Treatment and prevention of cancer using her3-binding molecules

Abstract

The present disclosure provides the use of an antigen-binding molecule that bind to HER3 for the treatment or prevention of a HER3-associated cancer, wherein the HER3-associated cancer comprises a mutation in ERBB3.

Description

[0001] Treatment and Prevention of Cancer Using HER3-Bindinq Molecules

[0002] This application claims priority from US 63 / 582904 filed 15 September 2023, the contents and elements of which are hereby incorporated by reference for all purposes.

[0003] Technical Field

[0004] The present disclosure relates to medical treatment and prophylaxis, particularly of cancers.

[0005] Background

[0006] A number of transmembrane protein kinases have been associated with oncogenesis (Roskoski Jr 2004). The human epidermal growth factor receptor 3 (HER3) has been identified as a key signaling hub in activating key growth factor signaling pathways such as the RAS-ERK and PI3K-Akt pathways, by forming heterodimers with either epidermal growth factor receptor (EGFR) or human epidermal growth factor receptor 2 (HER2) (Gala and Chandarlapaty, Clinical Cancer Research (2014) 6:1410-1416) (Haikala and Janne, Clinical Cancer Research (2021) 27(13):3528-3539). Increased HER3 expression is linked to poor prognosis in multiple solid tumors, including breast, gastric, head & neck, pancreatic, ovarian, and lung cancers. HER3-mediated signaling has adverse consequences for tumor progression; HER3 upregulation is associated with resistance to anti-HER2 and anti-EGFR therapy, and solid tumors refractory to anti-PD-1 therapy have been shown to have higher HER3 expression compared to responders to anti-PD-1 therapy. HER3 may be involved in acquired resistance to EGFR / HER2 therapies through feedback regulation via Akt signaling. There are two key mechanisms of HER3 activation (Gala and Chandarlapaty, Clinical Cancer Research (2014) 6:1410-1416): ligand-dependent activation which relies on NRG1 to stabilize HER3 in a dimerization ready state on a low EGFR / HER2 environment, and ligand-independent activation on a high EGFR / HER2 setting where the HER3 is already transiently open. Overexpression of HER3 has been observed in multiple tumor types including non-small cell lung cancers (NSCLC) (Janne, et al., Cancer Discovery (2022) 12(1)74-89).

[0007] HER3-binding antibodies are described e.g. in Zhang et al., Acta Biochimica et Biophysica Sinica (2016) 48(1): 39-48. The anti-HER3 antibody LJM-716 binds to an epitope on subdomains II and IV of the HER3 extracellular domain, locking HER3 in the inactive conformation (Garner et al., Cancer Res (2013) 73: 6024-6035). MM-121 (also known as seribantumab) has been shown to inhibit HER3-mediated signaling by blocking binding of heregulin (HRG) to HER3 (Schoeberl et al., Sci. Signal. (2009) 2(77): ra31). Patritumab (also known as U-1287 and AMG-888) also blocks binding of heregulins to HER3 (see e.g. Shimizu et al. Cancer Chemother Pharmacol. (2017) 79(3):489-495). RG7116 (also known as lumretuzumab and RO-5479599) recognizes an epitope in subdomain I of the HER3 extracellular domain (see e.g. Mirschberger et al. Cancer Research (2013) 73(16) 5183-5194). KTN3379 binds to HER3 through interaction with amino acid residues in subdomain III (corresponding to the following positions of SEQ ID NO:1 : Gly476, Pro477, Arg481 , Gly452, Arg475, Ser450, Gly420, Ala451 , Gly419, Arg421 , Thr394, Leu423, Arg426, Gly427, Lys356, Leu358, Leu358, Lys356, Ala330, Lys329 and Gly337), and Met310, Glu311 and Pro328 of subdomain II (see Lee et al., Proc Natl Acad Sci U S A. 2015 Oct 27;

[0008] 112(43): 13225). AV-203 (also known as CAN-017) has been shown to block binding of NRG1 to HER3 and to promote HER3 degradation (see Meetze et al., Eur J Cancer 2012; 48:126). REGN1400 also inhibits binding of ligand to HER3 (see Zhang etal., Mol Cancer Ther (2014) 13:1345-1355). RG7597 (duligotuzumab) is a dual action Fab (DAF) capable of binding to both HER3 and EGFR, and binds to subdomain III of HER3 (see Schaefer etal., Cancer Cell (2011) 20(4):472-486). MM-111 and MM-141 are bispecific antibodies having HER3-binding arms which inhibit HRG ligand binding to HER3 (see McDonagh et al. Mol Cancer Ther (2012) 11 :582-593 and Fitzgerald et al. , Mol Cancer Ther (2014) 13:410-425).

[0009] Lung cancer is the leading cause of cancer-related mortality globally, accounting for almost 1 in 5 cancer- related deaths (Cancer Genome Atlas Research Network 2012). Lung squamous cell carcinoma (LUSC) accounts for approximately 30% of all lung cancers (Perez-Moreno et al., Clinical Cancer Research (2012) 18(9):2443-2451). Squamous NSCLC is initiated in epithelial tissue, subject to environmental insults such as smoking, and patients with NSCLC have a 28% 5-year survival rate following diagnosis (Detterbeck and Gibson, Journal of Thoracic Oncology (2008) 3(7):781-792). Metastatic NSCLC reduces the 5-year survival rate to only about 9% (American Cancer Society 2023). The standard first line of treatment for metastatic LUSC is immunotherapy with or without combination with platinum-based chemotherapy, as actionable biomarkers for the use of approved targeted therapies are rare in this NSCLC subtype (Yuan et al., Molecules (2021) 26(5):1392). Once patients progress following the combined therapy, subsequent treatment lines confer only limited clinical benefit, presenting a significant area of need.

[0010] Characteristics of early oncogenesis in squamous cell carcinomas include amplifications of chromosome 3q (Chr3q) and loss of chromosome 3p (Chr3p), which are well known genetic aberrations associated with carcinogen exposures (Rooney et al. Oncologist (2013) 18(6):707-716). Chr3q amplifications leads to increased transcriptional activities of a number of genes including TP63 (which directly promotes HER3 ligand NRG1 expression), SOX2 (which directly promotes expression of EGFR ligands), and PIK3CA genes (which enhances activation of the PI3K pathway) (Perez-Moreno et al., Clinical Cancer Research (2012) 18(9):2443-2451). Chr3p loss, on the other hand, leads to the deletion of several putative tumor suppressor proteins, including tumor suppressive candidate 2 (TUSC2), which inhibits EGFR (Perez- Moreno et al., Clinical Cancer Research (2012) 18(9):2443-2451). In addition, chromosome 7p (Chr7p) encoding EGFR has also been found to be frequently amplified in LUSC (Couceiro, et al. Revista Portuguesa de Pneumologia (2010) 16(3):453-462).

[0011] Successful targeting of driver mutations in cancer, supported by the robust progress of genomic technology allowing timely patient selection, has transformed patient outcomes in multiple cancer indications (Martinez-Jimenez et al., Nat Rev Cancer (2020) 20(10):555-572).

[0012] HER3 mutations have been identified in ~3% of cancers and represent a genetically defined patient population that could be exquisitely responsive to HER3 modulations. Preclinical data has shown that such mutations can lead to increased oncogenic signaling that usually translates to enhanced tumor growth (Jaiswal et al., Cancer Cell (2013) 23(5): 603-617; Mishra etal., Oncotarget (2018) 9(45): 27773- 27788). Additionally, anti-HER3 therapies have demonstrated significant efficacy in HER3 mutant xenograft models, indicating the sensitivity of such cancers to HER3-targeted treatments (Hong et al., Cancer Res (2020) 80(16_Supplement): 3042; Jaiswal et al., Cancer Cell (2013) 23(5): 603-617). In the clinic, metastatic platinum-refractory urothelial carcinoma patients with HER2 and / or HER3 alterations achieved progression free survival in response to treatment with afatinib, while none of patients without alterations showed any response (Choudhury et al., J Clin Oncol (2016) 34(18): 2165-2171). There are presently no approved treatments for cancer patients with HER3 mutations, highlighting a significant clinical unmet need.

[0013] The efficacy of combination chemotherapeutic approach using gemcitabine and albumin-bound paclitaxel (nab-paclitaxel) was established in the phase III MPACT trial comparing gemcitabine plus nab-paclitaxel to gemcitabine alone; treatment with gemcitabine plus nab-paclitaxel improved the median overall survival to 8.7 months compared to 6.6 months with gemcitabine alone, and the overall response rate to 23% compared to 7% with gemcitabine alone (Von Hoff et al., N Engl J Med (2013) 369(18):1691-703). There remains significant need for improved therapeutic option for this patient population.

[0014] Summary

[0015] In a first aspect, the present disclosure relates to an antigen-binding molecule that binds to HER3 for use in a method of treating or preventing a HER3-associated cancer in a subject, wherein the HER3- associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

[0016] The present disclosure also provides the use of an antigen-binding molecule that binds to HER3 in the manufacture of a medicament for use in a method of treating or preventing a HER3-associated cancer in a subject, wherein the HER3-associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

[0017] The present disclosure also provides a method of treating or preventing a HER3-associated cancer in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of an antigen-binding molecule that binds to HER3, wherein the HER3-associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

[0018] In some embodiments in accordance with the various aspects of the present disclosure, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 in the region shown in SEQ ID NO:77.

[0019] In some embodiments, the mutation in ERBB3 results in an increase in the expression of, or an increase in the activity of a gene product of, ERBB3.

[0020] In some embodiments, the mutation in ERBB3 results in a change in the amino acid sequence of HER3 in the region shown in SEQ ID NO:9. In some embodiments, the mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : P30L, G40S, M60K, M60R, M91 I, F94L, R103G, R103H, V104L, V104M, V119I, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, A232V, G233W, G253R, P262H, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, D313H, G325R, K329E, K329R, K329T, E332Q, G337R, S345L, T355A, T355P, T389K, G420V, R426W, L431 S, S445F, R475W, E480Q, G513C, G513D, R521Q, D581 N, P590H, V606A, R667H, M677I, R683W, V714M, K742E, H768R, L792V, L795V, Q809R, K820N, S846I, V855A, H884R, G898D, D922Y, E928A, E928G, E928K, E928Q, E952Q, R967K, L1027M, V1035D, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221 D, S1234C, E1261A, D1320H and A1337T.

[0021] In some embodiments, the mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : M60R, M911, V104L, V104M, N126K, H228Q, H228R, A232T, A232V, P262H, G284R, D297V, D297Y, T355P, R475W, T389K, R426W, D581 N and P590H.

[0022] In some embodiments, the antigen-binding molecule that binds to HER3 comprises:

[0023] (i) a heavy chain variable (VH) region incorporating the following CDRs:

[0024] HC-CDR1 having the amino acid sequence of SEQ ID NQ:40 HC-CDR2 having the amino acid sequence of SEQ ID NO:43 HC-CDR3 having the amino acid sequence of SEQ ID NO:48; and

[0025] (ii) a light chain variable (VL) region incorporating the following CDRs:

[0026] LC-CDR1 having the amino acid sequence of SEQ ID NO:66 LC-CDR2 having the amino acid sequence of SEQ ID NO:69 LC-CDR3 having the amino acid sequence of SEQ ID NO:74.

[0027] In some embodiments, the antigen-binding molecule that binds to HER3 comprises:

[0028] (i) a VH region incorporating the following CDRs:

[0029] HC-CDR1 having the amino acid sequence of SEQ ID NO:38 HC-CDR2 having the amino acid sequence of SEQ ID NO:42 HC-CDR3 having the amino acid sequence of SEQ ID NO:45; and

[0030] (ii) a VL region incorporating the following CDRs:

[0031] LC-CDR1 having the amino acid sequence of SEQ ID NO:63 LC-CDR2 having the amino acid sequence of SEQ ID NO:67 LC-CDR3 having the amino acid sequence of SEQ ID NQ:70.

[0032] In some embodiments, the antigen-binding molecule that binds to HER3 comprises: a VH region comprising an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:33; and a VL region comprising an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:58. In some embodiments, the antigen-binding molecule that binds to HER3 comprises: a polypeptide comprising, or consisting of, an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:75; and a polypeptide comprising, or consisting of, an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:76.

[0033] In some embodiments, the method of treating or preventing a HER3-associated cancer further comprises administering a taxoid.

[0034] In some embodiments, the taxoid is docetaxel or nab-paclitaxel.

[0035] In some embodiments, the method of treating or preventing a HER3-associated cancer further comprises administering a nucleoside analog.

[0036] In some embodiments, the nucleoside analog is a deoxycytidine nucleoside analog.

[0037] In some embodiments, the nucleoside analog is gemcitabine or a salt thereof.

[0038] In some embodiments, the HER3-associated cancer is: a cancer comprising cells expressing / overexpressing an EGFR family member (e.g. HER3, EGFR, HER2 or HER4), a cancer comprising cells expressing / overexpressing HER3, a cancer comprising cells having a mutation resulting in increased expression of a ligand for HER3, a cancer comprising cells having an NRG gene fusion, a cancer comprising cells having an NRG1 gene fusion, a cancer comprising cells having an NRG2 gene fusion a solid tumor, a hematological cancer, a squamous cell cancer, an EGFR-amplified squamous cell carcinoma, breast cancer, breast carcinoma, breast invasive carcinoma, ductal carcinoma, metastatic breast cancer, triple-negative breast cancer, HER2-positive breast cancer, gastric cancer, gastric carcinoma, gastric adenocarcinoma, gastrointestinal adenocarcinoma, ampullary adenocarcinoma, colorectal cancer, metastatic colorectal cancer, colon cancer, colorectal carcinoma, colorectal adenocarcinoma, colon adenocarcinoma, head and neck cancer, head and neck squamous cell carcinoma, lung cancer, non-small cell lung cancer, lung adenocarcinoma, invasive mucinous lung adenocarcinoma, squamous cell lung cancer, lung squamous cell carcinoma, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, ovarian cancer, ovarian carcinoma, ovarian serous adenocarcinoma, ovarian serous cystadenocarcinoma, fallopian tube cancer, renal cancer, renal cell carcinoma, renal clear cell carcinoma, renal cell adenocarcinoma, renal papillary cell carcinoma, pancreatic cancer, an exocrine cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma, metastatic pancreatic ductal adenocarcinoma, cervical cancer, cervical squamous cell carcinoma, skin cancer, melanoma, oral cavity cancer, oropharyngeal cancer, esophageal cancer, esophageal squamous cell carcinoma, esophageal adenocarcinoma, liver cancer, hepatocellular carcinoma, cholangiocarcinoma, gallbladder cancer, uterine cancer, endometrial cancer, endometrial adenocarcinoma, uterine corpus endometrial carcinoma, uterine carcinosarcoma, thyroid cancer, thyroid cancer, thyroid carcinoma, pheochromocytoma, paraganglioma, bladder cancer, bladder urothelial carcinoma, prostate cancer, prostate adenocarcinoma, retinoblastoma, sarcoma, soft tissue sarcoma, peritoneal cancer, thymoma, neuroendocrine tumor, neuroendocrine tumor of the nasopharynx, squamous cell carcinoma of the skin, astrocytoma, low grade astrocytoma, high grade astrocytoma, anaplastic astrocytoma and glioblastoma multiforme.

[0039] In some embodiments, the HER3-associated cancer is: a squamous cell cancer, esophageal squamous cell carcinoma, gastrointestinal adenocarcinoma, ampullary adenocarcinoma, endometrial adenocarcinoma, lung cancer, non-small cell lung cancer, squamous cell lung cancer, squamous nonsmall cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, pancreatic cancer, an exocrine cancer, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma or metastatic pancreatic ductal adenocarcinoma.

[0040] Description

[0041] The present disclosure is based on the inventors unexpected finding that cancers characterized by nonsynonymous mutations resulting in differences in the amino acid sequence of the extracellular domain of HER3 respond very well to HER3-targeted antibody therapy, in particular treatment with the anti-HER3 antibody 10D1 F.

[0042] The experimental examples of the present disclosure demonstrate that 10D1 F unexpectedly retains the ability to bind to HER3 variants comprising a variety of different amino acid substitutions relative to the amino acid sequence of wildtype HER3. They moreover demonstrate that cancers comprising mutations encoding such HER3 variants are highly susceptible to therapeutic intervention with 10D1 F.

[0043] HER3

[0044] HER3 (also known e.g. as ERBB3, LCCS2, MDA-BF-1) is the protein identified by UniProt P21860.

[0045] The structure and function of HER3 is described e.g. in Cho and Leahy Science (2002) 297 (5585):1330- 1333, Singer et al., Journal of Biological Chemistry (2001) 276, 44266-44274, Roskoski et al., Pharmacol. Res. (2014) 79: 34-74, Bazley and Gullick Endocrine-Related Cancer (2005) S17-S27 and Mujoo et al., Oncotarget (2014) 5(21):10222-10236, each of which are hereby incorporated by reference in their entirety. HER3 is a single-pass transmembrane ErbB receptor tyrosine kinase having an N-terminal extracellular region (SEQ ID NO:9) comprising two leucine-rich subdomains (domains I and III, shown in SEQ ID NOs:15 and 17, respectively) and two cysteine-rich subdomains (domains II and IV, shown in SEQ ID NOs:16 and 18, respectively). Domain II comprises a p hairpin dimerization loop (SEQ ID NO:19) which is involved in intermolecular interactions with other HER receptor molecules. The extracellular region is linked via a transmembrane region (SEQ ID NQ:10) to a cytoplasmic region (SEQ ID NO:11). The cytoplasmic region comprises a juxtamembrane segment (SEQ ID NO:12), a protein kinase domain (SEQ ID NO:13), and a C-terminal segment (SEQ ID NO:14).

[0046] In this specification ‘HER3’ refers to HER3 from any species and includes HER3 isoforms, fragments, variants (including mutants) or homologues from any species. As used herein, a ‘fragment’, ‘variant’ or ‘homologue’ of a protein may optionally be characterized as having at least 60%, preferably one of 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to the amino acid sequence of the reference protein (e.g. a reference isoform). In some embodiments, fragments, variants, isoforms and homologues of a reference protein may be characterized by ability to perform a function performed by the reference protein.

[0047] A ‘fragment’ generally refers to a fraction of the reference protein. A ‘variant’ generally refers to a protein having an amino acid sequence comprising one or more amino acid substitutions, insertions, deletions or other modifications relative to the amino acid sequence of the reference protein, but retaining a considerable degree of sequence identity (e.g. at least 60%) to the amino acid sequence of the reference protein. An ‘isoform’ generally refers to a variant of the reference protein expressed by the same species as the species of the reference protein (e.g. human HER3 isoforms 1 to 5 are all isoforms of one another). A ‘homologue’ generally refers to a variant of the reference protein produced by a different species as compared to the species of the reference protein. For example, human HER3 isoform 1 (P21860-1 , v1 ; SEQ ID NO:1) and Rhesus macaque HER3 (UniProt: F7HEH3-1 , v2; SEQ ID NO:20) are homologues of one another. Homologues include orthologues.

[0048] A ‘fragment’ of a reference protein may be of any length (by number of amino acids), although may optionally be at least 20% of the length of the reference protein (that is, the protein from which the fragment is derived) and may have a maximum length of one of 50%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% of the length of the reference protein.

[0049] A fragment of HER3 may have a minimum length of one of 10, 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1100, 1200 amino acids, and may have a maximum length of one of 20, 30, 40, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1100, 1200, or 1300 amino acids.

[0050] In some embodiments, the HER3 is HER3 from a mammal (e.g. a primate (rhesus, cynomolgous, nonhuman primate or human) and / or a rodent (e.g. rat or murine) HER3). Isoforms, fragments, variants or homologues of HER3 may optionally be characterized as having at least 70%, preferably one of 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to the amino acid sequence of an immature or mature HER3 isoform from a given species, e.g. human.

[0051] Isoforms, fragments, variants or homologues may optionally be functional isoforms, fragments, variants or homologues, e.g. having a functional property / activity of the reference HER3 (e.g. human HER3 isoform 1), as determined by analysis by a suitable assay for the functional property / activity. For example, an isoform, fragment, variant or homologue of HER3 may display association with one or more of: HER2, NRG1 (type I, II, III, IV, V or VI) or NRG2 (a or p). In some embodiments, the HER3 comprises, or consists of, an amino acid sequence having at least 70%, preferably one of 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to one of SEQ ID NOs:1 to 8.

[0052] In some embodiments, a fragment of HER3 comprises, or consists of, an amino acid sequence having at least 70%, preferably one of 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to one of SEQ ID NOs:9 to 19, e.g. one of 9, 16 or 19.

[0053] Signaling through HER3 involves receptor heteromultimerization ( / .e. with other ErBB receptors, e.g. HER2, EGFR) and consequent autophosphorylation by the protein kinase domain of tyrosine residues of the cytoplasmic region. HER3 lacks kinase activity and does not form stable homodimers. Therefore, HER3 must be transphosphorylated by binding to a kinase-active heterodimer partner (e.g. EGFR or HER2) for signal transduction to take place (Berger MB et al., FEBS Lett 2004;569:332-6; Kim HH et al., Biochem J 1998;334:189-95.).

[0054] Multimerization (e.g. dimerization) of HER receptor family members is required for activating cell growth signaling pathways, and HER3 can dimerize with other HER family members in both a ligand-dependent and ligand-independent manner. The HER3 extracellular domain (ECD) exists in a reversible equilibrium between a ‘closed’ inactive conformation and an ‘open’ active conformation, in which the dimerization arm within domain II is exposed to allow dimerization along the domain II dimerization interface, and in particular through the cysteine-rich CR1 region (Carraway, K. L., et al., Nature, 1997. 387(6632): 512-6; Riese, D. J., et al., Mol Cell Biol, 1995. 15(10): 5770-6; Harari, D., et al., Oncogene, 1999. 18(17): 2681- 9; Zhang, D., et al., Proc Natl Acad Sci USA, 1997. 94(18): 9562-7; Meyer et al., Nature, 1995. 378(6555):386-90; Jura, N., et al., Proc Natl Acad Sci USA, 2009. 106(51): 21608-13; Fornaro, L., et al., Nat Rev Gastroenterol Hepatol, 2011. 8(7):369-83; Mota et al., Oncotarget (2015) 5:89284-306). HER3 is ‘activated’ when the equilibrium is shifted in favor of the open conformation, increasing the probability of forming active heterodimers. The conventional model for activation is ligand-dependent, that is, the equilibrium shifts when HER3 in the open conformation is stabilized by binding of its ligand such as a neuregulin (NRG), e.g. NRG1 (also known as heregulin, HRG) or NRG2. In addition, the presence of any dimerization partner at a sufficient concentration will shift the equilibrium in favor of the open conformation, as they bind to and stabilize HER3 transiently in an open conformation. This is known as ligand-independent activation (Jura, N., et al., Proc Natl Acad Sci USA, 2009. 106(51): 21608-13; Fornaro, L., et al., Nat Rev Gastroenterol Hepatol, 2011. 8(7): p. 369-83; Mota et al., Oncotarget (2015) 5:89284-306).

[0055] Herein, ‘HER3-mediated signaling’ refers to signaling mediated by HER3 and / or multimeric ErbB family member receptor complexes comprising HER3. ‘Signaling’ refers to signal transduction and other cellular processes governing cellular activity. HER3-mediated signaling may be mediated by HER3 receptorcontaining complexes, e.g. by heteromultimeric complexes comprising HER3 and other HER receptors (e.g. HER2, EGFR). HER3-mediated signaling may be ligand-dependent, e.g. triggered by binding of NRG (e.g. NRG1 , NRG2), or may be ligand-independent. HER3-mediated signaling progresses intracellularly through the MAPK / ERK and PI3K / AKT / mT0R pathways to promote cell survival and proliferation. HER3-mediated signaling is described e.g. in Gala and Chandarlapaty, Clin Cancer Res. (2014) 20(6): 1410-1416, Mishra et al., Oncol Rev. (2018) 12(1): 355, Baselga et al., Nat Rev Cancer (2009) 9:463-75, Yarden et al. Nat Rev Mol Cell Biol (2001) 2:35052073, Mota et al., Oncotarget (2015) 5:89284-306 and Haikala and Janne, Clin. Cancer Res. (2021) 27:3528-39, all of which are hereby incorporated by reference in their entirety.

[0056] Phosphorylated tyrosine residues in the protein kinase domains of HER3-containing receptor complexes recruit adaptor / effector protein GRB2, via interaction with its SH2 domain. Upon ligand stimulation, the activated receptor (EGFR / HER2) undergoes autophosphorylation and provides phospho-tyrosine residues for recruiting GRB2. GRB2 binds via its SH3 domains to the guanine nucleotide exchange factor SOS. Activated SOS in GRB2-SOS complexes promotes removal of GDP from, and thereby activation of, Ras family GTPases such as H-Ras, N-Ras and K-Ras. Activated Ras GTPases in turn activate RAF kinases such as A-Raf, B-Raf and C-Raf. RAF kinases in turn phosphorylate and activate MEK1 and MEK2, which then phosphorylate and activate MAPKs (also known as ERKs). Activated MAPKs are able to directly regulate the activity of transcription factors such as c-Myc. Activated MAPKs also upregulate translation of mRNA into protein via phosphorylation of RSK, and consequent phosphorylation and activation of 40S ribosomal protein S6. Activated MAPKs also phosphorylate and activate MNK, which in turn phosphorylates and activates the transcription factor CREB.

[0057] Phosphorylated tyrosine residues in the protein kinase domain of HER3 also recruit the p85 subunit of PI3K, through its SH2 domain. Association of p85 causes allosteric activation of the lipid kinase p100a subunit of PI3K. Activated PI3K results in conversion of PIP2 to PIP3, which recruits AKT to be phosphorylated and activated by mTORC2 and PDK1. Phosphorylated AKT has a number of activities, including activating CREB and mTOR. PTEN antagonizes signaling through the PI3K / AKT / mTOR pathway by dephosphorylating PIP3 to PIP2, and PP2A inhibits the PI3K / AKT / mTOR pathway by dephosphorylating AKT.

[0058] Oncogenic Src homology region 2 protein tyrosine phosphatase 2 (SHP2) promotes tumor progression and serves as a pivotal hub to connect multiple oncogenic signaling pathways, such as PI3K / AKT, Ras / Raf / MAPK (Dong et al., Front. Cell Dev. Biol., 11 March 2021). GAB2 binds to GRB2 and becomes phosphorylated at multiple tyrosine residues, capable of binding to the SH2 domains of SHP2 and p85 (Adams et al., Mol Cancer Res. 2012 Oct; 10(10):1265-70; (Liu et al., Proc. Natl. Acad. Sci. U.S.A. (2016) 113, 984-989). The interactions induce conformation changes, relieving the auto-inhibition of the SHP2 catalytic site (Neel et al., Trends Biochem Sci. 2003 Jun; 28(6):284-93) and relieving the inhibition of p85 on the p110 catalytic subunit of PI3K (Cuevas et al., J Biol Chem. 2001 Jul 20; 276(29):27455-6), respectively. SHP2 has been shown to activate RAS by direct dephosphorylation of RAS (Bunda et al., Nat Commun. 2015 Nov 30; 6:8859), inhibition of RASGAP (RAS GTPase activating protein) (Neel et al., Trends Biochem Sci. 2003 Jun; 28(6):284-93) and SPRY (Hanafusa et al., J Biol Chem. 2004 May 28; 279(22) :22992-5). SHP2 overexpression has been shown to enhance tumor invasion by activating the PI3K / AKT axis (Hu et al., Onco Targets Ther. (2017) 10, 3881-3891) while SHP2 knockdown inhibits cell migration and the tumor-promoting effect of SHP2 is partially related to AKT signaling (Cao et al., Pathol. Res. Pract. (2019) 215:152621).

[0059] STAT3 and 5 proteins are transcription factors that enhance the expression of p85a, p110a and AKT1 and thereby augment signaling through the PI3K / AKT signal transduction cascade (Radler et al., Mol Cell Endocrinol. 2017 August 15; 451 : 31-39). Upon activation by JAK2, phosphorylated STAT5 binds to the SH2 domain of the p85a regulatory subunit of PI3K in a PRL signaling-dependent manner suggesting that STAT5 may also directly participate in the signaling of PI3K complexes. Another kinase that phosphorylates EGFR is the cytokine-regulated tyrosine kinase Jak2, thus allowing MAPK activation even by a kinase-defective mutant of EGFR (Mishra et al., Oncol Rev. (2018) 12(1): 355, Baselga etal., Nat Rev Cancer (2009) 9:463-75). The collective observations in genetic models overexpressing or lacking active STAT5 and AKT or expressing mutant PTEN supports the notion that STAT5 functions as a survival factor during normal mammary gland development and as an oncogene during mammary carcinogenesis are mediated by the PI3K / AKT pathway (Radler et al., Mol Cell Endocrinol. 2017 August 15; 451 : 31-39).

[0060] Antigen-binding molecules that bind to HER3

[0061] The present disclosure relates to the therapeutic and prophylactic use of antigen-binding molecules that bind to HER3.

[0062] An ‘antigen-binding molecule’ refers to a molecule that binds to a given target antigen. Antigen-binding molecules include antibodies ( / .e. immunoglobulins (Igs)) and antigen-binding fragments thereof. As used herein, ‘antibodies’ include monoclonal antibodies, polyclonal antibodies, monospecific and multispecific (e.g., bispecific, trispecific, etc.) antibodies, and antibody-derived antigen-binding molecules such as scFv, scFab, diabodies, triabodies, scFv-Fc, minibodies, single domain antibodies (e.g. VhH, etc.). Antigen-binding fragments of antibodies include e.g. Fv, Fab, F(ab’)2 and F(ab’) fragments. In some embodiments, an antigen-binding molecule may be an antibody or an antigen-binding fragment thereof.

[0063] Antigen-binding molecules according to the present disclosure also include antibody-derived molecules, e.g. molecules comprising an antigen-binding region / domain derived from an antibody. Antibody-derived antigen-binding molecules may comprise an antigen-binding region / domain that comprises, or consists of, the antigen-binding region of an antibody (e.g. an antigen-binding fragment of an antibody). In some embodiments, the antigen-binding region / domain of an antibody-derived antigen-binding molecule may be or comprise the Fv (e.g. provided as an scFv) or the Fab region of an antibody, or the whole antibody. For example, antigen-binding molecules according to the present disclosure include antibody-drug conjugates (ADCs) comprising a (cytotoxic) drug moiety (e.g. as described hereinbelow). Antigen-binding molecules according to the present disclosure also include multispecific antigen-binding molecules such as immune cell engager molecules comprising a domain for recruiting (effector) immune cells (reviewed e.g. in Goebeler and Bargou, Nat. Rev. Clin. Oncol. (2020) 17: 418-434 and Ellerman, Methods (2019) 154:102-117), both of which are hereby incorporated by reference in their entirety), including BiTEs, BiKEs and TriKEs. Antigen-binding molecules according to the present disclosure also include chimeric antigen receptors (CARs), which are recombinant receptors providing both antigen-binding and T cell activating functions (CAR structure, function and engineering is reviewed e.g. in Dotti etal., Immunol Rev (2014) 257(1) and Jayaraman et al., EBioMedicine (2020) 58:102931 , both of which are hereby incorporated by reference in their entirety).

[0064] The antigen-binding molecules of the present disclosure comprise a moiety or moieties capable of binding to a target antigen(s). In some embodiments, the moiety capable of binding to a target antigen comprises an antibody heavy chain variable region (VH) and an antibody light chain variable region (VL) of an antibody capable of specific binding to the target antigen. In some embodiments, the moiety capable of binding to a target antigen comprises or consists of an aptamer capable of binding to the target antigen, e.g. a nucleic acid aptamer (reviewed, for example, in Zhou and Rossi Nat Rev Drug Discov. 2017 16(3):181-202). In some embodiments, the moiety capable of binding to a target antigen comprises or consists of an antigen-binding peptide / polypeptide, e.g. a peptide aptamer, thioredoxin, monobody, anticalin, Kunitz domain, avimer, knottin, fynomer, atrimer, DARPin, affibody, nanobody ( / .e. a singledomain antibody (sdAb)), affilin, armadillo repeat protein (ArmRP), OBody or fibronectin - reviewed e.g. in Reverdatto et al., Curr Top Med Chem. 2015; 15(12): 1082-1101 , which is hereby incorporated by reference in its entirety (see also e.g. Boersma et al., J Biol Chem (2011) 286:41273-85 and Emanuel et al., Mabs (2011) 3:38-48).

[0065] As used herein, a ‘peptide’ refers to a chain of two or more amino acid monomers linked by peptide bonds. A peptide typically has a length in the region of about 2 to 50 amino acids. A ‘polypeptide’ is a polymer chain of two or more peptides. Polypeptides typically have a length greater than about 50 amino acids.

[0066] The antigen-binding molecules of the present disclosure generally comprise an antigen-binding domain comprising a VH and a VL of an antibody capable of specific binding to the target antigen. The antigenbinding domain formed by a VH and a VL may also be referred to herein as an Fv region.

[0067] An antigen-binding molecule may be, or may comprise, an antigen-binding polypeptide, or an antigenbinding polypeptide complex. An antigen-binding molecule may comprise more than one polypeptide which together form an antigen-binding domain. The polypeptides may associate covalently or non- covalently. In some embodiments, the polypeptides form part of a larger polypeptide comprising the polypeptides (e.g. in the case of scFv comprising VH and VL, or in the case of scFab comprising VH-CH1 and VL-CL).

[0068] An antigen-binding molecule may refer to a non-covalent or covalent complex of more than one polypeptide (e.g. 2, 3, 4, 6, or 8 polypeptides), e.g. an IgG-like antigen-binding molecule comprising two heavy chain polypeptides and two light chain polypeptides.

[0069] The antigen-binding molecules of the present disclosure may be designed and prepared using the sequences of monoclonal antibodies (mAbs) capable of binding to a given target antigen (e.g. HER3). Antigen-binding regions of antibodies, such as single chain variable fragment (scFv), Fab and F(ab’)2 fragments may also be used / provided. An ‘antigen-binding region’ is any fragment of an antibody that binds to the target for which the given antibody is specific.

[0070] Antibodies generally comprise six complementarity-determining regions (CDRs); three in the heavy chain variable (VH) region: HC-CDR1 , HC-CDR2 and HC-CDR3, and three in the light chain variable (VL) region: LC-CDR1 , LC-CDR2, and LC-CDR3. The six CDRs together define the paratope of the antibody, which is the part of the antibody that binds to the target antigen.

[0071] The VH region and VL region comprise framework regions (FRs) either side of each CDR, which provide a scaffold for the CDRs. From N-terminus to C-terminus, VH regions comprise the following structure: N term-[HC-FR1]-[HC-CDR1]-[HC-FR2]-[HC-CDR2]-[HC-FR3]-[HC-CDR3]-[HC-FR4]-C term; and VL regions comprise the following structure: N term-[LC-FR1]-[LC-CDR1]-[LC-FR2]-[LC-CDR2]-[LC-FR3]- [LC-CDR3]-[LC-FR4]-C term.

[0072] There are several different conventions for defining antibody CDRs and FRs, such as those described in Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD (1991), Chothia et a!., J. Mol. Biol. 196:901-917 (1987), and VBASE2, as described in Retter et al., Nucl. Acids Res. (2005) 33 (suppl 1): D671-D674. The CDRs and FRs of the VH regions and VL regions of the antibody clones described herein were defined according to the international IMGT (ImMunoGeneTics) information system (LeFranc et al., Nucleic Acids Res. (2015) 43 (Database issue):D413-22), which uses the IMGT V-DOMAIN numbering rules as described in Lefranc et al., Dev. Comp. Immunol. (2003) 27:55-77. In preferred embodiments, the CDRs and FRs of antigenbinding molecules referred to herein are defined according to the IMGT information system.

[0073] The VH and VL region of an antigen-binding region of an antibody together constitute the Fv region. In some embodiments, an antigen-binding molecule according to the present disclosure comprises, or consists of, an Fv region that binds to HER3. In some embodiments, the VH and VL regions of the Fv are provided as single polypeptide joined by a linker sequence, i.e. a single chain Fv (scFv).

[0074] The VL and light chain constant (CL) region, and the VH region and heavy chain constant 1 (CH1) region of an antigen-binding region of an antibody together constitute the Fab region. In some embodiments, the antigen-binding molecule comprises a Fab region comprising a VH, a CH1 , a VL and a CL (e.g. CK or CA). In some embodiments, the Fab region comprises a polypeptide comprising a VH and a CH1 (e.g. a VH-CH1 fusion polypeptide), and a polypeptide comprising a VL and a CL (e.g. a VL-CL fusion polypeptide). In some embodiments, the Fab region comprises a polypeptide comprising a VH and a CL (e.g. a VH-CL fusion polypeptide) and a polypeptide comprising a VL and a CH (e.g. a VL-CH1 fusion polypeptide); that is, in some embodiments, the Fab region is a CrossFab region. In some embodiments, the VH, CH1 , VL and CL regions of the Fab or CrossFab are provided as single polypeptide joined by linker regions, i.e. as a single chain Fab (scFab) or a single chain CrossFab (scCrossFab).

[0075] In some embodiments, an antigen-binding molecule described herein comprises, or consists of, a whole antibody which binds to HER3. As used herein, ‘whole antibody’ refers to an antibody having a structure which is substantially similar to the structure of an immunoglobulin (Ig). Different kinds of immunoglobulins and their structures are described e.g. in Schroeder and Cavacini J Allergy Clin Immunol. (2010) 125(202): S41-S52, which is hereby incorporated by reference in its entirety.

[0076] Immunoglobulins of type G ( / .e. IgG) are -150 kDa glycoproteins comprising two heavy chains and two light chains. From N- to C-terminus, the heavy chains comprise a VH followed by a heavy chain constant region comprising three constant domains (CH1 , CH2, and CH3), and similarly the light chains comprise a VL followed by a CL. Depending on the heavy chain, immunoglobulins may be classed as IgG (e.g. IgG 1 , lgG2, lgG3, lgG4), IgA (e.g. lgA1 , lgA2), IgD, IgE, or IgM. The light chain may be kappa (K) or lambda (A).

[0077] In some embodiments, the antigen-binding molecule comprises, or consists of, an IgG (e.g. lgG1 , lgG2, lgG3, lgG4), IgA (e.g. lgA1 , lgA2), IgD, IgE, or IgM which binds to HER3.

[0078] In some embodiments described herein, one or more amino acids of an amino acid sequence referred to herein (e.g. an amino acid sequence of an antigen-binding molecule, e.g. an amino acid sequence of a CDR or VHA / L region) are substituted with another amino acid. A substitution comprises substitution of an amino acid residue with a non-identical 'replacement' amino acid residue. A ‘replacement’ amino acid residue of a substitution according to the present disclosure may be a naturally-occurring amino acid residue ( / .e. encoded by the genetic code) which is non-identical to the amino acid residue at the relevant position of the equivalent, unsubstituted amino acid sequence, selected from: alanine (Ala), arginine (Arg), asparagine (Asn), aspartic acid (Asp), cysteine (Cys), glutamine (Gin), glutamic acid (Glu), glycine (Gly), histidine (His), isoleucine (lie): leucine (Leu), lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr), and valine (Vai). In some embodiments, a replacement amino acid may be a non-naturally occurring amino acid residue - i.e. an amino acid residue other than those recited in the preceding sentence. Examples of non-naturally occurring amino acid residues include norleucine, ornithine, norvaline, homoserine, aib, and other amino acid residue analogues such as those described in Ellman, etal., Meth. Enzym. 202 (1991) 301-336.

[0079] In some embodiments, a substitution may be biochemically conservative. In some embodiments, where an amino acid to be substituted is provided in one of rows 1 to 5 of the table below, the replacement amino acid of the substitution is another, non-identical amino acid provided in the same row: By way of illustration, in some embodiments wherein substitution is of a Met residue, the replacement amino acid may be selected from Ala, Vai, Leu, lie, Trp, Tyr, Phe and Norleucine.

[0080] In some embodiments, a replacement amino acid in a substitution may have the same side chain polarity as the amino acid residue it replaces. In some embodiments, a replacement amino acid in a substitution may have the same side chain charge (at pH 7.4) as the amino acid residue it replaces:

[0081] That is, in some embodiments, a nonpolar amino acid is substituted with another, non-identical nonpolar amino acid. In some embodiments, a polar amino acid is substituted with another, non-identical polar amino acid. In some embodiments, an acidic polar amino acid is substituted with another, non-identical acidic polar amino acid. In some embodiments, a basic polar amino acid is substituted with another, non- identical basic polar amino acid. In some embodiments, a neutral amino acid is substituted with another, non-identical neutral amino acid. In some embodiments, a positive amino acid is substituted with another, non-identical positive amino acid. In some embodiments, a negative amino acid is substituted with another, non-identical negative amino acid. In some embodiments, substitution(s) may be functionally conservative. That is, in some embodiments, the substitution may not affect (or may not substantially affect) one or more functional properties (e.g. target binding) of the antigen-binding molecule comprising the substitution as compared to the equivalent unsubstituted molecule.

[0082] The antigen-binding molecules of the present disclosure bind to HER3.

[0083] In some embodiments, the antigen-binding molecule comprises the CDRs of an antigen-binding molecule which is capable of binding to HER3. In some embodiments, the antigen-binding molecule comprises the FRs of an antigen-binding molecule which is capable of binding to HER3. In some embodiments, the antigen-binding molecule comprises the CDRs and the FRs of an antigen-binding molecule which is capable of binding to HER3. That is, in some embodiments the antigen-binding molecule comprises the VH region and the VL region of an antigen-binding molecule which is capable of binding to HER3.

[0084] In some embodiments, an antigen-binding molecule which is capable of binding to HER3 according to the present disclosure may be selected from: any embodiment of an antigen-binding molecule described in WO 2019 / 185878 A1 (which is hereby incorporated by reference in its entirety), 10D1 F (described e.g. in WO 2019 / 185878 A1), seribantumab (also known as MM-121 , described e.g. in Schoeberl etal., Sci. Signal. (2009) 2(77): ra31 ; DrugBank Acc. No. DB11857), elgemtumab (also known as LJM-716, described e.g. in Garner et al., Cancer Res (2013) 73: 6024-6035; DrugBank Acc. No. DB15430), patritumab (also known as U-1287 and AMG-888, described e.g. in Shimizu et al. Cancer Chemother Pharmacol. (2017) 79(3):489-495; DrugBank Acc. No. DB12090), GSK2849330 (described e.g. in Clarke et al., Eur J Cancer. (2014) 50:98-9), lumretuzumab (also known as RG7116 and RO-5479599, described e.g. in Mirschberger et al. Cancer Research (2013) 73(16) 5183-5194; DrugBank Acc. No. DB12683), CDX-3379 (also known as KTN3379, described e.g. in Lee et al., Proc Natl Acad Sci U S A. 2015 Oct 27; 112(43): 13225), AV-203 (also known as CAN-017, described e.g. in Meetze et al., Eur J Cancer 2012; 48:126), barecetamab (also known as ISU104, described e.g. in Kim et al., Cancer Res (2018) 78(13 Suppl): Abstract #830), TK-A3, TK-A4 (described e.g. in Malm et al., MAbs (2016) 8:1195- 209), MP-EV20 (described e.g. in Sala et al., Transl. Oncol. (2013) 6:676-84), 1A5-3D4 (described e.g. in Wang et al., Cancer Lett (2016) 380:20-30), 9F7-F11 , 16D3-C1 (described e.g. in Lazrek etal., Neoplasia (2013) 15:335-47), NG33, A5, F4 (described e.g. in Gaborit et al., PNAS USA (2015) 112:839-44), huHER3-8 (described e.g. in Kugel et al., Cancer Res. (2014) 74:4122-32), REGN1400 (described e.g. in Zhang etal., Mol Cancer Ther (2014) 13:1345-1355) and zenocutuzumab (also known as MCLA-128, described e.g. in de Vries Schultink et al., Clin Pharmacokinet. (2020) 59: 875-884; DrugBank Acc. No. DB15559).

[0085] In some embodiments, the antigen-binding molecule is 10D1 F. Herein, ‘10D1 F’ may refer to an antigenbinding molecule comprising a VH region having the amino acid sequence of SEQ ID NO:33, and a VL region having the amino acid sequence of SEQ ID NO:58. In some embodiments, the antigen-binding molecule binds to the extracellular region of HER3 (e.g. the region shown in SEQ ID NO:9). In some embodiments, the antigen-binding molecule binds to subdomain II of the extracellular region of HER3 (e.g. the region shown in SEQ ID NO:16).

[0086] In some embodiments, the antigen-binding molecule binds to the region of HER3 shown in SEQ ID NO:77. In some embodiments the antigen-binding molecule contacts one or more amino acid residues of the region of HER3 shown in SEQ ID NO:77. In some embodiments, the antigen-binding molecule binds to the regions of HER3 shown in SEQ ID NOs:78 and 79. In some embodiments the antigen-binding molecule contacts one or more amino acid residues of the regions of HER3 shown in SEQ ID NOs:78 and 79. In some embodiments, the antigen-binding molecule binds to the region of HER3 shown in SEQ ID NO:78. In some embodiments the antigen-binding molecule contacts one or more amino acid residues of the region of HER3 shown in SEQ ID NO:78. In some embodiments, the antigen-binding molecule binds to the region of HER3 shown in SEQ ID NO:79. In some embodiments the antigen-binding molecule contacts one or more amino acid residues of the region of HER3 shown in SEQ ID NO:79.

[0087] In some embodiments, the antigen-binding molecule does not bind to the region of HER3 corresponding to positions 260 to 279 of SEQ ID NO:1 . In some embodiments the antigen-binding molecule does not contact an amino acid residue of the region of HER3 corresponding to positions 260 to 279 of SEQ ID NO:1.

[0088] The region of a peptide / poly peptide to which an antibody binds can be determined by the skilled person using various methods well known in the art, including X-ray co-crystallography analysis of antibodyantigen complexes, peptide scanning, mutagenesis mapping, hydrogen-deuterium exchange analysis by mass spectrometry, phage display, competition ELISA and proteolysis-based ‘protection’ methods. Such methods are described, for example, in Gershoni et al., BioDrugs, 2007, 21 (3):145-156, which is hereby incorporated by reference in its entirety.

[0089] In some embodiments the antigen-binding molecule is capable of binding the same region of HER3, or an overlapping region of HER3, to the region of HER3 which is bound by an antibody comprising the VH and VL sequences of one of antibody clones 10D1_c89, 10D1 , 10D1_c75, 10D1_c76, 10D1_c77, 10D1_c78v1 , 10D1_c78v2, 10D1_11 B, 10D1_c85v1 , 10D1_c85v2, 10D1_c85o1 , 10D1_c85o2, 10D1_c87, 10D1_c90, 10D1_c91 , 10D1_c92 and 10D1_c93 described herein. In some embodiments the antigen-binding molecule is capable of binding the same region of HER3, or an overlapping region of HER3, to the region of HER3 which is bound by an antibody comprising the VH and VL sequences of antibody clone 10D1_c89.

[0090] In some embodiments, the antigen-binding molecule is capable of binding to a polypeptide comprising, or consisting of, the amino acid sequence of one of SEQ ID NOs:1 , 3, 4, 6 or 8. In some embodiments, the antigen-binding molecule is capable of binding to a polypeptide comprising, or consisting of, the amino acid sequence of SEQ ID NO:9. In some embodiments, the antigen-binding molecule is capable of binding to a polypeptide comprising, or consisting of, the amino acid sequence of SEQ ID NO:16. In some embodiments, the antigen-binding molecule is capable of binding to a peptide / polypeptide comprising, or consisting of, the amino acid sequence of SEQ ID NO:77. In some embodiments, the antigen-binding molecule is capable of binding to a peptide / polypeptide comprising, or consisting of, the amino acid sequences of SEQ ID NOs:78 and 79. In some embodiments, the antigen-binding molecule is capable of binding to a peptide / polypeptide comprising, or consisting of, the amino acid sequence of SEQ ID NO:78. In some embodiments, the antigen-binding molecule is capable of binding to a peptide / polypeptide comprising, or consisting of, the amino acid sequence of SEQ ID NO:79.

[0091] In some embodiments, the antigen-binding molecule is not capable of binding to a peptide consisting of the amino acid sequence corresponding to positions 260 to 279 of SEQ ID NO:1 .

[0092] The ability of an antigen-binding molecule to bind to a given peptide / polypeptide can be analyzed by methods well known to the skilled person, including analysis by ELISA, immunoblot (e.g. western blot), immunoprecipitation, Surface Plasmon Resonance (SPR; see e.g. Hearty et al., Methods Mol Biol (2012) 907:411-442) or Bio-Layer Interferometry (see e.g. Lad et al., (2015) J Biomol Screen 20(4): 498-507).

[0093] In embodiments where the antigen binding molecule is capable of binding to a peptide / polypeptide comprising a reference amino acid sequence, the peptide / polypeptide may comprise one or more additional amino acids at one or both ends of the reference amino acid sequence. In some embodiments the peptide / polypeptide comprises e.g. 1-5, 1-10, 1-20, 1-30, 1-40, 1-50, 5-10, 5-20, 5-30, 5-40, 5-50, IQ- 20, 10-30, 10-40, 10-50, 20-30, 20-40 or 20-50 additional amino acids at one or both ends of the reference amino acid sequence.

[0094] In some embodiments the additional amino acid(s) provided at one or both ends ( / .e. the N-terminal and / or C-terminal ends) of the reference sequence correspond to the positions at the ends of the reference sequence in the context of the amino acid sequence of HER3.

[0095] In some embodiments the antigen-binding molecule is capable of binding to a peptide / polypeptide which is bound by an antibody comprising the VH and VL sequences of one of antibody clones 10D1_c89, 10D1 , 10D1_c75, 10D1_c76, 10D1_c77, 10D1_c78v1 , 10D1_c78v2, 10D1_11B, 10D1_c85v1 , 10D1_c85v2, 10D1_c85o1 , 10D1_c85o2, 10D1_c87, 10D1_c90, 10D1_c91 , 10D1_c92 and 10D1_c93 described herein. In some embodiments the antigen-binding molecule is capable of binding to a peptide / polypeptide which is bound by an antibody comprising the VH and VL sequences of antibody clone 10D1_c89.

[0096] In some embodiments, the antigen-binding molecule comprises the CDRs of, or comprises the VH and VL of, a HER3-binding antibody clone selected from 10D1_c89, 10D1 , 10D1_c75, 10D1_c76, 10D1_c77, 10D1_c78v1 , 10D1_c78v2, 10D1_11 B, 10D1_c85v1 , 10D1_c85v2, 10D1_c85o1 , 10D1_c85o2, 10D1_c87, 10D1_c90, 10D1_c91 , 10D1_c92 and 10D1_c93.

[0097] In some embodiments, the antigen-binding molecule comprises:

[0098] (1) a VH region incorporating the following CDRs:

[0099] HC-CDR1 having the amino acid sequence of SEQ ID NQ:40 HC-CDR2 having the amino acid sequence of SEQ ID NO:43

[0100] HC-CDR3 having the amino acid sequence of SEQ ID NO:48, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0101] LC-CDR1 having the amino acid sequence of SEQ ID NO:66

[0102] LC-CDR2 having the amino acid sequence of SEQ ID NO:69

[0103] LC-CDR3 having the amino acid sequence of SEQ ID NO:74; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0104] (2) a VH region incorporating the following CDRs:

[0105] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0106] HC-CDR2 having the amino acid sequence of SEQ ID NO:41

[0107] HC-CDR3 having the amino acid sequence of SEQ ID NO:44, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0108] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0109] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0110] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0111] (3) a VH region incorporating the following CDRs:

[0112] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0113] HC-CDR2 having the amino acid sequence of SEQ ID NO:41

[0114] HC-CDR3 having the amino acid sequence of SEQ ID NO:44, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0115] LC-CDR1 having the amino acid sequence of SEQ ID NO:64

[0116] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0117] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0118] (4) a VH region incorporating the following CDRs:

[0119] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0120] HC-CDR2 having the amino acid sequence of SEQ ID NO:41

[0121] HC-CDR3 having the amino acid sequence of SEQ ID NO:44, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0122] LC-CDR1 having the amino acid sequence of SEQ ID NO:65

[0123] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0124] LC-CDR3 having the amino acid sequence of SEQ ID NO:71 ; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0125] (5) a VH region incorporating the following CDRs:

[0126] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0127] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0128] HC-CDR3 having the amino acid sequence of SEQ ID NO:45, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0129] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0130] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0131] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0132] (6) a VH region incorporating the following CDRs:

[0133] HC-CDR1 having the amino acid sequence of SEQ ID NO:39

[0134] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0135] HC-CDR3 having the amino acid sequence of SEQ ID NO:45, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0136] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0137] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0138] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0139] (7) a VH region incorporating the following CDRs:

[0140] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0141] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0142] HC-CDR3 having the amino acid sequence of SEQ ID NO:44, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs: LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0143] LC-CDR2 having the amino acid sequence of SEQ ID NO:68

[0144] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0145] (8) a VH region incorporating the following CDRs:

[0146] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0147] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0148] HC-CDR3 having the amino acid sequence of SEQ ID NO:46, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0149] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0150] LC-CDR2 having the amino acid sequence of SEQ ID NO:68

[0151] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0152] (9) a VH region incorporating the following CDRs:

[0153] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0154] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0155] HC-CDR3 having the amino acid sequence of SEQ ID NO:47, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0156] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0157] LC-CDR2 having the amino acid sequence of SEQ ID NO:68

[0158] LC-CDR3 having the amino acid sequence of SEQ ID NQ:70; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0159] (10) a VH region incorporating the following CDRs:

[0160] HC-CDR1 having the amino acid sequence of SEQ ID NO:38

[0161] HC-CDR2 having the amino acid sequence of SEQ ID NO:42

[0162] HC-CDR3 having the amino acid sequence of SEQ ID NO:45, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0163] LC-CDR1 having the amino acid sequence of SEQ ID NO:63

[0164] LC-CDR2 having the amino acid sequence of SEQ ID NO:67

[0165] LC-CDR3 having the amino acid sequence of SEQ ID NO:72; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0166] (11) a VH region incorporating the following CDRs:

[0167] HC-CDR1 having the amino acid sequence of SEQ ID NO:38 HC-CDR2 having the amino acid sequence of SEQ ID NO:41 HC-CDR3 having the amino acid sequence of SEQ ID NO:44, or a variant thereof in which one or two or three amino acids in one or more of HC-CDR1 , HC- CDR2, or HC-CDR3 are substituted with another amino acid; and a VL region incorporating the following CDRs:

[0168] LC-CDR1 having the amino acid sequence of SEQ ID NO:63 LC-CDR2 having the amino acid sequence of SEQ ID NO:67 LC-CDR3 having the amino acid sequence of SEQ ID NO:73; or a variant thereof in which one or two or three amino acids in one or more of LC-CDR1 , LC- CDR2 or LC-CDR3 are substituted with another amino acid.

[0169] In some embodiments, the antigen-binding molecule comprises:

[0170] (12) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:21 ; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:49.

[0171] (13) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:22; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NQ:50.

[0172] (14) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:23; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:51.

[0173] (15) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:24; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:52.

[0174] (16) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:25; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:53.

[0175] (17) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:26; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:53.

[0176] (18) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:27; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:53.

[0177] (19) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:28; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:54.

[0178] (20) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:29; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:54.

[0179] (21) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NQ:30; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:55.

[0180] (22) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:31 ; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:56.

[0181] (23) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:32; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:57.

[0182] (24) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:33; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:58.

[0183] (25) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:34; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:59.

[0184] (26) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:35; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NQ:60.

[0185] (27) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:36; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:61.

[0186] (28) a VH region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:37; and a VL region comprising an amino acid sequence having at least 70% sequence identity, more preferably one of at least 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%, sequence identity to the amino acid sequence of SEQ ID NO:62.

[0187] In some embodiments, an antigen-binding molecule comprises, or consists of:

[0188] (29) (i) one or more (e.g. two) polypeptides comprising, or consisting of, an amino acid sequence having at least 70%, preferably one of 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to the amino acid sequence of SEQ ID NO:75; and

[0189] (ii) one or more (e.g. two) polypeptides comprising, or consisting of, an amino acid sequence having at least 70%, preferably one of 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% amino acid sequence identity to the amino acid sequence of SEQ ID NO:76.

[0190] In some embodiments, the antigen-binding molecules of the present disclosure comprise an Fc region.

[0191] An Fc region is composed of CH2 and CH3 regions from one polypeptide, and CH2 and CH3 regions from another polypeptide. The CH2 and CH3 regions from the two polypeptides together form the Fc region.

[0192] Fc-mediated functions include Fc receptor binding, antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cell-mediated phagocytosis (ADCP), complement-dependent cytotoxicity (CDC), formation of the membrane attack complex (MAC), cell degranulation, cytokine and / or chemokine production, and antigen processing and presentation.

[0193] Cancers

[0194] The present disclosure relates to the treatment and prevention of cancers.

[0195] A cancer in accordance with the present disclosure may be any unwanted cell proliferation (or any disease manifesting itself by unwanted cell proliferation), neoplasm or tumor. The cancer may be benign or malignant. The cancer may be primary or secondary (e.g. metastatic). A neoplasm or tumor may be any abnormal growth or proliferation of cells, and may be located in (and / or derived from cells of) any organ / tissue.

[0196] A cancer may be of cells derived from e.g. the adrenal gland, adrenal medulla, anus, appendix, bladder, blood, bone, bone marrow, brain, breast, cecum, central nervous system (including or excluding the brain) cerebellum, cervix, colon, duodenum, endometrium, epithelial cells (e.g. renal epithelia), gallbladder, oesophagus, glial cells, heart, ileum, jejunum, kidney, lacrimal glad, larynx, liver, lung, lymph, lymph node, lymphoblast, maxilla, mediastinum, mesentery, myometrium, nasopharynx, omentum, oral cavity, ovary, pancreas, parotid gland, peripheral nervous system, peritoneum, pleura, prostate, salivary gland, sigmoid colon, skin, small intestine, soft tissues, spleen, stomach, testis, thymus, thyroid gland, tongue, tonsil, trachea, uterus, vulva, and / or white blood cells.

[0197] A cancer may be, or may comprise, one or more tumors. A cancer may be a glioma, medulloblastoma, meningioma, neurofibroma, ependymoma, Schwannoma, neurofibrosarcoma, astrocytoma and oligodendroglioma, melanoma, mesothelioma, myeloma, lymphoma, Non-Hodgkin’s lymphoma (NHL), Hodgkin’s lymphoma, cutaneous T-cell lymphoma (CTCL), leukemia, chronic myelogenous leukemia (CML), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), myelodysplastic syndrome (MDS), hepatoma, epidermoid carcinoma, prostate cancer, breast cancer, lung cancer, non-small cell lung cancer (NSCLC), colon cancer, ovarian cancer, pancreatic cancer, thymic cancer, hematologic cancer or sarcoma.

[0198] In some embodiments, a cancer according to the present disclosure is selected from: a solid tumor, breast cancer, breast carcinoma, ductal carcinoma, gastric cancer, gastric carcinoma, gastric adenocarcinoma, colorectal cancer, colorectal carcinoma, colorectal adenocarcinoma, head and neck cancer, squamous cell carcinoma of the head and neck (SCCHN), lung cancer, non-small cell lung cancer, lung adenocarcinoma, squamous cell lung carcinoma, ovarian cancer, ovarian carcinoma, ovarian serous adenocarcinoma, renal cancer, renal cell carcinoma, renal clear cell carcinoma, renal cell adenocarcinoma, renal papillary cell carcinoma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, cervical cancer, cervical squamous cell carcinoma, skin cancer, melanoma, esophageal cancer, esophageal adenocarcinoma, liver cancer, hepatocellular carcinoma, cholangiocarcinoma, uterine cancer, uterine corpus endometrial carcinoma, thyroid cancer, thyroid carcinoma, pheochromocytoma, paraganglioma, bladder cancer, bladder urothelial carcinoma, prostate cancer, prostate adenocarcinoma, sarcoma and thymoma.

[0199] In some embodiments, a cancer is selected from: a cancer comprising cells expressing / overexpressing an EGFR family member (e.g. HER3, EGFR, HER2 or HER4), a cancer comprising cells expressing / overexpressing HER3, a cancer comprising cells expressing / overexpressing EGFR, a cancer comprising cells expressing / overexpressing HER3 and EGFR, a cancer comprising cells having a mutation resulting in increased expression of a ligand for HER3, a cancer comprising cells having a mutation resulting in increased expression of a ligand for EGFR, a cancer comprising cells having an NRG gene fusion, a cancer comprising cells having an NRG1 gene fusion, or a cancer comprising cells having an NRG2 gene fusion, a solid tumor, a hematological cancer, a squamous cell cancer, an EGFR- amplified squamous cell carcinoma, breast cancer, breast carcinoma, breast invasive carcinoma, ductal carcinoma, metastatic breast cancer, triple-negative breast cancer, HER2-positive breast cancer, gastric cancer, gastric carcinoma, gastric adenocarcinoma, gastrointestinal adenocarcinoma, colorectal cancer, metastatic colorectal cancer, colon cancer, colorectal carcinoma, colorectal adenocarcinoma, colon adenocarcinoma, head and neck cancer, head and neck squamous cell carcinoma, lung cancer, non- small cell lung cancer, lung adenocarcinoma, invasive mucinous lung adenocarcinoma, squamous cell lung cancer, lung squamous cell carcinoma, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, ovarian cancer, ovarian carcinoma, ovarian serous adenocarcinoma, ovarian serous cystadenocarcinoma, fallopian tube cancer, renal cancer, renal cell carcinoma, renal clear cell carcinoma, renal cell adenocarcinoma, renal papillary cell carcinoma, pancreatic cancer, an exocrine cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma, metastatic pancreatic ductal adenocarcinoma, cervical cancer, cervical squamous cell carcinoma, skin cancer, melanoma, oral cavity cancer, oropharyngeal cancer, esophageal cancer, esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma, liver cancer, hepatocellular carcinoma, cholangiocarcinoma, gallbladder cancer, uterine cancer, endometrial cancer, uterine corpus endometrial carcinoma, uterine carcinosarcoma, thyroid cancer, thyroid cancer, thyroid carcinoma, pheochromocytoma, paraganglioma, bladder cancer, bladder urothelial carcinoma, prostate cancer, prostate adenocarcinoma, retinoblastoma, sarcoma, soft tissue sarcoma, peritoneal cancer, thymoma, neuroendocrine tumor, neuroendocrine tumor of the nasopharynx, squamous cell carcinoma of the skin, astrocytoma, low grade astrocytoma, high grade astrocytoma, anaplastic astrocytoma and glioblastoma multiforme.

[0200] In some embodiments, the cancer to be treated / prevented comprises cells expressing an EGFR family member (e.g. HER3, EGFR, HER2 or HER4), and / or cells expressing a ligand for an EGFR family member. In some embodiments, the cancer to be treated / prevented is a cancer which is positive for an EGFR family member. In some embodiments, the cancer comprises cells that overexpress an EGFR family member and / or a ligand for an EGFR family member. Overexpression can be determined by detection of a level of expression which is greater than the level of expression by equivalent non- cancerous cells / non-tumor tissue.

[0201] Expression may be determined by any suitable means. Expression may be gene expression or protein expression. Gene expression can be determined e.g. by detection of mRNA encoding HER3, for example by quantitative real-time PCR (qRT-PCR). Protein expression can be determined e.g. by antibody-based methods, for example by western blot, immunohistochemistry, immunocytochemistry, flow cytometry, or ELISA.

[0202] In some embodiments, the cancer is a cancer in which HER3 is pathologically-implicated. That is, in some embodiments the cancer is a cancer which is caused or exacerbated by the expression of HER3, a cancer for which expression of HER3 is a risk factor and / or a cancer for which expression of HER3 is positively associated with onset, development, progression, severity or metastasis of the cancer. The cancer may be characterized by expression of HER3, e.g. the cancer may comprise cells (e.g. cells of tumor tissue) expressing HER3. Such cancers may be referred to as being positive for HER3. A cancer which is ‘positive’ for HER3 may be a cancer comprising cells expressing HER3 (e.g. at the cell surface). A cancer which is ‘positive’ for HER3 may overexpress HER3.

[0203] In some embodiments, the cancer to be treated / prevented comprises cells harboring genetic variation (e.g. a mutation) which causes increased (gene and / or protein) expression and / or activity of HER3 relative to comparable cells harboring a reference allele not comprising the genetic variation (e.g. a nonmutated, or ‘wildtype’ allele). In some embodiments, a mutation which causes increased expression of HER3 may cause an increase in the level of HER3 on or at the cell surface of a cell comprising the mutation, relative to an equivalent cell not comprising the mutation.

[0204] Cells having increased expression of HER3 relative to the level of expression of HER3 by a reference cell (e.g. as a result of mutation) may be described as ‘overexpressing’ HER3, or having ‘upregulated expression’ of HER3. For example, a cancer comprising cells harboring a mutation resulting in increased expression of HER3 relative to equivalent cells lacking the mutation may be described as a cancer comprising cells displaying overexpression / upregulated expression of HER3. In some embodiments, the reference cell lacking the mutation may be a non-cancerous cell (e.g. of equivalent cell type) or a cancerous cell (e.g. of equivalent cancer type).

[0205] In some embodiments, a cancer to be treated / prevented in accordance with the present disclosure may be characterized by an increase in the expression and / or activity of HER3 ( / .e. gene and / or protein expression) in an organ / tissue / subject affected by the disease / condition e.g. as compared to normal organ / tissue / subject ( / .e. in the absence of the disease / condition). In some embodiments, cells and / or a tumor of a cancer to be treated / prevented may be characterized by an increase in the expression and / or activity of HER3, e.g. as compared to the level of expression and / or activity observed in equivalent non- cancerous cells / non-tumor tissue.

[0206] A HER3-overexpressing cancer may overexpress HER3 as a consequence of amplification of ERBB3. In some embodiments, a cancer to be treated / prevented in accordance with the present disclosure is a ERBB3-amplified cancer. In some embodiments, the cancer is an EGFR-amplified cancer. In some embodiments, the cancer is a cancer comprising amplification of ERBB3 and EGER. In some embodiments, a cancer to be treated / prevented in accordance with the present disclosure is a TP63- amplified cancer.

[0207] ERBB3, EGFR and / or TP63 amplification can be identified using techniques well known in the art, such as in situ hybridization.

[0208] ERBB3 amplification can be identified using techniques well known in the art, such as in situ hybridization. For example, ERBB3 amplification can be evaluated by fluorescence in situ hybridization, e.g. as described in Chung et al., J Gynecol Oncol. (2019) 30(5): e75.

[0209] In some embodiments, a cell comprising ERBB3 amplification comprises >2, e.g. one of 3, 4, 5, 6, 7, 8, 9, 10 or more copies of ERBB3, or >2, e.g. one of 3, 4, 5, 6, 7, 8, 9, 10 or more copies of a fragment of ERBB3. ERBB3 amplification may arise as a consequence of gene multiplication or polysomy. In some embodiments, a ERBB3-amplified cancer may comprise a ratio of ERBB3 to chromosome 12 >1 (e.g. as determined by ISH), e.g. >1.5, >2, >2.5. In some embodiments, a ERBB3-amplified cancer may comprise a ratio of ERBB3 to centromere 12 (CEN12) >1 (e.g. as determined by ISH), e.g. >1.5, >2, >2.5. In some embodiments, cells of a ERBB3-amplified cancer may comprise a ERBB3 gene copy number (GCN) >2, >3, >4, >5, >6, >7, >8, >9 or >10 (e.g. as determined by NGS). EGFR amplification can similarly be evaluated by in situ hybridization, e.g. as described in French etal., Neuro-Oncology (2019) 21 (10): 1263-1272. EGFR-amplified cancers may comprise a ratio of 7p11 .2- 7p12 to chromosome 7 centromere > 2, as determined by ISH. For example, TP63 amplification can be evaluated by fluorescence in situ hybridization, e.g. as described in Massion et al., Cancer Res. (2003) 63(21)7113-21. TP63-amplified cancers may comprise a ratio of 3q26-3qter to chromosome 3 centromere > 2, as determined by ISH.

[0210] HER3 and its association with and role in cancer is reviewed e.g. in Mishra, et al., Oncol Rev. (2018) 12(1): 355, Karachaliou et al., BioDrugs. (2017) 31 (1):63-73 and Zhang et al., Acta Biochimica et Biophysica Sinica (2016) 48(1): 39-48, all of which are hereby incorporated by reference in their entirety. Mishra, et al., Oncol Rev. (2018) 12(1): 355 also describes intervention targeting HER3 for the treatment of cancer, including monoclonal anti-HER3 antibody therapy.

[0211] In some embodiments, the cancer to be treated / prevented comprises cells expressing a ligand for HER3 (e.g. NRG1 and / or NRG2). In some embodiments, the cancer to be treated / prevented comprises cells expressing a level of expression of NRG1 and / or NRG2 which is greater than the level of expression by equivalent non-cancerous cells / non-tumor tissue. The cancer may be described as comprising cells that overexpress NRG1 and / or NRG2.

[0212] HER3-binding antigen-binding molecules described herein bind to HER3 with extremely high affinity when HER3 is bound by NRG ( / .e. when HER3 is provided in the ‘open’ conformation), and also when HER3 is not bound by NRG ( / .e. when HER3 is provided in the ‘closed’ conformation). Thus, they are particularly useful for the treatment / prevention of cancers characterized by HER3 ligand expression / overexpression, for example cancers / tumors comprising cells expressing / overexpressing a ligand for HER3.

[0213] In some embodiments, the cancer to be treated / prevented comprises cells harboring a genetic variant (e.g. a mutation) which causes increased (gene and / or protein) expression of a ligand for HER3, relative to comparable cells harboring a reference allele not comprising the genetic variant (e.g. a non-mutated, or ‘wildtype’ allele). The genetic variant may be or comprise insertion, deletion, substitution to, or larger- scale translocation / rearrangement of, the nucleotide sequence relative to the reference allele.

[0214] The most common version of the nucleotide sequence of a given gene may be referred to as the ‘wildtype’ allele of the gene. A version of the nucleotide sequence of a given gene comprising a mutation may be referred to as a ‘mutant’ or ‘mutated’ allele of the gene. It will be appreciated that the nucleotide sequence of a mutant allele of a given gene has a nucleotide sequence which is non-identical to the nucleotide sequence of the wildtype allele.

[0215] A mutation ‘resulting in’ increased expression of a ligand for HER3 may be known or predicted to cause, or may be associated with, increased gene / protein expression of a ligand for HER3. Mutations resulting in increased expression of a ligand for HER3 may be referred to as ‘activating’ mutations. A mutation which causes increased expression of a ligand for HER3 may result in gene or protein expression of a ligand for HER3 which is not expressed by, and / or not encoded by genomic nucleic acid of, an equivalent cell not harboring the mutation. That is, the ligand for HER3 may be a neoantigen arising as a result of the mutation, and thus ‘increased expression’ may be from no expression. By way of illustration, a cell comprising CD74-NRG1 gene fusion displays increased expression of the CD74-NRG1 fusion polypeptide encoded by the gene fusion relative to cells lacking the CD74-NRG1 gene fusion.

[0216] A mutation which causes increased expression of a ligand for HER3 may result in increased gene or protein expression of a ligand for HER3 which is expressed by, and / or which is encoded by genomic nucleic acid of, an equivalent cell not comprising the mutation. By way of illustration, a cell may comprise a mutation resulting in an increase in the level of transcription of nucleic acid encoding NRG1 relative to the level of transcription of nucleic acid encoding NRG1 by an equivalent cell not comprising the mutation.

[0217] In some embodiments, a mutation which causes increased expression of a ligand for HER3 may cause an increase in gene expression of a ligand for HER3 relative to an equivalent cell not comprising the mutation. In some embodiments, a mutation which causes increased expression of a ligand for HER3 may cause an increase in protein expression of a ligand for HER3 relative to an equivalent cell not comprising the mutation.

[0218] In some embodiments, a mutation which causes increased expression of a ligand for HER3 may cause an increase in the level of a ligand for HER3 on or at the cell surface of a cell comprising the mutation, relative to an equivalent cell not comprising the mutation. In some embodiments, a mutation which causes increased expression of a ligand for HER3 may cause an increase in the level of a secretion of a ligand for HER3 from a cell comprising the mutation, relative to an equivalent cell not comprising the mutation.

[0219] Cells having increased expression of a ligand for HER3 relative to the level of expression of the ligand for HER3 by a reference cell (e.g. as a result of mutation) may be described as ‘overexpressing’ the ligand for HER3, or having ‘upregulated expression’ of the ligand for HER3. For example, a cancer comprising cells harboring a mutation resulting in increased expression of a ligand for HER3 relative to equivalent cells lacking the mutation may be described as a cancer comprising cells displaying overexpression / upregulated expression of the ligand for HER3. In some embodiments, the reference cell lacking the mutation may be a non-cancerous cell (e.g. of equivalent cell type) or a cancerous cell (e.g. of equivalent cancer type).

[0220] Herein, a ‘ligand for HER3’ is generally intended to refer to a molecule capable of binding to HER3 through the ligand binding region of HER3 formed by domains I and III of HER3. In some embodiments, a ligand for HER3 binds to HER3 via interaction with domains I and / or III of HER3. Exemplary ligands for HER3 include neuregulins such as NRG1 and NRG2, which bind to HER3 via interaction between their EGF-like domains and the ligand binding region of HER3. The HER3 ligand is preferably able to bind and trigger signaling through the HER3 receptor and / or receptor complexes comprising HER3. As will be clear from the present disclosure, receptor complexes comprising HER3 may further comprise an interaction partner for HER3 as described herein, e.g. HER3, HER2, EGFR, HER4, HGFR, IGF1 R and / or cMet.

[0221] In some embodiments the ligand for HER3 is able to bind to HER3 receptor / receptor complex expressed by a cell other than the cell having increased expression of the HER3 ligand. For example, in some embodiments the ligand for HER3 is able to bind to a HER3-expressing cancer cell.

[0222] In some embodiments the ligand for HER3 is able to bind to HER3 receptor / receptor complex expressed by the cell having increased expression of the HER3 ligand.

[0223] In some embodiments the cancer to be treated / prevented comprises (i) cells expressing HER3, and (ii) cells expressing a ligand for HER3 (e.g. having increased expression of a ligand for HER3, e.g. as a consequence of mutation resulting in increased expression of a ligand for HER3).

[0224] In some embodiments the cancer to be treated / prevented comprises cells which (i) express HER3 and (ii) which also express a ligand for HER3 (e.g. which have increased expression of a ligand for HER3, e.g. as a consequence of mutation resulting in increased expression of a ligand for HER3).

[0225] In some embodiments, the ligand for HER3 comprises, or consists of, the amino acid sequence of a HER3-binding region of a ligand for HER3, or an amino acid sequence derived from a HER3-binding region of a ligand for HER3. An amino acid sequence which is derived from a HER3-binding region of a ligand for HER3 may comprise at least 60% (e.g. 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) amino acid sequence identity to the amino acid sequence from which it is derived.

[0226] In some embodiments, the ligand for HER3 comprises an EGF-like domain capable of binding to HER3, or a HER3-binding fragment thereof. In some embodiments, a HER3-binding EGF-like domain / fragment is, or is derived from, an EGF family member (e.g. heparin-binding EGF-like growth factor (HB-EGF), transforming growth factor-a (TGF-a), amphiregulin (AR), epiregulin (EPR), epigen, betacellulin (BTC), NRG1 , NRG2, NRG3 or NRG4).

[0227] Exemplary ligands for HER3 include neuregulins (NRGs). Neuregulins include NRG1 (including alpha, alpha2b, and alpha3 isoforms thereof), NRG2, NRG3 and NRG4. In some embodiments, an NRG is selected from NRG1 , NRG2, NRG3 and NRG4. In some embodiments, an NRG is selected from NRG1 and NRG2.

[0228] The EGF-like domain of human NRG1 , through which it binds to HER3, is formed by positions 178-222 of UniProt:Q02297-1 . The EGF-like domain of human NRG2 is formed by positions 341-382 of UniProt:O14511-1 . The EGF-like domain of human NRG3 is formed by positions 286-329 of UniProt:B9EGV5-1 . The EGF-like domain of human NRG4 is formed by positions 5-46 of UniProt:Q8WWG1-1 . In some embodiments, an EGF-like domain / fragment comprises, or consists of, an amino acid sequence having at least 60% (e.g. 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) amino acid sequence identity to the EGF-like domain of an NRG (NRG1 , NRG2, NRG3 or NRG4).

[0229] In some embodiments a ligand for HER3 is not an EGFR family protein (e.g. HER3, HER2, EGFR, HER4, HGFR, IGF1 R, cMet).

[0230] In some embodiments, the mutation resulting in increased expression of a ligand for HER3 is an NRG gene fusion. In some embodiments, the ligand for HER3 is the product of ( / .e. a polypeptide encoded by) an NRG gene fusion. In some embodiments the cancer comprises cells having an NRG gene fusion. As used herein, an ‘NRG gene fusion’ refers to a genetic variant encoding a polypeptide comprising (i) an amino acid sequence of an NRG protein (e.g. NRG1 , NRG2, NRG3 or NRG4; e.g. NRG1 or NRG2), and (ii) an amino acid sequence of a protein other than the NRG protein.

[0231] NRG gene fusions may be detected and characterized using appropriate molecular assays, which are well known to the skilled person.

[0232] NRG gene fusions according to the present disclosure are preferably correctly orientated ( / .e. with the nucleotide sequence encoding the NRG at the 3’ end of the transcript), and encode a fusion polypeptide comprising an EGF-like domain capable of binding to HER3.

[0233] It will be appreciated that an NRG gene fusion preferably encodes a HER3 ligand as described herein. In some embodiments, an NRG gene fusion encodes a polypeptide comprising a HER3-binding region of an NRG protein. In some embodiments, an NRG gene fusion encodes a polypeptide comprising the EGF- like domain of an NRG protein, or an amino acid sequence which is capable of binding to HER3 and having at least 60% (e.g. 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) amino acid sequence identity to the EGF-like domain of an NRG protein.

[0234] In some embodiments, an NRG gene fusion encodes a fusion polypeptide comprising a transmembrane domain. In some embodiments, an NRG gene fusion encodes a fusion polypeptide comprising the transmembrane domain of a protein other than the NRG protein.

[0235] In some embodiments, an NRG gene fusion is an NRG1 gene fusion. In some embodiments, the NRG1 gene fusion encodes a polypeptide comprising the EGF-like domain of NRG1 , or an amino acid sequence which is capable of binding to HER3 and having at least 60% (e.g. 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) amino acid sequence identity to the EGF-like domain of NRG1 .

[0236] NRG1 gene fusions represent an actionable fusion in tissue-agnostic cancers that can be targeted through HER3 inhibition. They are formed by inter-chromosomal translocation with a diverse set of genes leading to an overproduction of NRG1 ligands for HER3-binding, and aberrant activation leading to tumorigenesis. Studies have demonstrated a causal link between HER3 pathway activation and NRG1 gene fusions. NRG1 fusions are enriched among subjects having mucinous non-small cell lung cancer and pancreatic ductal adenocarcinoma; 8-32% of subjects with mucinous NSCLC have NRG1 gene fusions, while 10-20% (up to 70% in small studies) of subjects having KRAS wildtype PDAC have detectable NRG1 gene fusions. The therapeutic utility of monoclonal anti-HER3 antibody therapy targeting NRG1 gene fusions is demonstrated e.g. in WO 2021 / 048274 A1 .

[0237] NRG1 gene fusions are described e.g. in WO 2021 / 048274 A1 , WO 2018 / 182422 A1 , WO 2019 / 051155 A1 , Dhanasekaran etal., Nat Commun. (2014) 5: 5893, Drilon et al., Cancer Discov. (2018) 8(6):686-695, Nagasaka et al., Journal of Thoracic Oncology (2019) 14(8):1354-1359 and Jonna et al., Clin Cancer Res. (2019) 25(16):4966-4972, all of which are hereby incorporated by reference in their entirety. The diversity ot NRG 1 gene fusions may result from NRG1 being located on chromosome 8, which is particularly susceptible to genomic translocation events (Adelaide et al., Genes Chromosomes Cancer. (2003) 37(4):333-45).

[0238] In some embodiments, an NRG1 gene fusion is selected from CLU-NRG1, CD74-NRG1, DOC4-NRG1, SLC3A2-NRG1, RBPMS-NRG1, WRN-NRG1, SDC4-NRG1, RAB2IL1-NRG1, VAMP2-NRG1, KIF13B- NRG1, THAP7-NRG1, SMAD4-NRG1, MDK-NRG1, TNC-NRG1, DIP2B-NRG1, MRPL13-NRG1, PARP8- NRG1, ROCK1-NRG1, DPYSL2-NRG1, ATP1B1-NRG1, CDH6-NRG1, APP-NRG1, AKAP13-NRG1, THBS1-NRG1, FOXA1-NRG1, PDE7A- NRG1, RAB3IL1-NRG1, CDK1-NRG1, BMPRIB-NRG1, TNFRSF10B-NRG1, and MCPH1-NRG1. In some embodiments, an NRG1 gene fusion is CLU-NRG1.

[0239] CD74-NRG1 gene fusion is described e.g. in Fernandez-Cuesta et al. Cancer Discov. (2014) 4:415-22 and Nakaoku et al., Clin Cancer Res (2014) 20:3087-93. DOC4-NRG1 gene fusion is described e.g. in Liu et al., Oncogene. (1999) 18(50)7110-4 and Wang et al., Oncogene. (1999) 18(41):5718-21 . SLC3A2- NRG1 gene fusion is described e.g. in Nakaoku et al., Clin Cancer Res (2014) 20:3087-93, Shin et al., Oncotarget (2016) 7:69450-65 and Shin et al., Mol Cancer Ther. (2018) 17(9):2024-2033. RBPMS- NRG1, WRN-NRG1 , RAB2IL1-NRG1 and SDC4-NRG1 gene fusions are described e.g. in Dhanasekaran et al., Nat Commun. (2014) 5: 5893. VAMP2-NRG1 gene fusion is described e.g. in Jung et al., J Thorac Oncol. (2015) 10(7):1107-11 and Shim et al., J Thorac Oncol. (2015) 10(8):1156-62. KIF13B-NRG1 gene fusion is described e.g. in Xia et al., Int J Surg Pathol. (2017) 25(3):238-240. SMAD4-NRG1, AKAP13- NRG1, THBS1-NRG1, FOXA1-NRG1, PDE7A- NRG1, RAB3IL1-NRG1 and THAP7-NRG1 gene fusions are described e.g. in Drilon et al., Cancer Discov. (2018) 8(6):686-695. MDK-NRG1, TNC-NRG1, DIP2B- NRG1, MRPL13-NRG1, PARP8-NRG1, ROCK1-NRG1 and DPYSL2-NRG1 gene fusions are described e.g. in Jonna et al., Clin Cancer Res. (2019) 25(16):4966-4972. ATP1B1-NRG1 gene fusion is described e.g. in Drilon et al., Cancer Discov. (2018) 8(6):686-695 and Jones et al., Annals of Oncology (2017) 28:3092-3097. CLU-NRG1 gene fusion is described e.g. in Drilon et al., Cancer Discov. (2018) 8(6):686- 695 and Nagasaka et al., Journal of Thoracic Oncology (2019) 14(8):1354-1359.

[0240] In some embodiments, an NRG gene fusion is an NRG2 gene fusion. In some embodiments, the NRG2 gene fusion encodes a polypeptide comprising the EGF-like domain of NRG2, or an amino acid sequence which is capable of binding to HER3 and having at least 60% (e.g. 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) amino acid sequence identity to the EGF-like domain of NRG2.

[0241] NRG2 gene fusions include SLC12A2-NRG2 described e.g. in WO 2021 / 048274 A1 , WO 2015 / 093557 A1 , and ZNF208-NRG2 described in Dupain et al., Mol Ther. (2019) 27(1):200-218.

[0242] A cancer comprising cells having a mutation which results in increased expression of a ligand for HER3 (e.g. comprising cells having an NRG gene fusion, e.g. an NRG1 gene fusion or an NRG2 gene fusion) can be any cancer described herein. In some embodiments, such cancer may be of tissues / cells derived from the lung, breast, head, neck, kidney, ovary, pancreas, prostate, uterus, gallbladder, colon, rectum, bladder, soft tissue or nasopharynx.

[0243] In some embodiments, a cancer comprising cells having a mutation which results in increased expression of a ligand for HER3 (e.g. comprising cells having an NRG gene fusion, e.g. an NRG1 gene fusion or an NRG2 gene fusion) is selected from: lung cancer, non-small cell lung cancer, lung adenocarcinoma, invasive mucinous lung adenocarcinoma, lung squamous cell carcinoma, breast cancer, breast carcinoma, breast invasive carcinoma, head and neck cancer, head and neck squamous cell carcinoma, renal cancer, renal clear cell carcinoma, ovarian cancer, ovarian serous cystadenocarcinoma, pancreatic cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, prostate cancer, prostate adenocarcinoma, endometrial cancer, uterine carcinosarcoma, gallbladder cancer, cholangiocarcinoma, colorectal cancer, metastatic colorectal cancer, bladder cancer, urothelial bladder cancer, sarcoma, soft tissue sarcoma, neuroendocrine tumor and neuroendocrine tumor of the nasopharynx.

[0244] It will be appreciated that in embodiments herein, cancers comprising cells having specified characteristics may be, or comprise, tumors comprising cells having those characteristics.

[0245] As is common in the art, a cancer / tumor comprising cells having specified characteristics may be referred to herein simply as a cancer / tumor having those characteristics. By way of illustration, a cancer / tumor comprising cells having an NRG1 gene fusion may be referred to simply as ‘a cancer / tumor comprising NRG1 gene fusion’, or ‘an NRG1 gene fusion cancer / tumor’.

[0246] In some embodiments, the cancer to be treated / prevented comprises mutation conferring resistance to treatment with an inhibitor of B-Raf. In some embodiments, the mutation is mutation at B-Raf V600. In some embodiments, the mutation is B-Raf V600E or V600K. The cancer may be thyroid or colon cancer, e.g. RAS wildtype colorectal cancer. In some embodiments, the cancer to be treated / prevented comprises mutation conferring resistance to treatment with an inhibitor of B-Raf (e.g. mutation at B-Raf V600), and the treatment comprises administration of vemurafenib or darafenib.

[0247] In squamous cell cancer (SCC), the PI3K / AKT-signaling pathway is commonly altered by gene amplification and / or mutations. The frequently amplified 3q26 / 28 chromosomal region, in which PIK3CA is located, also resides the TP63 and SOX2 cell lineage genes. TP63 is a member of the TP53 gene family and is expressed in the basal compartment of the skin, esophagus, lung airways and larynx during development and homeostasis. TP63 is used as a diagnostic marker of squamous versus adenocarcinoma forms of lung and esophageal cancer. Preclinical data suggests that TP63 regulates NRG1 expression in SCC, suggesting that the HER3 signaling pathway is active in TP63-amplified squamous cell cancers.

[0248] In some embodiments, the cancer to be treated / prevented is a metastatic cancer. ‘Metastatic’ cancer is a cancer detectable at one or more secondary sites in the body other than the site of origin of the original (primary) cancer from which the metastatic cancer is derived.

[0249] In some embodiments, the cancer to be treated / prevented is an advanced cancer. Advanced cancer is cancer that has spread from the site of origin of the original (primary) cancer. In some embodiments, the cancer to be treated / prevented is a locally-advanced cancer. Locally-advanced cancer is cancer that has spread from the site of origin of the original (primary) cancer to nearby tissue or lymph nodes.

[0250] In some embodiments, the cancer to be treated / prevented is unresectable cancer. ‘Unresectable’ cancer is a cancer that cannot be removed completely through surgery. This can be the case for a variety of reasons, including tumor size, stage, and / or location.

[0251] In some embodiments, the cancer to be treated / prevented is locally-advanced and unresectable cancer.

[0252] In some embodiments, the cancer may be a relapsed cancer. As used herein, a ‘relapsed’ cancer refers to a cancer which responded to a treatment (e.g. a first line therapy for the cancer), but which has subsequently re-emerged / progressed, e.g. after a period of remission. For example, a relapsed cancer may be a cancer whose growth / progression was inhibited by a treatment (e.g. a first line therapy for the cancer), and which has subsequently grown / progressed.

[0253] In some embodiments, the cancer may be a refractory cancer. As used herein, a ‘refractory’ cancer refers to a cancer which has not responded to a treatment (e.g. a first line therapy for the cancer). For example, a refractory cancer may be a cancer whose growth / progression was not inhibited by a treatment (e.g. a first line therapy for the cancer). In some embodiments a refractory cancer may be a cancer for which a subject receiving treatment for the cancer did not display a partial or complete response to the treatment.

[0254] In some embodiments, the cancer is relapsed or refractory with respect to platinum-based chemotherapy. Platinum-based chemotherapies include cisplatin, carboplatin, oxaliplatin, nedaplatin, and lobaplatin.

[0255] In some embodiments, the cancer is advanced squamous non-small cell lung cancer. In some embodiments, the cancer is metastatic squamous non-small cell lung cancer. In some embodiments, the cancer is locally advanced and unresectable squamous non-small cell lung cancer.

[0256] In some embodiments, the cancer is a locally-advanced, unresectable or metastatic solid tumor. In some embodiments, a cancer is selected from: a cancer comprising cells expressing / overexpressing an EGFR family member (e.g. HER3, EGFR, HER2 or HER4), a cancer comprising cells expressing / overexpressing HER3, a cancer comprising cells having a mutation resulting in increased expression of a ligand for HER3, a cancer comprising cells having an NRG gene fusion, a cancer comprising cells having an NRG1 gene fusion, a cancer comprising cells having an NRG2 gene fusion a solid tumor, a hematological cancer, a squamous cell cancer, an EGFR-amplified squamous cell carcinoma, breast cancer, breast carcinoma, breast invasive carcinoma, ductal carcinoma, metastatic breast cancer, triple-negative breast cancer, HER2-positive breast cancer, gastric cancer, gastric carcinoma, gastric adenocarcinoma, gastrointestinal adenocarcinoma, colorectal cancer, metastatic colorectal cancer, colon cancer, colorectal carcinoma, colorectal adenocarcinoma, colon adenocarcinoma, head and neck cancer, head and neck squamous cell carcinoma, lung cancer, nonsmall cell lung cancer, lung adenocarcinoma, invasive mucinous lung adenocarcinoma, squamous cell lung cancer, lung squamous cell carcinoma, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, ovarian cancer, ovarian carcinoma, ovarian serous adenocarcinoma, ovarian serous cystadenocarcinoma, fallopian tube cancer, renal cancer, renal cell carcinoma, renal clear cell carcinoma, renal cell adenocarcinoma, renal papillary cell carcinoma, pancreatic cancer, an exocrine cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma, metastatic pancreatic ductal adenocarcinoma, cervical cancer, cervical squamous cell carcinoma, skin cancer, melanoma, oral cavity cancer, oropharyngeal cancer, esophageal cancer, esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma, liver cancer, hepatocellular carcinoma, cholangiocarcinoma, gallbladder cancer, uterine cancer, endometrial cancer, uterine corpus endometrial carcinoma, uterine carcinosarcoma, thyroid cancer, thyroid cancer, thyroid carcinoma, pheochromocytoma, paraganglioma, bladder cancer, bladder urothelial carcinoma, prostate cancer, prostate adenocarcinoma, retinoblastoma, sarcoma, soft tissue sarcoma, peritoneal cancer, thymoma, neuroendocrine tumor, neuroendocrine tumor of the nasopharynx, squamous cell carcinoma of the skin, astrocytoma, low grade astrocytoma, high grade astrocytoma, anaplastic astrocytoma and glioblastoma multiforme.

[0257] In some embodiments, a cancer is: a cancer comprising cells expressing / overexpressing an EGFR family member, a cancer comprising cells expressing / overexpressing HER3, a squamous cell cancer, lung cancer, non-small cell lung cancer, squamous cell lung cancer, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, pancreatic cancer, an exocrine cancer, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma, metastatic pancreatic ductal adenocarcinoma, a cancer comprising cells having a mutation resulting in increased expression of a ligand for HER3, a cancer comprising cells having an NRG gene fusion, a cancer comprising cells having an NRG1 gene fusion, or a cancer comprising cells having an NRG2 gene fusion.

[0258] Cancers characterized by genetic variation in ERBB3

[0259] The present disclosure is concerned with therapeutic and prophylactic intervention for the treatment / prevention of cancers characterized by the presence of genetic variation relating to ERBB3 (j.e. the gene encoding HER3). Genetic variation contemplated in accordance with the present disclosure includes mutation and gene amplification.

[0260] As used herein, a ‘mutation’ refers to a difference relative to a reference nucleotide sequence, e.g. the most common nucleotide sequence of a given gene (which may be referred to as the ‘wildtype’ nucleotide sequence). Mutations may be or comprise one or more of the following relative to the reference sequence (e.g. the wildtype sequence): a nucleotide polymorphism (e.g. a single nucleotide polymorphism (SNP) or a multiple nucleotide polymorphism (MNP)), an insertion, a deletion, a frame-shift mutation, a missense mutation or a translocation.

[0261] A nucleotide polymorphism may comprise substitution of a nucleotide of the reference sequence with another, non-identical nucleotide (e.g. in the case of a SNP), or may comprise substitution of two or more nucleotides of the reference sequence with non-identical nucleotides (e.g. in the case of a MNP). An ‘insertion’ refers to introduction of one or more nucleotides into the nucleotide sequence of the reference sequence. A ‘deletion’ refers to removal / excision of one or more nucleotides from the nucleotide sequence of the reference sequence. A ‘frame-shift’ mutation refers to an insertion or deletion mutation that changes the reading frame for translation of from RNA encoded by the mutant nucleotide sequence. Such frameshift mutations comprise insertion / deletion of a number of nucleotides that is not divisible by three. A ‘missense’ mutation refers to a substitution (or insertion or deletion) that does not alter the amino acid sequence of a peptide / polypeptide translated from RNA encoded by the mutant nucleotide sequence. Such missense mutations may result in the replacement of one or more nucleotides with (a) non-identical nucleotide(s), wherein the codon comprising the non-substituted nucleotide(s) and the codon comprising the substituted nucleotide(s) encode the same amino acid (as a consequence of degeneracy of the genetic code). Other such missense mutations may be provided in a non-protein encoding region of the nucleotide sequence, e.g. an intron. A ‘translocation’ refers large-scale replacement of a nucleotide, or sequence of nucleotides, within the reference sequence with a non- identical nucleotide / sequence of nucleotides. Translocation occurs as a consequence of recombination between nucleotide sequences, e.g. provided on different chromosomes.

[0262] As used herein, ‘amplification’ refers to an increase in the number of copies of a given gene or a fragment thereof. Thus, ‘amplification’ of a given reference gene refers to the provision of one or more additional copies of the given gene, or additional copies of a fragment of the given gene, relative to the number of copies of the gene / fragment present in a healthy (e.g. non-cancerous) diploid cell. Accordingly, a cell comprising amplification of a given reference gene comprises one or more additional copies of the given gene, or additional copies of a fragment of the given gene, relative to the number of copies of the gene / fragment present in a healthy (e.g. non-cancerous) diploid cell. In some embodiments, a cell comprising amplification of a given reference gene / fragment thereof comprises more than two copies of the relevant gene / fragment. In some embodiments, the cell comprises one of 3, 4, 5, 6, 7, 8, 9, 10 or more copies of the relevant gene / fragment. Amplification according to the present disclosure encompasses ‘gain’, which is sometimes used in the art to describe a relatively small increase in the number of copies of a given gene or a fragment thereof (e.g. to 3 or 4 copies of the relevant gene / fragment). Conversely, ‘gene deletion’ refers to decrease in the number of copies of a given gene or a fragment thereof. Thus, ‘deletion’ of a given reference gene refers to a reduction in the number of copies of the given gene, or a reduction in the number of copies of a fragment of the given gene, relative to the number of copies of the gene / fragment present in a healthy (e.g. non-cancerous) diploid cell. Accordingly, a cell comprising deletion of a given reference gene have a reduction in the number of copies of the given gene, or a reduction in the number of copies of a fragment of the given gene, relative to the number of copies of the gene / fragment present in a healthy (e.g. non-cancerous) diploid cell. In some embodiments, a cell comprising deletion of a given reference gene / fragment thereof comprises fewer than two copies of the relevant gene / fragment. In some embodiments, the cell comprises 0 or 1 copies of the relevant gene / fragment. Gene deletions encompass ‘shallow’ and ‘deep’ deletions. Shallow deletions may be heterozygous deletions, i.e. where only one copy of the gene / fragment is deleted. Deep deletions may be homozygous deletions, i.e. where both copies of the gene / fragment are deleted.

[0263] A version of the nucleotide sequence of a given gene comprising genetic variation may be referred to as a ‘variant’ or ‘mutant’ allele of the gene. It will be appreciated that the nucleotide sequence of a variant / mutant allele of a given gene has a nucleotide sequence which is non-identical to the nucleotide sequence of the wildtype allele.

[0264] The present disclosure is particularly concerned with mutations in ERBB3 resulting in a change in the amino acid sequence of a polypeptide encoded by the ERBB3 allele comprising the mutation (i.e. the mutant allele), relative to the amino acid sequence of a polypeptide encoded by the wildtype ERBB3 allele. Such mutations may be referred to as ‘non-synonymous’ mutations.

[0265] In some embodiments, a mutation to ERBB3 according to the present disclosure is an activating mutation.

[0266] As used herein, an ‘activating mutation’ refers to a mutation that is known, or that is predicted, to result in an increase in the level of (gene or protein) expression of the relevant gene (i.e. ERBB3), and / or a mutation that is known, or that is predicted, to result in an increase in an activity of a product of the gene. An activating mutation may give rise to one or more of the following in a cell comprising one or more alleles of a gene comprising the activating mutation: increased transcription of the gene; an increase the level of RNA encoded by the gene; decreased degradation of RNA encoded by the gene; an increase in the level of a product of the gene; an increase in the level of a peptide / polypeptide encoded by the gene; an increase in the level of normal splicing of pre-mRNA encoded by the gene; increased translation of mRNA encoding a peptide / polypeptide encoded by the gene; an increase in the level of normal post- translational processing of a peptide / polypeptide encoded by the gene; an increase in the level of normal trafficking of a peptide / polypeptide encoded by the gene; decreased degradation of a peptide / polypeptide encoded by the gene; an increase in the level of one or more functional properties displayed by a product of the gene; an increase in the level of one or more functional properties displayed by a peptide / polypeptide encoded by the gene; a novel functional property displayed by a product of the gene; and / or a novel functional property displayed by a peptide / polypeptide encoded by the gene. Conversely, an ‘inactivating mutation’ refers to a mutation resulting in a decrease in the level of expression of a given gene, and / or a mutation resulting in a decrease in an activity of a product of the gene. An inactivating mutation may give rise to one or more of the following in a cell comprising one or more alleles of a gene comprising the inactivating mutation: decreased transcription of the gene; a decrease the level of RNA encoded by the gene; increased degradation of RNA encoded by the gene; a decrease in the level of a product of the gene; a decrease in the level of a peptide / polypeptide encoded by the gene; a decrease in the level of normal splicing of pre-mRNA encoded by the gene; decreased translation of mRNA encoding a peptide / polypeptide encoded by the gene; a decrease in the level of normal post-translational processing of a peptide / polypeptide encoded by the gene; a decrease in the level of normal trafficking of a peptide / polypeptide encoded by the gene; increased degradation of a peptide / polypeptide encoded by the gene; a decrease in the level of one or more functional properties displayed by a product of the gene; and / or a decrease in the level of one or more functional properties displayed by a peptide / polypeptide encoded by the gene.

[0267] The present disclosure particularly contemplates genetic variation resulting in increase in the expression of ERBB3. Accordingly, in some embodiments, a mutation to ERBB3 according to the present disclosure results in increase in the expression of ERBB3. A mutation ‘resulting in’ increased expression of HER3 may be known or predicted to cause, or may be associated with, increased gene / protein expression of HER3.

[0268] ‘Expression’ may be gene expression and / or protein expression. Gene expression can be evaluated using techniques providing for the detection and / or quantification of RNA transcribed from the relevant gene and / or RNA encoding a gene product encoded by the relevant gene ( / .e. ERBB3). Such techniques include, e.g., quantitative real-time PCR (qRT-PCR). Protein expression can be evaluated using techniques providing for the detection and / or quantification of a peptide / polypeptide encoded by the relevant gene. Such techniques include, e.g., antibody-based methods, such as western blot, immunohistochemistry, immunocytochemistry, flow cytometry, etc.

[0269] It will be appreciated that protein expression of a given gene may also be referred to as expression of the relevant protein encoded by the gene. By way of illustration, ‘protein expression of ERBB3’ may alternatively be referred to as ‘expression of HER3’.

[0270] A mutation which causes increased expression of HER3 may result in gene or protein expression of HER3 which is not expressed by, and / or not encoded by genomic nucleic acid of, an equivalent cell not harboring the mutation. That is, the HER3 may be a neoantigen arising as a result of the mutation, and thus ‘increased expression’ may be from no expression. A mutation which causes increased expression of HER3 may result in increased gene or protein expression of HER3 which is expressed by, and / or which is encoded by genomic nucleic acid of, an equivalent cell not comprising the mutation. By way of illustration, a cell may comprise a mutation resulting in an increase in the level of transcription of nucleic acid encoding HER3 relative to the level of transcription of nucleic acid encoding HER3 by an equivalent cell not comprising the mutation. In some embodiments, a mutation which causes increased expression of HER3 may cause an increase in gene expression of HER3 relative to an equivalent cell not comprising the mutation. In some embodiments, a mutation which causes increased expression of HER3 may cause an increase in protein expression of HER3 relative to an equivalent cell not comprising the mutation. In some embodiments, a mutation which causes increased expression of HER3 may cause an increase in the level of HER3 on or at the cell surface of a cell comprising the mutation, relative to an equivalent cell not comprising the mutation.

[0271] In some embodiments, a mutation to ERBB3 according to the present disclosure results in increase in the activity of a gene product of ERBB3. A mutation ‘resulting in’ increased activity of HER3 may be known or predicted to cause, or may be associated with, increased HER3-mediated signaling. Mutations resulting in increased expression and / or activity of HER3 may be referred to as ‘activating’ mutations.

[0272] As used herein, a ‘gene product’ refers to a molecule produced by gene expression from a given gene ( / .e. ERBB3). A gene product may be an RNA encoded by the gene, e.g. an RNA transcribed from the gene, or an RNA produced by post-transcriptional processing of RNA transcribed from the gene. A gene product may be a peptide / polypeptide encoded by the gene, e.g. a peptide / polypeptide translated from RNA transcribed from the gene (e.g. after post-transcriptional processing), or peptide / polypeptide produced by post-translational processing of protein translated from RNA transcribed from the gene. In some embodiments, the gene product is a peptide / polypeptide encoded by the gene.

[0273] An activity of a gene product (e.g. a peptide / polypeptide encoded by the gene) may be any functional property displayed by the gene product. In some embodiments, the activity of a gene product is a functional property displayed by a gene product encoded by the wildtype allele of the relevant gene. By way of illustration, an activity of a gene product of ERBB3 may be a functional property displayed by HER3. A mutation which causes increased activity of HER3 may result in an increase in HER3-mediated signaling relative to the level of HER3-mediated signaling by an equivalent cell not comprising the mutation.

[0274] Genetic variation resulting in an increase in the (gene and / or protein) expression of a given gene may be known, or may be predicted, to give rise to one or more of the following in a cell comprising such genetic variation: an increase in the number of copies of the gene (e.g. to more than two copies); increased transcription of the gene; an increase the level of RNA encoded by the gene; decreased degradation of RNA encoded by the gene; an increase in the level of a product of the gene; an increase in the level of a peptide / polypeptide encoded by the gene; an increase in the level of normal splicing of pre-mRNA encoded by the gene; increased translation of mRNA encoding a peptide / polypeptide encoded by the gene; an increase in the level of normal post-translational processing of a peptide / polypeptide encoded by the gene; an increase in the level of normal trafficking of a peptide / polypeptide encoded by the gene; and / or decreased degradation of a peptide / polypeptide encoded by the gene. Genetic variation resulting in an increase in the activity of product of a given gene may be known, or may be predicted, to give rise to one or more of the following in a cell comprising such genetic variation: an increase in the level of one or more functional properties displayed by a product of the gene; an increase in the level of one or more functional properties displayed by a peptide / polypeptide encoded by the gene; a novel functional property displayed by a product of the gene; and / or a novel functional property displayed by a peptide / polypeptide encoded by the gene.

[0275] Conversely, genetic variation resulting in a decrease in the (gene and / or protein) expression of a given gene may be known, or may be predicted, to give rise to one or more of the following in a cell comprising such genetic variation: a decrease in the number of copies of the gene (e.g. to fewer than two copies); decreased transcription of the gene; a decrease the level of RNA encoded by the gene; increased degradation of RNA encoded by the gene; a decrease in the level of a product of the gene; a decrease in the level of a peptide / polypeptide encoded by the gene; a decrease in the level of normal splicing of pre- mRNA encoded by the gene; decreased translation of mRNA encoding a peptide / polypeptide encoded by the gene; a decrease in the level of normal post-translational processing of a peptide / polypeptide encoded by the gene; a decrease in the level of normal trafficking of a peptide / polypeptide encoded by the gene; and / or increased degradation of a peptide / polypeptide encoded by the gene. Genetic variation resulting in a decrease in the activity of product of a given gene may be known, or may be predicted, to give rise to one or more of the following in a cell comprising such genetic variation: a decrease in the level of one or more functional properties displayed by a product of the gene; and / or a decrease in the level of one or more functional properties displayed by a peptide / polypeptide encoded by the gene.

[0276] It will be appreciated that in embodiments herein, cancers comprising cells having specified characteristics may be, or may comprise, one or more tumors comprising cells having those characteristics. That is, where a cancer is described as having a given genetic variation, mutation status, allele or genotype it will be appreciated that cells of the cancer have the relevant genetic variation, mutation status, allele or genotype.

[0277] By way of illustration, where a cancer is described as comprising a given mutation, the cancer comprises cells comprising the mutation. Similarly, where a cancer is described as being homozygous for a given genetic variation / allele, the cancer comprises cells which are homozygous for the genetic variation / allele. Similarly, where a cancer is described as being heterozygous for a given genetic variation / allele, the cancer comprises cells which are heterozygous for the genetic variation / allele.

[0278] Where a cancer is described as having a given genetic variation, mutation status, allele or genotype, one or more cells of the cancer have the relevant genetic variation, mutation status, allele or genotype. In some embodiments, where a cancer is described as having a given genetic variation, mutation status, allele or genotype the majority ( / .e. >50%) of cells of the cancer have the relevant genetic variation, mutation status, allele or genotype. In some embodiments, one of >60%, >65%, >70%, >75%, >80%, >85%, >90%, >95% or 100% of the cells of the cancer possess the relevant genetic variation, mutation status, allele or genotype. In some embodiments, a cancer comprising a given genetic variation / mutation / allele / genotype may be a cancer in which >10% (e.g. one of >20%, >50%, >40%, >50%, >60%, >65%, >70%, >75%, >80%, >85%, >90%, >95% or 100%) of cells of the cancer comprise the genetic variation / mutation / allele / genotype. In some embodiments, a cancer not comprising ( / .e. lacking) a given genetic variation / mutation / allele / genotype may be a cancer in which <25% (e.g. one of <20%, <15%, <10%, <5%, <1% or none) of the cells of the cancer comprise the genetic variation / mutation / allele / genotype.

[0279] Herein, where a cell is described as comprising a given genetic variation / mutation, it will be appreciated that one or both alleles of the relevant gene comprise such genetic variation / mutation. In some embodiments, a cell comprising a given genetic variation / mutation may be heterozygous for an allele comprising the genetic variation / mutation. In some embodiments, a cell comprising a given genetic variation / mutation may be homozygous for an allele comprising the genetic variation / mutation.

[0280] Where a cell is described as not comprising a given genetic variation / mutation, it will be appreciated that none of the alleles of the relevant gene comprise such genetic variation / mutation ( / .e. the cell is not homozygous or heterozygous for the mutation / mutant allele).

[0281] As explained hereinabove, in some embodiments, a mutation in ERBB3 according to the present disclosure is a non-synonymous mutation. That is, in some embodiments a mutation in ERBB3 results in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele.

[0282] In some embodiments, the mutation in ERBB3 is associated with an alteration in the amino acid sequence in the extracellular domain of HER3.

[0283] In some embodiments, the mutation in ERBB3 is associated with an alteration in the amino acid sequence of HER3 in the region shown in SEQ ID NO:9. That is, in some embodiments, the mutation in ERBB3 results in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region shown in SEQ ID NO:9. In some embodiments, the mutant ERBB3 allele encodes HER3 polypeptide that does not comprise the amino acid sequence of SEQ ID NO:9.

[0284] In preferred embodiments, the mutation in ERBB3 according to the present disclosure does not prevent binding of an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) to the HER3 encoded by the mutant ERBB3 allele. In preferred embodiments, an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) binds to HER3 encoded by the mutant ERBB3 allele.

[0285] In preferred embodiments, the mutation in ERBB3 according to the present disclosure does not substantially reduce binding of an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) to the HER3 encoded by the mutant ERBB3 allele. In preferred embodiments, the level of binding of an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) to the HER3 encoded by the mutant ERBB3 allele is 0.8 times or greater, e.g. one of >0.85 times, >0.9 times, >0.91 times, >0.92 times, >0.93 times, >0.94 times, >0.95 times, >0.96 times, >0.97 times, >0.98 times or >0.99 times the level of binding displayed by the antigen-binding molecule to the HER3 encoded by the wildtype ERBB3 allele (e.g. HER3 having the amino acid sequence of SEQ ID NO:1).

[0286] In some embodiments, an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) binds to HER3 encoded by the mutant ERBB3 allele with similar affinity to the affinity with which it binds to HER3 encoded by the wildtype allele (e.g. HER3 having the amino acid sequence of SEQ ID NO:1).

[0287] The ability of an antigen-binding molecule to bind to a given peptide / polypeptide and the affinity of such binding can be analyzed by methods well known to the skilled person, including analysis by ELISA, immunoblot (e.g. western blot), immunoprecipitation, Surface Plasmon Resonance (SPR; see e.g. Hearty et al., Methods Mol Biol (2012) 907:411-442) or Bio-Layer Interferometry (BLI; see e.g. Lad et al., (2015) J Biomol Screen 20(4): 498-507).

[0288] In some embodiments, an antigen-binding molecule according to the present disclosure (e.g. 10D1 F) binds to HER3 encoded by the mutant ERBB3 allele with a KD (e.g. as determined by SPR or BLI analysis) that is > 0.5 times and < 2 times, e.g. one of > 0.75 times and < 1 .5 times, > 0.8 times and < 1 .25 times, or > 0.9 times and < 1.1 times the KD with which the antigen-binding molecule binds to HER3 encoded by the wildtype ERBB3 allele (e.g. HER3 having the amino acid sequence of SEQ ID NO:1), as determined in the same assay.

[0289] In some embodiments, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region of HER3 that is bound by an antigen-binding molecule according to the present disclosure.

[0290] In some embodiments, the mutation in ERBB3 is not associated with an alteration in the amino acid sequence of HER3 in the region shown in SEQ ID NO:78. That is, in some embodiments, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region shown in SEQ ID NO:78. In some embodiments, the mutant ERBB3 allele encodes HER3 polypeptide comprising the amino acid sequence of SEQ ID NO:78.

[0291] In some embodiments, the mutation in ERBB3 is not associated with an alteration in the amino acid sequence of HER3 in the region shown in SEQ ID NO:79. That is, in some embodiments, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region shown in SEQ ID NO:79. In some embodiments, the mutant ERBB3 allele encodes HER3 polypeptide comprising the amino acid sequence of SEQ ID NO:79.

[0292] In some embodiments, the mutation in ERBB3 is not associated with an alteration in the amino acid sequence of HER3 in the region shown in SEQ ID NO:77. That is, in some embodiments, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region shown in SEQ ID NO:77. In some embodiments, the mutant ERBB3 allele encodes HER3 polypeptide comprising the amino acid sequence of SEQ ID NO:77.

[0293] In some embodiments, the mutation in ERBB3 is not associated with an alteration in the amino acid sequence of HER3 in the region shown in SEQ ID NO:16. That is, in some embodiments, the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 encoded by the mutant allele relative to the amino acid sequence of HER3 encoded by the wildtype allele in the region shown in SEQ ID NO:16. In some embodiments, the mutant ERBB3 allele encodes HER3 polypeptide comprising the amino acid sequence of SEQ ID NO:16.

[0294] In some embodiments, a mutation in ERBB3 results in a difference at one or more of the following positions, relative to the amino acid sequence of SEQ ID NO:1 : P30, G40, M60, M91 , F94, R103, V104, V119, N126, S128, L155, F219, Q225, H228, A232, G233, G253, P262, V264, G284, V295, D297, P306, D313, G325, K329, E332, G337, S345, T355, T389, G420, R426, L431 , S445, R475, E480, G513, R521 , D581 , P590, V606, R667, M677, R683, V714, K742, H768, L792, L795, Q809, K820, S846, V855, H884, G898, D922, E928, E952, R967, L1027, V1035, V1112, S1119, P1142, L1177, E1191 , P1212, S1215, G1221 , S1234, E1261 , D1320 and A1337. By way of illustration, a mutant allele may encode HER3 comprising an amino acid other than proline at the position corresponding to position 30 of SEQ ID NO:1 .

[0295] In some embodiments, a mutation in ERBB3 results in a difference at one or more of the following positions, relative to the amino acid sequence of SEQ ID NO:1 : V104, A232, P262, T355, T389, D581 , P590, Q809, S846, V855, E928, A1337, R426, E928, V1035, P30, M60, M91 , F94, R103, V104, V119, N126, S128, L155, F219, Q225, H228, A232, G233, G253, P262, V264, G284, V295, D297, P306, G325, K329, E332, G337, S345, T355, G420, L431 , S445, R475, E480, G513, G513, R521 , V606, R667, M677, R683, K742, H768, L795, K820, H884, G898, D922, E928, E952, L1027, V1112, S1119, P1142, L1177, E1191 , P1212, S1215, G1221 , S1234, E1261 and D1320.

[0296] In some embodiments, a mutation in ERBB3 results in a difference at one or more of the following positions, relative to the amino acid sequence of SEQ ID NO:1 : V104, A232, P262, T355, T389, D581 , P590, Q809, S846, V855, E928, A1337, R426, E928 and V1035.

[0297] In some embodiments, a mutation in ERBB3 results in a difference at one or more of the following positions, relative to the amino acid sequence of SEQ ID NO:1 : M60, M91 , V104, N126, H228, A232, P262, G284, D297, E332, T355, R475, T389, R426, D581 and P590.

[0298] In some embodiments, a mutation in ERBB3 results in a difference at one or more of the following positions, relative to the amino acid sequence of SEQ ID NO:1 : D297, G284, V104 and R475.

[0299] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : P30L, G40S, M60K, M60R, M911, F94L, R103G, R103H, V104L, V104M, V119I, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, A232V, G233W, G253R, P262H, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, D313H, G325R, K329E, K329R, K329T, E332K, E332Q, G337R, S345L, T355A, T355I, T355P, T389K, G420V, R426W, L431S, S445F, R475W, E480Q, G513C, G513D, R521Q, D581 N, P590H, V606A, R667H, M677I, R683W, V714M, K742E, H768R, L792V, L795V, Q809R, K820N, S846I, V855A, H884R, G898D, D922Y, E928A, E928G, E928K, E928Q, E952Q, R967K, L1027M, V1035D, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221D, S1234C, E1261A, D1320H and A1337T. By way of illustration, a mutant allele may encode HER3 comprising leucine at the position corresponding to position 30 of SEQ ID NO:1.

[0300] Herein, a mutation in ERBB3 resulting in a given difference in the amino acid sequence of HER3 relative to the amino acid sequence of SEQ ID NO:1 may, for simplicity, be referred to simply as a mutation in ERBB3 resulting in the given amino acid substitution. By way of illustration, ‘a mutation in ERBB3 that results in the amino acid difference E332K in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 ’ may be referred to simply as ‘a mutation in ERBB3 that results in E332K’.

[0301] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : V104L, A232V, P262H, T355I, T389K, D581 N, P590H, Q809R, S846I, V855A, E928G, A1337T, R426W, E928A, E928K, V1035D, P30L, M60K, M60R, M91I, F94L, R103G, R103H, V104M, V119I, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, G233W, G253R, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, G325R, K329E, K329R, E332K, E332Q, G337R, S345L, T355A, T355P, G420V, L431S, S445F, R475W, E480Q, G513C, G513D, R521Q, V606A, R667H, M677I, R683W, K742E, H768R, L795V, K820N, H884R, G898D, D922Y, E928Q, E952Q, L1027M, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221 D, S1234C, E1261A and D1320H.

[0302] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : V104L, A232V, P262H, T355I, T389K, D581 N, P590H, Q809R, S846I, V855A, E928G, A1337T, R426W, E928A, E928K and V1035D.

[0303] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : M60R, M911, V104L, V104M, N126K, H228Q, H228R, A232T, A232V, P262H, G284R, D297V, D297Y, E332K, T355I, T355P, R475W, T389K, R426W, D581 N and P590H.

[0304] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : D297Y, G284R, V104L and R475W.

[0305] In some embodiments, a mutation in ERBB3 does not result in the amino acid difference E332K in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 . In some embodiments, a mutation in ERBB3 does not result in the amino acid difference T355I in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 .

[0306] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : P30L, G40S, M60K, M60R, M911, F94L, R103G, R103H, V104L, V104M, V119I, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, A232V, G233W, G253R, P262H, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, D313H, G325R, K329E, K329R, K329T, E332Q, G337R, S345L, T355A, T355P, T389K, G420V, R426W, L431 S, S445F, R475W, E480Q, G513C, G513D, R521Q, D581 N, P590H, V606A, R667H, M677I, R683W, V714M, K742E, H768R, L792V, L795V, Q809R, K820N, S846I, V855A, H884R, G898D, D922Y, E928A, E928G, E928K, E928Q, E952Q, R967K, L1027M, V1035D, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221 D, S1234C, E1261A, D1320H and A1337T.

[0307] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : V104L, A232V, P262H, T389K, D581 N, P590H, Q809R, S846I, V855A, E928G, A1337T, R426W, E928A, E928K, V1035D, P30L, M60K, M60R, M91I, F94L, R103G, R103H, V104M, V119I, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, G233W, G253R, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, G325R, K329E, K329R, E332Q, G337R, S345L, T355A, T355P, G420V, L431S, S445F, R475W, E480Q, G513C, G513D, R521Q, V606A, R667H, M677I, R683W, K742E, H768R, L795V, K820N, H884R, G898D, D922Y, E928Q, E952Q, L1027M, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221 D, S1234C, E1261A and D1320H.

[0308] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : V104L, A232V, P262H, T389K, D581 N, P590H, Q809R, S846I, V855A, E928G, A1337T, R426W, E928A, E928K and V1035D.

[0309] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : M60R, M911, V104L, V104M, N126K, H228Q, H228R, A232T, A232V, P262H, G284R, D297V, D297Y, T355P, R475W, T389K, R426W, D581 N and P590H.

[0310] In some embodiments, a mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : D297Y, G284R, V104L and R475W.

[0311] In some embodiments, the cancer comprises a mutation in ERBB3 that results in D297Y. In some embodiments, the cancer is an esophageal squamous cell carcinoma comprising a mutation in ERBB3 that results in D297Y. In some embodiments, the cancer comprises a mutation in ERBB3 that results in G248R. In some embodiments, the cancer is an ampullary adenocarcinoma comprising a mutation in ERBB3 that results in G248R. In some embodiments, the cancer comprises mutations resulting in the amino acid differences S31 OF and R678Q relative to the amino acid sequence of HER2 encoded by the wildtype allele of ERBB2. In some embodiments, the cancer comprises mutations resulting in the amino acid differences I582L and N581 T relative to the amino acid sequence of B-Raf encoded by the wildtype allele of BRAE.

[0312] In some embodiments, the cancer comprises a mutation in ERBB3 that results in V104L. In some embodiments, the cancer is a cholangiocarcinoma comprising a mutation in ERBB3 that results in V104L.

[0313] In some embodiments, the cancer comprises a mutation in ERBB3 that results in R475W. In some embodiments, the cancer is an endometrial adenocarcinoma comprising a mutation in ERBB3 that results in R475W. In some embodiments, the cancer comprises mutations resulting in the amino acid differences V842I, T798I and V1253M relative to the amino acid sequence of HER2 encoded by the wildtype allele of ERBB2. In some embodiments, the cancer comprises mutation resulting in the amino acid difference S403G relative to the amino acid sequence of NRG1 encoded by the wildtype allele of NRG1. In some embodiments, the cancer comprises mutation resulting in the amino acid difference A864V relative to the amino acid sequence of EGFR encoded by the wildtype allele of EGFR.

[0314] Taxoids

[0315] Aspects and embodiments of the present disclosure relate to taxoids. As used herein, a ‘taxoid’ refers to a taxane-derived diterpenoid. In the scientific literature, the term ‘taxane’ is sometimes used interchangeably with ‘taxoid’. The chemistry and functional properties of taxoids are reviewed e.g. in Kingston and Newman, Curr Opin Drug Discov Devel. (2007) 10(2):130-144 and Mosca et al., Drug Resist Updat. (2021) 54:100742, both of which are hereby incorporated by reference in their entirety.

[0316] Taxoids are inhibitors of mitosis, and exert their anti-cancer effects principally through disrupting microtubule formation. They stabilise GDP-bound tubulin in microtubules, preventing microtubule depolymerisation and thereby inhibiting cell division. Taxoids include docetaxel, paclitaxel, nab-paclitaxel, larotaxel and cabazitaxel. Paclitaxel, docetaxel and cabazitaxel are the three primary approved taxoids, and they are widely used for the treatment of a variety of solid tumors, including prostate cancers, lung cancer, ovarian cancer and breast cancer.

[0317] In some embodiments, the taxoid of the present disclosure is selected from docetaxel and nab-paclitaxel. In some embodiments, the taxoid is docetaxel. In some embodiments, the taxoid is nab-paclitaxel.

[0318] Nucleoside analogs

[0319] Aspects and embodiments of the present disclosure relate to nucleoside analogs. In particular, the present disclosure is concerned with nucleoside analog inhibitors of DNA replication. They function as antimetabolites, having a structure similar enough to nucleotides to be incorporated into the growing DNA strand. However, incorporation of the nucleoside analog prevents further synthesis of the DNA strand, and ultimately results in cell death. Nucleoside analogs and their use in the treatment of cancers is reviewed e.g. in Jordheim etal., Nat. Rev. Drug Discov. (2013) 12: 447-464, which is hereby incorporated by reference in its entirety. Gemcitabine is used for the treatment of testicular cancer, breast cancer, ovarian cancer, non-small cell lung cancer, pancreatic cancer, biliary tract cancer and bladder cancer.

[0320] In some embodiments, the nucleoside analog according to the present disclosure is a deoxycytidine nucleoside analog. In some embodiments, the nucleoside analog is gemcitabine or a salt thereof (e.g. gemcitabine hydrochloride).

[0321] Therapeutic and prophylactic intervention

[0322] Aspects and embodiments of the present disclosure relate to therapeutic and prophylactic intervention for the treatment and prevention of the cancers described herein.

[0323] The present disclosure provides an antigen-binding molecule that binds to HER3 described herein for use in a method of treating or preventing a cancer described herein in a subject. Also provided is the use of an antigen-binding molecule that binds to HER3 described herein in the manufacture of a medicament for use in treating or preventing a cancer described herein in a subject. Also provided is a method of treating or preventing a cancer described herein in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of an antigen-binding molecule that binds to HER3 described herein.

[0324] The present disclosure also provides an antigen-binding molecule that binds to HER3 described herein for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a taxoid. Also provided is a taxoid for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein. Also provided is the use of an antigenbinding molecule that binds to HER3 described herein in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a taxoid. Also provided is the use of a taxoid in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein. Further provided is a method of treating or preventing a cancer described herein in a subject, the method comprising administering a therapeutically- or prophylactically-effective amount of (i) an antigenbinding molecule that binds to HER3 described herein and (ii) a taxoid to a subject in need of treatment.

[0325] The present disclosure also provides an antigen-binding molecule that binds to HER3 described herein for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a nucleoside analog. Also provided is a nucleoside analog for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein. Also provided is the use of an antigen-binding molecule that binds to HER3 described herein in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a nucleoside analog. Also provided is the use of a nucleoside analog in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein. Further provided is a method of treating or preventing a cancer described herein in a subject, the method comprising administering a therapeutically- or prophylactically-effective amount of (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a nucleoside analog to a subject in need of treatment.

[0326] The present disclosure also provides an antigen-binding molecule that binds to HER3 described herein for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a taxoid and a nucleoside analog. Also provided is a taxoid for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein and a nucleoside analog. Also provided is a nucleoside analog for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigenbinding molecule that binds to HER3 described herein and a taxoid. Also provided is the use of an antigen-binding molecule that binds to HER3 described herein in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering a taxoid and a nucleoside analog. Also provided is the use of a taxoid in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein and a nucleoside analog. Also provided is the use of a nucleoside analog in the manufacture of a medicament for use in a method of treating or preventing a cancer described herein in a subject, wherein the method further comprises administering an antigen-binding molecule that binds to HER3 described herein and taxoid. Further provided is a method of treating or preventing a cancer described herein in a subject, the method comprising administering a therapeutically- or prophylactically- effective amount of an antigen-binding molecule that binds to HER3 described herein, a taxoid and a nucleoside analog, to a subject in need of treatment.

[0327] The present disclosure also provides (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a taxoid for use in a method of treating or preventing a cancer described herein in a subject. Also provided is the use of (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a taxoid in the manufacture of a medicament for use in treating or preventing a cancer described herein in a subject. Also provided is a method of treating or preventing a cancer described herein in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a taxoid.

[0328] The present disclosure also provides (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a nucleoside analog for use in a method of treating or preventing a cancer described herein in a subject. Also provided is the use of (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a nucleoside analog in the manufacture of a medicament for use in treating or preventing a cancer described herein in a subject. Also provided is a method of treating or preventing a cancer described herein in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of (i) an antigen-binding molecule that binds to HER3 described herein and (ii) a nucleoside analog.

[0329] In embodiments in accordance with aspects of the preceding two paragraphs, provision of (i) and (ii) may be as a combination therapy. In some embodiments, (i) and (ii) may be provided simultaneously or sequentially.

[0330] The present disclosure also provides (i) an antigen-binding molecule that binds to HER3 described herein, (ii) a taxoid, and (iii) a nucleoside analog for use in a method of treating or preventing a cancer described herein in a subject. Also provided is the use of (i) an antigen-binding molecule that binds to HER3 described herein, (ii) a taxoid, and (iii) a nucleoside analog in the manufacture of a medicament for use in treating or preventing a cancer described herein in a subject. Also provided is a method of treating or preventing a cancer described herein in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of (i) an antigen-binding molecule that binds to HER3 described herein, (ii) a taxoid, and (iii) a nucleoside analog.

[0331] In embodiments in accordance with aspects of the preceding paragraph, provision of (i), (ii) and (iii) may be as a combination therapy. In some embodiments, (i), (ii) and (iii) may be provided simultaneously or sequentially.

[0332] It will be appreciated that the antigen-binding molecule that binds to HER3 may be an antigen-binding molecule that binds to HER3 according to any embodiment described herein. In preferred embodiments, the antigen-binding molecule that binds to HER3 is selected from one of (1) to (29) above. It will similarly be appreciated that the taxoid may be a taxoid according to any embodiment described herein, e.g. docetaxel or nab-paclitaxel. Similarly, the nucleoside analog may be a nucleoside analog according to any embodiment described herein, e.g. a deoxycytidine nucleoside analog, e.g. gemcitabine or a salt thereof.

[0333] Therapeutic or prophylactic intervention in accordance with the present disclosure may be effective to reduce the development or progression of the cancer, alleviate one or more symptoms of the cancer or reduce the pathology of cancer. The intervention may be effective to prevent progression of the cancer, e.g. to prevent worsening of, or to slow the rate of development of, the cancer. In some embodiments, the intervention may lead to an improvement in the cancer, e.g. a reduction in the symptoms of the cancer or a reduction in some other correlate of the severity / activity of the cancer. In some embodiments, the methods may prevent development of the cancer to a later stage (e.g. a more severe stage or metastasis).

[0334] Treatment of a cancer in accordance with the methods of the present disclosure achieves one or more of the following treatment effects: reduces the number of cancer cells in the subject, reduces the size of a cancerous tumor / lesion in the subject, inhibits (e.g. prevents or slows) growth of cancer cells in the subject, inhibits (e.g. prevents or slows) growth of a cancerous tumor / lesion in the subject, inhibits (e.g. prevents or slows) the development / progression of a cancer (e.g. to a later stage, or metastasis), reduces the severity of symptoms of a cancer in the subject, increases survival of the subject (e.g. progression free survival or overall survival), reduces a correlate of the number or activity of cancer cells in the subject, and / or reduces cancer burden in the subject. Prevention may refer to prevention of development of a cancer, and / or prevention of worsening of a cancer, e.g. prevention of progression of a cancer, e.g. to a later stage (e.g. metastasis).

[0335] In some embodiments, the therapeutic or prophylactic intervention may be aimed at one or more of: delaying / preventing the onset / progression of symptoms of the cancer, reducing the severity of symptoms of the cancer, reducing the survival / growth / invasion / metastasis of cells of the cancer, reducing the number of cells of the cancer and / or increasing survival of the subject.

[0336] In some embodiments, therapeutic or prophylactic intervention according to the present disclosure may be associated with one or more of: inhibition of the development / progression of the cancer, a delay to / prevention of onset of the cancer, a reduction in / delay to / prevention of tumor growth, a reduction in / delay to / prevention of tissue invasion, a reduction in / delay to / prevention of metastasis, a reduction in the severity of one or more symptoms of the cancer, a reduction in the number of cancer cells, a reduction in the cancer burden, a reduction in tumor size / volume, and / or an increase in survival of subjects having the cancer (e.g. progression free survival or overall survival).

[0337] In accordance with various aspects of the present disclosure, methods are provided which are for, or which comprise (e.g. in the context of treatment / prevention of a cancer described herein) inhibiting the growth of a tumor, reducing the size / volume of a tumor, and / or increasing the survival of a subject having a cancer. Also provided are agents according to the present disclosure for use in such methods, and the use of agents according to the present disclosure in the manufacture of compositions (e.g. medicaments) for use in such methods.

[0338] Similarly, inhibition of tumor growth and / or reduction of tumor size / volume, and / or increased survival of a subject may be observed in a subject following therapeutic or prophylactic intervention in accordance with the present disclosure. In some embodiments, therapeutic / prophylactic intervention in accordance with the present disclosure may be described as being ‘associated with’ such effects. The skilled person is readily able to evaluate such properties using techniques that are routinely practiced in the art.

[0339] Subjects may be evaluated in accordance with the response evaluation criteria in solid tumors (RECIST) criteria, e.g. the RECIST 1.1 criteria as described in Eisenhauer et al., Eur J Cancer. 2009 Jan;45(2):228- 47, which is hereby incorporated by reference in its entirety. In some embodiments, subjects may be evaluated in accordance with the Revised Criteria for Response Assessment: The Lugano Classification (described e.g. in Cheson et al., J Clin Oncol (2014) 32: 3059-3068, incorporated by reference hereinabove) in order to determine their response to treatment. In some embodiments, treatment of a subject in accordance with the methods of the present disclosure achieves one of the following: an overall response, complete response, partial response, or stable disease.

[0340] An overall response (OR) is a Complete Response (CR) or a Partial Response (PR).

[0341] A complete response (CR) refers to a complete macroscopic disappearance of all target and / or nontarget tumors. A CR may involve normalization of tumor marker level.

[0342] A partial response (PR) refers to a reduction of at least 30% in the sum of all target tumor diameters compared to baseline sum diameters calculated before treatment.

[0343] Stable disease refers to neither partial response nor progressive disease compared to the tumor burden at the start of treatment.

[0344] Progressive disease (PD) refers to an at least a 20% increase in the sum of diameters of target lesions taking as reference the smallest sum on study = nadir (this includes the baseline sum if that is the smallest on study). In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5 mm. Unequivocal progression of existing non target lesions or the appearance of one or more new lesions will also constitute progressive disease.

[0345] In some embodiments, treatment of a subject in accordance with the methods of the present disclosure achieves one of the following (e.g. as compared to the absence of such treatment, or as compared to a known treatment for the relevant cancer): increased overall survival, increased progression-free survival, increased disease control rate, or increased objective response rate.

[0346] Overall survival (OS) refers to the time from randomization of subjects to study arms to death.

[0347] Progression free survival (PFS) refers to the time from randomization of subjects to study arm until first evidence of disease progression or death.

[0348] Disease control rate (DOR) refers to the proportion of patients whose therapeutic intervention has led to a complete response, partial response, or stable disease.

[0349] Objective response rate (ORR) refers to the proportion of patients having an Overall Response.

[0350] Administration of the agents and compositions of the present disclosure is preferably in a ‘therapeutically- effective’ or ‘prophylactically-effective’ amount, this being sufficient to show therapeutic or prophylactic benefit to the subject. The actual amount administered, and rate and time-course of administration, will depend on the nature and severity of the disease / condition and the particular article administered.

[0351] Prescription of treatment, e.g. decisions on dosage etc., is within the responsibility of general practitioners and other medical doctors, and typically takes account of the disease / disorder to be treated, the condition of the individual subject, the site of delivery, the method of administration and other factors known to practitioners. Examples of the techniques and protocols mentioned above can be found in Remington’s ‘The Science and Practice of Pharmacy’ (Ed. A. Adejare), 23rd Edition (2020), Academic Press.

[0352] Therapeutic / prophylactic agents according to the present disclosure (e.g. the antigen-binding molecule that binds to HER3, the taxoid, the nucleoside analog) may be provided in the form of a composition comprising the agent. Such compositions may comprise the relevant agent in a formulation suitable for clinical use.

[0353] The compositions may comprise one or more pharmaceutically-acceptable carriers (e.g. liposomes, micelles, microspheres, nanoparticles), diluents / excipients (e.g. starch, cellulose, a cellulose derivative, a polyol, dextrose, maltodextrin, magnesium stearate), adjuvants, fillers, buffers, preservatives (e.g. vitamin A, vitamin E, vitamin C, retinyl palmitate, selenium, cysteine, methionine, citric acid, sodium citrate, methyl paraben, propyl paraben), anti-oxidants (e.g. vitamin A, vitamin E, vitamin C, retinyl palmitate, selenium), lubricants (e.g. magnesium stearate, talc, silica, stearic acid, vegetable stearin), binders (e.g. sucrose, lactose, starch, cellulose, gelatin, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), xylitol, sorbitol, mannitol), stabilisers, solubilisers, surfactants (e.g., wetting agents), masking agents or colouring agents (e.g. titanium oxide).

[0354] The term ‘pharmaceutically-acceptable’ as used herein pertains to compounds, ingredients, materials, compositions, dosage forms, etc., which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of the subject in question (e.g. a human subject) without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit / risk ratio. Each carrier, diluent, excipient, adjuvant, filler, buffer, preservative, anti-oxidant, lubricant, binder, stabiliser, solubiliser, surfactant, masking agent, colouring agent, flavouring agent or sweetening agent of a composition according to the present disclosure must also be ‘acceptable’ in the sense of being compatible with the other ingredients of the formulation. Suitable carriers, diluents, excipients, adjuvants, fillers, buffers, preservatives, anti-oxidants, lubricants, binders, stabilisers, solubilisers, surfactants, masking agents, colouring agents, flavouring agents or sweetening agents can be found in standard pharmaceutical texts, for example, Remington’s ‘The Science and Practice of Pharmacy’ (Ed. A. Adejare), 23rd Edition (2020), Academic Press.

[0355] The articles of the present disclosure may be formulated for administration to a subject, e.g. administration via a route of administration as appropriate for the nature of the therapeutic agent and the disease to be treated / prevented. Administration of the articles of the present disclosure may be parenteral, systemic, topical, intracavitary, intravascular, intravenous, intra-arterial, intramuscular, intrathecal, intraocular, intraconjunctival, intratumoral, subcutaneous, intradermal, oral or transdermal. In some embodiments, administration may be by injection or infusion, or by ingestion.

[0356] Medicaments and pharmaceutical compositions may be formulated for administration to a blood vessel, or to a tissue / organ of interest (e.g. a tissue / organ affected by the disease / condition affected by the condition; e.g. a tissue / organ in which symptoms of the disease / condition manifest), or a tumor. The pharmaceutical compositions / medicaments may comprise the agent(s) in a sterile or isotonic medium. The pharmaceutical compositions / medicaments may be provided in fluid, including gel, form. Fluid formulations may be formulated for administration by injection or infusion (e.g. via cannula) to a blood vessel, or a selected region of the human or animal body, or to a tumor. The pharmaceutical compositions / medicaments may be provided in solid form, e.g. in lyophilized form.

[0357] In some embodiments, the antigen-binding molecule that binds to HER3 described herein is provided in a 50 mg / mL solution. In some embodiments, the antigen-binding molecule that binds to HER3 described herein is formulated in a composition comprising 20 mM histidine, 8% (w / v) sucrose, 0.02% (w / v) polysorbate 80 at pH 5.8.

[0358] In some embodiments, docetaxel is formulated in a composition comprising 0.9% (w / v) sodium chloride.

[0359] In some embodiments, nab-paclitaxel is formulated in a composition comprising 0.9% (w / v) sodium chloride.

[0360] In some embodiments, gemcitabine is formulated in a composition comprising 0.9% (w / v) sodium chloride.

[0361] In some aspects and embodiments, articles of the present disclosure may be administered to a tissue / organ of interest (e.g. a tissue / organ affected by the disease / condition) affected by the condition (e.g. a tissue / organ in which symptoms of the disease / condition manifest). In some aspects and embodiments, articles of the present disclosure may be administered to the blood ( / .e. intravenous / intra- arterial administration) by injection or infusion (e.g. via cannula), or may be administered subcutaneously or orally. In some aspects and embodiments, articles of the present disclosure may be administered to a tumor.

[0362] Where two or more agents are administered in combination in connection with therapeutic / prophylactic intervention according to the present disclosure, the agents may be administered either simultaneously or sequentially.

[0363] Simultaneous administration refers to administration of the two or more agents together, for example as a pharmaceutical composition containing both agents ( / .e. as a combined preparation), or immediately after each other (e.g. within 1 , 4, 6, 8 or 12 hours), and optionally via the same route of administration, e.g. to the same artery, vein or other blood vessel.

[0364] Sequential administration refers to administration of one of the agents followed after a given time interval by separate administration of another agent. It is not required that the agents are administered by the same route, although this is the case in some embodiments. The time interval may be any time interval. Multiple doses of the agents, pharmaceutical combinations and pharmaceutical compositions may be provided. Multiple doses may be separated by a predetermined time interval, which may be selected to be one of 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 , 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, or 31 days, or 1 , 2, 3, 4, 5, or 6 months. By way of example, doses may be given once every 7, 14, 21 or 28 days (plus or minus 3, 2, or 1 days: such as 4, 5, 6, 8, 9 or 10 days; 11 , 12, 13, 15, 16 or 17 days; 18, 19, 20, 22, 23, or 24 days; or 25, 26, 27, 29, 30 or 31 days). That is, there may be one treatment event every 7 days, every 14 days, every 21 days, or every 28 days. There may be a treatment holiday between doses / administrations of about 7 days (plus or minus 3, 2, or 1 days), about 14 days (plus or minus 3, 2, or 1 days), about 21 days (plus or minus 3, 2, or 1 days), or about 28 days (plus or minus 3, 2, or 1 days), respectively.

[0365] In some embodiments, the antigen-binding molecule that binds to HER3 (e.g. 10D1 F) is administered once every week (e.g. once every 7 days, plus or minus 3, 2, or 1 days). In some embodiments, the antigen-binding molecule that binds to HER3 (e.g. 10D1 F) is administered at a dose of 150-6000 mg per administration, e.g. one of 600-3000 mg, 900-3000 mg, 900-2400 mg, 1500-3000 mg, 1500-2400 mg, 1500-2100 mg or about 1800 mg per administration. In some embodiments, the antigen-binding molecule that binds to HER3 (e.g. 10D1 F) is administered intravenously. In some embodiments, the antigenbinding molecule that binds to HER3 (e.g. 10D1 F) is administered essentially as described in Example 4 herein.

[0366] In some embodiments, therapeutic / prophylactic intervention in accordance with the present disclosure comprises administering 10D1 F (e.g. intravenously) once weekly (e.g. at a dose of 1500-2500 mg, e.g. about 1800 mg per administration).

[0367] In some embodiments, the taxoid (e.g. docetaxel) is administered one every three weeks (e.g. once every 21 days, plus or minus 3, 2, or 1 days). In some embodiments, the taxoid (e.g. docetaxel) is administered at a dose of 10-300 mg / m2per administration, e.g. one of 20-200 mg / m2, 25-150 mg / m2, 30-125 mg / m2, 50-100 mg / m2, 60-90 mg / m2, or about 75 mg / m2per administration. In some embodiments, the taxoid (e.g. docetaxel) is administered intravenously. In some embodiments, the taxoid (e.g. docetaxel) is administered essentially as described in Example 4 herein.

[0368] In some embodiments, the taxoid (e.g. nab-paclitaxel) is administered on Days 1 , 8 and 15 (plus or minus 3, 2, or 1 days) of a 28 day cycle. In some embodiments, the taxoid (e.g. nab-paclitaxel) is administered at a dose of 15-420 mg / m2per administration, e.g. one of 30-300 mg / m2, 35-210 mg / m2, 40-175 mg / m2, 70-140 mg / m2, 85-130 mg / m2, or about 125 mg / m2per administration. In some embodiments, the taxoid (e.g. nab-paclitaxel) is administered intravenously. In some embodiments, the taxoid (e.g. nab-paclitaxel) is administered essentially as described in Example 4 herein.

[0369] In some embodiments, the nucleoside analog (e.g. gemcitabine) is administered on Days 1 , 8 and 15 (plus or minus 3, 2, or 1 days) and subsequently once every four weeks (e.g. once every 28 days, plus or minus 3, 2, or 1 days). In some embodiments, the nucleoside analog (e.g. gemcitabine) is administered at a dose of 100-2000 mg / m2per administration, e.g. one of 200-1750 mg / m2, 500-1500mg / m2, 750-1250 mg / m2, 900-1100 mg / m2, or about 1000 mg / m2per administration. In some embodiments, the nucleoside analog (e.g. gemcitabine) is administered intravenously. In some embodiments, the nucleoside analog (e.g. gemcitabine) is administered essentially as described in Example 4 herein.

[0370] In aspects and embodiments according to the present disclosure in which docetaxel is administered to a subject, the therapeutic / prophylactic intervention may further comprise administration of dexamethasone. In some embodiments, 8 mg dexamethasone is administered PO ( / .e. per os: by mouth) twice daily with or after food, on the day prior to administration of docetaxel, on the day of administration of docetaxel, and on the day after administration of docetaxel.

[0371] In aspects and embodiments according to the present disclosure in which gemcitabine is administered to a subject, the therapeutic / prophylactic intervention may further comprise administration of dexamethasone and / or palnosetron. In some embodiments, 8 mg dexamethasone is administered PO with or after food 60 min ± 15 min prior to administration of gemcitabine, and 0.25 mg palnosetron is administered intravenously 30 min ± 10 min prior to administration of gemcitabine.

[0372] In aspects and embodiments according to the present disclosure in which nab-paclitaxel is administered to a subject, the therapeutic / prophylactic intervention may further comprise administration of dexamethasone and / or palnosetron. In some embodiments, 8 mg dexamethasone is administered PO with or after food 60 min ± 15 min prior to administration of nab-paclitaxel, and 0.25 mg palnosetron is administered intravenously 30 min ± 10 min prior to administration of nab-paclitaxel.

[0373] In some embodiments, the intervention comprises additional therapeutic or prophylactic intervention, e.g. for the treatment / prevention of a cancer. In some embodiments, the additional therapeutic or prophylactic intervention is selected from chemotherapy, immunotherapy, radiotherapy, surgery, vaccination and / or hormone therapy. In some embodiments, the additional therapeutic or prophylactic intervention comprises leukapheresis. In some embodiments, the additional therapeutic or prophylactic intervention comprises a stem cell transplant.

[0374] Diagnostic and prognostic methods, and patient selection

[0375] The present disclosure also provides diagnostic, prognostic and predictive methods in connection with the cancers described herein.

[0376] The methods may be performed in vitro on a sample obtained from a subject, or following processing of a sample obtained from a subject. Once the sample is collected, the subject is not reguired to be present for the in vitro method to be performed, and therefore the method may be one which is not practised on the human or animal body. However, in some embodiments the methods may be performed in vivo.

[0377] A sample may be taken from any tissue or bodily fluid. A sample may comprise or may be derived from: a guantity of blood; a guantity of serum derived from a subject’s blood which may comprise the fluid portion of the blood obtained after removal of the fibrin clot and blood cells; a tissue sample or biopsy; pleural fluid; cerebrospinal fluid (CSF); or cells isolated from a subject. In some embodiments, the sample may be obtained or derived from a tissue or tissues which are affected by the disease / condition (e.g. tissue or tissues in which symptoms of the disease manifest, or which are involved in the pathogenesis of the disease / condition). In some embodiments, the sample may be obtained or derived from a cancer, tumor, or cells thereof.

[0378] The methods may be performed for the purpose of diagnosing a cancer (e.g. a cancer described herein). The methods may be performed for the purpose of prognosing / predicting the likely response of a subject to therapeutic / prophylactic intervention as described herein. The methods may be useful to predict the likely response to a given therapeutic / prophylactic intervention, e.g. in terms of efficacy, and may therefore by useful for supporting clinical decision-making. The methods may be performed for the purpose of identifying / selecting a subject for therapeutic / prophylactic intervention as described herein.

[0379] In some aspects and embodiments, the methods comprise analyzing a subject’s cancer to determine whether the cancer is a cancer described herein.

[0380] In some embodiments, the methods comprise evaluating a cancer to determine whether it comprises genetic variation as described herein. In some embodiments, the methods comprise evaluating a cancer to determine whether it comprises cells comprising genetic variation as described herein.

[0381] Aspects and embodiments of the present disclosure also comprise selecting a subject for therapeutic or prophylactic intervention in accordance with the present disclosure.

[0382] A subject having a cancer which is identified following such analysis to be a cancer described herein may be selected for therapeutic / prophylactic intervention using an antigen-binding molecule that binds to HER3 according to the present disclosure.

[0383] In some embodiments, a subject is selected / not selected for therapeutic / prophylactic intervention in accordance with the present disclosure based on the result of analysis of their cancer to determine whether the cancer is a cancer described herein.

[0384] In some aspects and embodiments, the methods comprise:

[0385] (a) analyzing a subject’s cancer to determine whether the cancer is a cancer according to an embodiment described herein; and

[0386] (b) selecting a subject for treatment with an antigen-binding molecule that binds to HER3 according to the present disclosure where the subject’s cancer is determined in step (a) to be a cancer according to an embodiment described herein.

[0387] In some embodiments, the methods further comprise:

[0388] (c) administering an antigen-binding molecule that binds to HER3 according to the present disclosure to a subject selected for treatment in step (b). Analysis of a cancer may comprise analyzing the nucleotide sequence(s) of gene(s) / gene region(s) described herein (e.g. in a nucleic acid-containing sample obtained from the cancer), to determine whether the cancer comprises genetic variation as described herein. Analysis may be of cells of a cancer. Analysis may be of a nucleic acid-containing sample / biopsy obtained from a cancer / cells thereof. Such analysis is preferably performed in vitro.

[0389] Methods for evaluating the nucleotide sequence(s) of genes of interest are well known in the art, and include e.g. sequencing by the classic chain termination method, and next generation sequencing (NGS) technologies, which are reviewed e.g. by Metzker, M.L., Nat Rev Genet (2010) 11 (1): 31-46 (hereby incorporated by reference in its entirety). Further methods for evaluating the nucleotide sequence(s) of genes of interest for the presence / absence of genetic variation include restriction fragment length polymorphism identification (RFLPI) of genomic DNA, random amplified polymorphic detection (RAPD) of genomic DNA, amplified fragment length polymorphism detection (AFLPD), multiple locus variable number tandem repeat (VNTR) analysis (MLVA), SNP genotyping, multilocus sequence typing, allele specific oligonucleotide (ASO) probes, and oligonucleotide microarrays or beads. Other suitable methods are described e.g. in Edenberg HJ and Liu Y, Cold Spring Harb Protoc; 2009; doi : 10.1101 / pdb.top62, and Tsuchihashi Z and Dracopoli NC, Pharmacogenomics J., 2002, 2:103-110.

[0390] In further aspects, the present disclosure provides methods for determining whether a subject is likely to respond to therapeutic or prophylactic intervention using an antigen-binding molecule that binds to HER3 described herein.

[0391] In some embodiments, the methods comprise: analyzing a subject’s cancer to determine whether the cancer is a cancer described herein, wherein a subject having determined to comprise a cancer described herein is determined to be likely to respond to therapeutic or prophylactic intervention using an antigen-binding molecule that binds to HER3 described herein ( / .e. as a monotherapy).

[0392] Subjects

[0393] The subject in accordance with aspects described herein may be any animal or human. The subject is preferably mammalian, more preferably human. The subject may be a non-human mammal, but is more preferably human. The subject may be male or female. The subject may be a patient. A subject may have been diagnosed with a disease or condition requiring treatment (e.g. a cancer, e.g. a cancer described herein), may be suspected of having such a disease / condition, or may be at risk of developing / contracting such a disease / condition.

[0394] In some embodiments, the subject to be treated according to a therapeutic or prophylactic method of the present disclosure herein is a subject having, or at risk of developing, a cancer, e.g. a cancer described herein. In embodiments according to the present disclosure, a subject may be selected for treatment according to the methods based on characterization for certain markers of such disease / condition.

[0395] In some embodiments, a subject may be selected for treatment described herein based on the detection of a cancer described herein, e.g. in a sample obtained from the subject (e.g. a biopsy, e.g. of a tumor). In some embodiments, the subject to be treated in accordance with the present disclosure has previously been treated with an inhibitor of the PD-L1 / PD-1 signaling axis. In some embodiments, the subject has previously been treated with an antagonist of PD-L1 / PD-1 -mediated signaling. In some embodiments, the subject has previously been treated with an anti-PD-1 antibody antagonist of PD-L1 / PD-1 -mediated signaling. In some embodiments, the subject has previously been treated with an anti-PD-L1 antibody antagonist of PD-L1 / PD-1 -mediated signaling.

[0396] In some embodiments, the subject to be treated in accordance with the present disclosure has not received more than 2 prior lines of systemic anti-cancer therapy for advanced disease.

[0397] In some embodiments, the subject has not received prior treatment with a HER3-targeted agent. In some embodiments, the subject to be treated in accordance with the present disclosure has not received prior treatment with an anti-HER3 antibody. In some embodiments, the subject has not received prior treatment with HMBD-001 ( / .e. 10D1 F). In some embodiments, the subject has not received prior treatment with pertuzumab.

[0398] In some embodiments, the subject to be treated in accordance with the present disclosure has not received prior treatment with a tyrosine kinase inhibitor that substantially inhibits HER3 tyrosine kinase activity. In some embodiments, the subject has not received prior treatment with a tyrosine kinase inhibitor. In some embodiments, the subject has not received prior treatment with a pan-HER tyrosine kinase inhibitor.

[0399] In some embodiments, the subject to be treated in accordance with the present disclosure has not received prior treatment with a nucleoside analog. In some embodiments, the subject has not received prior treatment with gemcitabine or a salt thereof (e.g. gemcitabine hydrochloride).

[0400] In some embodiments, the subject to be treated in accordance with the present disclosure has not received prior treatment with a taxoid. In some embodiments, the subject has not received prior treatment with nab-paclitaxel. In some embodiments, the subject has not received prior treatment with docetaxel.

[0401] In some embodiments, the subject to be treated in accordance with the present disclosure has disease measurable in accordance with the RECIST 1 .1 criteria, as described in Eisenhauer et al., Eur J Cancer. 2009 Jan;45(2):228-47.

[0402] In some embodiments, the subject to be treated in accordance with the present disclosure has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 ( / .e. fully active, able to carry on all predisease performance without restriction) to 1 ( / .e. restricted in physically strenuous activity but ambulatory and able to carry out work of a light or sedentary nature, e.g., light house work, office work). The ECOG Performance Status Scale is described e.g. in Oken et al. Am J Clin Oncol. (1982) 5(6):649-655, which is hereby incorporated by reference in its entirety. In some embodiments, the subject to be treated in accordance with the present disclosure has a locally- advanced, unresectable or metastatic solid tumor harboring mutation in ERBB3. In some embodiments, the mutation in ERBB3 results in an amino acid difference in the extracellular domain of HER3 encoded by the mutant ERBB3 allele. In some embodiments, the mutation in ERBB3 does not affect binding of 10D1 F to HER3 encoded by the mutant ERBB3 allele.

[0403] In some embodiments, the subject to be treated in accordance with the present disclosure furthermore:

[0404] (i) has a cancer that is resistant or refractory to standard systemic therapy, or for which there is no standard systemic therapy or reasonable therapy in the physician’s judgment likely to result in clinical benefit, or where the subject has been demonstrated to be intolerable to such therapy, or if such therapy has been refused by the subject;

[0405] (ii) has RECIST v1 .1 measurable disease;

[0406] (iii) has sufficient tumor material ( / .e. 1 archival tumor FFPE block or at least 15 consecutive, unstained tumor slides) available for shipment to the central lab at time of enrolment OR, alternatively, a fresh tumor sample;

[0407] (iv) is > 18 years old;

[0408] (v) has standard contraception requirements;

[0409] (vi) has adequate baseline organ function, as demonstrated by the following:

[0410] Serum creatinine <2 x institutional ULN

[0411] Serum albumin >2.5 g / dl

[0412] Bilirubin <2.0 x institutional ULN

[0413] AST and ALT <2.5 x institutional ULN. Subjects with hepatitis metastases enrolled may have ALT and AST < 5 x institutional ULN if the subject has hepatic metastases;

[0414] (vii) where the subject is not taking warfarin or other oral anticoagulants, the subject has an international normalized ratio (INR) <1 .5 or prothrombin time (PT) <1 .5 x ULN; and either partial thromboplastin time or activated partial thromboplastin time (PTT or aPTT) <1 .5 x ULN.

[0415] (viii) where the subject is taking warfarin, they are on a stable dose that results in a stable INR <3.5.

[0416] (ix) where the subject is receiving other oral anticoagulant therapy, PT or aPTT is within the intended therapeutic range of the anticoagulant;

[0417] (x) has adequate baseline hematologic function, as demonstrated by the following:

[0418] ANC >1.5x109 / L.

[0419] Hemoglobin >8 g / dL and no red blood cell (RBC) transfusions during the prior 14 days. Platelet count >100x109 / L and no platelet transfusions during the prior 14 days;

[0420] (xi) is willing to adhere to protocol requirements, including follow-up for survival assessment;

[0421] (x) has not displayed persistent clinically significant toxicities (Grade >2) from previous anticancer therapy (excluding Grade 2 chemotherapy-related neuropathy and alopecia which are permitted), nor any prior toxicities that resulted in laboratory abnormalities that have not resolved to Grade <1 unless a higher-grade abnormality is allowed by the inclusion criteria. If medical therapy is required for the treatment of a laboratory abnormality, the dose and laboratory value(s) should be stable; (xi) where the subject is a subject having pancreatic ductal adenocarcinoma, they have not received more than 2 prior regimens for advanced / metastatic disease, excluding neoadjuvant treatment / adjuvant, unless the PDAC had recurred within 6 months of such treatment;

[0422] (xii) has not received prior treatment with chemotherapy, external-beam radiation, or other systemic anticancer therapy within 14 days prior to commencement of treatment in accordance with the present disclosure (or 42 days for prior nitrosourea or mitomycin-C);

[0423] (xiii) has not received prior cytotoxic chemotherapy, monoclonal antibody therapy, small molecule tyrosine kinase inhibitor therapy and / or an investigational systemic anticancer agent therapy within 28 days or 5 half-lives (whichever is shorter) prior to commencement of treatment in accordance with the present disclosure;

[0424] (xiv) has not received wide-field radiation therapy within 28 days of treatment with HMBD-001 ( / .e. 10D1 F); excluding palliative treatment to a bone metastasis or similar narrow-field radiation.

[0425] (xv) does not have any additional active malignancy that may confound the assessment of the study endpoints (subjects having the following concomitant neoplastic diagnoses are not excluded: nonmelanoma skin cancer, carcinoma in situ (including transitional cell carcinoma, cervical intraepithelial neoplasia, and melanoma in situ), organ-confined prostate cancer with no evidence of progressive disease);

[0426] (xvi) does not have clinically significant cardiovascular disease (e.g. uncontrolled or any New York Heart Association Class 3 or 4 heart failure, uncontrolled angina, history of myocardial infarction, unstable angina or stroke within 6 months prior to study entry, uncontrolled hypertension or clinically significant arrhythmias not controlled by medication);

[0427] (xvii) does not have uncontrolled, clinically-significant medical issues such as pulmonary disease (e.g. chronic obstructive pulmonary disease, pulmonary hypertension), or an uncontrolled intercurrent illness including, but not limited to, uncontrolled infection requiring systemic therapy, disseminated intravascular coagulation, or psychiatric illness / social situations;

[0428] (xix) does not have known active or suspected brain or leptomeningeal metastases (subjects having stable treated brain metastases are not excluded provided there is no evidence of CNS disease growth on imaging for at least 4 weeks following radiation therapy or other locoregional ablative therapy to the CNS);

[0429] (xx) does not have any condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days prior to commencement of treatment in accordance with the present disclosure (inhaled or topical steroids are permitted in the absence of active autoimmune disease);

[0430] (xxi) does not have a QTc interval > 450 ms (male) or 470 ms (female);

[0431] (xxii) is not pregnant or breast feeding;

[0432] (xxii) does not have positive status for human immunodeficiency virus;

[0433] (xxiv) does not have active or chronic hepatitis B or C; and / or

[0434] (xxv) does not have any medical condition which places the subject at an unacceptably high risk for toxi cities.

[0435] In some embodiments, the subject according to the present disclosure conforms to the inclusion and exclusion criteria of Arm D of the study of the study of Example 4 herein. Kits

[0436] The present disclosure also provides kits of parts. A kit according to the present disclosure may comprise components for performing a method described herein, in whole or in part.

[0437] The kit may have at least one container having a predetermined quantity of one or more agents or compositions described herein. Agents / compositions may be provided in a predetermined quantity. Where the kit comprises multiple different agents / compositions, they may be provided in separate containers, or in the same container.

[0438] In some embodiments, the kit comprises an antigen-binding molecule which binds to HER3 as described herein. In some embodiments, the kit comprises a taxoid as described herein. In some embodiments, the kit comprises a nucleoside analog as described herein. In some embodiments, the kit comprises a pharmaceutical combination according to the present disclosure.

[0439] The kit may further comprise reagents, buffers and / or standards required for execution of a method according to the present disclosure.

[0440] In some embodiments, a kit may comprise means for evaluating a cancer to determine whether it comprises genetic variation as described herein. Means for evaluating a cancer to determine whether it comprises genetic variation described herein may comprise e.g. one or more oligonucleotides having complementarity to the nucleotide sequence of one or more gene(s) described herein.

[0441] Kits according to the present disclosure may include instructions for use, e.g. in the form of an instruction booklet or leaflet. The instructions may include a protocol for performing any one or more of the methods described herein. The kit may comprise instructions for evaluation of a cancer to determine whether it comprises genetic variation as described herein. The kit may comprise instructions for administering an antigen-binding molecule that binds to HER3 as described herein to a subject.

[0442] Sequence identity

[0443] As used herein, ‘sequence identity’ refers to the percent of nucleotides / amino acid residues in a subject sequence that are identical to nucleotides / amino acid residues in a reference sequence, after aligning the sequences and, if necessary, introducing gaps, to achieve the maximum percent sequence identity between the sequences. Pairwise and multiple sequence alignment for the purposes of determining percent sequence identity between two or more amino acid or nucleic acid sequences can be achieved in various ways known to a person of skill in the art, for instance, using publicly available computer software such as ClustalOmega (Soding, J. 2005, Bioinformatics 21 , 951-960), T-coffee (Notredame et al. 2000, J. Mol. Biol. (2000) 302, 205-217), Kalign (Lassmann and Sonnhammer 2005, BMC Bioinformatics, 6(298)) and MAFFT (Katoh and Standley 2013, Molecular Biology and Evolution, 30(4) 772-780) software. When using such software, the default parameters, e.g. for gap penalty and extension penalty, are preferably used. Sequences

[0444]

[0445]

[0446] The present disclosure includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided.

[0447] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0448] Aspects and embodiments of the present disclosure will now be illustrated, by way of example, with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0449] Throughout this specification, including the claims which follow, unless the context requires otherwise, the word ‘comprise,’ and variations such as ‘comprises’ and ‘comprising,’ will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms ‘a’, ‘an’, and ‘the’ include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from ‘about’ one particular value, and / or to ‘about’ another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent ‘about’, it will be understood that the particular value forms another embodiment.

[0450] Where a nucleic acid sequence is disclosed or referred to herein, the reverse complement thereof is also expressly contemplated.

[0451] Methods described herein may preferably be performed in vitro. The term ‘in vitro’ is intended to encompass procedures performed with cells in culture whereas the term ‘in vivo’ is intended to encompass procedures with / on intact multi-cellular organisms.

[0452] Values may be expressed herein as ‘about’ a particular value. Similarly, ranges may be expressed herein as from ‘about’ a particular value, and / or to ‘about’ another particular value. The term ‘about’ in relation to a numerical value is optional, and means for example + / - 10 %. By way of illustration, reference e.g. to ‘about 10 %’ is to be construed as 9 % to 11 %. In instances herein where ‘about’ is recited, the value it precedes is also specifically contemplated. By way of illustration, reference e.g. to ‘about 10 %’ also specifically contemplates 10 %.

[0453] Brief Description of the Figures

[0454] Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures.

[0455] Figure 1. Graph showing the ability of 10D1 F to bind to cells expressing wildtype human HER3 (Wild type), or cells expressing variants of human HER3 comprising the indicated amino acid substitutions, as determined by flow cytometry.

[0456] Figure 2. Graph showing the effects of treatment of mice having a KYSE-150 cell-derived mouse model of esophageal squamous cell carcinoma with 10D1 F (HMBD-001), cetuximab, 10D1 F in combination with cetuximab, or vehicle control (PBS). Graphs shows tumor volume over time, for mice in the different treatment groups.

[0457] Figures 3A and 3B. Graphs showing the effects of treatment of mice having mouse models of esophageal squamous cell carcinoma with 10D1 F (HMBD-001) or vehicle control (PBS). Graphs shows tumor volume over time, for mice in the different treatment groups. (3A) Graph showing the effects in a KYSE-150 cell-derived mouse model of esophageal squamous cell carcinoma. (3B) Graph showing the effects in a OE21 cell-derived mouse model of esophageal squamous cell carcinoma. Figure 4. Graph showing the effects of treatment of mice having a TGBC18TKB cell-derived mouse model of ampullary adenocarcinoma with 10D1 F (HMBD-001) or vehicle control (PBS). Graph shows tumor volume over time, for mice in the different treatment groups.

[0458] Figure 5. Graph showing the effects of treatment of mice having a CTG-2246 tumor-derived mouse model of cholangiocarcinoma with 10D1 F (HMBD-001) or vehicle control (PBS). Graph shows tumor volume over time, for mice in the different treatment groups.

[0459] Figure 6. Graph showing the effects of treatment of mice having a HEC-1-B cell-derived mouse model of endometrial adenocarcinoma with 10D1 F (HMBD-001) or vehicle control (PBS). Graph shows tumor volume over time, for mice in the different treatment groups.

[0460] Figures 7A and 7B. Immunoblots showing co-immunoprecipitation of (7 A) EGFR and HER3 or (7B) HER2 and HER3 in CAL27 HER3 wild-type and mutant overexpressing cells.

[0461] Figure 8. Graph showing cell growth of parental KYSE-150 cells (WT / D297Y (Parental)), KYSE- 150 cells homozygous for the D297Y variant of HER3 (D297Y / D297Y-1 , D297Y / D297Y-3) or KYSE-150 cells modified to express HER3 WT (WT / WT-1 , WT7WT-3). Data points indicates average of three replicates.

[0462] Figure 9. Immunoblot showing pHER3 and pAKT levels in HER3 D297Y mutant cell line KYSE-150 upon incubation with 0, 10, 100 or 1000 pg / ml HMBD-001 .

[0463] Figure 10. Graph showing levels of HER3, pHER3, AKT, pAKT, PRAS40, pPRAS40, mTOR and pmTOR in KYSE-150 derived tumours treated with vehicle or HMBD-001 .

[0464] Examples

[0465] Example 1 : Characterization of 10D1 F in WO 2019 / 185878 A1 and WO 2021 / 048274 A1

[0466] The HER3-binding antibody clone designated 10D1 F is described in WO 2019 / 185878 A1 (incorporated by reference in its entirety).

[0467] 10D1 F comprises the heavy chain variable region shown in SEQ ID NO:36 of WO 2019 / 185878 A1 (= SEQ ID NO:33 of the present disclosure), and the light chain variable region shown in SEQ ID NO:83 of WO 2019 / 185878 A1 (= SEQ ID NO:58 of the present disclosure). 10D1 F is also referred to in WO 2019 / 185878 A1 as ‘10D1_c89’, and is sometimes referred to herein as HMBD-001 .

[0468] Example 2.2 of WO 2019 / 185878 A1 describes a molecule (molecule

[0016] ) comprising the VH and VL regions of 10D1 F in human lgG1A / K format (10D1 F hlgG 1 ) , formed of SEQ ID NO:206 of WO 2019 / 185878 A1 (= SEQ ID NO:75 of the present disclosure) and SEQ ID NO:207 of WO 2019 / 185878 A1 (= SEQ ID NO:76 of the present disclosure). Examples 8.1 to 8.3 and Figures 42 to 46 of WO 2019 / 185878 A1 show that 10D1 F hlgG1 binds to human HER3 with high affinity and specificity (displaying no cross-reactivity with other human EGFR family members), while retaining high-affinity binding to cyno, mouse and rat HER3.

[0469] Example 8.6 and Figures 49A and 49B of WO 2019 / 185878 A1 demonstrate that 10D1 F hlgG1 binds to HER3 in a ligand (NRG)-independent fashion, and through a topologically distant epitope of HER3 to the epitope bound by anti-HER3 antibodies M-05-74 and M-08-11. Example 8.10 and Figure 78 of WO 2021 / 048274 A1 demonstrate that 10D1 F hlgG1 binds to human HER3 with subpicomolar affinity in the presence or absence of human NRG1 .

[0470] WO 2021 / 048274 A1 at Example 3.5 also discloses that antibody clone 10D1 and 10D1-derived clones (including 10D1 F) bind to human HER3 in the region corresponding to positions 218 to 235 of SEQ ID NO:1 ( / .e. SEQ ID NO:77 of the present disclosure), and that within this region, two consensus binding site motifs were identified (shown in SEQ ID NOs:78 and 79 of the present disclosure).

[0471] Example 4.1 and Figure 65, and Example 8.7 and Figure 52 of WO 2019 / 185878 A1 demonstrate that 10D1 F hlgG1 is highly potent at inhibiting interaction between HER3 and HER2, and does so in a dosedependent manner. Example 8.7 and Figure 53 of WO 2019 / 185878 A1 show that 10D1 F h I gG 1 inhibits interaction between HER3 and EGFR in a dose-dependent fashion.

[0472] Example 8.8 and Figure 54 of WO 2019 / 185878 A1 show that 10D1 F h I gG 1 induces ADCC activity against HER3 overexpressing cells in a dose-dependent manner.

[0473] Example 8.9 and Figures 55, 63 and 64 of WO 2019 / 185878 A1 demonstrate that 10D1 F h I gG 1 inhibits HER3-mediated signaling in cells of HER3-expressing cancer cell lines in vitro.

[0474] Example 11 and Figure 71 of WO 2019 / 185878 A1 show that 10D1 F hlgG1 also inhibits HER3-mediated signaling in HER3-expressing human cancer cell line-derived xenograft tumors in vivo. Example 14 and Figure 79 of WO 2021 / 048274 A1 demonstrate that 10D1 F is extremely potent at inhibiting growth of xenograft tumors derived from a human cancer cell line harboring an NRG gene fusion.

[0475] Examples 9.3, 9.4 and Figures 59, 60, 61 , 62, 74 and 77 of WO 2019 / 185878 A1 demonstrate that 10D1 F potently inhibits the growth of cancer cells in vitro, and also potently inhibits growth of human cancer cell line-derived xenograft tumors in vivo. Example 10 and Figures 67 and 68 of WO 2019 / 185878 A1 show that 10D1 F hlgG1 inhibits in vitro proliferation of thyroid cancer cell lines harboring the V600E BRAF mutation.

[0476] Example 12 and Figures 72 and 73 of WO 2019 / 185878 A1 show that 10D1 F hlgG1 is not substantially internalized by HER3-expressing cells.

[0477] Example 13 and Figures 75 and 76 of WO 2019 / 185878 A1 demonstrate the utility of 10D1 F h I gG 1 to be employed for the detection of HER3. Example 8.4 and Figure 47A of WO 2019 / 185878 A1 show that 10D1 F hlgG1 is thermostable, having a melting temperature of 70.0°C as determined by Differential Scanning Fluorimetry.

[0478] Example 9.1 , 9.2 and Figures 56, 57, 58 and 69, 70 of WO 2019 / 185878 A1 evidence that 10D1 F hlgG1 has favorable pharmacological and toxicological profiles.

[0479] Example 2: Analysis of the ability of 10D1F to bind to HER3 comprising mutations in vitro

[0480] The ability of 10D1 F hlgG1 ( / .e. the antibody formed by the polypeptide consisting of SEQ ID NO:75 and the polypeptide consisting of SEQ ID NO:76) to bind to various different mutated versions of HER3 was evaluated in vitro.

[0481] Briefly, 4.5 x 105HEK293T cells were seeded in 6 well plates in DMEM + 10% FBS overnight for cell attachment. Cells were subsequently transfected (using optiMEM and Lipofectamine 2000) with 2.5 pg of plasmid pCMV30-HER3 plasmid encoding wildtype HER3 (Sinobiological, HG10201-UT), or encoding HER3 comprising one of the following mutations: M60R, M911 , V104L, V104M, N126K, H228Q, H228R, A232T, A232V, P262H, G284R, D297V, D297Y, E332K, T355I, T355P, R475W, T389K, R426W, D581 N, P590H. 24 h post transfection, cells were harvested for evaluation of the ability of 10D1 F to bind to cells expressing the different versions of HER3 by flow cytometry.

[0482] The cells were first stained with zombie NIR for 15 min at RT. Cells were subsequently washed and incubated with serial dilutions of 10D1 F (starting at 10 pg / ml, 3-fold, 11 point dilution series) for 1 h at 4°C. Cells were then washed three times and incubated with F(ab’)2 goat anti-human IgG Fc secondary antibody AF488 (ThermoFisher, #H10120) at 1 :2000 dilution for 1 h at 4°C. Cells were analyzed using a Cytek Northern Lights 3000 machine.

[0483] In separate wells, to evaluate transfection and expression efficiency of the different versions of HER3, after staining with zombie NIR, cells were fixed and permeabilized (ThermoFisher, #GAS004). Cells were incubated with rabbit anti-HER3 mAb (CST, #12708), which binds to the C-terminal region of HER3 receptor. Cells were then washed three times and incubated with goat anti-Rabbit IgG (H+L) Cross adsorbed secondary antibody AF488 at 1 :400 dilution for 1 h at 4°C. Cells were analyzed using a Cytek Northern Lights 3000 machine. Cells showed expression of HER3.

[0484] Figure 1 shows the binding signal for 10D1 F to live cells transfected with constructs encoding different versions of HER3. 10D1 F was found to bind to all versions of HER3 investigated, except the E332K and T355I variants.

[0485] Example 3: Analysis of the ability of 10D1F to treat cancers comprising mutant HER3 in vivo The therapeutic efficacy of 10D1 F hlgG1 to treat cancer comprising mutations to HER3 was investigated in vivo, in human cell line and patient tumor-derived xenograft models. Mice approximately 6-8 weeks old were housed under specific pathogen-free conditions and treated in compliance with the Institutional Animal Care and Use Committee (IACUC) guidelines. Human cancer cell-derived tumors were established by admixture of cells with equal volume of Matrigel (Corning, USA), and subcutaneous implantation into the right or left flanks of mice, as indicated. Treatment was initiated when tumors reached approximately 100 to 300 mm3.

[0486] ESCC CDX:

[0487] Model: Human cell line-derived model of esophageal squamous cell carcinoma

[0488] Cell line: KYSE-150 (CVCL_1348). KYSE-150 cells harbor the D297Y variant of HER3.

[0489] Model established by: injection of 1 x 107cells into upper right flanks of NOD / SCID mice.

[0490] Treatment groups:

[0491] Vehicle control (phosphate buffered saline; IP injection, weekly; n = 10).

[0492] HMBD-001 (IP injection of 20 mg / kg bodyweight, weekly; n = 10). cetuximab (IP injection of 10 mg / kg bodyweight, weekly; n = 10).

[0493] HMBD-001 + cetuximab (IP injection of 20 mg / kg bodyweight of HMBD-001 + 10 mg / kg bodyweight of cetuximab, weekly; n = 10).

[0494] ESCC CDX:

[0495] Model: Human cell line-derived model of esophageal squamous cell carcinoma

[0496] Cell line: OE21 (CVCL_2661). OE21 cells harbor wildtype HER3.

[0497] Model established by: injection of 1 x 106cells into upper right flanks of NOD / SCID mice.

[0498] Treatment groups:

[0499] Vehicle control (phosphate buffered saline; IP injection, weekly; n = 10). HMBD-001 (IP injection of 20 mg / kg bodyweight, weekly; n = 10).

[0500] AC CDX:

[0501] Model: Human cell line-derived model of ampullary adenocarcinoma

[0502] Cell line: TGBC18TKB (CVCL_3338). TGBC18TKB cells harbor the G248R variant of HER3. They also harbor HER2 comprising S310F and R678Q, and B-Raf comprising I582L and N581T.

[0503] Model established by: injection of 4 x 106cells into right flanks of NOD / SCID mice.

[0504] Treatment groups:

[0505] Vehicle control (phosphate buffered saline; IP injection, weekly; n = 8). HMBD-001 (IP injection of 20 mg / kg bodyweight, weekly; n = 8).

[0506] CC PDX:

[0507] Model: Human patient tumor-derived model of cholangiocarcinoma

[0508] Patient tumor: CTG-2246 (CVCL_RT21). CTG-2246 tumor cells harbor the V104L variant of HER3. Model established by: implantation of tumor fragments into left flanks of Athymic Nude-Foxn1 nu mice. Treatment groups:

[0509] Vehicle control (phosphate buffered saline; IP injection, weekly; n = 10).

[0510] HMBD-001 (IP injection of 20 mg / kg bodyweight, weekly; n = 10). Endometrial AC CDX (1):

[0511] Model: Human cell line-derived model of endometrial adenocarcinoma

[0512] Cell line: HEC-1-B (CVCL_0294). HEC-1-B cells harbor the R475W variant of HER3. They also harbor HER2 comprising V842I, T798I and V1253M, NRG1 comprising S403G, and EGFR comprising A864V. Model established by: injection of 2 x 106cells into right flanks of CB17 / SCID mice.

[0513] Treatment groups:

[0514] Vehicle control (phosphate buffered saline; IP injection, weekly; n = 5).

[0515] HMBD-001 (IP injection of 20 mg / kg bodyweight, weekly; n = 5).

[0516] Tumor volume was measured 2 times a week using a digital caliper, and calculated using the formula [L x Wx W) / 2]. Study end point was reached once the mean tumor volume of the control group reached 1500 mm3. Bodyweights of the mice were also monitored.

[0517] The results are shown in Figures 2 to 6.

[0518] HMBD-001 was found to display end of study tumor growth inhibition of 60% in a cancer comprising the D297Y variant of HER3 when given as a monotherapy, and of 102% when given in combination with cetuximab (Figure 2).

[0519] Figures 3A and 3B show that monotherapy with HMBD-001 achieved tumor growth inhibition at day 15 of 98.2% in a model of ESCC comprising the D297Y variant of HER3 (Figure 3A), while monotherapy with HMBD-001 achieved tumor growth inhibition at day 15 of 69.3% in a model of ESCC comprising wildtype HER3 (Figure 3B).

[0520] Monotherapy with HMBD-001 was found to display tumor growth inhibition of 114.1% in a cancer comprising the G284R variant of HER3 (Figure 4).

[0521] Monotherapy with HMBD-001 was found to display tumor growth inhibition of 55.9% in a cancer comprising the V104L variant of HER3 (Figure 5).

[0522] Monotherapy with HMBD-001 was found to display tumor growth inhibition of 54% in a cancer comprising the R475W variant of HER3 (Figure 6).

[0523] Example 4: A Phase 1b study to evaluate HMBD-001 with or without chemotherapy in patients with advanced solid tumors harboring NRG1 gene fusions or HER3 mutations

[0524] A Phase 1 b study of combination treatment employing HMBD-001 ( / .e. 10D1 F) with chemotherapy in NRG1 gene fusion cancers or cancers comprising HER3 mutation is performed.

[0525] The use of targeted therapies against HER2 / HER3 for cancers with NRG1 fusions have shown early signs of clinical efficacy with response rates of 30% for seribantumab (Carrizosa et al., Journal of Clinical Oncology (2022) 40 (16_suppl): 3006) and 34% for zenocutuzumab (Schram et al. 2022 Journal of Clinical Oncology (2022) 40 (16_suppl): 105). Both seribantumab and zenocutuzumab, however, largely inhibits ligand-dependent HER3 activation.

[0526] HMBD-001 ( / .e.10D1 F) is the only anti-HER3 mAb in development that blocks both ligand-dependent and ligand-independent HER3 activation and oncogenic signaling through blockade of a key epitope located at the interface where HER3 forms heterodimers with HER2 or EGFR, independent of the upstream process. Preclinical models evaluating 10D1 F have confirmed superior affinity and tumor control across multiple cancer types when evaluated head-to-head against other anti-HER3 agents in development. In a phase 1 study performed by Cancer Research United Kingdom (CRUK), 10D1 F demonstrated promising clinical activity with 5 out of 17 patients (29.4%) achieving disease stability with a median duration disease control of up to 20 weeks.

[0527] Preclinical studies have demonstrated the potential synergy between PI3K and MAPK pathway blockade in combination with gemcitabine and nab-paclitaxel chemotherapy, improving survival of 67% in mice models (Awasthi et al. Cancer Letters (2019) 459:41 ;49). Given the demonstrated preclinical efficacy of 10D1 F in blocking MAPK and PI3K pathways in cancers with NRG1 fusion, Arm A of this explores the safety and tolerability as well as signs of preliminary efficacy of the combination gemcitabine, nab- paclitaxel and 10D1 F in locally-advanced and unresectable or metastatic PDAC.

[0528] NRG1 fusions account for only 1% of all NSCLCs, however they have recently been recognized as a distinct group of NSCLCs characterized by no or low programmed death ligand-1 (PD-L1) expression, low tumor mutational burden, and limited response to systemic therapy including cytotoxic, immunotherapy and targeted therapy regimens (Drilon, et al. J Clin Oncol. (2021) 39(25):2791-2802). There is a significant need to identify effective treatment options for patients with NRG1 fusion NSCLC. Arm B of this study, therefore, seeks to explore the safety and efficacy of combination therapy using docetaxel and 10D1 F in patients with NSCLC.

[0529] Subjects are divided into four arms, Arms A, B, C and D, and treated as follows:

[0530] Arm A:

[0531] 10D1 F 1800 mg by intravenous infusion, once weekly

[0532] Gemcitabine 1000 mg / m2by intravenous infusion on Days 1 , 8, 15 of each 28 day cycle, Nab-Paclitaxel 125 mg / m2by intravenous infusion on Days 1 , 8, 15 of each 28 day cycle

[0533] Arm B:

[0534] 10D1 F 1800 mg by intravenous infusion, once weekly

[0535] Docetaxel 75 mg / m2by intravenous infusion once every 3 weeks

[0536] Arm C:

[0537] 10D1 F 1800 mg by intravenous infusion, once weekly

[0538] Arm D: 10D1 F 1800 mg by intravenous infusion, once weekly

[0539] For Arms A and B, the treatment period is an initial induction period of up to 6 cycles of chemotherapy in combination with 10D1 F, with an option to extend to 8 cycles on a case-by-case basis. This induction period is followed by 10D1 F monotherapy ( / .e. 10D1 F 1800 mg by intravenous infusion, once weekly) until participant discontinuation of study treatment due to intolerable toxicity, confirmed disease progression, withdrawal of consent, lost to follow-up, death or study termination, whichever occurs earlier. Re-induction with combination chemotherapy and 10D1 F may be approved on a case-by-case basis at the time of disease progression on 10D1 F monotherapy maintenance.

[0540] For Arms C and D, treatment continues until subject discontinuation of study treatment due to intolerable toxicity, confirmed disease progression, withdrawal of consent, lost to follow-up, death or study termination, whichever occurs earlier.

[0541] Subjects in Arm A have locally-advanced, unresectable pancreatic ductal adenocarcinoma harboring NRG1 gene fusion with an epidermal growth factor (EGF) signaling domain, or metastatic pancreatic ductal adenocarcinoma harboring NRG1 gene fusion with an epidermal growth factor (EGF) signaling domain.

[0542] Subjects in Arm B have non-small cell lung cancer harboring NRG1 gene fusion with an epidermal growth factor (EGF) signaling domain.

[0543] Subjects in Arm C have locally-advanced, unresectable or metastatic solid tumors harboring NRG1 gene fusion with an epidermal growth factor (EGF) signaling domain, or metastatic solid tumor harboring NRG1 gene fusion with an epidermal growth factor (EGF) signaling domain, and are not eligible for Arm A, Arm B or Arm D.

[0544] Subjects in Arm D have locally-advanced, unresectable or metastatic solid tumors harboring ERBB3 mutation, and are not eligible for Arm A, Arm B or Arm C.

[0545] The key patient eligibility criteria are as follows.

[0546] Inclusion criteria

[0547] Subjects included in the study meet all of the following inclusion criteria:

[0548] 1 . Willing, able to and has provided written informed consent prior to start of any study procedures and assessments and must be willing to comply with all study procedures.

[0549] 2. Adult participants > 18 years of age at the time of informed consent.

[0550] 3. ECOG performance status 0-1 .

[0551] 4. Histologic or cytologic evidence of an advanced malignant solid cancer (any histology) that is resistant / refractory to standard systemic therapy, or for which there is no standard systemic therapy or reasonable therapy in the physician’s judgment likely to result in clinical benefit, or the participant has demonstrated to be intolerable to such therapy, or if such therapy has been refused by the participant.

[0552] 5. Cancer harboring an NRG1 gene fusion identified by a molecular assay with the fusion transcript defined as being correctly oriented (i.e., with the NRG1 coding mRNA at the 3’end of the transcript) AND containing the EGF-like domain which is capable of binding to HER3.

[0553] • Arm A: o Locally advanced unresectable or metastatic pancreatic adenocarcinoma; o Participants must not have received prior therapy with gemcitabine or nab-paclitaxel; o Participants must not have received >2 prior lines of systemic therapy for advanced disease. Adjuvant or neoadjuvant therapy received within 6 months of proposed cycle 1 day 1 (C1 D1) will be counted as 1 line of therapy.

[0554] • Arm B: o Locally advanced unresectable or metastatic non-small cell lung cancer; o Participants must not have received prior therapy with docetaxel; o Participants must not have received >2 prior lines of systemic therapy for advanced disease. Adjuvant or neoadjuvant therapy received within 6 months of proposed cycle 1 day 1 (C1 D1) will be counted as 1 line of therapy.

[0555] • Arm C: o Participants must not be eligible to participate in Arm A, B or D.

[0556] • Arm D: o Participants must not be eligible to participate in Arm A, B, or C. o Participants must have cancer harboring ERBB3 mutation limited to the extracellular domain and not affecting HMBD-001 binding site, such as V104M, V104L, G284R, D297Y, or A232V. Other HER3 mutations may be approved to enroll on a case-by-case basis in discussion.

[0557] 6. Participants must have a life expectancy of >3 months in the opinion of the Investigator.

[0558] 7. Participants must have measurable disease by RECIST V1 .1 .

[0559] 8. Participants must have available archival tissue (at least 15 consecutive, unstained, formalin-fixed, paraffin embedded [FFPE] slides or 1 FFPE block) OR, alternatively, a fresh tumor biopsy sample. Participants without any archival tissue or fresh biopsy sample, or who refuse to provide archival tissue may be approved to enroll on a case-by-case basis in discussion with the Sponsor.

[0560] 9. Women of childbearing potential (WOCBP) must have a negative beta-human chorionic gonadotropin (p-hCG) test within 72 hours before the first dose of study drug and must not be breastfeeding.

[0561] 10. WOCBP are defined as those who are not surgically sterile or post-menopausal. Female participants will be considered post-menopausal if they have been amenorrheic for 12 months without an alternative medical cause. Female participants < 50 years old who meet the criteria for postmenopausal status without previous surgical sterilization should be considered for further investigation with luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels to confirm serological post-menopausal status.

[0562] 11 . WOCBP must agree to use a highly effective method of contraception during the study and for 90 days after the last dose of study treatment.

[0563] 12. Male participants who are able to father a child must agree to avoid impregnating a partner and to adhere to a highly effective method of contraception during the study and for 90 days after the last dose of study treatment. All male participants must agree to not donate sperm during the study and for 90 days after the last dose of study treatment.

[0564] 13. Adequate baseline organ function, as demonstrated by the following:

[0565] • Serum creatinine <2 x institutional ULN

[0566] • Serum albumin >2.5 g / dl.

[0567] • Bilirubin <2.0 x institutional ULN.

[0568] • AST and ALT <2.5 x institutional ULN. Participants with hepatitis metastases enrolled may have ALT and AST < 5 x institutional ULN if the participant has hepatic metastases.

[0569] 14. For participants not taking warfarin or other oral anticoagulants: international normalized ratio (INR) <1 .5 or prothrombin time (PT) <1 .5 x ULN; and either partial thromboplastin time or activated partial thromboplastin time (PTT or aPTT) <1 .5 x ULN. participants taking warfarin should be on a stable dose that results in a stable INR <3.5. Among participants receiving other oral anticoagulant therapy, PT or aPTT must be within the intended therapeutic range of the anticoagulant.

[0570] 15. Adequate baseline hematologic function, as demonstrated by the following:

[0571] • ANC >1.5x109 / L.

[0572] • Hemoglobin >9 g / dL and no red blood cell (RBC) transfusions during the prior 14 days.

[0573] • Platelet count >100x109 / L and no platelet transfusions during the prior 14 days.

[0574] Exclusion criteria

[0575] Subjects meeting any of the following exclusion criteria are excluded from study:

[0576] 1 . Prior treatment with HMBD-001 , pertuzumab, or an investigational agent that specifically targets HER3, including pan-HER tyrosine kinase inhibitors.

[0577] 2. Persistent clinically significant toxicities (Grade >2) from previous anti-cancer therapy. Prior toxicities that resulted in laboratory abnormalities should have resolved to Grade <1 unless a higher-grade abnormality is allowed by the inclusion criteria. If medical therapy is required for the treatment of a laboratory abnormality, the dose and laboratory value(s) should be stable. Participants with residual toxicities Grade >2 considered unlikely to put the participant at an increased risk of treatment-related toxicity and / or impact the integrity of study outcome may be permitted on a case-by-case basis in discussion with study Sponsor (e.g., alopecia, thyroid disorders or cortisol insufficiency on stable hormone replacement therapy).

[0578] 3. Treatment with anticancer therapies including cytotoxic chemotherapy, monoclonal antibodies, small molecule tyrosine kinase inhibitors and / or an investigational systemic anticancer agent within 28 days (42 days for prior nitrosourea or mitomycin-C) prior to study therapy administration, or 5 half-lives, whichever is shorter. Participants with advanced prostate cancer who are receiving luteinizing hormone releasing hormone (LHRH) agonists are permitted onto the study and should continue use of these agents during study treatment.

[0579] 4. Prior radiotherapy or major surgery within 4 weeks prior to first dose of study drug. Focal radiotherapy for palliation or minor surgical procedures within 4 weeks of first dose of study drug may be approved on a case-by-case basis in discussion with study Sponsor, if it is determined not to put the participant at an increased risk of adverse drug effects and / or interfere with the integrity of study outcome.

[0580] 5. Participants with brain metastases, unless they meet all of the following criteria:

[0581] • they are clinically and radiologically stable (no evidence of progression by imaging; same imaging modality (MRI or computed tomography [CT] scan) must be used for each assessment) for at least 28 days prior to the first dose of study drug;

[0582] • any neurologic symptoms returned to baseline;

[0583] • Note: Subjects with a history of leptomeningeal disease may not participate even if clinically stable.

[0584] 6. Any other known, active malignancy, except for treated cervical intraepithelial neoplasia, or nonmelanoma skin cancer. Participants with a history of malignancies of low recurrence potential who have received curative-intent therapy may be approved on a case-by-case basis in discussion with study Sponsor, if it is determined not to put the participant at an increased risk of adverse drug effects and / or interfere with the integrity of study outcome.

[0585] 7. History of uncontrolled allergic reactions and / or known or expected hypersensitivity to HMBD-001 or any of its excipients, and / or gemcitabine, nab-paclitaxel or docetaxel, where relevant for the arm that the participant is enrolled into.

[0586] 8. Participation in any other investigational trial.

[0587] 9. Lef ventricular ejection fraction of < 50%.

[0588] 10. Clinically significant cardiovascular disease (e.g., uncontrolled or any New York Heart Association Class 3 or 4 heart failure, uncontrolled angina, history of myocardial infarction, unstable angina or stroke within 6 months prior to study entry, uncontrolled hypertension or clinically significant arrhythmias not controlled by medication.

[0589] 11. Uncontrolled clinically significant medical issues such as pulmonary disease (e.g., chronic obstructive pulmonary disease, pulmonary hypertension), or an uncontrolled intercurrent illness including, but not limited to, uncontrolled infection requiring systemic therapy, disseminated intravascular coagulation, or psychiatric illness / social situations that would limit compliance with study requirements.

[0590] 12. QTc interval > 450 ms (male) or > 470 ms (female).

[0591] 13. Positive status for human immunodeficiency virus.

[0592] 14. Active or chronic hepatitis B or C.

[0593] 15. Any medical condition which, in the opinion of the Investigator, places the participant at an unacceptably high risk for toxicities.

[0594] 16. COVID-19 infection within 3 months prior to C1 D1.

[0595] 17. COVID-19 vaccination within 14 days of C1 D1.

[0596] 18. Any uncontrolled intercurrent illness or clinically significant uncontrolled condition(s), including but not limited to active bacterial, fungal, or viral infections requiring systemic therapy.

[0597] For Arms A and B, an initial Safety Lead-in strategy will be adopted to determine the recommended phase 2 dose (RP2D) for the combination of HMBD-001 and chemotherapy. Enrolment of the remaining participants will then proceed according to Simon 2-stage design.

[0598] Safety Lead-in strategy for Arms A and B:

[0599] 10D1 F

[0600] Dose level (DL)1 = 1800 mg

[0601] DL-1 = 1200 mg Arm A Safety Lead-in

[0602] Arm A Non-Safety Lead-in

[0603] 5 Arm B Safety Lead-in

[0604] Arm B Non-Safety Lead-in

[0605] Arm C and Arm D

[0606] 5 Objectives and Endpoints

[0607] Arm A

[0608] Arm B

[0609] Arm C

[0610] Arm D Example 5: Analysis of the effects of HER3 comprising mutations on dimerization and cell growth

[0611] CAL27 overexpressing HER3 WT and HER3 mutant cells were adapted in the presence of doxycycline for at least 1 week prior to cell seeding. One set of CAL27 overexpressing HER3 V104M cells were cultured in the absence of doxycycline to serve as a control. The following concentrations of doxycycline were used for cells overexpressing HER3 WT and the various HER3 mutants: WT: 0.25 ug / ml; V104L: 1.5 ug / ml; V104M: 0.5 ug / ml; G284R & D297Y: 0.3 ug / ml.

[0612] CAL27 overexpressing HER3 WT, V104L, V104M, G284R and mutants were seeded (3 wells per cell line) at a density of 700k / well in 6 well plates in DMEM + 10% TET-Free FBS + various concentrations of doxycycline at 37°C and 5% CO2. Control cells (CAL27 overexpressing HER3 V104M cells that were not exposed to doxycycline) were also seeded in the absence of doxycycline as a control.

[0613] The next day, cells were serum starved with 0.2% TET-free FBS at 37°C, 5% CO2 overnight (with the appropriate concentration of Doxycycline for each cell line). Cells were then exposed to complete media for 1 hour before being harvested and snap frozen. Protein was extracted from the cell lines in IP lysis buffer and cell lysates were quantified using a standard Bradford protein assay. 800 pg of protein was incubated with 2.5ul of anti-EGFR Rabbit mAb (#54359, Cell Signaling) or 10 pl of Anti-Flag magnetic beads in 1000 pl IP lysis buffer overnight at 4°C with gentle rotation following manufacturer’s protocol. For the EGFR immunoprecipitation, 100 pl of Dynabeads Protein G (#10004D, ThermoFisher) were washed twice with cold PBS then added to each sample and incubated at room temperature (RT) for 1 hour. The reaction mix was washed 3 times with cold PBS then beads were resuspended in 20 pl of 1x sample buffer and boiled at 95°C for 5 minutes. Simultaneously, 50 pg of total protein lysate was fractionated by SDS-PAGE and transferred to a nitrocellulose membrane. Membranes were then blocked with 5% Skim milk in TBST (0.05%) and immunoblotted with antibodies in 5% BSA in TBST (0.05%). The antibodies and conditions used were as follows: Pan EGFR (CS2239S) 1 :1000, 1 hr RT; Anti-FLAG-HRP (ab2493) 1 :5000, ON 4°C; Pan HER2 (#MA5-13657, Thermo), 1 h RT; Secondary anti mouse HRP (A24512) was used at 1 :5000, 1 hr RT. The results were visualized via Bio-Rad Clarity Western ECL substrate.

[0614] The results show that HER3 mutant receptors exhibit increased dimerization with EGFR and HER2 compared to HER3 WT (Figure 7A and Figure 7B).

[0615] In a further experiment, an assay was performed using KYSE-150 cells. KYSE-150 cells harbor the D297Y variant of HER3. The assay was performed measuring cell proliferation of parental KYSE-150 cells (WT / D297Y (Parental)), or KYSE-150 cells homozygous for the D297Y variant of HER3 (D297Y / D297Y-1 , D297Y / D297Y-3) or KYSE-150 cells modified to express HER3 WT (WT / WT-1 , WT / WT-3).

[0616] A 96-well plate was seeded with 250 cells / well in media (49% RPMI 1640 + 49% Ham's F12 + 2% h.i. FBS) and incubated at 37°C and 5% CO2for 6 days. Cell viability was measured using CCK-8 cell proliferation assay (Cell Counting Kit-8, Dojindo # SKU-CK04) at Day 1 , 4, 5 and 6. A decrease in cell growth was observed upon the conversion of HER3 mutation D297Y into HER3 wildtype, suggesting that HER3 mutation promotes growth of KYSE-150 cells (Figure 8).

[0617] Example 6: Analysis of the ability of 10D1F to reduce cell signaling mediated by the D297Y variant of HER3 in vitro

[0618] HER3-mediated signaling progresses intracellularly through pathways including the PI3K / AKT / mT0R pathway to promote cell survival and proliferation. An assay was performed to measure levels of phosphorylated HER3 and phosphorylated AKT in KYSE-150 cells in the absence or presence of HMBD- 001 at various concentrations.

[0619] KYSE-150 cells were seeded in 2 wells in a 6-well plate at 350 000 cells per well, in full serum RPMI / F12 + 2% HI FBS media overnight to facilitate cell attachment. After 24 hours, the medium was replaced with serum free (SF) medium and incubated overnight for starvation. Afterward, the medium was replaced with full serum medium, with or without HMBD-001 at doses of 10, 100 and 1000 ug / ml. Cells were then incubated for 24 hours, and harvested.

[0620] Protein was extracted from the cell lines in IP lysis buffer and cell lysates were quantified using standard Bradford protein assay. 40 pg of each protein sample was fractionated by SDS-PAGE and transferred to nitrocellulose membrane. Membranes were then blocked and immunoblotted with antibodies: pHER3 Y1289 (CS2842S) 1 :1000, overnight 4°C; pAKT S473 (CS4060S) 1 :2000, overnight 4°C; Pan HER3 (CS12708S) 1 :1000, RT 1 h; Pan AKT (CS2920S) 1 :2000, RT 1 h; Secondary anti rabbit HRP (CS7074S) was used at 1 :1000, 1 hr RT; Secondary anti mouse HRP (A24512) was used at 1 :5000, 1 hr RT. The results were visualized via Bio-Rad Clarity Western ECL substrate.

[0621] A dose-dependent reduction of pHER3 and pAKT levels were observed in the KYSE-150 (HER3 D297Y mutant cell line) upon addition of HMBD-001 (Figure 9) demonstrating that treatment with HMBD-001 reduces HER3 D297Y-mediated cell signaling.

[0622] Example 7: Analysis of the ability of 10D1F to reduce cell signaling mediated by the D297Y variant of HER3 in vivo

[0623] Tumors were obtained from a xenograft study where KYSE-150 cells were implanted into NOD / SCID mice subcutaneously and treated with either vehicle or 20 mg / kg of HMBD-001 weekly. The tumors were then subjected to signaling proteins analysis using Theralink’s RPPA assay. 8 pm cryostat sections were cut from each OCT-frozen tumor at -20°C. Sections were transferred to microscopy slides, fixed in 70% ethanol, stained in hematoxylin, and dehydrated in increasing concentrations of ethanol (70%-95%- 100%) and 100% xylene, prior to LCM using CapSure Macro Caps and an ArcturusXT instrument (Thermo Fisher Scientific) using infrared laser-based direct cellular capture.

[0624] Lysates for reverse phase protein array (RPPA) analysis were prepared using T-PER lysis buffer (Thermo Fisher Scientific). Lysates were diluted to 0.25 mg / mL and boiled prior to printing in technical triplicates on nitrocellulose-coated glass slides using an Aushon 2470 arrayer (Aushon Biosystems). The arrays were probed with antibodies that have been validated by Western Blot to determine antibody specificity. Only antibodies showing a single band at the expected molecular weight were used on the arrays. Biotinylated anti-rabbit (Vector Laboratories, Inc.) or anti-mouse secondary antibody (CSA; Dako Cytomation) was used in conjunction with GenPoint™ kit (Dako Cytomation), a commercially available tyramide-based signal amplification system. Fluorescent detection was obtained through the use of IRDye 680RD Streptavidin (LI-COR Biosciences) according to the manufacturer’s recommendations. Antibody and Sypro Ruby stained slides were scanned on a Tecan laser scanner (TECAN, Monnedorf, Switzerland) using the 620nm and 580nm weight length channel, respectively. Images were analyzed with Micro Vigene Software Version 5.1 .0.0 (Vigenetech). The software performs spot finding along with subtraction of the local background and non-specific binding generated by the secondary antibody. Each sample signal was normalized to the corresponding amount of protein derived from the Sypro Ruby stained slides and triplicates were averaged. Only proteins / phosphoproteins with intensities above detection limit in at least 95% of the samples were analyzed. Intensity values were Iog2-transformed in order for the data to be more suitable to standard statistical analysis techniques.

[0625] Levels of various signaling proteins within the HER3 / AKT / mTOR pathway of KYSE-150 tumors treated with HMBD-001 were significantly reduced in comparison to the those treated with vehicle (Figure 10) demonstrating that treatment with HMBD-001 reduces HER3 D297Y-mediated cell signaling.

Claims

Claims:1 . An antigen-binding molecule that binds to HER3 for use in a method of treating or preventing a HER3- associated cancer in a subject, wherein the HER3-associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

2. Use of an antigen-binding molecule that binds to HER3 in the manufacture of a medicament for use in a method of treating or preventing a HER3-associated cancer in a subject, wherein the HER3-associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

3. A method of treating or preventing a HER3-associated cancer in a subject, comprising administering to the subject a therapeutically- or prophylactically-effective amount of an antigen-binding molecule that binds to HER3, wherein the HER3-associated cancer comprises a mutation in ERBB3, and wherein the antigen-binding molecule that binds to HER3 binds to the region of HER3 shown in SEQ ID NO:77.

4. The antigen-binding molecule for use according to claim 1 , the use according to claim 2, or the method according to claim 3, wherein the mutation in ERBB3 does not result in a change in the amino acid sequence of HER3 in the region shown in SEQ ID NO:77.

5. The antigen-binding molecule for use according to claim 1 or claim 4, the use according to claim 2 or claim 4, or the method according to claim 3 or claim 4, wherein the mutation in ERBB3 results in an increase in the expression of, or an increase in the activity of a gene product of, ERBB3.

6. The antigen-binding molecule for use according to any one of claims 1 , 4 or 5, the use according to any one of claims 2, 4 or 5, or the method according to any one of claims 3 to 5, wherein the mutation in ERBB3 results in a change in the amino acid sequence of HER3 in the region shown in SEQ ID NO:9.

7. The antigen-binding molecule for use according to any one of claims 1 or 4 to 6, the use according to any one of claims 2 or 4 to 6, wherein the mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : P30L, G40S, M60K, M60R, M91 I, F94L, R103G, R103H, V104L, V104M, V1191, N126I, N126K, S128R, L155I, F219C, Q225T, H228Q, H228R, A232T, A232V, G233W, G253R, P262H, P262S, V264A, G284R, V295A, D297A, D297H, D297N, D297V, D297Y, P306H, D313H, G325R, K329E, K329R, K329T, E332Q, G337R, S345L, T355A, T355P, T389K, G420V, R426W, L431 S, S445F, R475W, E480Q, G513C, G513D, R521Q, D581 N, P590H, V606A, R667H, M677I, R683W, V714M, K742E, H768R, L792V, L795V, Q809R, K820N, S846I, V855A, H884R, G898D, D922Y, E928A, E928G, E928K, E928Q, E952Q, R967K, L1027M, V1035D, V1112A, S1119C, P1142H, L1177I, E1191 D, P1212S, S1215R, G1221D, S1234C, E1261A, D1320H and A1337T.

8. The antigen-binding molecule for use according to any one of claims 1 or 4 to 7, the use according to any one of claims 2 or 4 to 7, or the method according to any one of claims 3 to 7, wherein the mutation in ERBB3 results in one or more of the following differences in the amino acid sequence of HER3, relative to the amino acid sequence of SEQ ID NO:1 : M60R, M91 I, V104L, V104M, N126K, H228Q, H228R, A232T, A232V, P262H, G284R, D297V, D297Y, T355P, R475W, T389K, R426W, D581 N and P590H.

9. The antigen-binding molecule for use according to any one of claims 1 or 4 to 8, the use according to any one of claims 2 or 4 to 8, or the method according to any one of claims 3 to 8, wherein the antigenbinding molecule that binds to HER3 comprises:(i) a heavy chain variable (VH) region incorporating the following CDRs:HC-CDR1 having the amino acid sequence of SEQ ID NO:40 HC-CDR2 having the amino acid sequence of SEQ ID NO:43 HC-CDR3 having the amino acid sequence of SEQ ID NO:48; and(ii) a light chain variable (VL) region incorporating the following CDRs:LC-CDR1 having the amino acid sequence of SEQ ID NO:66 LC-CDR2 having the amino acid sequence of SEQ ID NO:69 LC-CDR3 having the amino acid sequence of SEQ ID NO:74.

10. The antigen-binding molecule for use according to any one of claims 1 or 4 to 9, the use according to any one of claims 2 or 4 to 9, or the method according to any one of claims 3 to 9, wherein the antigenbinding molecule that binds to HER3 comprises:(i) a VH region incorporating the following CDRs:HC-CDR1 having the amino acid sequence of SEQ ID NO:38 HC-CDR2 having the amino acid sequence of SEQ ID NO:42 HC-CDR3 having the amino acid sequence of SEQ ID NO:45; and(ii) a VL region incorporating the following CDRs:LC-CDR1 having the amino acid sequence of SEQ ID NO:63 LC-CDR2 having the amino acid sequence of SEQ ID NO:67 LC-CDR3 having the amino acid sequence of SEQ ID NOTO.11 . The antigen-binding molecule for use according to any one of claims 1 or 4 to 10, the use according to any one of claims 2 or 4 to 10, or the method according to any one of claims 3 to 10, wherein the antigen-binding molecule that binds to HER3 comprises: a VH region comprising an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:33; and a VL region comprising an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:58.

12. The antigen-binding molecule for use according to any one of claims 1 or 4 to 11 , the use according to any one of claims 2 or 4 to 11 , or the method according to any one of claims 3 to 11 , wherein the antigen-binding molecule that binds to HER3 comprises:a polypeptide comprising, or consisting of, an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:75; and a polypeptide comprising, or consisting of, an amino acid sequence having at least 70% sequence identity to the amino acid sequence of SEQ ID NO:76.

13. The antigen-binding molecule for use according to any one of claims 1 or 4 to 12, the use according to any one of claims 2 or 4 to 12, or the method according to any one of claims 3 to 12, wherein the method of treating or preventing a HER3-associated cancer further comprises administering a taxoid.

14. The antigen-binding molecule for use according to claim 13, the use according to claim 13, or the method according to claim 13, wherein the taxoid is docetaxel or nab-paclitaxel.

15. The antigen-binding molecule for use according to any one of claims 1 or 4 to 14, the use according to any one of claims 2 or 4 to 14, or the method according to any one of claims 3 to 14, wherein the method of treating or preventing a HER3-associated cancer further comprises administering a nucleoside analog.

16. The antigen-binding molecule for use according to claim 15, the use according to claim 15, or the method according to claim 15, wherein the nucleoside analog is a deoxycytidine nucleoside analog.

17. The antigen-binding molecule for use according to claim 15 or claim 16, the use according to claim 15 or claim 16, or the method according to claim 15 or claim 16, wherein the nucleoside analog is gemcitabine or a salt thereof.

18. The antigen-binding molecule for use according to any one of claims 1 or 4 to 17, the use according to any one of claims 2 or 4 to 17, or the method according to any one of claims 3 to 17, wherein the HER3-associated cancer is: a cancer comprising cells expressing / overexpressing an EGFR family member (e.g. HER3, EGFR, HER2 or HER4), a cancer comprising cells expressing / overexpressing HER3, a cancer comprising cells having a mutation resulting in increased expression of a ligand for HER3, a cancer comprising cells having an NRG gene fusion, a cancer comprising cells having an NRG1 gene fusion, a cancer comprising cells having an NRG2 gene fusion a solid tumor, a hematological cancer, a squamous cell cancer, an EGFR-amplified squamous cell carcinoma, breast cancer, breast carcinoma, breast invasive carcinoma, ductal carcinoma, metastatic breast cancer, triple-negative breast cancer, HER2-positive breast cancer, gastric cancer, gastric carcinoma, gastric adenocarcinoma, gastrointestinal adenocarcinoma, ampullary adenocarcinoma, colorectal cancer, metastatic colorectal cancer, colon cancer, colorectal carcinoma, colorectal adenocarcinoma, colon adenocarcinoma, head and neck cancer, head and neck squamous cell carcinoma, lung cancer, non-small cell lung cancer, lung adenocarcinoma, invasive mucinous lung adenocarcinoma, squamous cell lung cancer, lung squamous cell carcinoma, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, ovarian cancer, ovarian carcinoma, ovarian serous adenocarcinoma, ovarian serous cystadenocarcinoma, fallopian tube cancer, renal cancer, renal cell carcinoma, renal clear cell carcinoma, renal cell adenocarcinoma, renal papillary cell carcinoma,pancreatic cancer, an exocrine cancer, pancreatic adenocarcinoma, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma, metastatic pancreatic ductal adenocarcinoma, cervical cancer, cervical squamous cell carcinoma, skin cancer, melanoma, oral cavity cancer, oropharyngeal cancer, esophageal cancer, esophageal squamous cell carcinoma, esophageal adenocarcinoma, liver cancer, hepatocellular carcinoma, cholangiocarcinoma, gallbladder cancer, uterine cancer, endometrial cancer, endometrial adenocarcinoma, uterine corpus endometrial carcinoma, uterine carcinosarcoma, thyroid cancer, thyroid cancer, thyroid carcinoma, pheochromocytoma, paraganglioma, bladder cancer, bladder urothelial carcinoma, prostate cancer, prostate adenocarcinoma, retinoblastoma, sarcoma, soft tissue sarcoma, peritoneal cancer, thymoma, neuroendocrine tumor, neuroendocrine tumor of the nasopharynx, squamous cell carcinoma of the skin, astrocytoma, low grade astrocytoma, high grade astrocytoma, anaplastic astrocytoma and glioblastoma multiforme.

19. The antigen-binding molecule for use according to any one of claims 1 or 4 to 18, the use according to any one of claims 2 or 4 to 18, or the method according to any one of claims 3 to 18, wherein the HER3-associated cancer is: a squamous cell cancer, esophageal squamous cell carcinoma, gastrointestinal adenocarcinoma, ampullary adenocarcinoma, endometrial adenocarcinoma, lung cancer, non-small cell lung cancer, squamous cell lung cancer, squamous non-small cell lung cancer, advanced squamous non-small cell lung cancer, metastatic squamous non-small cell lung cancer, pancreatic cancer, an exocrine cancer, pancreatic ductal adenocarcinoma, advanced pancreatic ductal adenocarcinoma or metastatic pancreatic ductal adenocarcinoma.

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