Methods and compositions for the treatment of POU2f3-driven cancer

Abstract

The present disclosure provides compositions and methods for the treatment of cancer, including small cell lung cancer. The present disclosure further methods and compositions comprising a HER2-targeting ADC, a TROP2-targeting ADC, a DLL3-targeted therapy, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor. Aspects of the disclosure further relate to methods for treating diseases or disorders associated with increased expression, activity, or function of POU2F3.

Description

TITLE OF THE INVENTIONMETHODS AND COMPOSITIONS FOR THE TREATMENT OF POU2F3-DRIVEN CANCERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of U.S. Provisional Appl. Ser. No. 63 / 620,060, filed January 11, 2024, and U.S. Provisional Appl. Ser. No. 63 / 572,563, filed April 1, 2024, the entire disclosure of each of which is incorporated herein by reference.FIELD OF THE INVENTION

[0002] This present disclosure relates to the field of cancer therapeutics, and more specifically to compositions and methods for the treatment of small cell lung cancer (SCLC) and pulmonary large cell neuroendocrine carcinoma (LCNEC).BACKGROUND OF THE INVENTION

[0003] Small cell lung cancer (SCLC) and pulmonary large cell neuroendocrine carcinoma (LCNEC) are aggressive high-grade neuroendocrine carcinomas (hgNECs) with poor prognoses. SCLC accounts for 15% of all lung cancers and the 5-year survival of patients remains <7%. The recent addition of immune checkpoint blockade (ICB) to chemotherapy as frontline treatment for extensive-stage (ES) SCLC confers only a modest, 2-month improvement in median overall survival (OS). Pulmonary LCNEC is a rare hgNEC and accounts for 3% of lung cancers that is often treated similar to SCLC. In contrast to non-small cell lung cancer, there are no validated predictive biomarkers for hgNECs, and the treatment is “one-size fits all.” There is an urgent unmet need to develop effective, personalized therapies for the treatment of pulmonary hgNECs and to develop biomarkers to personalized treatment.

[0004] A method for classifying SCLC tumors into four unique subtypes based on their transcriptional profiles was recently developed (Gay et al., Cancer Cell 39(3) :346-360, 2021), which broadly applies to LCNEC as well (Stewart et al. 2023 AACR Annual Meeting, Orlando, Florida, 2023). Three subtypes are driven by the differential expression of the transcription factors ASCL1 (SCLC-A), NEURODI (SCLC-N), and POU2F3 (SCLC-P). A fourth subtype (SCLC-Inflamed, or SCLC-I) is defined by increased expression of inflammatory and immunegenes. Retrospective analyses of the IMpowerl33 trial (which led to the approval of atezolizumab with chemotherapy as frontline treatment for extensive- stage SCLC) demonstrates that the benefit atezolizumab addition was largely concentrated among SCLC-I tumors and virtually absent from other subtypes. Moreover, patients with SCLC-P subtype have a worse prognosis with current treatments (median overall survival ~7-9 months) versus other SCLC subtypes (mOS 11-18 months).

[0005] HER2 and TROP2-targeting antibody drug conjugates (ADCs) such as trastuzumab deruxtecan and sacituzumab govitecan have been approved by the FDA in several solid tumor types, including breast cancer and non-small cell lung cancer. Another TROP2 ADC, datopotamab deruxtecan shows promising clinical efficacy in the ongoing TROPION-Lung02 study. The present disclosure demonstrates that HER2 is an effective surface target in the SCLC-P subtype and that treatment with HER2 ADCs is effective in SCLC-P (POU2F3) models. The present disclosure further demonstrates an abundance of TROP2 expression across several subtypes of SCLC, with increased TROP2 expression following frontline chemotherapy treatment, demonstrating that TROP2-targeting ADCs are a strong candidate therapy for relapsed hgNECs.SUMMARY OF THE INVENTION

[0006] In one aspect, the present disclosure provides a method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3-driven cancer and administering to the subject an effective amount of a HER2- targeting antibody drug conjugate. In another aspect, the present disclosure provides a method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3-driven cancer and expressing increased levels SLFN11 in at least one cancer cell, and administering to the subject an effective amount of a HER2- targeting antibody drug conjugate, wherein the antibody drug conjugate comprises a topoisomerase inhibitor. In yet another aspect, the present disclosure provides a method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3 -driven cancer, wherein the subject has received prior chemotherapy, and administering to the subject an effective amount of a HER2-targeting antibody drug conjugate and a TROP2-targeting antibody drug conjugate. The present disclosure provides, in one aspect, a method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a SCLC-P subtype ora SCLC-I subtype cancer, and administering to the subject an effective amount of a HER2- targeting antibody drug conjugate or a TROP2-targeting antibody drug conjugate. The present disclosure provides, in another aspect, a method of treating a subject in need thereof, the method comprising: a) identifying a subject afflicted with or at risk of developing a small cell lung cancer; b) identifying the small cell lung cancer as expressing HER2 or TR0P2; and c) administering to the subject an effective amount of a HER2-targeting antibody drug conjugate, wherein the small lung cancer is identified as expressing HER2, or administering to the subject an effective amount of a TROP2-targeting antibody drug conjugate, wherein the small cell lung cancer is identified as expression TR0P2. The present disclosure provides, in yet another aspect, a method of treating a subject in need thereof, the method comprising administering to the subject an effective amount of a HER2-targeting antibody drug conjugate and a DLL3- targeted therapy. In certain embodiments, the method may further comprise identifying the subject as being subject afflicted with or at risk of developing a SCLC-P subtype cancer prior to the administering.

[0007] In one embodiment, the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado-trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A 166, ZW49, BDC-1001 , T-PNU, FS-1502, GQ1001 , YH012, and HER2xPRLR bsADC. In another embodiment, the TROP2-targeting antibody drug conjugate is selected from the group consisting of sacituzumab govitecan, datopotamab deruxtecan, and YH012. The DLL3-targeted therapy, in certain embodiments, is an antibody, an antibody-drug conjugate, a bi-specific T-cell engager, a tri-specific T-cell engager, or a CAR-T cell. The DLL3-targeted therapy, in particular embodiments, is selected from the group consisting of tarlatamab, rovalpituzumab tesirine, BI-764532, HPN328, and AMG 119. In yet another embodiment, the POU2F3-driven cancer is resistant to a standard of care therapy. The POU2F3-driven cancer, in still yet another embodiment, is resistant to a delta-like protein 3 (DLL3)-targeted therapy. In another embodiment, the HER2-targeting antibody drug conjugate or the TROP2-targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant. Nonlimiting examples of topoisomerase inhibitors include a topoisomerase I inhibitor, a topoisomerase II inhibitor, deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin,merbarone, PNU-159682, and anthracycline aclarubicin. Examples of DNA alkylating agents include, but are not limited to, a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin. Non-limiting examples of tubulin targeting agents include a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM1. Examples of immune stimulants include, but are not limited to, a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

[0008] In some embodiments, the POU2F3-driven cancer is selected from the group consisting of lung cancer, small cell lung cancer, pulmonary large cell neuroendocrine carcinoma, skin cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, appendiceal cancer, hematopoietic cancer, breast cancer, head and neck cancer, prostate cancer, kidney cancer, bladder cancer, liver cancer, esophagus cancer, stomach cancer, thyroid cancer, small bowel adenocarcinoma, hepatobiliary cancer, and gynecological cancer. In one embodiment, the POU2F3-driven cancer is small cell lung cancer or pulmonary large cell neuroendocrine carcinoma. In another embodiment, the subject is a mammalian subject. In yet another embodiment, the subject is a human subject.

[0009] In certain embodiments, the administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration. In one embodiment, the methods of the present disclosure may further comprise administering a second therapy to the subject. The second therapy, in another embodiment, is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery. The second therapy, in yet another embodiment, comprises administering an effective amount of a PARP inhibitor. Non-limiting examples of PARP inhibitors include veliparib, talazoparib, olaparib, rucaparib, and niraparib.

[0010] In particular embodiments, the methods of the present disclosure may further comprise administering a pharmaceutical composition comprising the effective amount of the HER2- targeting antibody drug conjugate, the TROP2-targeting antibody drug conjugate, the DLL3- targeted therapy, the topoisomerase inhibitor, the DNA alkylating agent, the tubulin targetingagent, the immune stimulant, the chemotherapy, the immunotherapy, or the PARP inhibitor to the subject.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

[0012] FIG. 1 shows the molecularly defined subsets of SCLC. FIG. 1A shows gene signatures defining four unique subtypes of SCLC tumors (n=81): SCLC-A (ASCL1), SCLC- N (NEURODI) and SCLC-P (POU2F3) and SCLC-I (“Inflamed”). FIG. IB shows IHC of patient SCLC tumors for ASCL1, NEURODI and POU2F3 demonstrating the subtypes.

[0013] FIG. 2 demonstrates that SLFN11 is a predictive biomarker to PARP and TOPI inhibitors in SCLC. FIG. 2A shows that high SLFN11 protein levels correlate to PARP and TOP I inhibitor sensitivity. FIG. 2B shows representative IHC images for SLFNl l-high, - intermediate, and -negative tumors. FIG. 2C shows increased survival in patients with SLFN11-positive SCLC treated with veliparib and temozolomide (TMZ).

[0014] FIG. 3 demonstrates HER2 expression in pulmonary hgNECs. FIG. 3 A shows expression of HER2 cross different subtypes in SCLC and LCNEC patient datasets. FIG. 3B shows higher expression levels of HER2 detected in SCLC-P. FIG. 3C shows enrichment of HER2 expression in POU2F3+ cells in scRNAseq analysis of tumor samples from relapsed SCLC patients.

[0015] FIG. 4 demonstrates TROP2 expression in pulmonary hgNECs. FIG. 4A shows TROP2 expression in SCLC and LCNEC patient datasets. FIG. 4B shows TROP2 expression by SCLC subtypes.

[0016] FIG. 5 shows HER2- and TROP2-targeting ADC IC50, and SLFN11 and target expression levels in SCLC cell lines. FIG. 5A shows IC50 of SCLC cell lines treated with HER2 ADC with corresponding SLFN11 status of each cell line (H: high, L:low). FIG. 5B shows the percentage of cells expressing cell surface HER2 measured by flow cytometry in SCLC cell lines. FIG. 5C shows the IC50 of SCLC cell lines treated with a TROP2 ADC with corresponding SLFN11 status. FIG. 5D shows the percentage of cells expressing TROP2 measured by flow in SCLC cell lines. FIG. E shows the percentage of cells expressing surfaceTR0P2 measured by flow when treated with DMSO control versus cisplatin / etoposide (EP) combined.

[0017] FIG. 6 demonstrates ERBB2 (HER2) and SLFN11 gene expression levels in SCLC cell lines of different subtypes (SCLC-A (A), SCLC-N (N), SCLC-P (P) and SCLC-I (TN).

[0018] FIG. 7 shows HER2 expression in the SCLC-P subtype. FIG. 7A shows cell surface expression of HER2 in a panel of SCLC cell lines, including SCLC-P cells, by flow cytometry. SCLC-A (SLF I l-High) cell lines include H1876, DMS53, H209, DMS79, and H2195. SCLC-A (SLFN11-Low) cell lines include H865, H2029, H2196, and H69. SCLC-N cell lines include NJH29, H82, and H524. SCLC-P cell lines include H211, H526, and H1048. SCLC- I cell lines include H841 and SW1271. FIG. 7B shows ERBB2 expression in POU2F3+ SCLC cells in relapsed SCLC patient biopsies, determined by single-cell RNAseq. FIG. 7C shows a comparison of ERBB2 and DLL3 expression in treatment-naive SCLC tumors.

[0019] FIG. 8 shows in vitro and in vivo targeting of SCLC-P cell lines using a HER2 ADC. FIG. 8A shows the sensitivity (IC50) of a panel of SCLC cell lines, including SCLC-P cell lines, to Trastuzumab deruxtecan (HER2 ADC), following 72 h of treatment. FIG. 8B shows the efficacy of Trastuzumab deruxtecan (HER2 ADC) and Trastuzumab (HER2 mAb) on tumor growth inhibition in a SCLC-P, SLFN11-High xenograft model (H1048) in athymic nude mice. FIG. 8C demonstrates that combined treatment of SCLC-P, SLFN11-High cells (H1048) using a DLL3 CAR-T and a HER2 ADC was more effective than single agent alone in treatment resistant cell lines.DETAILED DESCRIPTION OF THE INVENTION

[0020] The present disclosure provides compositions and method for the treatment of P0U2F3-driven cancers. In contrast to non-small cell lung cancer, there are no validated predictive biomarkers for hgNECs, and the treatment is “one-size fits all.” There is an urgent unmet need to develop effective, personalized therapies for the treatment of pulmonary hgNECs and to develop biomarkers to personalized treatment. The present disclosure provides a significant advance in the art by providing such a targeted and mechanism-based approach for treatment of POU2F3-driven cancers.A. Antibodies and Antibody Drug Conjugates

[0021] As used herein the term “antibody-drug conjugate” refers to a composition comprising an antigen binding protein conjugated to a drug. Any drug known in the art may be conjugated to an antigen binding protein of the present disclosure. HER2-targeting antibody drugconjugates, include but are not limited to, fam-trastuzumab-deruxtecan-nxki, ado-trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC. TROP2-targeting antibody drug conjugates, include, but are not limited to sacituzumab govitecan, datopotamab deruxtecan, and YH012. DLL3- targeting antibody drug conjugates include but are not limited to rovalpituzumab tesirine. Non-limiting examples of drugs that may be conjugated to an antigen binding protein of the present disclosure include a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, a chemotherapeutic agent, an immunotherapeutic agent, and a radiotherapeutic agent. In particular embodiments, an antibody-drug conjugate of the present disclosure may comprise a cleavable linker, which conjugates the antigen binding protein to the drug. A variety of cleavable linkers and methods for use in the production of antibody-drug conjugates are known in the art and any such linker or method may be used according to the embodiments of the present disclosure. Non-limiting methods for producing antibody-drug conjugates include those which use a metal chelate complex utilizing, for example, an organic chelating agent such a diethylenetriaminepentaacetic acid anhydride (DTPA); ethylenetriaminetetraacetic acid; N-chloro-p-toluenesulfonamide; or tetrachloro-3a-6a- diphenylglycouril-3, those which use an enzyme and a coupling agent such as glutaraldehyde or periodate, and those which utilize a reaction with an isothiocyanate. Non-limiting examples of linkers with may be used according to certain embodiments of the present disclosure include methyl-p-hydroxybenzimidate and N-succinimidyl-3-(4- hydroxyphenyljpropionate. In particular embodiments, antibody-drug conjugates may be produced by selectively introducing sulfhydryl groups into the Fc region of an immunoglobulin, or by site-specific attachment of effector or reporter molecules to a carbohydrate residue in the Fc region.

[0022] Antibodies and antigen binding fragments are both members of the broader genus that includes all antigen binding proteins. The term “antibody” as used herein refers to an intact immunoglobulin of any isotype or an antibody fragment that can compete with an intact antibody for specific binding to the target antigen. An “antigen binding fragment” as used herein refers to refers to a portion of a protein which is capable of binding specifically to an antigen. The term “antigen binding protein” as used herein refers to any protein that binds a specified target antigen. In some embodiments of the present disclosure the specified target antigen is the HER2 protein or a fragment thereof, the TROP2 protein or a fragment thereof, both the HER2 and TROP2 proteins or fragments thereof, or the DLL3 protein or a fragmentthereof. An antigen binding protein includes but is not limited to antibodies and antigen binding fragments. Antibodies of the present disclosure, may include but are not limited to chimeric, humanized, fully human, and bispecific antibodies. In certain embodiments, the methods of the present disclosure may comprise administering a HER2 / TROP2 bispecific antibody. In one embodiment, the HER2 / TROP2 bispecific antibody is YH012. An intact antibody may comprise, in certain embodiments, two full-length heavy chains and two full- length light chains. In other embodiments, however, an antibody may include fewer chains. For example, antibodies naturally occurring in camelids can comprise only heavy chains. Antibodies can be derived from a single source or may be chimeric. As used herein the term “chimeric antibody” refers to an antibody that comprises portions that are derived from two different antibodies or an antibody variable region derived from one species paired with a constant region from a different species. The antigen binding proteins, antibodies, and binding fragments of the present disclosure may be produced using any technique known in the art. Non-limiting examples of such techniques include production in hybridomas, production by recombinant DNA techniques, and production by enzymatic or chemical cleavage of intact antibodies. An antibody or antigen binding fragment may include, in many embodiments, two full-length heavy chains and two full-length light chains. In some embodiments, an antibody, antigen binding fragment, or an antigen binding protein may include an antibody derivative, an antibody variant, an antibody fragment, or an antibody mutant. Non-limiting examples of antibodies, antigen binding fragments, and antigen binding proteins include monoclonal antibodies, bispecific antibodies, minibodies, domain antibodies, synthetic antibodies, antibody mimetics, chimeric antibodies, humanized antibodies, human antibodies, antibody fusions, antibody conjugates, peptibodies, and fragments thereof.

[0023] In some embodiments, an antigen binding fragment may be derived from an antibody comprising one or more CDRs, or any other antibody fragment that binds to an antigen but does not comprise an intact native antibody structure. In certain embodiments, the antigen binding fragment is not derived from an antibody but rather is derived from a receptor. Examples of antigen binding fragment include but are not limited to a diabody, a Fab, a Fab', a F(ab')2, an Fv fragment, a disulfide stabilized Fv fragment (dsFv), a (dsFv)2, a bispecific dsFv (dsFv-dsFv'), a disulfide stabilized diabody (ds diabody), a single-chain antibody molecule (scFv), an scFv dimer (bivalent diabody), a multispecific antibody, a single domain antibody (sdAb), a camelid antibody or a nanobody, a domain antibody, and a bivalent domain antibody. An antigen binding fragment, in many embodiments, is capable of binding to the same antigento which the parent antibody binds. In particular embodiments, an antigen binding fragment may comprise one or more CDRs from a particular antibody grafted onto a framework region of one or more different antibodies. The antigen binding fragment, in certain embodiments, may be derived from a receptor. In particular embodiments, an antigen binding fragment may comprise one or more amino acid substitutions, additions, deletions, or mutations. In certain embodiments, an antigen binding fragment does may not bind to the natural ligand of the receptor from which the antigen binding fragment is derived. The term “Fab fragment” as used herein refers to an antigen binding protein that comprises one light chain and the CHi and variable regions of one heavy chain. The heavy chain of a Fab molecule cannot form a disulfide bond with another heavy chain molecule. The term “Fab' fragment” as used herein refers to an antigen binding protein that comprises one light chain and a portion of one heavy chain that contains the VH domain and the CHi domain and also the region between the CHi and CH2 domains, such that an interchain disulfide bond may be formed between two heavy chains of two Fab' fragments to form an F(ab')2 molecule. A “F(ab')2 fragment” as used herein refers to an antigen binding protein that comprises two light chains and two heavy chains comprising a portion of the constant region between the CHi and CH2 domains, such that an interchain disulfide bond is formed between the two heavy chains. A F(ab')2 fragment thus comprises two Fab' fragments with a disulfide bond between the two heavy chains.

[0024] A single chain variable fragment (scFv) is a fusion protein produced by the fusion of the variable regions of the heavy and light chains. In certain embodiments, the heavy and light chains are linked using a short linker sequence. In one embodiment, the linker sequence comprises helix-turn-helix promoting amino acid residues. In another embodiment, the linker sequence comprises the amino acids alanine, serine, or glycine. This chimeric molecule retains the antigen specificity, despite removal of the constant regions and the introduction of a linker peptide. Single chain variable fragments may be produced using any method known in the art, including but not limited to phage display and subcloning of heavy and light chains derived from a hybridoma. Single chain variable fragments may be purified or immobilized using any method known in the art, including but not limited to Protein L purification or immobilization.

[0025] A “Fc region” as used herein refers to a portion of an antibody comprising two heavy chain fragments comprising the CHi and CH2 domains of an antibody. The two heavy chain fragments are held together by two or more disulfide bonds and by hydrophobic interactions. The “Fv region” as used herein refers to a portion of an antibody comprising the variable regions from both the heavy chain and the light chain. The Fv region does not comprise theconstant regions of an antibody. A “single-chain antibody” as used herein refers to an Fv molecule in which the heavy and light chain variable regions have been connected by a flexible linker to form a single polypeptide chain that forms an antigen binding region. Single chain antibodies are described in International Patent Application Publication No. WO 88 / 01649, U.S. Pat. No. 4,946,778, and U.S. Pat. No. 5,260,203, the disclosures of which are incorporated by reference. A “domain antibody” as used herein refers to an immunologically functional immunoglobulin fragment containing only the variable region of a heavy chain or the variable region of a light chain. In some embodiments, a domain antibody may comprise two or more VH regions which are covalently joined with a peptide linker to create a bivalent domain antibody. In certain embodiments, the two VH regions of a bivalent domain antibody can target the same or different antigens.

[0026] Naturally occurring antibodies are usually produced as a tetramer. Each tetramer typically comprises two identical pairs of polypeptide chains, each pair comprising one full- length light chain and one full-length heavy chain. In some embodiments, the light chain of an antibody is about 25 kDa in size, and the heavy chain of an antibody is about 50-70 kDa in size. The amino-terminal portion of each chain typically includes an antigen binding variable region of about 100 to 110 amino acids that is responsible for antigen specific binding. The carboxy-terminal portion of each chain typically includes a constant region that may be responsible for effector function. In some embodiments, light chains may be classified as kappa light chains or lambda light chains. Heavy chains, in particular embodiments, may be classified as mu, delta, gamma, alpha, or epsilon. Heavy chain classification, in many embodiments, defines isotype of the antibody as IgM, IgD, IgG, IgA, or IgE. The IgG isotype has several subclasses, including, but not limited to, IgGl, IgG2, IgG3, and IgG4. The IgM isotype has subclasses including, but not limited to, IgMl and IgM2. The IgA isotype is similarly subdivided into subclasses including, but not limited to, IgAl and IgA2. In many embodiments, the variable and constant regions of a full-length heavy chain and the variable and constant regions of a full-length light chain are joined by a “J” region of about 12 or more amino acids. In certain embodiments, the variable regions and the constant regions of a heavy chain may also be joined by a “D” region of about 10 more amino acids in addition to the “J” region. See, e.g., Fundamental Immunology, Ch.7 (Paul, W., ed., 2nd ed. Raven Press, N.Y. 1989) (incorporated herein by reference). The variable regions of each light / heavy chain pair typically form the antigen binding site of any antibody or antigen binding fragment.

[0027] The term “variable region” or “variable domain” as used herein refers the variable portion of the heavy and / or light chain of an antibody, antigen binding fragment, or antigen binding protein. In some embodiments, the variable region may include about 120 to about 130 amino-terminal amino acids of the heavy chain and about 100 to 110 amino- terminal amino acids of the light chain. The variable region of different antibodies, antigen binding fragments, or antigen binding proteins, in particular embodiments, may differ extensively in amino acid sequence, even when the different antibodies are of the same species. The variable region of an antibody, antigen binding fragment, or antigen binding protein typically determines antigen binding specificity. The variable regions of an antibody, antigen binding fragment, or antigen binding protein may, in a number of embodiments, exhibit the same general structure of relatively conserved framework regions (FR) joined by three hyper variable regions, also called complementarity determining regions or CDRs. The CDRs from the light chain and the heavy chain, in particular embodiments, are aligned by the framework regions, allowing for epitope specific binding. From N-terminal to C-terminal, both light and heavy chain variable regions may comprise the domains FR1, CDR1, FR2, CDR2, FR3, CDR3, and FR4. The assignment of amino acids to each domain is typically in accordance with the definitions of Kabat Sequences of Proteins of Immunological Interest (National Institutes of Health, Bethesda, Md. (1987 and 1991)), Chothia & Lesk, J. Mol. Biol., 196:901-917 (1987) or Chothia et al., Nature, 342:878-883 (1989).

[0028] In certain embodiments, an antibody heavy chain may specifically bind to an antigen in the absence of an antibody light chain. In some embodiments, an antibody light chain may specifically bind to an antigen in the absence of an antibody heavy chain. An antibody binding region, in particular embodiments, may specifically bind to an antigen in the absence of an antibody light chain. In certain embodiments, an antibody binding region may specifically bind to an antigen in the absence of an antibody heavy chain. An individual variable region, in some embodiments, specifically binds to an antigen in the absence of other variable regions.

[0029] In certain embodiments, definitive delineation of a CDR and identification of residues comprising the binding site of an antibody is accomplished by solving the structure of the antibody and / or solving the structure of the antibody-ligand complex. This can be accomplished, in some embodiments, by any of a variety of techniques known to those skilled in the art, such as X-ray crystallography. In particular embodiments, various methods of analysis can be employed to identify or approximate the CDR regions. Examples of such methods include, but are not limited to, the Kabat definition, the Chothia definition, the AbMdefinition, IMGT definition, and the contact definition. The Kabat definition is a standard for numbering the residues in an antibody and is typically used to identify CDR regions. See, e.g., Johnson & Wu, Nucleic Acids Res., 28: 214-8 (2000). The Chothia definition is similar to the Kabat definition, but the Chothia definition considers positions of certain structural loop regions. See, e.g., Chothia et al., J. Mol. Biol., 196: 901-17 (1986); Chothia et al., Nature, 342: 877-83 (1989). The AbM definition uses an integrated suite of computer programs produced by Oxford Molecular Group that model antibody structure. See, e.g., Martin et al., Proc Natl Acad Sci (USA), 86:9268-9272 (1989); “AbM™, A Computer Program for Modeling Variable Regions of Antibodies,” Oxford, UK; Oxford Molecular, Ltd. The AbM definition models the tertiary structure of an antibody from primary sequence using a combination of knowledge databases and other methods, such as those described by Samudrala et al., “Ab Initio Protein Structure Prediction Using a Combined Hierarchical Approach,” in PROTEINS, Structure, Function and Genetics Suppl., 3:194-198 (1999). The contact definition is based on an analysis of the available complex crystal structures. See, e.g., MacCallum et al., J. Mol. Biol., 5:732- 45 (1996). The IMGT definition uses a unique numbering system that combines the definition of framework (FR) and CDR regions, structural data from X-ray diffraction studies, and the characterization of the hypervariable loops, as described in by Lefranc M-P et al., “IMGT unique numbering for immunoglobulin and T cell receptor variable domains and Ig superfamily V-like domains,” Dev Comp Immunol 27:55-77 (2003). In one embodiment, the CDR sequences are based on IMGT definition. In some embodiments, the CDR regions in the heavy chain are typically referred to as Hl, H2, and H3 and are numbered sequentially in the direction from the amino terminus to the carboxy terminus. In particular embodiments, the CDR regions in the light chain are typically referred to as LI, L2, and L3 and are numbered sequentially in the direction from the amino terminus to the carboxy terminus. In the present disclosure, the CDR regions of the light chain variable region are also designated as LC-CDR 1 , LC-CDR2, and LC- CDR3, and the CDR regions of the heavy chain variable region are designated as HC-CDR1, HC-CDR2, and HC-CDR3.

[0030] The term “light chain” as used herein refers to a full-length light chain and fragments thereof having sufficient variable region sequence to confer binding specificity. A full-length light chain includes a variable region domain, VL, and a constant region domain, CL. The variable region domain of the light chain, in many embodiments, is located at the aminoterminus of the polypeptide. Non-limiting examples of light chains include kappa chains and lambda chains. The term “heavy chain” as used herein refers to a full-length heavy chain andfragments thereof having sufficient variable region sequence to confer binding specificity. A full-length heavy chain includes a variable region domain, VH, and three constant region domains, CHi, CH2, and CH3. The VH domain, in a number of embodiments, is located at the amino terminus of the polypeptide. In many embodiments, the CH domains are located at the carboxyl-terminus, with the CH3 being closest to the carboxy-terminus of the polypeptide. Heavy chains can be of any isotype, including IgG (including IgGl, IgG2, IgG3 and IgG4 subtypes), IgA (including IgAl and lgA2 subtypes), IgM and IgE.

[0031] The term “bispecific antigen binding protein” as used herein refers to a molecule with two antigen binding domains, which may bind the same antigen or may bind different antigens. In some embodiments, the two binding sites of a bispecific antigen binding protein or antibody may bind to two different epitopes, which can reside on the same or different protein targets. Bispecific antibodies can be produced by a variety of methods including, but not limited to, fusion of hybridomas or linking of Fab " fragments. See, e.g., Songsivilai et al., Clin. Exp. Immunol., 79: 315-321 (1990); Kostelny et al., J. Immunol., 148:1547-1553 (1992). A “bivalent antigen binding protein” or “bivalent antibody” as used herein refers to an antigen binding protein comprising two antigen binding sites. In certain embodiments, the two binding sites of a bivalent antigen binding protein have the same antigen specificity. In particular embodiments, bivalent antigen binding proteins and bivalent antibodies can be bispecific.

[0032] The phrase “specifically (or selectively) binds” or “specifically (or selectively) immunoreactive with,” when referring to a protein or peptide, refers to a binding reaction that is determinative of the presence of the protein or complex, often in a heterogeneous population of proteins or complexes. For example, the antigen binding proteins of the present disclosure may specifically bind HER2, TROP2, or both HER2 and TROP2, as is the case with bispecific antibody YH012. HER2 and TROP2 specific antigen binding proteins are known in the art and any such antigen binding protein may be used according to the methods of the present disclosure. Non-limiting examples of antigen binding proteins that specifically bind HER2 include trastuzumab, pertuzumab, and margetuximab. Non-limiting examples of antigen binding proteins that specifically bind TROP2 include sacituzumab and datopotamab. Thus, under typical immunoassay conditions, a specified antigen binding protein may bind to a particular protein or complex at least two times the background. In specific embodiments, a specified antigen binding protein may bind a particular protein or complex at least 2, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, 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, atleast 95, or at least 100 times background, including any range derivable therebetween. Specific binding to an antigen binding protein under such conditions requires an antigen binding protein that is selected by virtue of its specificity for a particular protein or complex. A variety of assay formats known in the art may be used to select antigen binding protein specifically immunoreactive with a particular protein or complex and any such assay may be used to select an antigen binding protein of the present disclosure. The antigen binding protein of the present disclosure may specifically bind, in particular embodiments, to HER2 or TROP2. In one embodiment, the antigen binding protein of the present disclosure may specifically bind HER2, TROP2, or DLL3. In another embodiment, the antigen binding protein of the present disclosure may specifically bind HER2, DLL3, or TROP2 and block HER2, TROP2, or DLL3 from engaging with HER2, TROP2, or DLL3 ligands. In some embodiments, an antigen binding protein of the present disclosure may cross-react with a small number of highly similar antigens. The term “compete” as used herein in the context of antigen binding proteins that compete for the same epitope refers to the competition between antigen binding proteins as determined by an assay in which the antigen binding protein being tested prevents or reduces specific binding of a reference antigen binding protein to a common antigen. Numerous types of competitive binding assays can be used to determine if one antigen binding protein competes with another, for example: solid phase direct or indirect radioimmunoassay (RIA), solid phase direct or indirect enzyme immunoassay (EIA), sandwich competition assay (see, e.g., Stahli et al., 1983, Methods in Enzymology 9:242-253); solid phase direct biotin-avidin EIA (see, e.g., Kirkland et al., 1986, 1. Immunol.l37:3614-3619) solid phase direct labeled assay, solid phase direct labeled sandwich assay (see, e.g., Harlow and Lane, 1988, Antibodies, A Laboratory Manual, Cold Spring Harbor Press); solid phase direct label RIA using 1-125 label (see, e.g., Morel et al., 1988, Molec. Immunol.25:7-15); solid phase direct biotin-avidin EIA (see, e.g., Cheung, et al., 1990, Virology 176:546-552); and direct labeled RIA (Moldenhauer et al., 1990, Scand. J. Immunol.32:77-82). In certain embodiments, antigen binding proteins identified by a competition assay (competing antigen binding proteins) include antigen binding proteins that bind to the same epitope as the reference antigen binding protein, and antigen binding proteins binding to an adjacent epitope sufficiently proximal to the epitope bound by the reference antigen binding protein for steric hindrance to occur. In particular embodiments, when a competing antigen binding protein is present in excess, the competing antigen binding protein will reduce specific binding of a reference antigen binding protein to a common antigen by at least about 40% to about 45%, about 45% to about 50%, about 50% to about 55%, about 55% to about 60%, about 60% to about 65%, about 65% to about 70%, about 70% to about 75%,about 75% to about 85%, about 80% to about 85%, about 85% to about 90%, about 90% to about 95%, or about 95% to about 99%, including all ranges derivable therebetween.

[0033] “Binding affinity” as used herein refers to the strength of the sum total of non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding partner (e.g., an antigen). In some embodiments, the term binding affinity may refer to the intrinsic binding affinity reflecting a 1: 1 interaction between members of a binding pair (e.g., antibody and antigen). The affinity of a molecule X for its partner Y can generally be represented by the dissociation constant (Kd). Binding affinity can be measured by any number of common methods known in the art, and any such method may be used according to the embodiments of the present disclosure. Low-affinity antibodies generally bind antigen slowly and tend to dissociate readily, whereas high-affinity antibodies generally bind antigen faster and tend to remain bound longer.

[0034] The term “antigen” as used herein refers to a substance capable of inducing an adaptive immune response. Antigen binding proteins associated with an adaptive immune response specifically bind to their target antigen. In some embodiments, an antigen may be a molecule that binds to antigen- specific receptors but cannot induce an immune response alone. Nonlimiting examples of antigens include proteins, polysaccharides, and lipids. Antigens, in particular embodiments, may include but are not limited to parts of bacteria (coats, capsules, cell walls, flagella, fimbria, and toxins), viruses, and other microorganisms. In some embodiments, antigens also include tumor antigens that antigens generated by mutations in tumors. Antigens may also include immunogens and haptens.

[0035] The term “epitope” as used herein refers to the specific group of atoms or amino acids of an antigen to which an antigen binding protein specifically binds. In some embodiments, an epitope may be a linear epitope or a conformational epitope. A linear epitope, in particular embodiments, may be formed by a continuous sequence of amino acids of the antigen. A conformational epitope, in certain embodiments, may be comprised of discontinuous sections of the amino acid sequence of an antigen. A linear epitope many interact with an antigen binding protein, in particular embodiments, based on primary structure. A conformational epitope may interact with an antigen binding protein, in certain embodiments, based on the 3D structure of the antigen. An epitope, in some embodiments, may be about 3 to about 10, about 4 to about 9, about 4 to about 8, about 4 to about 7, or about 5 to about 6 amino acids in length, including all ranges derivable therebetween. In particular embodiments, two antigen binding proteins may bind the same epitope if they exhibit competitive binding for the antigen.

[0036] The term “chimeric antigen receptor” or “CAR” as used herein refers to an artificially constructed hybrid protein or polypeptide containing an antigen binding protein linked to a domain that activates an immune cell. In certain embodiments, a chimeric antigen reception may comprise a single chain variable fragment (scFv)) and a T-cell signaling, T-cell activation, or NK cell activation domain (see, e.g., Kershaw et al., supra, Eshhar et al., Proc. Natl. Acad. Sci. USA, 90(2): 720-724 (1993), and Sadelain et al., Curr. Opin. Immunol. 21(2): 215-223 (2009)). CARs are capable of directing an immune response against a selected target in a non- MHC-restricted manner. In other embodiments, a CAR may comprise a TCRa chain-derived and / or a TCRP chain-derived antigen binding variable region. See, for example, Oh, et al., Sci Rep. 9: 17291, 2019. In certain embodiments, a CAR may comprise an antigen binding variable region fused to a CD3^ transmembrane and intracellular signaling domain, an antigen binding variable region fused to a CD28 transmembrane region with CD28 and CD3c intracellular signaling domains, or an antigen binding variable region fused to a CD28 transmembrane region with CD28, 4-1BB, and CD3^ intracellular signaling domains. In many embodiments, a CAR may be a first generation, second generation, third generation, or any generation CAR. Non-limiting examples of a CAR-T cell targeting DLL3 is AMG 119.

[0037] The term "isolated " as used herein in reference to, for example, an antibody, antigen binding fragment, an antigen binding protein, a polypeptide, or polynucleotide molecule, refers to a molecule that is not associated with naturally associated components that accompany the molecule in its native state. In some embodiments, an isolated molecule is substantially free of other molecules from the same species, is expressed by a cell from a different species, or is expressed by a different cell type that the cell type in which it is expressed in nature. A molecule that is chemically synthesized or that is expressed in a cellular system different from the cell from which it naturally originates, will be isolated from its naturally associated components. A molecule, in certain embodiments, may also be rendered substantially free of naturally associated components by isolation, using purification techniques well known in the art. Molecule purity or homogeneity may be assayed by a number of means well known in the art. For example, the purity of a polypeptide sample may be assayed using polyacrylamide gel electrophoresis and staining of the gel to visualize the polypeptide using techniques well known in the art. For certain purposes, higher resolution may be provided by using HPLC or other means well known in the art for purification.

[0038] The terms “linked” or “conjugated” as used herein refer to the association of one molecule with another molecule through intramolecular interactions or intermolecularinteractions. Non- limiting example of such intramolecular interactions include covalent bonds, metallic bonds, and ionic bonds. Non-limiting examples of intermolecular interactions include hydrogen bonds and nonco valent bonds.

[0039] The present disclosure further provides engineered antigen binding proteins, which comprise one or more HC-CDRs or LC-CDRS of the disclosure. As used herein the term “engineered” when used in reference to an antibody, antigen binding fragment, or antigen binding protein refers to an antibody, antigen binding fragment, or antigen binding protein which comprises a recombinant protein or is encoded by a recombinant polynucleotide molecule of the present disclosure. In some embodiments, an engineered antigen binding protein may comprise a chimeric polypeptide comprising an antigen binding fragment of the present disclosure and a heterologous antibody constant region. In particular embodiments, the LC-CDRs and the HC-CDRs of the present disclosure are used with framework region sequences from a different mammalian species, for example a primate. The framework sequences, in certain embodiments may be humanized or human framework sequences, which may be used to create an antibody that specifically binds HER2, TROP2, or DLL3. In some embodiments, the light chain variable region comprises four light chain framework regions, designated as FRLCI, FRLC2, FRLC3, and FRLC4. The LC-CDRs of the present disclosure may be organized, in particular embodiments, as follows from the NH2 to the COOH direction: FRLC1-LC-CDR1-FRLC2-LC-CDR2-FRLC3,-LC-CDR3-FRLC4. In certain embodiments, the heavy chain variable region comprises four heavy chain framework regions, designated as FRHCI, FRHC2, FRHC3, and FRHC4. The HC-CDRs of the present disclosure may be organized, in certain embodiments, as follows from the NH2 to the COOH direction: FRucl-HC-CDRl- FRHC2-HC-CDR2-FRHC3-HC-CDR3-FRHC4. In some embodiments, the framework regions of a parent light chain variable region may be replaced with framework regions of human light chain variable regions to form humanized light chain variable regions. In particular embodiments, the framework regions of a parent heavy chain variable region may be replaced with framework regions of human heavy chain variable regions to form humanized heavy chain variable regions.

[0040] The engineered antigen binding proteins of the present disclosure may, in certain embodiments, specifically bind to the proteins and complexes described herein. The engineered antigen binding proteins of the present disclosure may specifically bind, in particular embodiments, a HER2, TROP2, or DLL3. In one embodiment, the engineered antigen binding proteins of the present disclosure may specifically mouse HER2, TROP2, orDLL3 or human HER2, TROP2, or DLL3. In another embodiment, the antigen binding proteins of the present disclosure may specifically bind HER2, TROP2, or DLL3 and block HER2, TROP2, or DLL3 from engaging with HER2, TROP2, or DLL3 ligands. In some embodiments, the engineered antigen binding proteins of the present disclosure may crossreact with a small number of highly similar antigens. In some embodiments, the polynucleotide or protein sequences of the engineered antigen binding proteins of the present disclosure may comprise heterologous sequences that are used for cloning, enhanced expression, detection, secretion, or for therapeutic control of the recombinant polynucleotide molecule or protein that are not present in endogenous antigen binding proteins. Non-limiting examples of such heterologous sequences include, multiple cloning sites, linkers, hinge sequences, modified hinge sequences, modified transmembrane sequences, a polynucleotide or protein molecule used for detection, or therapeutic controls that allow for selection or screening of cells comprising the antigen binding protein. In some aspects of the present disclosure, the engineered antigen binding protein may comprise non-antibody sequences. Accordingly, certain aspects of the present disclosure relate to engineered antigen binding proteins comprising sequences that are not naturally found in antibodies. In certain embodiments, the engineered antigen binding protein is chimeric, and thus comprises, for example, sequences which are found normally found or encoded by an antibody gene.

[0041] In some aspects, a cell specifically recognized by an antigen binding protein of the present disclosure may be any cell which expresses HER2, TROP2, or DLL3. In one embodiment, the cell is a cancer cell. In another embodiment, the cell may be a SCLC or LCNEC cancer cell.B. T cells and T cell receptors

[0042] T cell receptors comprise two different polypeptide chains, termed the T cell receptor a (TCRa) and P (TCR ) chains, linked by a disulfide bond. Each TCRa and TCRP chain comprises a variable antigen binding region, and the structure of these chains is similar to that of a Fab fragment of an immunoglobulin molecule. The TCRa and TCRP chains are responsible for the antigen recognition demonstrated by most T cells, although a minority of T cells instead comprise an alternative but structurally similar TCR, which comprises a pair of polypeptide chains designated TCRy and TCRS. TCRa and TCRyS receptors differ from membrane-bound immunoglobulins that serve as B-cell receptors in the following ways: 1) TCRs have only one antigen binding site, whereas immunoglobulins have two; and 2) TCRs are never secreted, whereas immunoglobulins may be secreted as an antibody.

[0043] Both chains of a TCR comprise an amino-terminal variable (V) region, a constant (C) region, and a short hinge region containing a cysteine residue that forms the interchain disulfide bond. The TCR V region shares homology with the immunoglobulin V domain, and the TCR C region shares homology with the immunoglobulin C domain. Each TCR chain comprises a hydrophobic transmembrane domain that spans the lipid bilayer and ends in a short cytoplasmic tail. In some embodiments, a TCR of the present disclosure may be a single chain TCR. Methods for producing single chain TCRs are known in the art and any such method may be used according to the embodiments of the present disclosure. Non-limiting examples of single chain TCRs are described in Knies, et al. , Oncotarget 7(16): 21199-21221 and U.S. 10,538,573.

[0044] The three-dimensional structure of the TCR has been determined. The TCR chains fold in a manner similar to a Fab fragment, although the final 3D structure appears a little shorter and wider. There are, however, some distinct differences between TCRs and Fab fragments. The most striking difference is in the Ca domain, which folds differently than any other immunoglobulin-like domain. The half of the domain that is juxtaposed with the CP domain forms a sheet similar to that found in other immunoglobulin-like domains, but the other half of the domain is formed of loosely packed strands and a short segment of a helix. The intramolecular disulfide bond of the Ca domain joins a P strand to this segment of a helix, however, in most immunoglobulin-like domains the intramolecular disulfide bond joins two P strands.

[0045] There are also differences in domain interaction between TCRs and immunoglobulins. The interface between the V and C domains of both TCR chains is more extensive than that demonstrated by antibodies, which may decrease the flexibility of the hinge region between the TCR domains. Furthermore, the interaction between the Ca and CP domains is distinct in that it is assisted by carbohydrate, with a sugar group from the Ca domain making a number of hydrogen bonds to the CP domain. Finally, a comparison of the variable binding sites shows that, although the complementarity-determining region (CDR) loops align fairly closely with those of antibody molecules, there is some displacement. This displacement is particularly prevalent in the Va CDR2 loop, which is oriented at roughly a right angle compared to the equivalent loop of an antibody V domain. This displacement is a result of a shift in the P strand that anchors one end of the loop from one face of the domain to the other. A strand displacement also causes a change in the orientation of the V CDR2 loop in two of the seven VP domains for which structures are known.

[0046] As used herein the term “antigen binding variable region” refers to the region of a TCR chain which binds a pMHC. The antigen binding region of a TCR may comprise, in some embodiments, one, two, three, or four hypervariable complementarity-determining regions (CDRs). These CDRs form a binding site that specifically bind to a pMHC. The antigen binding variable region may comprise, for example, a CDR1 region, a CDR2 region, a CDR3 region, and / or a CDR4 region. The CDR3 region is particularly important for TCR-peptide binding. The phrase “specifically (or selectively) binds” or “specifically (or selectively) immunoreactive with,” when referring to a protein or peptide, refers to a binding reaction that is determinative of the presence of the protein or complex, often in a heterogeneous population of proteins or complexes. Thus, under typical immunoassay conditions, a specified antigen binding variable region may bind to a particular protein or complex at least two times the background. In specific embodiments, a specified antigen binding variable region may bind a particular protein or complex at least 2, at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, 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 100 times background, including any range derivable therebetween. Specific binding to an antigen binding variable region under such conditions requires an antigen binding variable region that is selected by virtue of its specificity for a particular protein or complex. A variety of assay formats known in the art may be used to select antigen binding variable regions specifically immunoreactive with a particular protein or complex and any such assay may be used to select an antigen binding variable region of the present disclosure. The antigen binding variable region of the present disclosure may specifically bind, in particular embodiments, a pMHC comprising a peptide derived from DLL3. In some embodiments, an antigen variable binding region of the present disclosure may cross-react with a small number of highly similar pMHCs.

[0047] As used herein, the term “recombinant” refers to a polynucleotide molecule, protein, or cell that is not naturally present, or is not naturally present in the same form or structure and was created by human intervention. In one embodiment, a recombinant polynucleotide may be a DNA molecule or may be an RNA molecule. A recombinant polynucleotide molecule or a recombinant polypeptide molecule or protein may comprise, in certain embodiments, a combination of two or more polynucleotide or polypeptide sequences that do not naturally occur together in the same manner, such as a polynucleotide molecule or protein that comprises at least two polynucleotide or protein sequences that are operably linked but heterologous with respect to each other. As used herein the term “heterologous” refers to a polynucleotidemolecule or protein that is not naturally present or is not naturally present in the same form or structure and was created by human intervention. For example, a heterologous polynucleotide molecule or protein may not naturally occur in the cell being transformed or may be expressed in a manner or genomic context that differs from the natural expression pattern or genomic context found in the cell being transformed. The heterologous polynucleotide molecule or protein, in some embodiments, may be overexpressed in the cell being transformed. In certain embodiments, a recombinant polynucleotide molecule, protein, construct, or vector may comprise any combination of two or more polynucleotide or protein sequences in the same molecule which are heterologous to one another, such that the combination is man-made and not normally found in nature. As used herein, the phrase “not normally found in nature” means not found in nature without human intervention. A recombinant polynucleotide or protein molecule, may comprise, for example, polynucleotide or protein sequences that are separated from other polynucleotide or protein sequences that exist in proximity to each other in nature. A recombinant polynucleotide or protein molecule may also comprise, for example, polynucleotide or protein sequences that are adjacent to or contiguous with other polynucleotide or protein sequences that are not naturally in proximity with each other. Such a recombinant polynucleotide molecule, protein, or expression construct may also refer to a polynucleotide or protein molecule or sequence that has been genetically engineered or constructed outside of a cell. For example, a recombinant polynucleotide molecule may comprise any engineered or man-made plasmid, vector, or expression construct, and may include a linear or circular DNA molecule. Such plasmids, vectors, and expression constructs may comprise, for example, various maintenance elements including, but not limited to, a heterologous promoter sequence, a prokaryotic origin of replication, or a selectable marker.

[0048] The present disclosure further provides engineered TCRs which comprise an antigen binding variable region of the present disclosure. As used herein the term “engineered TCR” refers to a TCR which comprises a recombinant polynucleotide molecule or a recombinant protein of the present disclosure. In some embodiments, an engineered TCR may comprise a chimeric polypeptide comprising an antigen binding variable region of the present disclosure and a heterologous TCR constant region. The engineered TCRs of the present disclosure may, in certain embodiments, specifically bind to the proteins and complexes described herein. The engineered TCRs of the present disclosure may specifically bind, in particular embodiments, a pMHC comprising a peptide derived from DLL3. In some embodiments, the engineered TCRs of the present disclosure may cross-react with a small number of highly similar pMHCs. Insome embodiments, the polynucleotide or protein sequences of the engineered TCRs of the present disclosure may comprise heterologous sequences that are used for cloning, enhanced expression, detection, or for therapeutic control of the recombinant polynucleotide molecule or that are not present in endogenous TCRs. Non-limiting examples of such heterologous sequences include, multiple cloning sites, linkers, hinge sequences, modified hinge sequences, modified transmembrane sequences, a polynucleotide or protein molecule used for detection, or therapeutic controls that allow for selection or screening of cells comprising the TCR. In some aspects of the present disclosure, the engineered TCR may comprise non-TCR sequences. Accordingly, certain aspects of the present disclosure relate to engineered TCRs comprising sequences that are not naturally found in TCRs. In certain embodiments, the engineered TCR is chimeric, and thus comprises, for example, sequences which are found normally found or encoded by a TCR gene.

[0049] In certain aspects, the present disclosure provides a bi-specific T cell engager (BiTE) or a trispecific T cell engager comprising a TCR of the disclosure or antigen-binding fragment thereof. In some embodiments, a BiTE or TCR of the present disclosure is capable of binding epitopes derived from DLL3. Non- limiting examples of DLL3-targed BiTEs and tri-specific T cell engagers include tarlatamab, BI-764532, and HPN328. As used herein, the term "Bispecific T cell engager" or "BiTE" refers to a class of artificial bispecific monoclonal antibodies that have been investigated for use as anti-cancer drugs. BiTEs direct the host’s immune system, or more specifically the host’s T cells, to attack cancer cells. BiTEs are fusion proteins that may comprise, for example, two single-chain antigen binding variable fragments (scFvs) of different antibodies or TCRs, or amino acid sequences from four different genes, on a single peptide chain of about 55 kilodaltons. In certain embodiments, one of the scFvs may bind to T cells through the CD3 receptor, and the other scFv may bind to a tumor cell through a tumor specific molecule. Unlike monospecific antibodies, BiTEs form a link between T cells and tumor cells through their specificity for an antigen on the T cell and an antigen on the tumor cell. This link results in a cytotoxic T cell response against tumor cells and leads to the production of proteins such as perforin and granzymes, independent of the presence of MHC I or co- stimulatory molecules. These produced proteins enter tumor cells and initiate apoptosis, mimicking the physiological processes observed during T cell-mediated responses against tumor cells. BiTE is a registered trademark of Micromet AG (a fully owned subsidiary of Amgen Inc).

[0050] In some aspects, a BiTE may comprise an antigen binding variable region, an antibody, or an antigen binding fragment that targets an antigen or a targeted epitope of interest expressed on the surface of a cell, such as a cancer cell, and also comprise an antigen binding variable region, an antibody, or an antigen binding fragment that specifically binds a CD3 coreceptor of a T cell. In some aspects a BiTE of the present disclosure is capable of activating antigen specific T cells, which kill target cancer cells expressing a particular epitope of interest. In one embodiment, a BiTE of the present disclosure activates T cells that specifically bind an antigenic peptide derived from DLL3. In some aspects, a BiTE of the present disclosure may be specific for at least one surface antigen on a T cell of interest. Non-limiting examples of such T cell surface antigens include CD3, CD2, VLA-1, CD8, CD4, CCR6, CXCR5, CD25, CD31, CD45RO, CD 197, CD 127, CD38, CD27, CD 196, CD277 and CXCR3. In particular embodiments, a BiTE may comprise (i) an antigen binding region specific for a T cell surface antigen, such as CD3, and (ii) an antigen binding region specific for an antigenic peptide derived from DLL3. In one embodiment, the T cell surface antigen may be selected from the group consisting of CD3 delta, CD3 epsilon, and CD3 gamma. In certain aspects, an immune cell engager of the present disclosure, such as T cell engager, may be arranged in the format VLl-linkerl-VHl-linkerl-VH2-linker3-VL2.C. Topoisomerase Inhibitors

[0051] Topoisomerase inhibitors are chemical compounds that block the action of topoisomerases. Topoisomerase are divided into two subclasses: type I topoisomerases (Topi) and type II topoisomerases (TopII). Topoisomerases mediate the cleavage of single and double stranded DNA to relax supercoils, untangle catenanes, and condense chromosomes in eukaryotic cells and thus play important roles in cellular reproduction and DNA organization. Topoisomerase inhibitors interrupt these processes, which can lead to cell apoptosis, making them valuable therapeutics for cancer.

[0052] Test samples or assays comprising topoisomerase I or topoisomerase II that are treated with a potential inhibitor may be compared to a control sample lacking the inhibitor in order to determine the extent of inhibition. Control samples to which a test sample or assay is compared may be assigned a relative protein activity value of 100%. Inhibition of topoisomerase I or topoisomerase II is achieved when the activity value of the test sample relative to the control sample is less than about 80%, including less than about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 45%, about 40%, about 35%, about30%, about 25%, about 20%, about 15%, about 10%, about 5%, and about 1%, including all ranges and values derivable therebetween.

[0053] Any test or assay known in the art may be used to detect or measure topoisomerase activity. Non-limiting examples of which include the in vivo Complex of Enzyme (ICE) assay and the topoisomerase I and topoisomerase II activity assays described in Nitiss et al., Curr Protoc Pharmacol. 2012.

[0054] Any topoisomerase inhibitor may be used according to the embodiments of the present disclosure. Exemplary topoisomerase inhibitors include, but are not limited to, deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin.D. DNA Alkylating Agents

[0055] DNA alkylating agents transfer alkyl groups to DNA, often resulting in cross-linking of DNA strands. DNA alkylation can result in cell death, making DNA alkylating agents a valuable therapeutic strategy for cancer therapy.

[0056] Test samples or assays that are treated with a potential DNA alkylating agent may be compared to a control sample lacking the DNA alkylating agent in order to determine the extent of alkylation. Control samples to which a test sample or assay is compared may be assigned a relative alkylation value of 0%. DNA alkylation is achieved when the alkylation value of the test sample relative to the control sample is greater than about 20%, including greater than about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, and about 99%, including all ranges and values derivable therebetween.

[0057] Any test or assay known in the art may be used to detect or measure DNA alkylation. Non-limiting examples of which include high performance liquid chromatography (HPLC), a modified comet assay comprising the digestion of alkylated DNA bases with 3-methyladenine DNA glycosylase followed by the standard comet assay to detect where alkyl adducts occur, and assays to analyze structure-activity relationships known in the art.

[0058] Any DNA alkylating agent may be used according to the embodiments of the present disclosure. Exemplary Examples of DNA alkylating agents include, but are not limited to, a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide,mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin.E. Tubulin Targeting Agents

[0059] Tubulin targeting agents bind soluble and / or polymerized tubulin in the microtubules, modulate microtubule dynamics, and inhibit cell proliferation. Tubulin targeting agents promote cell death, making them a valuable therapeutic strategy for cancer.

[0060] Test samples or assays that are treated with a potential tubulin targeting agent may be compared to a control sample lacking the tubulin targeting agent in order to determine the extent of activity. Control samples to which a test sample or assay is compared may be assigned a relative tubulin binding value of 0%. Tubulin binding is achieved when the tubulin binding value of the test sample relative to the control sample is greater than about 20%, including greater than about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, and about 99%, including all ranges and values derivable therebetween. Control samples to which a test sample or assay is compared may also be assigned a relative cytotoxicity value of 0%. Tubulin inhibitory activity is achieved when the cytotoxicity value of the test sample relative to the control sample is greater than about 20%, including greater than about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, and about 99%, including all ranges and values derivable therebetween.

[0061] Any test or assay known in the art may be used to detect or measure the activity of a tubulin targeting agent. Non-limiting examples of which include binding assays, competition assays with known tubulin targeting agents, affinity measurement, spectrometric analysis of the kinetic of tubulin assembly, tracking the growth of individual microtubules reconstituted in vitro using time-lapse fluorescence microscopy, immunofluorescence analysis of the microtubule network, FACS analysis of cell cycle, and cytotoxicity assays known in the art.

[0062] Any tubulin targeting agent known in the art may be used according to the embodiments of the present disclosure. Non-limiting examples of which include a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate,monomethyl auristatin E, auristatin F-hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM1.F. Immune Stimulants

[0063] Cells of the immune system can inhibit tumor growth and progression through the recognition and rejection of malignant cells. Immune stimulants promote the activation of specific and / or non-specific immune cells, and thus are a promising therapeutic strategy for cancer therapy.

[0064] Test samples or assays that are treated with a potential immune stimulant may be compared to a control sample lacking the immune stimulant in order to determine the extent of activity. Control samples to which a test sample or assay is compared may be assigned a relative immune activity value of 0%. Immune stimulation is achieved when the immune activity value of the test sample relative to the control sample is greater than about 20%, including greater than about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, and about 99%, including all ranges and values derivable therebetween.

[0065] Any test or assay known in the art may be used to detect or measure the activity of an immune stimulant. Non-limiting examples of which include the measurement of cytokine levels using protein or mRNA based assays known in the art including RT-PCR and ELISA, tumor cell cytotoxicity assays following incubation with immune cells stimulated with the immune stimulant, measurement of immunoglobulin levels in serum from a subject, measurement of B-cell responses, and measurement of T-cell responses.

[0066] Any immune stimulant known in the art may be used according to the embodiments of the present disclosure. Non-limiting examples of which include a toll-like receptor TLR 7 / 8 agonist, a pattern recognition receptor (PRR) agonist, an interferon, an interleukin, a colonystimulating factor, and a T-cell engager.

[0067] As used herein, the term "Bi-specific T-cell engager" or "BiTE" refers to a class of artificial bispecific monoclonal antibodies that have been investigated for use as anti-cancer drugs. BiTEs direct the host’s immune system, or more specifically the host’s T-cells, to attack cancer cells. BiTEs are fusion proteins that may comprise, for example, two single-chain antigen binding variable fragments (scFvs) of different antibodies, or amino acid sequences from four different genes, on a single peptide chain of about 55 kilodaltons. In certain embodiments, one of the scFvs may bind to T-cells through the CD3 receptor, and the otherscFv may bind to a tumor cell through a tumor specific molecule, such as through an antibody or antigen binding fragment thereof that binds HER2, TROP2, or both HER2 and TR0P2. Unlike monospecific antibodies, BiTEs form a link between T-cells and tumor cells through their specificity for an antigen on the T-cell and an antigen on the tumor cell. This link results in a cytotoxic T-cell response against tumor cells and leads to the production of proteins such as perforin and granzymes, independent of the presence of MHC I or co-stimulatory molecules. These produced proteins enter tumor cells and initiate apoptosis, mimicking the physiological processes observed during T-cell-mediated responses against tumor cells. BiTE is a registered trademark of Micromet AG (a fully owned subsidiary of Amgen Inc).

[0068] In some aspects, a BiTE may comprise an antigen binding variable region, an antibody, or an antigen binding fragment that targets an antigen or a targeted epitope of interest expressed on the surface of a cell, such as a cancer cell, and also comprise an antigen binding variable region, an antibody, or an antigen binding fragment that specifically binds a CD3 coreceptor of a T-cell. In some aspects a BiTE of the present disclosure is capable of activating antigen specific T-cells, which kill target cancer cells expressing a particular epitope of interest. In one embodiment, a BiTE of the present disclosure activates T-cells that specifically bind an antigenic peptide derived from the HER2 and / or the TROP2 protein.

[0069] In some aspects, a BiTE of the present disclosure may be specific for at least one surface antigen on a T-cell of interest. Non-limiting examples of such T-cell surface antigens include CD3, CD2, VLA-1, CD8, CD4, CCR6, CXCR5, CD25, CD31, CD45RO, CD197, CD127, CD38, CD27, CD196, CD277 and CXCR3. In particular embodiments, a BiTE may comprise (i) an antigen binding region specific for a T-cell surface antigen, such as CD3, and (ii) an antigen binding region specific for an antigenic peptide derived from HER2 and / or TROP2. In one embodiment, the T-cell surface antigen may be selected from the group consisting of CD3 delta, CD3 epsilon, and CD3 gamma.

[0070] In certain aspects, an immune cell engager of the present disclosure, such as T-cell engager, may be arranged in the format VLl-linkerl-VHl-linkerl-VH2-linker3-VL2. In some embodiments, a BiTE of the present disclosure may bind an epitope derived from HER2 and / or TROP2.21G. PARP Inhibitors

[0071] Poly ADP ribose polymerase (PARP) is an enzyme involved in DNA repair. PARP inhibitors prevent cells from repairing damaged DNA within cells, making them an attractive therapeutic strategy for cancer.

[0072] Test samples or assays comprising PARP that are treated with a potential inhibitor may be compared to a control sample lacking the inhibitor in order to determine the extent of inhibition. Control samples to which a test sample or assay is compared may be assigned a relative protein activity value of 100%. Inhibition of PARP is achieved when the activity value of the test sample relative to the control sample is less than about 80%, including less than about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 45%, about 40%, about 35%, about 30%, about 25%, about 20%, about 15%, about 10%, about 5%, and about 1%, including all ranges and values derivable therebetween.

[0073] Any test or assay known in the art may be used to detect or measure the activity of a PARP inhibitor. Non-limiting examples of which include the PARP Universal Colorimetric Assay, the PARP activity screening and inhibitor testing assay (PASTA), chemiluminescent assays, and apoptosis assays.

[0074] Any PARP inhibitor known in the art may be used according to the embodiments of the present disclosure. Non-limiting examples of which include veliparib, talazoparib, olaparib, rucaparib, and niraparib.H. Therapeutic and Pharmaceutical Compositions

[0075] In certain aspects, the present disclosure provides pharmaceutical and therapeutic compositions comprising a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor. In some embodiments, a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor of the present disclosure may be combined with a pharmaceutically acceptable carrier. As used herein, a “pharmaceutically acceptable carrier,” “pharmaceutically acceptable adjuvant,” or “adjuvant” refers to reagents, cells, compounds, materials, compositions, and / or dosage forms that are not only compatible with a HER2- targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor, or other agents to be administered therapeutically, but also are, within the scope of sound medical judgment,suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other complication commensurate with a reasonable benefit / risk ratio. Also included may be an agent that modifies the effect of other agents and is useful in preparing a therapeutic compound or pharmaceutical compound or composition that is generally safe, non-toxic, and neither biologically nor otherwise undesirable. Such an agent may be added to a therapeutic composition or pharmaceutical composition to modify for example the cellular target, cellular localization, or cellular uptake of a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor as described herein. Such an agent may include any excipient, diluent, carrier, or adjuvant that is acceptable for pharmaceutical use. Such an agent may be non-naturally occurring, or may be naturally occurring, but not naturally found in combination with other agents in the therapeutic or pharmaceutical composition.

[0076] As used herein, a “therapeutic compound” or “therapeutic composition” refers to a composition comprising a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor of the present disclosure. In one embodiment, the composition is capable of reducing, stabilizing, or eliminating tumor growth or tumor progression in a subject. In another embodiment, the composition is capable of reducing, stabilizing, or eliminating tumor size in a subject.

[0077] A compound or composition of the present disclosure is meant to encompass a composition suitable for administration to a subject, such as a mammal, particularly a human subject. In general, a therapeutic composition is sterile, and preferably free of contaminants that are capable of eliciting an undesirable response within the subject (e.g., the compound(s) in the composition are pharmaceutical grade). Therapeutic compositions may be designed for administration to subjects in need thereof via a number of different routes of administration including oral, intravenous, intraarticular, intraarterial, buccal, rectal, parenteral, intraperitoneal, intradermal, intratracheal, intramuscular, subcutaneous, inhalation, vaginal, intraosseous, trans nasal, injection, microneedle, topical, and transdermal. The appropriate dosage of a composition, as described herein, may be determined based on the type of disease to be treated, the severity and course of the disease, the clinical condition of the individual, clinical history, response to the treatment, and the discretion of the attending physician. In some embodiments, therapeutic compositions provided by the present disclosure may includevarious "unit doses." A unit dose is defined as containing a predetermined quantity of the therapeutic composition. The quantity to be administered, and the particular route and formulation, is within the skill of determination of those in the clinical arts. A unit dose need not be administered as a single injection but may comprise continuous infusion over a set period of time. In some aspects, a unit dose comprises a single administrable dose.

[0078] Precise amounts of the therapeutic composition also depend on the judgment of the practitioner and are peculiar to each individual. Factors affecting dose include physical and clinical state of the patient, the route of administration, the intended goal of treatment (alleviation of symptoms versus cure) and the potency, stability and toxicity of the particular therapeutic substance or other therapies a subject may be undergoing.

[0079] As used herein, “subject” or “patient” refers to animals, including humans, who are treated with the inhibitors, therapeutic compounds, or compositions or in accordance with the methods described herein. For diagnostic or research applications, a wide variety of mammals may be suitable subjects, including rodents (e.g., mice, rats, hamsters), rabbits, primates, and swine, such as inbred pigs and the like. In particular embodiments, a subject in need of therapy may be any subject who comprises a POU2F3-driven cancer cell as described herein. In another embodiment, the subject may be afflicted with or at risk of developing a disease or condition associated with POU2F3-driven cancer as described herein. As used herein the term “POU2F3 -driven” refers to a state or condition associated with increased expression, activity, or function of POU2F3. Non-limiting examples of such diseases or conditions include lung cancer, small cell lung cancer, pulmonary large cell neuroendocrine carcinoma, skin cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, appendiceal cancer, hematopoietic cancer, breast cancer, head and neck cancer, prostate cancer, kidney cancer, bladder cancer, liver cancer, esophagus cancer, stomach cancer, thyroid cancer, small bowel adenocarcinoma, hepatobiliary cancer, and gynecological cancer.

[0080] A composition, as described herein, may include, in particular embodiments, a combination of therapeutic agents. In some embodiments, a composition as described here may be administered as a single composition or as more than one composition. Different compositions as provided herein, in certain embodiments, may be administered by the same route of administration or by different routes of administration.

[0081] A pharmaceutical composition of the present disclosure may comprise, in certain embodiments, a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor,a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor. Any HER2-targeting ADC, TROP2-targeting ADC, topoisomerase inhibitor, DNA alkylating agent, tubulin targeting agent, immune stimulant, and / or PARP inhibitor known in the art may be used in a pharmaceutical composition of the present disclosure.

[0082] A pharmaceutical composition of the present disclosure may comprise, in some embodiments, a targeting molecule. In one embodiment, the targeting molecule may be cellspecific or tissue-specific. Numerous such targeting molecules are known in the art and any such targeting molecule may be used according to the present disclosure. In certain embodiments, a composition of the present disclosure may be modified with or conjugated to a peptide, a protein, a colloidal molecule, or a polymer to facilitate delivery or adsorption. The pharmaceutical composition of the present disclosure, in some embodiments, may be serum-free, endotoxin-free, or sterile.

[0083] In certain aspects, a therapeutic composition of the present disclosure may comprise a HER2-targeting ADC, a TROP2-targeting ADC, a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, an immune stimulant, and / or a PARP inhibitor of the present disclosure and a second therapeutic agent or a detectable label. Non-limiting example of therapeutic agents that may be used according to the present disclosure include a chemotherapeutic agent, an immunotherapeutic agent, or a radiotherapeutic agent. Nonlimiting examples of detectable labels that may be used according to embodiments of the present disclosure include a paramagnetic ion, a radioactive isotope, a fluorochrome, an NMR- detectable agent, or an X-ray imaging agent. As used herein, the term "label" refers to a directly or indirectly detectable compound or composition that is conjugated directly or indirectly to the composition to be detected. In certain embodiments, an inhibitor, a polynucleotide molecule, protein, or cell may be labeled to generate a labeled composition. In particular embodiments, labeled compositions also include sequences which are conjugated a polynucleotide molecule that will provide a signal upon expression of the inserted sequences, such as green fluorescent protein (GFP) and the like. The label may be detectable by itself (e.g., radioisotope labels or fluorescent labels) or, in the case of an enzymatic label, may catalyze chemical alteration of a substrate compound or composition that is detectable. Labels may be suitable for small scale detection or for high-throughput screening. As such, suitable labels include, but are not limited to radioisotopes, fluorochromes, chemiluminescent compounds, dyes, and proteins, including enzymes. Labels may be simply detected or may be quantified. In certain embodiments, labels that may be quantified provide numericallyreportable value. In luminescence or fluorescence assays, the detectable response may be generated directly using a luminophore or fluorophore associated with an assay component involved in binding, or indirectly using a luminophore or fluorophore associated with another (e.g., reporter or indicator) component.

[0084] In certain embodiments, the compositions and methods for treating an individual described herein may be combined with any other composition or method of treatment known in the art. The compositions and methods may be administered in any suitable manner known in the art. For example, a first and a second therapeutic agent or inhibitor may be administered sequentially (at different times) or concurrently (at the same time). In some aspects, a first and a therapeutic agent or inhibitor may be administered in separate compositions. In certain embodiments, a first and a second cancer treatment or inhibitor may be administered in the same composition.

[0085] Non-limiting examples of additional treatment modalities that may be included in combination with the compositions and methods provided herein include a therapeutic agent or surgery. In specific embodiments, the methods and compositions of the present disclosure may be combined with other therapies directed towards the treatment of POU2F3-driven cancer as described herein.

[0086] The term "about" is used to indicate that a value includes the standard deviation of the mean for the device or method being employed to determine the value. The use of the term "or" in the claims is used to mean "and / or" unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive. When used in conjunction with the word "comprising" or other open language in the claims, the words "a" and "an" denote "one or more," unless specifically noted otherwise. The terms "comprise," "have," and "include" are open-ended linking verbs. Any forms or tenses of one or more of these verbs, such as "comprises," "comprising," "has," "having," "includes," and "including," are also open-ended. For example, any method that "comprises," "has," or "includes" one or more steps is not limited to possessing only those one or more steps and also covers other unlisted steps. Similarly, any system or method that "comprises," "has," or "includes" one or more components is not limited to possessing only those components and covers other unlisted components.

[0087] Other objects, features, and advantages of the present disclosure are apparent from detailed description provided herein. It should be understood, however, that the detaileddescription and any specific examples provided, while indicating specific embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. Any embodiment of the present disclosure may be used in combination with any other embodiment described herein.

[0088] All references herein are incorporated herein by reference in their entirety.EXAMPLES

[0089] The following examples are included to illustrate embodiments of the present disclosure. It should be appreciated by those of skill in the art that the techniques disclosed in the examples that follow represent techniques discovered by the inventor to function well in the practice of the invention. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.Example 1: Transcriptomic Analysis Defines Distinct Molecular Subtypes of SCLC.

[0090] A method for classifying SCLC tumors into four unique subtypes based on their transcriptional profiles was developed by applying non-negative matrix factorization (NMF) to mRNA expression data from resected SCLC tumors (George et al., Nature 524(7563):47- 53, 2015 dataset) and identified four mutually exclusive molecular subtypes (FIG. 1). Three subtypes were attributable to differential expression of established SCLC transcription factors: ASCL1 (SCLC-A), NEURODI (SCLC-N), and POU2F3 (SCLC-P). The NMF analyses further uncovered a novel fourth subtype (SCLC-Inflamed, or SCLC-I) that is characterized by interferon signatures, immune checkpoints, and HLA genes (FIG. 1A). While this signature can be used to distinguish subtypes, a more clinically applicable immunohistochemical (IHC) assay was developed for ASCL1, NEURODI, and POU2F3 that also robustly distinguishes subtypes (FIG. IB). Subtypes were further validated in ES-SCLC patients from the Phase 3 Impowerl33 trial (which established the addition of ICB tochemotherapy as anew standard). Importantly, distinct therapeutic vulnerabilities within each subtype of SCLC were identified as detailed below. For example, cell surface target DLL3 was found to be highly expressed in SCLC- A, while SSTR2 was expressed highly in SCLC- N (NEURODI). A similar approach to resolving transcriptional subtypes among LCNEC tumors was utilized and a similar differential expression of ASCL1, NEURODI, and POU2F3 subtypes present in LCNEC was observed.Example 2: SLFN11 is a Biomarker of Sensitivity to Topoisomerase 1 Inhibitors.

[0091] The putative DNA / RNA helicase, SLFN11, is the top biomarker of in vitro and in vivo sensitivity to DNA damaging chemotherapy agents, including TOP I inhibitors such as SN38 and topotecan, as well as PARP inhibitors such as talazoparib (FIG. 2A). SLFN11 is present in about 50% of SCLC tumors by IHC. A CLIA-certified assay for SLFN11 IHC was developed, allowing clinical validation of SLFN11 as a predictive marker in a Phase 2, randomized trial of temozolomide (TMZ) / placebo versus TMZ / veliparib (PARPi) (FIG. 2B) and Pietanza et al., J Clin Oncol. 36(23):2386-2394, 2018. In this retrospective analyses, patients with SLFN 11 -positive tumors had improved mPFS and mOS compared to patients with SLFN 11 -negative tumors in the TMZ / veliparib.Example 3: HER2 (ERBB2) and TROP2 (TACSTD2) are Expressed in Pulmonary hgNECs, with HER2 enriched in the POU2F3 subtype.

[0092] Following analysis of published mRNA data from SCLC and LCNEC, variable expression of HER2 and TROP2 across subtypes of SCLC and LCNEC was found (FIG. 3A; FIG. 4A). Specifically, a statistically significant enrichment of HER2 expression in SCLC-P was observed (FIG. 3A, FIG. 3B). For TROP2, there was no significant difference in expression levels among the four subtypes (FIG. 4, FIG. 4B), or on the basis of YAP1 expression.

[0093] Single cell RNAseq analyses was performed using patient tumor samples from patients with relapsed SCLC to study intra-tumoral heterogeneity and evaluate target expressions at single cell level. It was found that EEER2 expression is significantly enriched in POU2F3+ cells (FIG. 3C).Example 4: Expression of ADC Targets HER2 or TROP2 and SLFN11 positivity predict robust in vitro cytotoxicity in SCLC cell lines.

[0094] Cytotoxicity of ADCs targeting HER2 (trastuzumab deruxtecan) and TROP2 (sacituzumab govitecan) was assessed in SCLC cell lines (FIG. 5A; FIG. 5C). Sensitivity correlated with high SLFN11 expression. Further, three SCLC-P cell lines (H526, H1048, H211) were among the most sensitive cell lines to the HER2 ADC (IC50 ranging from 14 to 46 ug / ml), consistent with higher surface expression of HER2 by flow cytometry (FIG. 5B). More than half of the cell lines tested were highly sensitive to the TROP2 ADC with IC50 < 0.2ug / ml without a clear subtype enrichment, and TROP2 expression is detected in cell lines from different subtypes (FIG. 5C, FIG. 5D). SLFN11 status is an important predictor of sensitivity independent of target expression. For example, SHP77 has high HER2 surface expression, but low SLFN 11 expression, resulting in a higher IC50. Similar observations were seen with H82 and H211, with SLFN11 low models being relatively resistant despite high TROP2 expression. These results indicate that SLFN11 and target expression levels are important determinants of sensitivity to HER2 and TROP2 ADCs with TOP I inhibitor pay load. Notably, when cell lines are treated with standard frontline chemotherapy regimen for hgNECs (cisplatin / etoposide,luM each) for 72 hours compared to DMSO control, increased surface expression of TROP2 was observed, demonstrating that TROP2 is upregulated in post-chemotherapy treatment setting (FIG. 5E).Example 5: HER2-and TROP2- antibody drug conjugates (ADCs) are effective in small cell lung cancer (SCLC) with SLFN11 as a predictive biomarker.

[0095] Human epidermal growth factor receptor 2 (HER2 / ERBB2) has been previously described in a subset of SCLCs and has been linked to poor prognosis. HER2 ADCs, for example trastuzumab deruxtecan (T-DXd) having a topoisomerase I inhibitor payload have received FDA approval for various solid tumors. Similarly, the TROP2 (TACSTD2) ADC sacituzumab govitecan has demonstrated promising clinical efficacy in SCLC (TROPiCS-03 basket trial).

[0096] ERBB2 and TACSTD2 mRNA expression was analyzed using publicly available patient datasets. HER2 and TROP2 protein expression was also analyzed in SCLC cell lines by flow cytometry, at baseline and after cisplatin / etoposide treatment (frontline chemotherapy for SCLC). The cytotoxicity of T-dxd and sacituzumab govitecan was then tested in a panel ofcell lines representative of the heterogeneity of SCLC, and potential biomarkers of response were analyzed, including target (HER2, TR0P2) and SLFN11 expression.

[0097] Analyses of HER2 / ERBB2 and PROP2 / TACSTD2 in SCLC cell lines and patient datasets demonstrated a range of ERBB2 and TACSTD2 mRNA expression with enrichment in the non-neuroendocrine subtypes (SCLC-P and SCLC- I subtypes). FIG. 6 demonstrates ERBB2 (HER2) and SLFN11 gene expression levels in SCLC cell lines of different subtypes (SCLC-A (A), SCLC-N (N), SCLC-P (P) and SCLC-I (TN). HER2 and TROP2 expression was further evaluated at protein level by flow cytometry in a subset of SCLC cell lines. Intriguingly, the cell surface expression levels of both HER2 and TROP2 increase after cisplatin / etoposide treatment. Furthermore, T-dxd and sacituzumab govitecan exhibit cytotoxicity in a subset of SCLC cell lines. A strong correlation between the in vitro cytotoxicity (IC50) of sacituzumab govitecan with SLFN11 (p.r= 0737, p=0.015) expression was observed. Importantly, SLFN11 is bimodally distributed in SCLC and these experiments demonstrate that expression of ERBB2 and TACSTD2 is enriched in the SLFNll-high group of SCLC in patient datasets. Furthermore, ERBB2 and TACSTD2 expression correlate with each other (Spearman Rho = 0.53, p <0.001).

[0098] This study demonstrates that HER2 / ERBB2 and TROP2 / TACSTD2 are enriched in a subset of SCLC. Furthermore, FDA-approved ADCs, trastuzumab deruxtecan and sacituzumab govitecan demonstrate efficacy in SCLC with SLFN 11 as a predictive biomarker. In addition, HER2 and TROP2 target levels increase after frontline chemotherapy (cisplatin / etoposide) in SCLC, which supports their efficacy in relapsed SCLC where current treatment options are extremely limited.Example 6: HER2 targeting in POU2F3-driven SCLC

[0099] Analyses of HER2 / ERBB2 (protein and mRNA) in SCLC cell lines and treatment-naive patient datasets showed a range of ERBB2 expression. The non-neuroendocrine SCLC-P subtype, among others, express ERBB2. Cell surface HER2 expression was confirmed by flow cytometry in a panel of SCLC cell lines, including in SCLC-P cell lines (FIG. 7A). Consistent with this, single-cell RNA-seq profiling also revealed ERBB2 expression in POU2F3+ (SCLC- P) cells in tumor biopsies from patients with relapsed SCLC (FIG. 7B). Furthermore, a comparison of ERBB2 and DLE3 expression in treatment-naive SCLC tumors highlights that SCLC tumors that do not expression DLL3, target of the newly approved drug tarlatamab, express abundant levels of ERBB2 (FIG. 7C).

[0100] The efficacy of trastuzumab deruxtecan, an FDA-approved ADC for various solid tumors, was tested in SCLC preclinical models. SCLC cell lines showed sensitivity to trastuzumab deruxtecan, but not to the HER2 antibody trastuzumab. Notably, SCLC-P cell lines were highly sensitive to the HER2 ADC (FIG. 8A). The efficacy of trastuzumab deruxtecan was also tested in a SCLC-P xenograft model (H1048) in athymic nude mice. The HER2 ADC showed sustained tumor growth inhibition after 3 cycles of dosing, with prolonged tumor regression seen in 5 out of 9 mice (FIG. 8B). Given that SCLC-P cells lack or have low DLL3 expression, the possibility of combining DLL3 targeting together with the HER2 ADC was examined. The combinatorial effect of a DLL3 CAR-T and HER2 ADC in SCLC-P cells (Hl 048) was investigated, and the results showed that the combination was more effective in reducing cell viability compared to either single agent alone (FIG. 8C).

[0101] The non-neuroendocrine POU2F3-driven SCLC subtype (SCLC-P) is associated with poor prognosis and resistance to standard of care (SOC) therapies. The present disclosure demonstrates expression of the human epidermal growth factor receptor 2 HER2 / ERBB2) in SCLC, including on SCLC-P tumors and that targeting cell surface HER2 using an antibody drug conjugates (ADCs) is an effective treatment approach in SCLC, inclusive of SCLC-P. The present disclosure further demonstrates that SCLC-P is resistant to tarlatamab, a recent FDA approved T-cell engager for relapsed SCLC, due to its very low / negative expression of DLL3, the target of tarlatamab. As shown herein, , SCLC-P, which responds poorly to SOC therapies and express few of the targets associated with these other agents, preferentially benefit from HER2 targeting.Example 7 : Materials and Methods

[0102] Profiling subtype-specific surface expression of HER2 and TROP2 across SCLC and LCNEC. A large panel of molecularly profiled human-derived cell lines is utilized to profile subtype specific surface expression of HER2 and TROP2. These cell lines represent the molecular heterogeneity seen in patient tumors, including each of the subtypes. A unique panel of patient-derived xenograft models established either from patients’ tumors (PDX) or blood / circuiting tumors cells (CTC-derived xenografts, or “CDXs”) is also used. Both cell lines and patient-derived models have been extensively profiled for molecular features, drug sensitivity, and represent the diverse molecular landscape of patient tumors. Total protein expression is assessed by western blot, and surface expression levels is characterized by IHC and flow cytometry. The expression levels of the targets with subtypes and other molecularbiomarkers are correlated, including mRNA and proteomic expression levels (RPPA). SCLC and LCNEC cell lines are treated with DMSO control, cisplatin and etoposide alone and in combination (all drugs at luM concentration) for 72 hours, and flow cytometry is performed to determine changes in surface expression of TROP2 and HER2 in chemotherapy-treated group compared to DMSO control.

[0103] Determining predictive biomarkers to HER2- and TROP2- targeting ADCs alone and in combination with PARP inhibitors in hgNECs. HER2 or TROP2 expressing hgNEC PDX / CDX models are selected that that are SLFN11 high (n=3) or -low (n=3) to test vehicle control, control ADC, and target ADC. PDX / CDX tumors are transplanted into the flanks of nude mice. When tumors reach 150-200 mm3, animals are randomized (n=12 per treatment arm) to receive no treatment, control ADC (isotype linked to TOPI inhibitor pay load), or targeted ADC. SLFN 11 -positive models are selected that are HER2-high / low (n=3 models each), or TROP2 high / low (n=3 each) to test vehicle, target ADC alone, olaparib alone, and ADC / olaparib (PARPi) combination. After flank tumors reach 150-200 mm3, animals are randomized (n=12) to receive no treatment, target ADC, or a combination of target ADC with olaparib. Tumor volume is measured by caliper. Animals are treated and euthanized according to AVMA guidelines. Five mice are sacrificed, and tumors are collected at day 14 to assess target expression levels by THC and send for bulk RNAseq analyses (optional flow cytometry / western blot when enough tissue). The remaining seven mice per group continue treatment for long-term efficacy studies. Drug dosing and schedule: HER2 ADC (T-dxd), TROP2 ADC (Datopotamab Deruxtecan), and control ADC: lOmg / kg every 3-week intravenous injection (tail vein). Olaparib: 75mg / kg / weekday, p.o.• * *

[0104] All of the methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments or aspects, it will be apparent to those of skill in the art that variations may be applied to the methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain agents which are both chemically and physiologically related may be substituted for the agents described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3-driven cancer and administering to the subject an effective amount of a HER2-targeting antibody drug conjugate.

2. The method of claim 1, wherein the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado-trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC.

3. The method of claim 1 , wherein the HER2-targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant.

4. The method of claim 3, wherein: a) the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin; b) the DNA alkylating agent is selected from the group consisting of a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin; c) the tubulin targeting agent is selected from the group consisting of a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM1; ord) the immune stimulant is selected from the group consisting of a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

5. The method of claim 1, wherein the POU2F3-driven cancer is selected from the group consisting of lung cancer, small cell lung cancer, pulmonary large cell neuroendocrine carcinoma, skin cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, appendiceal cancer, hematopoietic cancer, breast cancer, head and neck cancer, prostate cancer, kidney cancer, bladder cancer, liver cancer, esophagus cancer, stomach cancer, thyroid cancer, small bowel adenocarcinoma, hepatobiliary cancer, and gynecological cancer.

6. The method of claim 1, wherein the POU2F3 -driven cancer is small cell lung cancer or pulmonary large cell neuroendocrine carcinoma.

7. The method of claim 1 , wherein the subject is a mammalian subject.

8. The method of claim 1, wherein the subject is a human subject.

9. The method of claim 1, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

10. The method of claim 1, further comprising administering a second therapy to said subject.

11. The method of claim 10, wherein said second therapy is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery.

12. The method of claim 10, wherein the second therapy comprises administering an effective amount of a PARP inhibitor.

13. The method of claim 1 , further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate to said subject.

14. A method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3-driven cancer and expressing increased levels SLFN11 in at least one cancer cell, and administering to the subject an effective amount of a HER2-targeting antibody drug conjugate, wherein the antibody drug conjugate comprises a topoisomerase inhibitor.

15. The method of claim 14, wherein the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin.

16. The method of claim 14, wherein the antibody drug conjugate is fam-trastuzumab- deruxtecan-nxki.

17. The method of claim 14, wherein the POU2F3-driven cancer is selected from the group consisting of lung cancer, small cell lung cancer, pulmonary large cell neuroendocrine carcinoma, skin cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, appendiceal cancer, hematopoietic cancer, breast cancer, head and neck cancer, prostate cancer, kidney cancer, bladder cancer, liver cancer, esophagus cancer, stomach cancer, thyroid cancer, small bowel adenocarcinoma, hepatobiliary cancer, and gynecological cancer.

18. The method of claim 14, wherein the POU2F3-driven cancer is small cell lung cancer or pulmonary large cell neuroendocrine carcinoma.

19. The method of claim 14, wherein the subject is a mammalian subject.

20. The method of claim 14, wherein the subject is a human subject.

21. The method of claim 14, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

22. The method of claim 14, further comprising administering a second therapy to said subject.

23. The method of claim 22, wherein said second therapy is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery.

24. The method of claim 22, wherein the second therapy comprises administering an effective amount of a PARP inhibitor.

25. The method of claim 14, further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate to said subject.

26. A method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a POU2F3-driven cancer, wherein the subject has received prior chemotherapy, and administering to the subject an effective amount of a HER2-targeting antibody drug conjugate and a TROP2-targeting antibody drug conjugate.

27. The method of claim 26, wherein the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado-trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC, or wherein the TROP2-targeting antibody drug conjugate is selected from the group consisting of sacituzumab govitecan, datopotamab deruxtecan, and YH012.

28. The method of claim 26, wherein the HER2-targeting antibody drug conjugate or the TROP2-targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant.

29. The method of claim 28, wherein: a) the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin; b) the DNA alkylating agent is selected from the group consisting of a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin; c) the tubulin targeting agent is selected from the group consisting of a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM 1 ; ord) the immune stimulant is selected from the group consisting of a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

30. The method of claim 26, wherein the POU2F3-driven cancer is selected from the group consisting of lung cancer, small cell lung cancer, pulmonary large cell neuroendocrine carcinoma, skin cancer, pancreatic cancer, non-small cell lung cancer (NSCLC), colorectal cancer, appendiceal cancer, hematopoietic cancer, breast cancer, head and neck cancer, prostate cancer, kidney cancer, bladder cancer, liver cancer, esophagus cancer, stomach cancer, thyroid cancer, small bowel adenocarcinoma, hepatobiliary cancer, and gynecological cancer.

31. The method of claim 26, wherein the POU2F3-driven cancer is small cell lung cancer or pulmonary large cell neuroendocrine carcinoma.

32. The method of claim 26, wherein the subject is a mammalian subject.

33. The method of claim 26, wherein the subject is a human subject.

34. The method of claim 26, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

35. The method of claim 26, further comprising administering a second therapy to said subject.

36. The method of claim 35, wherein said second therapy is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery.

37. The method of claim 26, further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate or of the TROP2-targeting antibody drug conjugate to said subject.

38. A method of treating a subject in need thereof, the method comprising: identifying a subject afflicted with or at risk of developing a SCLC-P subtype or a SCLC-T subtype cancer and administering to the subject an effective amount of a HER2-targeting antibody drug conjugate or a TROP2-targeting antibody drug conjugate.

39. The method of claim 38, wherein: a) the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado- trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC; b) the TROP2-targeting antibody drug conjugate is selected from the group consisting of sacituzumab govitecan, datopotamab deruxtecan, and YH012; or c) the HER2-targeting antibody drug conjugate or the TROP2-targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant.

40. The method of claim 39, wherein: a) the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin; b) the DNA alkylating agent is selected from the group consisting of a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin; c) the tubulin targeting agent is selected from the group consisting of a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM 1 ; or d) the immune stimulant is selected from the group consisting of a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

41. The method of claim 38, wherein the subject is a mammalian subject.

42. The method of claim 38, wherein the subject is a human subject.

43. The method of claim 38, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

44. The method of claim 38, further comprising administering a second therapy to said subject.

45. The method of claim 44, wherein said second therapy is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery.

46. The method of claim 44, wherein the second therapy comprises administering an effective amount of a PARP inhibitor.

47. The method of claim 38, further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate or the effective amount of the TROP2-targeting antibody drug conjugate to said subject.

48. A method of treating a subject in need thereof, the method comprising: a) identifying a subject afflicted with or at risk of developing a small cell lung cancer; b) identifying the small cell lung cancer as expressing HER2 or TR0P2; and c) administering to the subject an effective amount of a HER2-targeting antibody drug conjugate, wherein the small lung cancer is identified as expressing HER2 or administering to the subject an effective amount of a TROP2-targeting antibody drug conjugate, wherein the small cell lung cancer is identified as expression TROP2.

49. The method of claim 48, wherein: a) the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado- trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC;b) the TR0P2-targeting antibody drug conjugate is selected from the group consisting of sacituzumab govitecan, datopotamab deruxtecan, and YH012; or c) the HER2-targeting antibody drug conjugate or the TR0P2- targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant.

50. The method of claim 49, wherein: a) the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin; b) the DNA alkylating agent is selected from the group consisting of a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin; c) the tubulin targeting agent is selected from the group consisting of a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM1; or d) the immune stimulant is selected from the group consisting of a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

51. The method of claim 48, wherein the subject is a mammalian subject.

52. The method of claim 48, wherein the subject is a human subject.

53. The method of claim 48, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

54. The method of claim 48, further comprising administering a second therapy to said subject.

55. The method of claim 54, wherein said second therapy is selected from the group consisting of chemotherapy, radiation therapy, immunotherapy, and surgery.

56. The method of claim 54, wherein the second therapy comprises administering an effective amount of a PARP inhibitor.

57. The method of claim 48, further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate or the effective amount of the TROP2-targeting antibody drug conjugate to said subject.

58. The method of claim 1 , wherein the POU2F3-driven cancer is resistant to a standard of care therapy.

59. The method of claim 1, wherein the POU2F3-driven cancer is resistant to a delta-like protein 3 (DLL3)-targeted therapy.

60. The method of claim 59, wherein the DLL3-targeted therapy is selected from the group consisting of tarlatamab, rovalpituzumab tesirine, BI-764532, HPN328, and AMG 119.

61. A method of treating a subject in need thereof, the method comprising administering to the subject an effective amount of a HER2-targeting antibody drug conjugate and a DLL3- targeted therapy.

62. The method of claim 61, further comprising identifying the subject as being subject afflicted with or at risk of developing a SCLC-P subtype cancer prior to said administering.

63. The method of claim 61 , wherein: a) the HER2-targeting antibody drug conjugate is selected from the group consisting of fam-trastuzumab-deruxtecan-nxki, ado-trastuzumab emtansine, disitamab vedotin, vic-trastuzumab duocarmazin, XMT-1522, ALT-P7, ARX788, PF-06804103, MRG002, A166, ZW49, BDC-1001, T-PNU, FS-1502, GQ1001, YH012, and HER2xPRLR bsADC; b) the HER2-targeting antibody drug conjugate comprises a topoisomerase inhibitor, a DNA alkylating agent, a tubulin targeting agent, or an immune stimulant; c) the DLL3-targeted therapy is an antibody, an antibody-drug conjugate, a bispecific T-cell engager, a tri-specific T-cell engager, or a CAR-T cell; ord) the DLL3-targeted therapy is selected from the group consisting of tarlatamab, rovalpituzumab tesirine, BI-764532, HPN328, and AMG 119.

64. The method of claim 63, wherein: a) the topoisomerase inhibitor is selected from the group consisting of deruxtecan, topotecan, irinotecan, belotecan, indenoisoquinoline, a phenanthridine, an indolocarbazole, an anthracycline, doxorubicin, daunorubicin, epirubicin, idarubicin, etoposide, teniposide, a bisdioxopiperazine compound, dexrazoxane, novobiocin, merbarone, PNU- 159682, and anthracycline aclarubicin; b) the DNA alkylating agent is selected from the group consisting of a nitrogen mustard, bendamustine, chlorambucil, cyclophosphamide, ifosfamide, mechlorethamine, melphalan, a nitrosourea, carmustine, lomustine, streptozocin, an alkyl sulfonate, busulfan, a triazine, dacarbazine, temozolomide, an ethylenimine, altretamine, thiotepa, cisplatin, and duocarmycin; c) the tubulin targeting agent is selected from the group consisting of a taxane, an epothilone, a discodermolide, an auristatin derivative, a maytansinoid derivative, eribulin, paclitaxel, docetaxel, ixabepilone, cabazitaxel, vedotin, emtansine, tirbanibulin, paclitaxel ceribate, monomethyl auristatin E, auristatin F- hydroxypropylamide, dolastatin, AurOlOl, duostatin 5, auristatin, monomethyl auristatin F, and DM 1 ; or d) the immune stimulant is selected from the group consisting of a TLR 7 / 8 agonist, a PRR agonist, an interferon, an interleukin, a colony-stimulating factor, and a T-cell engager.

65. The method of claim 61, wherein the subject is a mammalian subject.

66. The method of claim 61, wherein the subject is a human subject.

67. The method of claim 61, wherein said administering comprises injection, microneedle administration, oral administration, buccal administration, vaginal administration, inhalation, intraosseous administration, trans nasal application, topical administration, transdermal application, or rectal administration.

68. The method of claim 61, further comprising administering a pharmaceutical composition comprising the effective amount of HER2-targeting antibody drug conjugate or the effective amount of the DLL3-targeted therapy to said subject.

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