (TETA), 3,6,9,15-tetraazabicyclo 88. The pharmaceutical composition according to any one of embodiments 76 to 87, comprising a chelating agent selected from the group consisting of [9.3.1]-pentadeca-1(15),11,13-triene-4-(S)-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (PCTA), 5-S-(4-aminobenzyl)-1-oxa-4,7,10-triazacyclododecane-4,7,10-tris(acetic acid) (DO3A), and derivatives thereof. 89. The pharmaceutical composition according to any one of embodiments 76-87, wherein the radioactive metal complex comprises a chelating agent which is DOTA. 90. Radioactive metal complexes are chelated to DOTA. 225 The pharmaceutical composition according to any one of embodiments 76 to 89, comprising Ac. 91. A radioactive conjugate comprising: (a) a compound represented by formula (IV)

[0298] [ka] (In the formula, R1 is hydrogen and R2 is -L1-R4; Alternatively, R1 is -L1-R4 and R2 is hydrogen; R3 is hydrogen; or R2 and R3 together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, the 5- or 6-membered cycloalkyl being optionally substituted with -L1-R4; L1 is absent or is a linker, or a pharma- ceutically acceptable salt thereof; or (b) Formula (V)

[0299] [ka] (In the formula, L1 is absent or is a linker, R4 is an antibody, or a pharma- ceutical acceptable salt thereof; For example, the chelating agent used to form the radioconjugate may have the following formula:

[0300] [ka] or a pharma- ceutically acceptable salt thereof. 92. The pharmaceutical composition of any one of embodiments 77 to 91, wherein the one or more radioprotectants include sodium ascorbate, gentisic acid, or a combination thereof (e.g., in an amount of about 0.1 to about 5 w / v%, or about 0.1 to about 4 w / v%, or about 0.1 to about 3 w / v%, about 0.1 to about 2 w / v%, or about 0.1 to about 1 w / v%, or about 0.25 to about 0.75 w / v%, or about 0.5 w / v%). 93. The pharmaceutical composition according to any one of embodiments 77 to 91, wherein the one or more radioprotectants include sodium ascorbate (e.g., in an amount of about 0.1 to about 5 w / v%, or about 0.1 to about 4 w / v%, or about 0.1 to about 3 w / v%, about 0.1 to about 2 w / v%, or about 0.1 to about 1 w / v%, or about 0.25 to about 0.75 w / v%, or about 0.5 w / v%). 94. The pharmaceutical composition according to any one of embodiments 77 to 91, wherein the one or more radioprotectants include gentisic acid (e.g., in an amount of about 0.1 to about 5 w / v%, or about 0.1 to about 4 w / v%, or about 0.1 to about 3 w / v%, about 0.1 to about 2 w / v%, or about 0.1 to about 1 w / v%, or about 0.25 to about 0.75 w / v%, or about 0.5 w / v%). 95. The pharmaceutical composition according to any one of embodiments 76 to 94, wherein the one or more pharma- ceutically acceptable excipients further comprise one or more surfactants. 96. The pharmaceutical composition according to embodiment 95, wherein the one or more surfactants comprises polysorbate 20. 97. The pharmaceutical composition according to any one of embodiments 76 to 96, wherein the one or more pharma- ceutically acceptable excipients further comprise an acetate buffer. 98. The pharmaceutical composition according to any one of embodiments 76 to 97, comprising a radioactive conjugate, sodium ascorbate, polysorbate 20, an acetate buffer, and water (acetic acid may optionally be added for pH adjustment). 99. A pharmaceutical composition according to any one of embodiments 76 to 97, comprising a radioactive conjugate, about 24-28 mM acetic acid, about 0.25-0.75 w / v% sodium ascorbate, and about 0.01-0.15 w / v% polysorbate 20 in water. 100. A pharmaceutical composition according to any one of embodiments 76 to 97, comprising a radioactive conjugate, about 25 mM acetic acid, about 0.5 w / v% sodium ascorbate, and about 0.04 w / v% polysorbate 20 in water. 101. A pharmaceutical composition according to any one of embodiments 76 to 97, comprising a radioactive conjugate, about 26.75 mM acetic acid, about 0.5 w / v% sodium ascorbate, and about 0.04 w / v% polysorbate 20 in water. 102. The pharmaceutical composition according to any one of embodiments 76-101, wherein the pharmaceutical composition has a pH of about 5 to about 6 (e.g., about 5.5). 103. The pharmaceutical composition according to any one of embodiments 76-101, wherein the pharmaceutical composition does not contain any preservatives. 104. The pharmaceutical composition according to any one of embodiments 76-103, wherein the pharmaceutical composition does not contain any sucrose. 105. The pharmaceutical composition according to any one of embodiments 76-103, wherein the pharmaceutical composition does not contain any monosaccharides, disaccharides, oligosaccharides, or polysaccharides. 106. The pharmaceutical composition according to any one of embodiments 76 to 103, wherein the pharmaceutical composition does not contain any monosaccharides or disaccharides. 107. The pharmaceutical composition according to any one of embodiments 76 to 103, wherein the pharmaceutical composition does not contain any disaccharides. 108. The pharmaceutical composition according to any one of embodiments 76 to 103, wherein the one or more pharma- ceutically acceptable excipients consist of, or consist essentially of, acetate buffer, sodium ascorbate, and polysorbate 20 in water. 109. The pharmaceutical composition according to any one of embodiments 76-108, wherein the pharmaceutical composition is formulated for intravenous administration. 110. The pharmaceutical composition according to any one of embodiments 76 to 109, wherein the pharmaceutical composition is stable at a temperature range of about 2 to 8 °C for at least 72 hours, or at least 96 hours, or at least 120 hours. 111. The pharmaceutical composition according to any one of embodiments 77 to 110, wherein the radioconjugate comprises an average of about 1 to about 4, or about 2 to about 3, chelator molecules conjugated to the antibody. 112. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 350 μCi per about 2 mg of total antibody. 112A. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 350 μCi per about 2 mg to about 10 mg of total antibody. 112B. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a specific radioactivity of about 350 μCi to about 500 μCi per about 2 mg to about 10 mg of total antibody. 113. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 300 μCi per about 2 mg of total antibody. 113A. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 300 μCi per about 2 mg to about 10 mg of total antibody. 114. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 250 μCi per about 2 mg of total antibody. 114A. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 250 μCi per about 2 mg to about 10 mg of total antibody. 115. Radioactive metals, 225The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 200 μCi per about 2 mg of total antibody. 116. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 150 μCi per about 2 mg of total antibody. 117. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a specific radioactivity of about 50 μCi to about 100 μCi per about 2 mg of total antibody. 118. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77-111, wherein the radiometal is Ac and provides a target specific radioactivity of about 50 μCi to about 200 μCi per about 2 mg of total antibody upon dosing. 119. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a target specific radioactivity of about 50 μCi per about 2 mg of total antibody upon dosing. 120. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and the radiometal provides a target specific activity of about 100 μCi per about 2 mg of total antibody upon dosing. 121. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a target specific radioactivity of about 150 μCi per about 2 mg of total antibody upon dosing. 122. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and the radiometal provides a target specific activity of about 200 μCi per about 2 mg of total antibody upon dosing. 122A. Radioactive metals, 225 The pharmaceutical composition of any one of embodiments 77 to 111, wherein the radiometal is Ac and provides a target specific radioactivity of about 300 μCi per about 4 mg of total antibody upon dosing. 123. The pharmaceutical composition according to any one of embodiments 77 to 122, comprising from about 1 mg to about 20 mg of whole antibody. 124. The pharmaceutical composition of any one of embodiments 77 to 122, comprising from about 1 mg to about 10 mg of whole antibody. 125. The pharmaceutical composition of any one of embodiments 77 to 122, comprising from about 1 mg to about 5 mg of total antibody. 126. A pharmaceutical composition according to any one of embodiments 77 to 122, comprising about 2 mg of whole antibody. 127. A pharmaceutical composition according to any one of embodiments 77 to 122, comprising about 10 mg of whole antibody. 128. The pharmaceutical composition according to any one of embodiments 77 to 127, comprising a total amount of the conjugate intermediate and the radioactive conjugate in an amount of about 0.1 to 1.0 mg / mL. 129. The pharmaceutical composition according to any one of embodiments 77 to 127, comprising a total amount of the conjugate intermediate and the radioactive conjugate in an amount of about 0.4 to 0.6 mg / mL. 130. The pharmaceutical composition according to any one of embodiments 77 to 127, comprising a total amount of the conjugate intermediate and the radioactive conjugate in an amount of about 0.5 mg / mL. 131. The pharmaceutical composition of any one of embodiments 77 to 127, further comprising a non-radiolabeled antibody (e.g., a conjugated intermediate such as a DOTA-mAb, e.g., DOTA-h11B6), wherein the non-radiolabeled antibody is the same antibody as the antibody conjugated to the radioactive metal complex. 132. The pharmaceutical composition according to embodiment 131, wherein the total amount of conjugated antibody and non-radiolabeled antibody does not exceed about 10 mg, or about 9 mg, or about 8 mg, or about 7 mg, or about 6 mg, or about 5 mg, or about 4 mg, or about 3 mg, or about 2 mg. 133. A method for treating cancer in a patient, comprising administering to the patient a therapeutically effective amount of a pharmaceutical composition according to any one of embodiments 76-132 or 112A or 112B or 113A or 114A or 122A. 134. The method of embodiment 133, comprising administering the pharmaceutical composition to the patient about once every 4 weeks. 135. The method of embodiment 133, comprising administering the pharmaceutical composition to the patient about once every 8 weeks. 136. The method according to embodiment 133, comprising administering the pharmaceutical composition to the patient about once every 12 weeks. 137. The method of any one of embodiments 133-136, wherein the cancer is prostate cancer. 138. The method of any one of embodiments 133-136, wherein the cancer is non-localized prostate cancer. 139. The method of any one of embodiments 133-136, wherein the cancer is metastatic prostate cancer. 140. The method of any one of embodiments 133-136, wherein the cancer is castration-resistant prostate cancer (CRPC). 141. The method of any one of embodiments 133-136, wherein the cancer is metastatic castration-resistant prostate cancer (mCRPC). 142. The method of any one of embodiments 133-136, wherein the cancer is mCRPC with adenocarcinoma. 143. The method of any one of embodiments 133-142, wherein the patient's castrate testosterone level is about 50 ng / dL or less. 144. The method of any one of embodiments 133-143, wherein the patient has previously been exposed to at least one androgen receptor (AR) targeted therapy. 145. The method of embodiment 144, wherein the AR targeted therapy is abiraterone acetate, enzalutamide, apalutamide, darolutamide, or any combination of the foregoing. 146. The method of any one of embodiments 133-145, wherein the patient has previously undergone chemotherapy. 147. The method of embodiment 146, wherein the chemotherapy included administration of a taxane. 148. The method of any one of embodiments 133-147, wherein the patient has previously undergone orchiectomy or medical castration. 149. The method of any one of embodiments 133-148, wherein the patient is undergoing ongoing androgen deprivation therapy with a gonadotropin releasing hormone (GnRH) agonist or antagonist. 150. A pharmaceutical composition according to any one of embodiments 76 to 132 or 112A or 112B or 113A or 114A or 122A for use in the treatment of cancer, e.g. prostate, such as mCRPC. 151. A method of making a pharmaceutical composition according to any one of embodiments 76-132 or 112A or 112B or 113A or 114A or 122A, comprising combining a first intermediate composition and a second intermediate composition to form the pharmaceutical composition, wherein the first intermediate composition comprises a radioactive conjugate, and the second intermediate composition comprises a conjugated intermediate and does not contain any radioactive conjugate. 152. The method of embodiment 151, wherein the radioconjugate and the conjugate intermediate comprise the same antibody. 153. The method of embodiment 151, wherein the radioconjugate and the conjugate intermediate comprise the same antibody and the same chelator. 154. The method of any one of embodiments 151-153, wherein the first intermediate composition and the second intermediate composition comprise the same pharma- ceutically acceptable excipient. 155. The method of any one of embodiments 151-153, wherein the first intermediate composition and the second intermediate composition comprise the same pharma- ceutically acceptable excipient in the same or substantially the same amount. 156. The method of any one of embodiments 151-155, further comprising chelating a radioactive metal to the conjugate intermediate to form a radioactive conjugate.

[0301] According to certain embodiments, including any one of the above recited embodiments 1-156, or 16A, 17A, 18A, 28A, 32A, 75A, 112A, 112B, 113A, 114A, or 122A, the radioconjugate is 225 Ac-DOTA-h11B6.

[0302] According to certain embodiments, including any one of the above-enumerated embodiments 1-156, or 16A, 17A, 18A, 28A, 32A, 75A, 112A, 112B, 113A, 114A, or 122A, the radioconjugate is (e.g., as illustrated in Figures 6A-6C). 225 TOPA-[C7]-phenylthiourea-h11B6 antibody conjugates, such as Ac-TOPA-h11B6.

[0303] The following examples are intended to further illustrate the nature of the present invention. It should be understood that the following examples do not limit the present invention. EXAMPLES

[0304] The h11B6 antibody used in the examples below comprises a heavy chain according to SEQ ID NO:12 and a light chain according to SEQ ID NO:13.

[0305] Example 1: In humans 111 Phase 0 imaging study of In-DOTA-h11B6 111 A first-in-human Phase 0 imaging study of In-DOTA-h11B6 was conducted to determine the potential of hK2-targeted radioimmunotherapy in subjects with advanced prostate cancer (Clinical Trial Identifier NCT04116164).

[0306] A single slow bolus injection of 2 mg of [111In]-DOTA-h11B6 (nominal 185 MBq [111In]) was administered intravenously with or without 8 mg of h11B6. The formulation administered to patients was 0.5 mg / mL in 25 mM acetic acid, 8.5% sucrose (w / v), 0.04% polysorbate 20 (w / v), pH 5.5. 111 In-DOTA-h11B6. The UV and radio-HPLC chromatograms of this formulation were obtained. See Figure 1A and Figure 1B.

[0307] Patients were observed for adverse events (AEs) for at least 2 weeks. Serial gamma camera imaging, including at least one SPECT / CT scan, was performed up to 8 days post-dose. Serial blood samples were obtained over 2 weeks to determine serum radioactivity and h11B6 protein levels. Normal organ dosimetry was estimated using OLINDA-EXM.

[0308] The results of the first six patients are summarized in Table 1. Treatment was well tolerated in all patients, with no adverse events and no evidence of high accumulation in any organ, including the salivary glands. The initial volume of distribution appeared to be restricted to the vascular compartment. In all patients, slow clearance of radioactivity from the vascular compartment was observed with gradual targeting to skeletal and non-skeletal lesions. h11B6 mAb localized to bone and soft tissue metastases, with no significant normal tissue uptake, sparing the salivary glands. Both serum pharmacokinetics and key normal organ (liver, spleen, kidney) biodistribution revealed essentially no difference in the biological behavior of the antibody at 2 mg and 10 mg antibody masses.

[0309] [Table 2]

[0310] Example 2: 225 Preparation of formulation “A” containing Ac-DOTA-h11B6 To prepare a formulation containing actinium conjugated to h11B6, the same formulation was made as used in Phase 0, but 111 In-DOTA-h11B6 225 Ac-DOTA-h11B6 was substituted at 0.5 mg / mL in 26.75 mM acetic acid. 225"Formulation A" was prepared containing Ac-DOTA-h11B6, 8.5% sucrose (w / v), and 0.04% polysorbate 20 (w / v), pH 5.5. Radiolytic degradants were observed in the UV and radio-HPLC chromatograms of this formulation. See Figures 2A and 2B. The radiolytic degradants were identified as resulting from the radiolysis of sucrose in the formulation.

[0311] Example 3: 225 Preparation of formulation "B" containing Ac-DOTA-h11B6 The cryoprotectant, sucrose, was excluded from Formulation A due to the formation of secondary radiolytic degradation products from the primary radiation. The morphology was modified from a frozen solid to a liquid solution. However, the elimination of sucrose 225 This resulted in accelerated degradation of the Ac-DOTA-h11B6 drug product, especially the h11B6 antibody. 0.5% w / v sodium ascorbate (vitamin C) was added as a sacrificial radioprotectant to attenuate the degradation, resulting in 0.5 mg / mL of DOTA in 26.75 mM acetic acid. 225 "Formulation B" was obtained, containing Ac-DOTA-h11B6, 0.5% w / v sodium ascorbate (vitamin C), and 0.04% polysorbate 20, pH 5.5. UV and radio-HPLC chromatograms of this formulation were obtained. See Figures 3A-3D. 225 The degradation of Ac-DOTA-h11B6 drug product was significantly reduced in Formulation B.

[0312] Example 4: 225 Ac-DOTA-h11B6, and 225 Preparation of formulation "B" containing Ac-DOTA-h11B6 This embodiment is 225 The preparation of a drug product containing Ac-DOTA-h11B6 is described, however, similar methods can also be used. 225 Instead of Ac-DOTA-h11B6 225 It can also be used in the manufacture of drug products containing Ac-TOPA-h11B6.

[0313] This embodiment is225 Describe the process for the preparation of Ac-DOTA-h11B6 drug product and the solution containing this drug product.Antibody h11B6 can be prepared, for example, as described in US Patent No. 10,100,125, which is incorporated herein by reference.Antibody h11B6 can also be prepared using the method described in US Patent No. 9,873,891, using CHO DG44 derived cell line and hEF1α promoter double gene vector commercially available from Fujifilm Diosynth Biotechnologies, which is incorporated herein by reference.

[0314] Following pre-cultivation and growth, the cell culture may be clarified using known filtration techniques. The filtrate is concentrated and diafiltered to a target final concentration of 10 g / L in buffer (25 mM NaOAc, pH 5.5). h11B6 may be filtered through a 0.2 μm filter, packed into sterile bags, and frozen at −65° C. or below for long-term storage prior to conjugation.

[0315] The thawed h11B6 is then diafiltered (buffer exchanged) into 50 mM bicine, 120 mM NaCl, pH 8.5 for subsequent conjugation of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to h11B6. The retentate from the previous step is transferred to a reactor and stirred while warming to 25° C. An aqueous solution of p-SCN-Bn-DOTA is prepared and added to the reactor. The reaction was maintained at 25° C. for 20 hours. The product of the conjugation reaction (DOTA-h11B6) is transferred directly to the retentate container for final diafiltration with 25 mM NaOAc, pH 5.5. The DOTA-h11B6 conjugate intermediate is then filtered through a 0.2 μm filter, filled into sterile polycarbonate containers, and may be frozen at −65° C. or below for long-term storage.

[0316] The conjugation reaction results in the addition of multiple DOTA molecules to the epsilon amino groups of the lysine side chains of h11B6 mAb. The conjugate-to-antibody ratio (CAR), which indicates the number of DOTA molecules per h11B6 mAb molecule, can be measured by intact mass analysis using RP-HPLC with online mass spectrometry. Based on the molecular structure of p-SCN-Bn-DOTA, each DOTA residue adds a mass of 552 Da to the antibody, which can be easily detected by intact mass analysis. To reduce the complexity of the sample, the DOTA-h11B6 conjugate intermediate was treated with PNGase F to remove N-linked glycans and with carboxypeptidase B to remove the C-terminal lysine residue. The average CAR of DOTA-h11B6 of 2.6 was calculated as a weighted average from all CAR species detected.

[0317] 225 The Ac-DOTA-h11B6 drug product is produced in a continuous process from the precursor DOTA-h11B6 conjugate intermediate, which is a trichloride 225 Reacts with actinium and has a target specific activity of 170 μCi / mg or more 225 Actinium-radiolabelled drug substance is produced. 225 Ac-DOTA-h11B6 drug substance is synthesized, purified by PD-10 column purification, and formulated in situ, as described below. 225 Four drug product presentations (50, 100, 150, and 200 μCi in 2 mg protein) are manufactured by blending Ac-DOTA-h11B6 drug substance with DOTA-h11B6 and reformulation buffer. The blended product presentations are individually sterile filtered and aseptically filled into final patient vials.

[0318] An intermediate purification buffer (26.75 mM acetic acid, 0.04% polysorbate 20, acetic acid, pH 5.5) can be prepared for the final blended purification buffer and stored at 2-8°C for no more than 30 days prior to use. Sodium ascorbate is added to the intermediate purification buffer and filtered through a 0.2 μm sterile filter into a sterile product holding container to produce the final blended purification buffer (26.75 mM acetic acid, 0.5% (w / v) sodium ascorbate, 0.04% (w / v) polysorbate 20, acetic acid, pH 5.5).

[0319] The DOTA-h11B6 conjugate intermediate is thawed at room temperature. A solution of actinium trichloride is prepared by dissolving actinium trinitrate in 0.1 N hydrochloric acid (it is also possible to use a source of Ac-225 that is already in trichloride form). Actinium trichloride (800-1300 μCi) is incubated with 4.4 mg of DOTA-h11B6 and sodium acetate buffer (pH adjusted with acetic acid prepared in advance and stored for no more than 6 months) and the pH adjusted to 6.5. Then, 225 Ac-DOTA-h11B6 is purified on a pre-conditioned PD-10 column and eluted with the final purification buffer. After purification, the amount of radioactivity is measured.

[0320] In preparations to achieve four doses (50, 100, 150, and 200 μCi), the DOTA-h11B6 conjugate intermediate is reformulated to 0.5 mg / mL (26.75 mM acetic acid, 0.5% (w / v) sodium ascorbate, 0.04% (w / v) polysorbate 20, acetate pH 5.5) using the final reformulation buffer and filtered through a 0.2 μm sterile filter. 225Dispense Ac-DOTA-h11B6 into intermediate vials to achieve the desired unit doses (50, 100, 150, and 200 μCi in 4 mL at the anticipated administration time to the patient) and add reformulated DOTA-h11B6 conjugate intermediate to a volume of 6.8 mL to generate the drug product. The drug product is then filtered through a 0.2 μm sterile filter and aseptically filled to a volume of 4.8 mL. The remaining drug product is also filtered through a 0.2 μm sterile filter and aseptically filled for drug product release testing. Store the drug product immediately at 2-8 °C.

[0321] Therefore, radiolabeled drug products 225 Ac-DOTA-h11B6 is prepared as a sterile solution for intravenous injection and contains no preservatives. 225 Ac-DOTA-h11B6 is available in four drug product (DP) unit doses: 50, 100, 150, and 200 μCi at the anticipated time of administration to the patient.

[0322] The target composition of the drug product is provided in Table 2 below. 225 Instead of Ac-DOTA-h11B6 and DOTA-h11B6, 225 Ac-TOPA-h11B6 and TOPA-h11B6 may be used to prepare compositions.

[0323] [Table 3] a Target fill volume (4.8 mL) includes an overfill of 0.8 mL. b Target activity concentration at the time of calibration. c As described herein, 225 Ac-DOTA-h11B6 is combined with DOTA-h11B6 and reformulation buffer to produce the respective drug product unit dose.

[0324] Example 5A: DOTA-h11B6 Stability Study This study was conducted to monitor the attributes of DOTA-h11B6 drug substance intermediate (10 mg / mL formulated in 25 mM acetic acid, pH adjusted to 5.5) stabilized under various environmental conditions and for various lengths of time. Research specimens were prepared by aliquoting the drug substance intermediate (DSI) into 20 mL polycarbonate bottles at 9 mL fill volumes.

[0325] [Table 4]

[0326] Stability test results The stability results of DOTA-h11B6 DSI kept under the recommended, accelerated, and two stressed conditions are listed below. At all time points for DSI kept under the recommended storage conditions, all test parameter result values ​​observed per assay test exceeded criteria consistent with the most preferred embodiment of stability when kept at a temperature of about -65°C for about 48 months or more, after about 6 months or more at a temperature of about -40°C, after about 6 months or more at a temperature of about 5°C, and / or after about 4 years or more at a temperature of about -65°C. Of particular note, DSI kept at accelerated conditions (-40°C) for 6 months and DSI kept at stressed conditions (5°C) for 6 months showed results consistent with the preferred embodiment of stability when kept at -65°C for about 4 years or more.

[0327] Results for DOTA-h11B6 DSI held at stressed conditions (25°C) for 1 month showed the following degradation rates for the drug substance intermediate exposed to this stressed storage condition:

[0328] -65℃ data

[0329] [Table 5]

[0330] [Table 6]

[0331] [Table 7] SE-HPLC = size-exclusion high performance liquid chromatography HMW = high molecular weight; LMW = low molecular weight; CE-SDS = capillary electrophoresis sodium dodecyl sulfate; LC = light chain; HC = heavy chain; NGHC = nonglycosylated heavy chain; IgG = immunoglobulin G; CIEF = cation exchange; NR = not reported

[0332] -40℃ data

[0333] [Table 8]

[0334] [Table 9]

[0335] [Table 10] SE-HPLC = size-exclusion high performance liquid chromatography HMW = high molecular weight; LMW = low molecular weight; CE-SDS = capillary electrophoresis sodium dodecyl sulfate; LC = light chain; HC = heavy chain; NGHC = nonglycosylated heavy chain; IgG = immunoglobulin G; cIEF = capillary isoelectric focusing; RP-HPLC = reversed-phase high performance liquid chromatography

[0336] 5℃ data

[0337] [Table 11]

[0338] [Table 12]

[0339] [Table 13] SE-HPLC = size-exclusion high performance liquid chromatography HMW = high molecular weight; LMW = low molecular weight; CE-SDS = capillary electrophoresis sodium dodecyl sulfate; LC = light chain; HC = heavy chain; NGHC = nonglycosylated heavy chain; IgG = immunoglobulin G; cIEF = capillary isoelectric focusing; RP-HPLC = reversed-phase high performance liquid chromatography

[0340] 25℃ data

[0341] [Table 14]

[0342] [Table 15]

[0343] [Table 16] SE-HPLC = size-exclusion high performance liquid chromatography HMW = high molecular weight; LMW = low molecular weight; CE-SDS = capillary electrophoresis sodium dodecyl sulfate; LC = light chain; HC = heavy chain; NGHC = nonglycosylated heavy chain; IgG = immunoglobulin G; cIEF = capillary isoelectric focusing; RP-HPLC = reversed-phase high performance liquid chromatography

[0344] Example 5B: 111 In-DOTA-h11B6 stability study This test was performed on samples that were stable under the recommended storage conditions. 111 Conducted to monitor In-DOTA-h11B6 drug product (DP) attributes. Research specimens were prepared by filling the drug product through the septa of previously stoppered, capped and crimp-sealed 10R borosilicate vials.

[0345] [Table 17]

[0346] Stability test results Held under recommended and accelerated conditions 111 The stability results for the In-DOTA-h11B6 DP are listed below: At all time points for the DP held at the recommended storage conditions, all test parameter result values ​​observed per assay test exceeded criteria consistent with the most preferred embodiment of stability when held following storage at a temperature of about -40°C for about 72 hours or more and / or at a temperature of about 5°C for about 72 hours or more.

[0347] The DP results after 72 hours at accelerated temperature (5° C.) showed results consistent with the preferred embodiment of stability when held at −40° C. for approximately 72 hours or more.

[0348] 40℃ data

[0349] [Table 18]

[0350] [Table 19] ND = not detected, HMWS = high molecular weight species, LMWS = low molecular weight species

[0351] 5℃ data

[0352] [Table 20]

[0353] [Table 21] HMWS = high molecular weight species, LMWS = low molecular weight species, μCi = microcuries, ND = not detected

[0354] Example 5C: 225 Ac-DOTA-h11B6 stability test This test was performed on samples that were stable under the recommended storage conditions. 225 Conducted to monitor Ac-DOTA-h11B6 drug product (50 μCi and 200 μCi) attributes. Research specimens were prepared by filling the drug product through the septa of pre-sealed 10R cyclic olefin polymer vials.

[0355] [Table 22]

[0356] Stability test results Stored under recommended storage conditions 225 The stability results for Ac-DOTA-h11B6 DP are listed below: At all time points for the DP held at the recommended storage conditions, all test parameter result values ​​observed per assay test exceeded criteria consistent with the most preferred embodiment of stability when held after approximately 96 hours of storage.

[0357] 2~8℃ data

[0358] [Table 23]

[0359] [Table 24]

[0360] [Table 25]

[0361] [Table 26] SEC = size exclusion chromatography, HMWS = high molecular weight species, LMWS = low molecular weight species, μCi = microcuries

[0362] Example 6: Use of Actinium-225 Labeled Antibodies Targeting Human Kallikrein-2 (hK2) for Advanced Prostate Cancer (Study ID: NCT04644770; 69086420PCR1001) This example is administered to adult patients with mCRPC who have disease progression on or after AR targeted therapy. 225 A first-in-human Phase 1 study to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of Ac-DOTA-h11B6 is described. Formulation B, as described in Examples 3 and 4, is administered to patients in the Phase 1 study. As discussed herein, 225 Ac-DOTA-h11B6 is a cytochrome P450 (DOTA)-labeled alpha particle-emitting radionuclide. 225 The hK2-specific monoclonal antibody h11B6, chelated to Ac, is a radioimmunotherapy targeting the hK2 antigen. The patient cohort in this study was treated with similar pharmaceutical compositions according to similar clinical procedures described in this example. 225 Instead of Ac-DOTA-h11B6 225 Note that Ac-TOPA-h11B6 is administered.

[0363] The main objectives are: 225 The objectives of the study are to determine the safety and recommended Phase 2 dose (RP2D) of Ac-DOTA-h11B6, as well as to evaluate the incidence, duration, and severity of adverse events, including dose-limiting toxicity (DLT). Secondary objectives and endpoints are to assess preliminary antitumor activity and 225 To provide further understanding of the pharmacology of Ac-DOTA-h11B6, see, for example, Table 3.

[0364] [Table 27] 225 Ac-DOTA-h11B6 will be administered to adult males aged 18 years or older with mCRPC who have been previously exposed to at least one novel AR-targeted therapy. 225Ac-DOTA-h11B6 will be administered in two parts: dose escalation (Part 1) and dose expansion (Part 2).

[0365] Response to treatment will be assessed according to PCWG3 response criteria.

[0366] Blood samples will be collected to characterize the pharmacokinetics of serum radioactivity and concentrations of h11B6 antibody; 225 Characterize the presence of anti-drug antibodies of Ac-DOTA-h11B6.

[0367] 225 Safety of Ac-DOTA-h11B6 will be assessed by physical examination, Eastern Cooperative Oncology Group (ECOG) performance status, electrocardiogram, clinical laboratory tests, vital signs, and monitoring of adverse events. Echocardiogram or multi-gated acquisition scan will be assessed at screening. Subsequent evaluations will be performed as clinically indicated. Severity of adverse events will be assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events (version 5.0). Use of concomitant medications will be recorded.

[0368] Dose escalation decisions are supported by a modified continual reassessment method (mCRM) based on a Bayesian logistic regression model (BLRM) using escalation with overdose control (EWOC).

[0369] Inclusion criteria included: Each potential patient must meet all of the following criteria:

[0370] [Table 28]

[0371] Exclusion criteria included: Any patient who may meet any of the following criteria will be excluded.

[0372] [Table 29]

[0373] A. Part 1: Dose Escalation Participants: 225 Patients will receive intravenous (IV) injections of Ac-DOTA-h11B6 in one or multiple doses in the amounts listed below.

[0374] In Part 1, 50μCi / 2mg 225 Ac-DOTA-h11B6 will be administered in the first dose escalation cohort. After DLT evaluation in this initial cohort, radioactive 225 Dose escalation of Ac-DOTA-h11B6 to the next dose level will be based on consideration of all available additional data, including but not limited to pharmacokinetics, pharmacodynamics, safety, and preliminary antitumor activity.

[0375] Table 4 shows the planned (tentative) dose escalation schedule illustrating possible dose escalation routes, including doses greater than 200 μCi (e.g., 300 μCi or greater). Intermediate dose level increments are possible to ensure the safety of study participants. Initial cohorts will receive a dose of 50 μCi of radioactivity. 225 Receive Ac-DOTA-h11B6. Escalation will occur in 50 μCi increments initially. A dosing interval of one dose every 8 weeks will be used. The starting antibody (h11B6) mass will be 2 mg and may increase up to 10 mg. Initially, the antibody mass dose will be kept constant with increasing activity across the cohorts.

[0376] [Table 30]

[0377] The final drug product administered to participants in this study will contain two components: 225 There is Ac-DOTA-h11B6 and unlabeled DOTA-h11B6 antibody. The two components may be premixed in a single vial. The two components are provided for each participant visit with the prescribed radioactivity dose and between 2-10 mg total antibody mass. See Table 5.

[0378] [Table 31]

[0379] The 225Ac-DOTA-h11B6 radioactive investigational product is a single-use, sterile, refrigerated solution for injection in a cyclic olefin polymer vial closed with a latex-free stopper and aluminum seal. 225Ac-DOTA-h11B6 is formulated with 26.75 mM acetic acid, 0.5% sodium ascorbate, and 0.04% polysorbate 20 in sterile water at pH 5.5. The investigational product is clear, colorless to slightly yellow, and free of visible particulate matter. Store the 225Ac-DOTA-h11B6 vials refrigerated at a temperature range of 2-8°C and protected from light. The drug product does not contain any preservatives and is designed for single use only. Vials supplied to the clinic contain an overfill of 0.8 mL (4.8 mL total) to allow for a final dose discontinuation of 4.0 ± 0.4 mL depending on the actual administration time. Radioactivity concentrations of 225Ac-DOTA-h11B6 will be targeted initially at 50, 100, 150, or 200 μCi in 4 mL (2 mg), followed by doses above 200 μCi (e.g., 300 μCi, which has a total volume of 8 mL and a protein concentration of 2 mg / 4 mL, thus 4 mg total protein at the anticipated dosing time). Intermediate dose level increments are possible to ensure the safety of study participants. As noted above, similar investigational products for this study will be tested for additional patient cohorts. 225 Instead of Ac-DOTA-h11B6, 225 Contains Ac-TOPA-h11B6.

[0380] Dose escalation will be supported using an adaptive dose escalation strategy guided by a modified continuous reassessment method based on BLRM using EWOC.

[0381] The RP2D will be determined after consideration of all available pharmacokinetic, pharmacodynamic, safety, and efficacy data. Once the RP2D is determined, patients will be treated to achieve the RP2D in Part 2. 225 The safety, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity of Ac-DOTA-h11B6 will be confirmed.

[0382] B. Part 2: Dose Expansion In the second part, the 225 The RP2D of Ac-DOTA-h11B6 is administered to one or more cohorts of patients.

[0383] All adverse events, and those that meet the criteria for DLT, will be reviewed and confirmed. Adverse events will be evaluated according to the NCI CTCAE version 5.0. The criteria for DLT are outlined in Table 6.

[0384] As noted above, the patient cohort in this study was treated with the following clinical methods similar to those described in this Example: 225 Instead of Ac-DOTA-h11B6 225 Ac-TOPA-h11B6 is administered.

[0385] [Table 32]

[0386] Outcome measures are provided in Table 7.

[0387] [Table 33]

[0388] Secondary endpoints are provided in Table 8.

[0389] [Table 34]

[0390] Interim clinical results 69086420 Across four radioactivity dose levels of 50, 100, 150, and 200 μCi in the PCR1001 study 225 For 23 participants with metastatic castration-resistant prostate cancer (mCRPC) who received Ac-DOTA-h11B6, the median dose received was 2 doses (range: 1-6), and the median treatment duration was 1.87 months (range: 1-10.8). No dose-limiting toxicities (DLTs) were reported at any of the four radiation dose levels.

[0391] The most frequently reported (≥15%) treatment-emergent adverse events (TEAEs) in these participants were fatigue (39.1%), decreased appetite (34.8%), diarrhea (26.1%), anemia and thrombocytopenia (21.7% each), and nausea and leukopenia (17.4% each). The majority of these commonly reported TEAEs were grade 1 or 2, except for one 50 μCi participant with grade 3 fatigue, one 150 μCi participant with grade 4 thrombocytopenia, and two participants (one 50 μCi and one 200 μCi) with grade 3 anemia. Serious treatment-emergent adverse events (SAEs) were reported in two participants: hypokalemia in one 100 μCi participant and hypocalcemia in one 150 μCi participant. One participant at 150 μCi discontinued due to thrombocytopenia, but all other discontinued participants were due to progressive disease or other reasons. No dose reductions were required in any participant. No on-treatment deaths were observed. Efficacy signals in these participants include, for example, a PSA decrease of 50% or more from baseline in patients at radioactivity doses of 100 uCi or greater.

[0392] The disclosures of each patent, patent application, and publication cited or described in this specification are hereby incorporated by reference in their entirety for all purposes.

Claims

**Claim 1** A pharmaceutical composition comprising a radioactive conjugate and one or more pharmaceutically acceptable excipients, wherein the radioactive conjugate comprises at least one radioactive metal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2, wherein the radioactive metal complex comprises a radioactive metal, wherein the radioactive metal provides a target specific activity of about 50 μCi to about 350 μCi per dose of the pharmaceutical composition at the time of dosing. A pharmaceutical composition. **Claim 2** The pharmaceutical composition according to claim 1, wherein the one or more pharmaceutically acceptable excipients comprise one or more radioprotective agents. **Claim 3** The pharmaceutical composition according to claim 1, wherein the radioactive conjugate comprises at least one radioactive metal complex conjugated to an antibody having binding specificity for hK2. **Claim 4** The pharmaceutical composition according to claim 3, wherein the antibody comprises a heavy chain variable region comprising the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 2, and SEQ ID NO: 3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO:

6. **Claim 5** The pharmaceutical composition according to claim 3, wherein the antibody comprises a heavy chain variable region (VH) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 8, and a light chain variable region (VL) having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:

9. **Claim 6** The pharmaceutical composition according to claim 3, wherein the antibody comprises a heavy chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 10, and a light chain constant region having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:

11. **Claim 7** The pharmaceutical composition according to claim 3, wherein the antibody comprises a heavy chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 12, and a light chain having at least 80%, at least 85%, at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO:

13.

8. The radioactive metal is ２２５ Ac, １１１ In, １７７ Lu, ３２ P, ４７ Sc, ６７ Cu, ７７ As, ８９ Sr, ９０ Y, ９９ Tc, １０５ Rh, １０９ Pd, １１１ Ag, １３１ I, １３４ Ce, １４９ Tb, １５２ Tb, １５５ Tb, １５３ Sm, １５９ Gd, １６５ Dy, １６６ Ho, １６９ Er, １８６ Re, １８８ Re, １９４ Ir, １９８ Au, １９９ Au, ２１１ At, ２１２ Pb, ２１２ Bi, ２１３ Bi, ２２３ Ra, ２５５ Fm, and ２２７ Th, and the pharmaceutical composition according to claim 1, selected from the group consisting of

9. The radioactive metal is ２２５ Ac, and the pharmaceutical composition according to claim 1.

10. The pharmaceutical composition according to claim 1, wherein the radiometal complex comprises a chelating agent selected from the group consisting of 1,4,7,10 - tetraazacyclododecane - 1,4,7,10 - tetraacetic acid (DOTA), S - 2 - (4 - isothiocyanatobenzyl) - 1,4,7 - triazacyclononane - 1,4,7 - triacetic acid (NOTA), 1,4,8,11 - tetraazacyclodocedan - 1,4,8,11 - tetraacetic acid (TETA), 3,6,9,15 - tetraazabicyclo[9.3.1] - pentadeca - 1(15),11,13 - triene - 4 - (S) - (4 - isothiocyanatobenzyl) - 3,6,9 - triacetic acid (PCTA), 5 - S - (4 - aminobenzyl) - 1 - oxa - 4,7,10 - triazacyclododecane - 4,7,10 - tris(acetic acid) (DO3A), and derivatives thereof.

11. The pharmaceutical composition according to claim 1, wherein the radiometal complex comprises a chelating agent that is DOTA.

12. The radioactive metal complex is chelated with DOTA ２２５ The pharmaceutical composition according to claim 1, comprising Ac

13. The pharmaceutical composition according to claim 1, wherein the radiometal complex is conjugated via a 2 - isothiocyanatobenzyl linker to an antibody or antigen - binding fragment having binding specificity for hK2.

14. The pharmaceutical composition according to claim 1, wherein the radio - conjugate comprises 1, 2, 3, or 4 radiometal complexes conjugated to an antibody or antigen - binding fragment having binding specificity for hK2.

15. The radiometal complex comprises a chelating agent, The method or pharmaceutical composition according to claim 1, wherein the chelating agent is conjugated to the fragment crystallizable (Fc) region of an antibody having binding specificity for hK2.

16. The radio - conjugate is (a) a compound of formula (IV) 【Chemical 1】 wherein, R １ is hydrogen, and R ２ is -L １ -R ４ wherein Alternatively, R １ is -L １ -R ４ and R ２ is hydrogen, R ３ is hydrogen, and Alternatively, R ２ and R ３ together with the carbon atom to which they are attached form a 5- or 6-membered cycloalkyl, and the 5- or 6-membered cycloalkyl is optionally substituted with -L １ -R ４ and is optionally substituted with L １ is absent or is a linker, R ４ is the antibody) or a pharmaceutically acceptable salt thereof, or (b) a compound of formula (V) [Chemical Formula 2] wherein, L １ is absent or is a linker, R ４ (wherein R is an antibody) The pharmaceutical composition according to claim 1, comprising the radioactive metal chelated to the compound or a pharmaceutically acceptable salt thereof.

17. wherein the one or more radioprotective agents are (a) containing sodium ascorbate, genisteic acid, or a combination thereof (for example, in an amount of about 0.1 to 1% w / v, or about 0.25 to 0.75% w / v, or about 0.5% w / v), (b) containing sodium ascorbate (for example, in an amount of about 0.1 to 1% w / v, or about 0.25 to 0.75% w / v, or about 0.5% w / v), or (c) containing genisteic acid (for example, in an amount of about 0.1 to 1% w / v, or about 0.25 to 0.75% w / v, or about 0.5% w / v), the pharmaceutical composition according to claim 2.

18. The pharmaceutical composition according to claim 1, wherein the one or more pharmaceutically acceptable excipients further comprise one or more surfactants.

19. The pharmaceutical composition according to claim 18, wherein the one or more surfactants comprise polysorbate 20.

20. The pharmaceutical composition according to claim 1, wherein the one or more pharmaceutically acceptable excipients further comprise an acetate buffer.

21. The pharmaceutical composition according to claim 1, comprising the radioactive conjugate, sodium ascorbate, polysorbate 20, acetate buffer, and water.

22. (a) In water, comprising the radioactive conjugate, about 24 to 28 mM acetic acid, about 0.25 to 0.75% sodium ascorbate, and about 0.01 to 0.1% polysorbate 20, (b) In water, comprising the radioactive conjugate, about 25 mM acetic acid, about 0.5% sodium ascorbate, and about 0.04% polysorbate 20, (c) In water, comprising the radioactive conjugate, about 26.75 mM acetic acid, about 0.5% sodium ascorbate, and about 0.04% polysorbate 20, the pharmaceutical composition according to claim 1.

23. The pharmaceutical composition according to claim 1, having a pH of about 5 to about 6 (for example, about 5.5).

24. The pharmaceutical composition (a) contains no preservatives, (b) contains no sucrose, (c) contains no monosaccharides, disaccharides, oligosaccharides, or polysaccharides, (d) contains no monosaccharides or disaccharides, or (e) containing no disaccharide The pharmaceutical composition according to claim 1.

25. The pharmaceutical composition according to claim 1, wherein the one or more pharmaceutically acceptable excipients consist of, or consist essentially of, an acetate buffer, sodium ascorbate, and polysorbate 20 in water.

26. The pharmaceutical composition according to claim 1, wherein the pharmaceutical composition is formulated for intravenous administration.

27. The pharmaceutical composition according to claim 1, wherein the pharmaceutical composition is stable at a temperature range of about 2 to 8 °C for at least 72 hours, or at least 96 hours, or at least 120 hours.

28. The pharmaceutical composition according to claim 3, wherein the radioactive conjugate comprises from about 1 to about 4, or about 2 to about 3, chelator molecules conjugated to the antibody.

29. wherein the radioactive metal is ２２５ Ac, and the radioactive metal provides a specific activity of about 50 μCi to about 350 μCi, about 50 μCi to about 300 μCi, about 50 μCi to about 250 μCi, about 50 μCi to about 200 μCi, about 50 μCi to about 150 μCi, about 50 μCi to about 100 μCi per about 2 mg of total antibody, the pharmaceutical composition according to claim 3.

30. The radioactive metal is ２２５ Ac, and the radioactive metal provides a target specific radioactivity of about 50 μCi to about 350 μCi, about 50 μCi to about 200 μCi, about 50 μCi, about 100 μCi, about 150 μCi, about 200 μCi per about 2 mg of total antibody at the time of dosing. The pharmaceutical composition according to claim 3.

31. The method according to claim 3, wherein the pharmaceutical composition comprises a target radioactivity concentration of about 1 μCi / mL to about 100 μCi / mL.

32. The pharmaceutical composition according to claim 3, wherein the pharmaceutical composition comprises the whole antibody in an amount of about 0.01 to 5.0 mg / mL.

33. The pharmaceutical composition according to claim 3, comprising from about 1 mg to about 20 mg, from about 1 mg to about 10 mg, about 2 mg, about 10 mg of the whole antibody.

34. The pharmaceutical composition according to claim 1, comprising the conjugate intermediate and the total amount of the radioactive conjugate in an amount of about 0.1 to 1.0 mg / mL, about 0.4 to 0.6 mg / mL, about 0.5 mg / mL.

35. The pharmaceutical composition according to claim 3, further comprising a non-radiolabeled antibody, wherein the non-radiolabeled antibody is the same antibody as the antibody conjugated to the radioactive metal complex.

36. The pharmaceutical composition according to claim 35, wherein the total amount of the conjugated antibody and the non-radiolabeled antibody does not exceed about 10 mg, or about 9 mg, or about 8 mg, or about 7 mg, or about 6 mg, or about 5 mg, or about 4 mg, or about 3 mg, or about 2 mg.

37. The pharmaceutical composition according to claims 1 to 36, for use in the treatment of cancer in a patient.

38. The pharmaceutical composition according to claim 37, wherein the dosage of the pharmaceutical composition has a volume of about 1 mL to about 20 mL, or about 1 mL to about 10 mL, or about 2 mL to about 6 mL, or about 3 mL to about 5 mL, or about 4 mL.

39. The pharmaceutical composition according to claim 37, wherein the dosage of the pharmaceutical composition contains about 2 mg of total antibody per about 4 mL of the dosage.

40. The pharmaceutical composition according to claim 37, wherein the pharmaceutical composition is administered intravenously to the patient.

41. The pharmaceutical composition according to claim 37, wherein after chelating the radioactive metal to a conjugate intermediate to form the radioactive conjugate, the pharmaceutical composition is administered to the patient within about 168 hours, or within about 144 hours, or within about 120 hours, or within about 96 hours, or within about 72 hours, or within about 48 hours, or within about 24 hours.

42. The pharmaceutical composition according to claim 37, wherein the pharmaceutical composition is administered to the patient once every about 4 weeks, once every about 8 weeks, or once every about 12 weeks.

43. The pharmaceutical composition according to claim 37, wherein the cancer is prostate cancer, non-localized prostate cancer, metastatic prostate cancer, castration-resistant prostate cancer (CRPC), metastatic castration-resistant prostate cancer (mCRPC), or mCRPC with adenocarcinoma.

44. The pharmaceutical composition according to claim 37, wherein the testosterone castration level of the patient is about 50 ng / dL or less.

45. The patient is (a) previously exposed to at least one androgen receptor (AR) targeted therapy, (b) previously received chemotherapy, (c) previously received orchiectomy or medical castration, according to the method of claim 37.

46. The pharmaceutical composition according to claim 45, wherein the AR targeted therapy is abiraterone acetate, enzalutamide, apalutamide, darolutamide, or any combination of the foregoing.

47. The pharmaceutical composition according to claim 45, wherein the chemotherapy included administration of a taxane.

48. The pharmaceutical composition according to claim 45, wherein the patient is receiving ongoing androgen deprivation therapy with a gonadotropin-releasing hormone (GnRH) agonist or antagonist.

49. The pharmaceutical composition according to claim 37, wherein the pharmaceutical composition is administered to the patient as a single dose, multiple doses of two or more partial doses, or two partial doses.

50. A pharmaceutical composition comprising a radioactive conjugate and one or two or more pharmaceutically acceptable excipients, The radioactive conjugate comprises at least one radioactive metal complex conjugated to an antibody or antigen-binding fragment having binding specificity for hK2, The radioactive metal complex comprises a radioactive metal that is 225Ac and a chelating agent that is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), The chelating agent is conjugated via a 2-isothiocyanatobenzyl linker to an antibody or antigen-binding fragment having binding specificity for hK2, The radioactive metal provides a target specific radioactivity of 50 μCi to 350 μCi per dose of the pharmaceutical composition at the time of dosing, or The radioactive metal provides a specific radioactivity of 50 μCi to 350 μCi per about 2 mg of total antibody, a pharmaceutical composition.

51. An antibody or antigen-binding fragment having binding specificity for hK2 is a heavy chain variable region comprising the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 2, and SEQ ID NO: 3, and a light chain variable region comprising the amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6, or, a heavy chain variable region (VH) comprising the amino acid sequences of SEQ ID NO: 1, SEQ ID NO: 2, and SEQ ID NO: 3 and having at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 8, and a light chain variable region (VL) comprising the amino acid sequences of SEQ ID NO: 4, SEQ ID NO: 5, and SEQ ID NO: 6 and having at least 90%, at least 95%, or at least 98% sequence identity to the amino acid sequence of SEQ ID NO: 9, or, a heavy chain variable region (VH) comprising the amino acid sequence of SEQ ID NO: 8, and a light chain variable region (VL) comprising the amino acid sequence of SEQ ID NO: 9, the pharmaceutical composition according to claim 50.

52. The pharmaceutical composition according to claim 50, wherein the radioactive conjugate comprises 1, 2, 3, or 4 radioactive metal complexes conjugated to an antibody or antigen-binding fragment having binding specificity for hK2.

53. The pharmaceutical composition according to any one of claims 50 to 52, wherein the chelating agent is conjugated to the fragment crystallizable (Fc) region of an antibody having binding specificity for hK2.

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