WO2024083185A1

WO2024083185A1 - Antibodies binding fgfr2b and uses thereof

Info

Publication number: WO2024083185A1
Application number: PCT/CN2023/125402
Authority: WO
Inventors: Jiangmei Li; Wenqi Hu; Feng Li
Original assignee: Beijing Mabworks Biotech Co., Ltd
Priority date: 2022-10-21
Filing date: 2023-10-19
Publication date: 2024-04-25
Also published as: CN117917435A

Abstract

The application relates to an isolated monoclonal antibody that specifically binds FGFR2B, or an antigen binding portion thereof. The application also relates to a nucleic acid molecule encoding the antibody or antigen binding portion thereof, and an expression vector, a host cell and a method for expressing the antibody or antigen binding portion thereof. The application further relates to a treatment method using the antibody or antigen binding portion thereof, the nucleic acid molecule, the expression vector or the host cell of the disclosure.

Description

ANTIBODIES BINDING FGFR2B AND USES THEREOF

This application claims priority to Chinese Patent Application No. 202211299274.6 filed on October 21, 2022.

FIELD OF THE INVENTION

The present disclosure relates to an antibody that is able to specifically bind FGFR2B, or an antigen binding portion thereof. The present disclosure also relates to the preparation and the use of the antibody or antigen binding portion thereof of the disclosure, especially the use in treating FGFR2B associated diseases such as cancers.

BACKGROUND OF THE INVENTION

The fibroblast growth factors (FGF) play an important role in e.g., embryonic development and organogenesis, and also mediate metabolic functions and nervous system regeneration. The FGF molecule binds the heparan sulfate proteoglycan (HSPG) to form a complex that has an affinity for the FGF receptor (FGFR) . The FGF receptor contains an extracellular immunoglobulin (Ig) -like domain and an intracellular tyrosine kinase domain, the ligand-dependent FGFR dimerization triggers tyrosine phosphorylation (Katoh M. (2008) Int J Oncol. 33 (2) : 233-7) .

The alternative splicing of the fgfr2 gene generates two isoforms, i.e., FGFR2 IIIB (FGFR2B) and FGFR2 IIIC (FGFR2C) , which differ only in part of the third extracellular Ig-like domain. The FGFR2B isoform is mainly expressed on the epithelial cells and functions as the high-affinity receptor for FGF1, FGF3, FGF7, FGF10 and FGF22, while the FGFR2C molecule, mainly found on mesenchymal cells, is the high-affinity receptor for FGF1, FGF2, FGF4, FGF6, FGF9, FGF16, and FGF20 (Ornitz DM et al., (1996) J Biol Chem 271 (25) : 15292-15297; Zhang X et al., (2006) J Biol Chem 281 (23) : 15694-15700) . The FGFR2B has two subtypes, one is FGFR2Bα that contains all three extracellular Ig-like domains, the other is FGFR2Bβ which lacks the first extracellular Ig-like domain. The FGF7-FGFR2b interaction is involved in wound healing and mucosa repair, and the FGF10-FGFR2b signaling is essential to the embryonic development.

The high expression of or the mutation in the fgfr2 gene may lead to abnormal activation of the FGF-FGFR2 signaling pathways and thus uncontrolled cell divisions, generating tumors. For example, the FGFR2B protein may be highly expressed on tumors, such as gastric cancer, squamous cell lung cancer, three-negative breast cancer, ovarian cancer, pancreatic cancer and intrahepatic cholangiocarcinoma, via fgfr2 gene amplification or upregulated fgfr2b transcription. Aberrant FGFR2b transcripts may be generated due to the exclusion of exon 21 from the FGFR2 amplicon during fgfr2 gene amplification, and such transcripts may phosphorylate FRS2 in a ligand-independent manner, constitutively activating the MAPK and PI3K signaling pathways (Moffa AB et al., (2004) Mol Cancer Res 2 (11) : 643-652) . In addition, the missense mutations that occur mostly in the hinge region, the third Ig-like domain and the tyrosine kinase domain of the FGFR2 molecule may alter the molecule’s ligand binding specificity and/or trigger the ligand-independent phosphorylation, leading to oncogenic activation of FGFR2. For example, the missense mutations such as S252W are frequently found in the uterus cancer. Up till now, the missense mutations have been found to be related to breast cancer, gastric cancer, lung cancer, ovarian cancer, and endometrial cancer (Jang JH et al., (2001) Cancer Res 61 (9) : 3541-3543; Davies H et al., (2005) Cancer Res 65 (17) : 7591-7595; Pollock PM et al., (2007) Oncogene 26 (50) : 7158-7162) . The aberrant activation of the FGF-FGFR2 signaling, whatever the cause is, may induce tumor cell proliferation and survival, and epithelial-mesenchymal transition, and correlates to poor prognosis in several tumors.

Bemarituzumab, also known as FPA144, is a monoclonal anti-FGFR2b antibody developed by Five Prime. This antibody can suppress cancer progression by inhibiting FGFR2 signaling and the downstream pathways that promote cancer development, and inducing enhanced antibody dependent cell mediated cytotoxicity against FGFR2⁺ tumor cells (Xiang H et al., (2021) MAbs 13 (1) : 1981202) . It is currently tested for its effect against tumors with excessive FGFR2b expression, including gastric cancer and gastroesophageal junction cancer. In a global double-blind trial, bemarituzumab was tested in combination with mFOLGOX6 (a kind of chemotherapy) for the efficacy and safety as a first-line therapy in 155 previously untreated patients with FGFR2b⁺ HER2^-advanced gastric cancer or gastroesophageal junction cancer enrolled in 15 countries from Asia, Europe and America. The results showed that, the trial achieved statistical and clinical significance for the primary endpoint (progression free survival, PFS) and secondary endpoints (overall survival (OS) and overall response rate (ORR) ) , as compared to the placebo group, and the treatment benefits are positively correlated with the percent of FGFR2b⁺ tumor cells in lesion tissues.

However, there is undoubtedly room for improvement in the safety aspect. For example, some adverse events were observed in the trial above, including dry eye syndrome, keratitis, punctata keratitis, stomatitis, and aminotransferase level increase. It might be urgent and important to find out the causes of these adverse events and develop new therapeutic antibodies with more desired characteristics, including differential binding and blocking capabilities.

Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.

SUMMARY OF THE INVENTION

The present application provides an isolated monoclonal antibody capable of specifically binding FGFR2B (such as human, monkey and/or mouse FGFR2B) , or an antigen binding portion thereof, which i) has comparable, if not higher, binding affinity/activity to the human, monkey and/or mouse FGFR2B protein (s) (including FGFR2Bα, FGFR2Bβ, and FGFR2Bα-S252W) , ii) has comparable, if not higher, binding capability to FGFR2B⁺ cells, iii) is able to induce comparable, if not higher, antibody dependent cell mediated cytotoxicity (ADCC) against FGFR2B⁺ cells, iv) is able to induce comparable, if not higher, complement dependent cytotoxicity (CDC) against FGFR2B⁺ cells, v) has comparable, if not higher, FGF-FGFR2B blocking capability, and/or vi) has comparable, if not higher, in vivo anti-tumor effect, compared to the prior art antibodies such as FPA114. The monoclonal antibody or antigen binding portion thereof of the disclosure can be internalized by FGFR2B⁺ cells.

The antibody or antigen binding portion of the disclosure has numerous utilities, including, e.g., in vitro detection of the FGFR2B protein, and treatment of FGFR2B associated diseases such as cancers.

Therefore, in a first aspect, the disclosure provides an isolated monoclonal antibody (such as a mouse, chimeric or humanized antibody) or an antigen binding portion thereof, capable of specifically binding FGFR2B, which may comprise i) a heavy chain variable region that may comprise a VH CDR1, a VH CDR2 and a VH CDR3, wherein the VH CDR1, the VH CDR2 and the VH CDR3 may comprise amino acid sequences having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to (1) SEQ ID NOs: 1, 2 and 3, respectively; or (2) SEQ ID NOs: 7, 8 and 9, respectively; or ii) a light chain variable region that may comprise a VL CDR1, a VL CDR2 and a VL CDR3, wherein the VL CDR1, the VL CDR2 and the VL CDR3 may comprise amino acid sequences having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to (1) SEQ ID NOs: 4, 5 and 6, respectively; or (2) SEQ ID NOs: 10, 11 and 12, respectively.

The antibody or antigen binding portion thereof of the disclosure may comprise a heavy chain variable region and a light chain variable region, wherein the VH CDR1, the VH CDR2, the VH CDR3, the VL CDR1, the VL CDR2 and the VL CDR3 may comprise amino acid sequences having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to (1) SEQ ID NOs: 1, 2, 3, 4, 5 and 6, respectively; or (2) SEQ ID NOs: 7, 8, 9, 10, 11 and 12, respectively.

The heavy chain variable region of the disclosure may comprise an amino acid sequence having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to SEQ ID NOs: 13, 15, 17 or 19, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively; M, A, L, R, T and V, respectively; M, A, L, A, K and V, respectively; or I, A, L, A, K and A, respectively, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively; M, A, L, R, V and A, respectively; M, A, L, A, V and T, respectively; or I, A, L, A, A and T, respectively.

The light chain variable region of the disclosure may comprise an amino acid sequence having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to SEQ ID NOs: 14, 16, 18 or 20, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; or N and Y, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or W and Y, respectively.

The antibody or antigen binding portion thereof of the disclosure may comprise a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region and the light chain variable region may comprise amino acid sequences having at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to (1) SEQ ID NOs: 13 and 14; (2) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (3) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (4) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (5) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (6) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (7) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (8) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (9) SEQ ID NOs: 17 and 18; (10) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (11) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (12) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively; (13) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (14) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively; (15) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or (16) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively.

In another aspect, the disclosure may provide an isolated monoclonal antibody (such as a mouse, chimeric or humanized antibody) or an antigen binding portion thereof, capable of binding FGFR2B, comprising i) a heavy chain variable region comprising a VH CDR1, a VH CDR2 and a VH CDR3, and ii) a light chain variable region comprising a VL CDR1, a VL CDR2 and a VL CDR3, wherein the VH CDR1, the VH CDR2, the VH CDR3, the VL CDR1, the VL CDR2 and the VL CDR3 are from a heavy chain variable region and a light chain variable region respectively comprising the amino acid sequences of (1) SEQ ID NOs: 13 and 14; (2) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (3) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (4) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (5) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (6) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (7) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; (8) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively; (9) SEQ ID NOs: 17 and 18; (10) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (11) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (12) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively; (13) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; (14) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively; (15) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or (16) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively.

The VH CDRs and the VL CDRs may be delimited or determined by various common numbering/definition schemes/systems, including, but not limited to, Kabat, Chothia, IMGT, AbM, and Contact, based on heavy chain/light chain variable region sequences.

The isolated monoclonal antibody or antigen binding portion thereof of the disclosure may comprise a heavy chain constant region and a light chain constant region. The heavy chain constant region may be an IgG1, IgG2, IgG3 or IgG4 heavy chain constant region, or a functional fragment thereof such as a Fc region. The heavy chain constant region may naturally or be engineered to have enhanced binding affinity to the FcR and/or the complement system protein (s) , which can induce enhanced antibody dependent cell mediated cytotoxicity (ADCC) and/or complement dependnet cytotoxicity (CDC) against FGFR2B⁺ cells. The heavy chain constant region, in some embodiments, may be human IgG1 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 21, wherein the 97^th residue of SEQ ID NO: 21 may be K or R, respectively. The heavy chain constant region of SEQ ID NO: 21 is naturally occuring, whether the 97^th residue is K or R, respectively, and the heavy chain constant region of SEQ ID NO: 21 with K as the 97^th residue is functionally the same as the one with R as the 97^th residue. The light chain constant region may be κ light chain constant region, such as human κ light chain constant region comprising the amino acid sequence of SEQ ID NO: 22, or a functional fragment thereof. The N terminus of the heavy chain constant region is linked to the C terminus of the heavy chain variable region, and the N terminus of the light chain constant region is linked to the C terminus of the light chain variable region.

The antibody or the antigen binding portion thereof may be defucosylated via recombinant expression in certain mammal cells. The cell line for the defucosylation of the antibody or antigen binding portion thereof may include, but not limited to, the slc35c1-knock out cell line, the fut8-knock out cell line, the variant Chinese hamster ovary cell line Lec13, the rat myeloma cell line YB2/0, a cell line containing small interfering RNAs against the fut8 gene, and a cell line co-expressing β-1, 4-acetylglucosaminyltransferase III and Golgi α-mannosidase II.

The antibody or the antigen binding portion thereof of the disclosure, in certain embodiments, may comprise, or consist of, two heavy chains and two light chains, wherein each heavy chain may comprise the heavy chain CDRs, the heavy chain variable region and/or the heavy chain constant region described above, wherein each light chain may comprise the light chain CDRs, the light chain variable region and/or the light chain constant region described above. The antibody or antigen binding portion thereof of the disclosure, in certain embodiments, may be a single chain variable fragment (scFv) , a Fab or a F (ab’) 2 fragment.

The disclosure also provides an immunoconjugate, such as an antibody-drug conjugate, that may comprise the antibody or the antigen-binding portion thereof of the disclosure, linked to a therapeutic agent, such as a cytotoxin or an anti-cancer agent. The disclosure also provides a bispecific molecule that may comprise the antibody or the antigen binding portion thereof of the disclosure, linked to a second functional moiety (e.g., a second antibody) having a different binding specificity than the antibody or antigen binding portion thereof of the disclosure. In another aspect, the antibody or the antigen binding portion thereof of the disclosure may be made into part of a chimeric antigen receptor (CAR) or an engineered T cell receptor (TCR) . Also provided is an immune cell, such as a T cell and a NK cell, that may comprise the CAR or the TCR. The antibody or the antigen binding portion thereof of the disclosure may be encoded by or used in conjunction with an oncolytic virus.

The disclosure further provides a nucleic acid molecule encoding the antibody or antigen binding portion thereof, the bispecific molecule, or the CAR/TCR, of the disclosure, as well as an expression vector comprising such a nucleic acid molecule and a host cell comprising such an expression vector. The expression vector of the disclosure may comprise one or more nucleic acid molecules of the disclosure. In certain embodiments, the expression vector may comprise two nucleic acid molecules described above, one encoding the heavy chain variable region of an antibody or antigen binding portion thereof of the disclosure, and the other encoding the light chain variable region of the same antibody or antigen binding portion thereof. The two nucleic acid molecules may be contained in one expression vector, or in two expression vectors with each one containing one nucleic acid molecule. A method for preparing the antibody or antigen binding portion thereof, the bispecific molecule, or the CAR/TCR using the host cell of the disclosure is provided, comprising steps of (i) expressing the antibody or antigen binding portion thereof, the bispecific molecule, or the CAR/TCR in the host cell, and (ii) isolating the antibody or antigen binding portion thereof, the bispecific molecule, or the CAR/TCR from the host cell or its cell culture.

The disclosure provides a kit that may comprise the antibody or antigen binding portion thereof, the nucleic acid molecule, the expression vector, or the host cell of the disclosure. Optionally, the kit may further comprise an appropriate carrier, such as an appropriate vehicle. Optionally, the kit may further comprise an instruciton. The kit may be a detection kit, for determining the presence of or amount of the FGFR2B protein in a sample. In certain embodiments, the detection kit may comprise a reference standard.

The disclosure further provides a composition, which may comprise the antibody or antigen binding portion thereof, the immuneconjugate, the bispecific molecule, the immune cell, the oncolytic virus, the nucleic acid molecule, the expression vector, or the host cell, of the disclosure. The composition may be a pharmaceutical composition that may further comprise a pharmaceutically acceptable carrier.

In yet another aspect, the disclosure provides a method for treating or alleviating a FGFR2B associated disease in a subject in need thereof, which may comprise administering to the subject a therapeutically effective amount of the pharmaceutical composition of the disclosure. The FGFR2B associated disease may be a cancer associated with FGFR2B. The cancer may be a solid cancer, including, but not limited to, gastric cancer, gastroesophageal junction cancer, lung cancer (e.g., non-small cell lung cancer, such as squamous cell lung cancer) , breast cancer (e.g., three negative breast cancer) , ovarian cancer, pancreatic cancer, biliary duct cancer (e.g., intrahepatic cholangiocarcinoma) , cervical cancer, or endometrial cancer. In certain embodiments, the antibody or antigen binding portion thereof of the disclosure may be administered with at least one additional anti-cancer antibody, such as an anti-PD-1 antibody, an anti-PD-L1 antibody, and the like. In certain embodiments, the antibody or antigen binding portion thereof of the disclosure may be administered with a cytokine, e.g., IL-2 or IL-21, or a co-stimulatory antibody, e.g., an anti-CD137 antibody or an anti-GITR antibody. In certain embodiments, the antibody or antigen binding portion thereof of the disclosure may be administered with a chemotherapeutic agent, which may be a cytotoxic agent. The antibody or antigen binding portion thereof of the disclosure may be mouse, chimeric or humanized.

The disclosure may further provide a method for detecting the presence of or amount of the FGFR2B protein in a sample, comprising applying the detection kit of the disclosure to the sample, e.g., contacting the antibody or antigen binding portion thereof in the detection kit of the disclosure with the sample. The method may further comprise making a standard curve using the reference standard in the detection kit, and determining the amount of the FGFR2B protein in the sample using the standard curve.

Other features and advantages of the instant disclosure will be apparent from the following detailed description and examples, which should not be construed as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example, but not intended to limit the invention solely to the specific embodiments as described, may best be understood in conjunction with the accompanying drawings.

FIG. 1 shows the binding capability of the chimeric anti-FGFR2B antibodies to CHO/human FGFR2B cells over-expressing the human FGFR2Bα protein (A) , CHO/monkey FGFR2B cells over-expressing the monkey FGFR2B protein (B) , CHO/mouse FGFR2B cells over-expressing the mouse FGFR2B protein (C) and CHO/human FGFR2C cells over-expressing the human FGFR2C protein (D) .

FIG. 2 shows the binding capability of the humanized anti-FGFR2B antibodies to CHO/human FGFR2B cells over-expressing the human FGFR2Bα protein (A, B) , CHO/human FGFRβ2B cells over-expressing the human FGFR2Bβ protein (C) , CHO/human FGFR2B-S252W cells over-expressing the human FGFR2Bα variant protein (D) , CHO/monkey FGFR2B cells over-expressing the monkey FGFR2B protein (E) , CHO/mouse FGFR2B cells over-expressing the mouse FGFR2B protein (F) , FGFR2B⁺ tumor cells (including SNU-16 cells (G) , KATOIII cells (H) , OCUM-1 cells (I) ) , and CHO/human FGFR2C cells over-expressing the human FGFR2C protein (J) , wherein the antibodies with “CM” in the name are chimeric.

FIG. 3 shows the capability of the defucosylated humanized anti-FGFR2B antibodies to induce the NK cell mediated death of CHO/human FGFR2B cells (A) , CHO/human FGFR2C cells (B) and SNU-16 cells (C) .

FIG. 4 shows the capability of the defucosylated humanized anti-FGFR2B antibodies to induce the death of CHO/human FGFR2B cells (A) and CHO/human FGFR2C cells (B) by complement system proteins in human sera.

FIG. 5 shows the internalization of the defucosylated humanized anti-FGFR2B antibodies by SNU-16 cells.

FIG. 6 shows the competition between FPA144 and 113F4VH3VL0 (A) , 113F4VH4VL0 (B) , B18B6VH4VL0 (C) , or B18B6VH4VL2 (D) over epitope binding.

FIG. 7 shows the inhibitory effect of the defucosylated humanized anti-FGFR2B antibodies on FGF7 (A) or FGF10 (B) -mediated FGFR2 phosphorylation.

FIG. 8 shows the in vivo anti-tumor effect of the defucosylated humanized anti-FGFR2B antibodies in mice, wherein part of FIG. 8 (A) is enlarged and shown in FIG. 8 (B) .

FIG. 9 shows the immunochemical staining of CHO cells and CHO cells that over-express FGFR2Bα or FGFR2C using the chimeric anti-FGFR2B antibodies.

DETAILED DESCRIPTION OF THE INVENTION

To ensure that the present disclosure may be more readily understood, certain terms are first defined. Additional definitions are set forth throughout the detailed description.

The term “FGFR2B” refers to the IIIb type of fibroblast growth factor receptor 2, also known as keratinocyte growth factor receptor (KGFR) , including FGFR2Bα and FGFR2Bβ. The term comprises variants, isoforms, homologs, orthologs and paralogs. For example, an antibody specific for a human FGFR2B protein may, in certain cases, cross-react with a FGFR2B protein from a species other than human, such as monkey. In other embodiments, an antibody specific for a human FGFR2B protein may be completely specific for the human FGFR2B protein and exhibit no cross-reactivity to other species or of other types, or may cross-react with FGFR2B from certain other species but not all other species.

The term “human FGFR2B” refers to a FGFR2B protein having an amino acid sequence from a human, such as the FGFR2Bα protein comprising the amino acid sequence of SEQ ID NO: 23 (252^th residue being S) , a FGFR2Bα variant comprising the amino acid sequence of SEQ ID NO: 23 (252^th residue being W) , or the FGFR2Bβ protein comprising the amino acid sequence of SEQ ID NO: 27. The term “monkey or rhesus FGFR2B” refers to a monkey FGFR2B protein having an amino acid sequence from monkey, such as the amino acid sequence of SEQ ID NO: 24. The term “mouse FGFR2B” refers to an FGFR2B protein having an amino acid sequence from mouse, such as the amino acid sequence of SEQ ID NO: 25.

The term “antibody” as referred to herein includes IgG, IgA, IgD, IgE and IgM whole antibodies and any antigen binding fragment (i.e., “antigen-binding portion” ) thereof. Whole antibodies are glycoproteins comprising at least two heavy (H) chains and two light (L) chains inter-connected by disulfide bonds. Each heavy chain is comprised of a heavy chain variable region (abbreviated herein as V_H) and a heavy chain constant region. The heavy chain constant region is comprised of three domains, C_H1, C_H2 and C_H3. Each light chain is comprised of a light chain variable region (abbreviated herein as V_L) and a light chain constant region. The light chain constant region is comprised of one domain, C_L. The V_H and V_L regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDR) , interspersed with regions that are more conserved, termed framework regions (FR) . Each V_H and V_L is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and light chains contain a binding domain that interacts with an antigen. The heavy chain constant region may mediate the binding of the antibody or antigen binding portion thereof to host tissues or factors, including various cells of the immune system (e.g., effector cells) and the first component (C1q) of the classical complement system. The “functional fragment” of a heavy chain constant region refers to the part of the constant region that retains certain activity such as the binding affinity to FcRs and/or the complement system component (s) .

The term “antigen binding portion” of an antibody (or simply “antibody portion” ) , as used herein, refers to one or more fragments of an antibody that retain the ability to specifically bind to an antigen (e.g., a FGFR2B protein) . It has been shown that the antigen binding function of an antibody can be performed by fragments of a full-length antibody. Examples of binding fragments encompassed within the term “antigen-binding portion” of an antibody include (i) a Fab fragment, a monovalent fragment consisting of the V_L V_H, C_L and C _H1 domains; (ii) a F (ab') ₂ fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the V_H and C_H1 domains; (iv) a Fv fragment consisting of the V_L and V_H domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341: 544-546) , which consists of a V_H domain; (vi) an isolated complementarity determining region (CDR) . Furthermore, although the two domains of the Fv fragment, V_L and V_H, are coded by separate genes, they can be joined, using recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the V_L and V_H regions pair to form monovalent molecules. Such single chain antibodies are also intended to be encompassed within the term “antigen binding portion” of an antibody. These antibody fragments are obtained using conventional techniques known to those with skill in the art, and the fragments are screened for utility in the same manner as are intact antibodies.

An “isolated antibody” , as used herein, is intended to refer to an antibody that is substantially free of other antibodies having different antigenic specificities (e.g., an isolated antibody that specifically binds a FGFR2B protein is substantially free of antibodies that specifically bind antigens other than the FGFR2B protein) . An isolated antibody that specifically binds a human FGFR2B protein may, however, have cross-reactivity to other antigens, such as FGFR2B proteins from other species. Moreover, an isolated antibody can be substantially free of other cellular material and/or chemicals.

The term “monoclonal antibody” as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies are identical except for possible naturally occurring mutations and/or post-translation modifications (e.g., isomerizations, amidations) that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigenic site. In contrast to polyclonal antibody preparations which typically include different antibodies directed against different determinants (epitopes) , each monoclonal antibody is directed against a single determinant on the antigen.

The term “mouse antibody” , as used herein, is intended to include antibodies having variable regions in which both the framework and CDR regions are derived from mouse germline immunoglobulin sequences. Furthermore, if the antibody contains a constant region, the constant region also is derived from mouse germline immunoglobulin sequences. The mouse antibodies of the disclosure can include amino acid residues not encoded by mouse germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo) . However, the term “mouse antibody” , as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species have been grafted onto mouse framework sequences.

The term “chimeric antibody” refers to an antibody made by combining genetic material from a nonhuman source with genetic material from a human being. Or more generally, a chimeric antibody is an antibody having genetic material from a certain species with genetic material from another species.

The term “humanized antibody” , as used herein, refers to an antibody from non-human species whose protein sequences have been modified to increase similarity to antibody variants produced naturally in humans.

As used herein, an antibody that “specifically binds to human FGFR2B” is intended to refer to an antibody that binds to the human FGFR2B protein (and possibly a FGFR2B protein from one or more non-human species) but does not substantially bind to non-FGFR2B proteins. Preferably, the antibody binds to human FGFR2B protein with “high affinity” , namely with a K_D of 2.0 x10^-8 M or less.

The term “does not substantially bind” to a protein or cells, as used herein, means does not bind or does not bind with a high affinity to the protein or cells, i.e. binds to the protein or cells with a K_D of 1.0 x 10^-6 M or more, more preferably 1.0 x 10^-5 M or more, more preferably 1.0 x 10^-4 M or more, more preferably 1.0 x 10^-3 M or more, even more preferably 1.0 x 10^-2 M or more.

The term “EC₅₀” , also known as half maximal effective concentration, refers to the concentration of a molecule, such as an antibody or an antigen binding portion thereof, which induces a response halfway between the baseline and maximum after a specified exposure time.

The term “IC₅₀” , also known as half maximal inhibitory concentration, refers to the concentration of a molecule, e.g., an antibody or an antigen binding portion thereof, which inhibits a specific biological or biochemical function by 50%relative to the absence of the molecule.

The term “antibody-dependent cellular cytotoxicity” , “antibody-dependent cell-mediated cytotoxicity” or “ADCC, ” as used herein, refers to a mechanism of cell-mediated immune defense whereby an effector cell of the immune system actively lyses a target cell, such as a tumor cell, whose membrane-surface antigens have been bound by an anti-FGFR2B antibody or an antigen binding portion thereof.

The term “complement-dependent cytotoxicity” or “CDC” generally refers to an effector function of an IgG or IgM antibody or antigen binding portion thereof, which triggers classical complement pathway when the antibody or antigen binding portion thereof binds to a surface antigen on a target cell, such as a tumor cell, inducing formation of a membrane attack complex and target cell lysis.

The term “subject” includes any human or nonhuman animal. The term “nonhuman animal” includes all vertebrates, e.g., mammals and non-mammals, such as non-human primates, sheep, dogs, cats, cows, horses, chickens, amphibians, and reptiles, although mammals are preferred, such as non-human primates, sheep, dogs, cats, cows and horses.

The term “therapeutically effective amount” means an amount of the antibody or antigen-binding portion thereof of the present disclosure sufficient to prevent or ameliorate the symptoms associated with a disease or condition (such as a cancer) and/or lessen the severity of the disease or condition. A therapeutically effective amount is understood to be in context to the condition being treated, where the actual effective amount is readily discerned by those of skill in the art.

The percent “sequence identity” as used herein in the context of two or more nucleic acids or polypeptides, refers to two or more sequences or subsequences that are the same or have a specified percentage of nucleotides or amino acid residues that are the same, when compared and aligned (introducing gaps, if necessary) for maximum correspondence, considering or not considering conservative amino acid substitutions as part of the sequence identity. The percent identity can be measured using sequence comparison software or algorithms or by visual inspection. Various algorithms and software that can be used to obtain alignments of amino acid or nucleotide sequences are well-known in the art. These include, but are not limited to, BLAST, ALIGN, Megalign, BestFit, GCG Wisconsin Package, and variants thereof. In some embodiments, two nucleic acids or polypeptides of the disclosure are substantially identical, meaning they have at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, and in some embodiments at least 95%, 96%, 97%, 98%, 99%nucleotide or amino acid residue identity, when compared and aligned for maximum correspondence, as measured using a sequence comparison algorithm or by visual inspection.

Various aspects of the disclosure are described in further detail in the following subsections.

The antibody or the antigen binding portion thereof of the disclosure specifically binds the FGFR2B protein, e.g., the human, monkey and/or moues FGFR2B protein. Compared to the prior art antibodies such as FPA144, the antibody or antigen binding portion thereof of the disclosure i) has comparable, if not higher, binding affinity/activity to human, monkey and/or mouse FGFR2B protein (s) (including the FGFR2Bα, FGFR2Bβ, and FGFR2Bα-S252W) , ii) has comparable, if not higher, binding capability to FGFR2B⁺ cells, iii) is able to induce comparable, if not higher, antibody dependent cell mediated cytotoxicity (ADCC) against FGFR2B⁺ cells, iv) is able to induce comparable, if not higher, complement dependent cytotoxicity (CDC) against FGFR2B⁺ cells, v) has comparable, if not higher, FGF-FGFR2B blocking capability, and/or vi) has comparable, if not higher, in vivo anti-tumor efficacy. The monoclonal antibody or antigen binding portion thereof of the disclosure can be internalized by FGFR2B⁺ cells, with certain antibodies or antigen binding portions thereof internalized at a higher internalization rate than that of FPA144.

The exemplary antibodies or antigen binding portions thereof of the disclosure are those structurally and chemically characterized as described below and in the following Examples.

The heavy chain variable region CDRs and the light chain variable region CDRs of the antibody or antigen binding portion thereof have been defined by the Kabat numbering system and are set forth in Table 1. However, as is well known in the art, CDR regions can also be determined by other systems such as Chothia, IMGT, AbM, or Contact numbering system/method, based on heavy chain/light chain variable region sequences. CDR regions that are delimited or determined by systems other than Kabat are not shown here, but persons skilled in the art can delimit or determine the CDR regions in line with principles of these systems. There are also plenty of online tools to obtain CDR regions efficiently, such as https: //www. novopro. cn/tools/cdr. html, https: //novoprolabs. com/tools/cdr, www. abysis. org/abysis/sequence_input/key_annotation/key_annotation. cgi, and http: //cao. labshare. cn/AbRSA/abrsa. php.

The antibody or antigen binding portion thereof of the disclosure may comprise a heavy chain constant region, e.g., an IgG1 heavy chain constant region, such as human IgG1 heavy chain constant region comprising the amino acid sequence of SEQ ID NO: 21 (97^th residue being K or R) . The heavy chain constant region may naturally or be engineered to have enhanced binding capability to the FcR (s) and/or the complement system protein (s) . The light chain constant region may be a κ light chain constant region, such as human κ light chain constant region comprising the amino acid sequence of SEQ ID NO: 22.

The V_H and V_L sequences (or CDR sequences) of other anti-FGFR2B antibodies which bind to human FGFR2B can be “mixed and matched” with the V_H and V_L sequences (or CDR sequences) of the anti-FGFR2B antibody of the present disclosure. Preferably, when V_H and V_L chains (or the CDRs within such chains) are mixed and matched, a V_H sequence from a particular V_H/V_L pairing is replaced with a structurally similar V_H sequence. Likewise, preferably a V_L sequence from a particular V_H/V_L pairing is replaced with a structurally similar V_L sequence.

Accordingly, in one embodiment, an antibody of the disclosure, or an antigen binding portion thereof, comprises: (a) a heavy chain variable region comprising an amino acid sequence listed above in Table 1; and (b) a light chain variable region comprising an amino acid sequence listed above in Table 1, or the V_L of another anti-FGFR2B antibody, wherein the antibody specifically binds human FGFR2B.

In another embodiment, an antibody of the disclosure, or an antigen binding portion thereof, comprises: (a) the CDR1, CDR2, and CDR3 regions of the heavy chain variable region listed above in Table 1; and (b) the CDR1, CDR2, and CDR3 regions of the light chain variable region listed above in Table 1 or the CDRs of another anti-FGFR2B antibody, wherein the antibody specifically binds human FGFR2B.

In yet another embodiment, the antibody, or antigen binding portion thereof, includes the heavy chain variable CDR2 region of anti-FGFR2B antibody combined with CDRs of other antibodies which bind human FGFR2B, e.g., CDR1 and/or CDR3 from the heavy chain variable region, and/or CDR1, CDR2, and/or CDR3 from the light chain variable region of a different anti-FGFR2B antibody.

In addition, it is well known in the art that the CDR3 domain, independently from the CDR1 and/or CDR2 domain (s) , alone can determine the binding specificity of an antibody for a cognate antigen and that multiple antibodies can predictably be generated having the same binding specificity based on a common CDR3 sequence. See, e.g., Klimka et al., British J. of Cancer 83 (2) : 252-260 (2000) ; Beiboer et al., J. Mol. Biol. 296: 833-849 (2000) ; Rader et al., Proc. Natl. Acad. Sci. U.S.A. 95: 8910-8915 (1998) ; Barbas et al., J. Am. Chem. Soc. 116: 2161-2162 (1994) ; Barbas et al., Proc. Natl. Acad. Sci. U.S.A. 92: 2529-2533 (1995) .

In another embodiment, an antibody or an antigen binding portion thereof of the disclosure comprises a heavy and/or light chain variable region sequences of CDR1, CDR2 and CDR3 sequences which differ from those of the anti-FGFR2B antibodies of the present disclosure by one or more conservative modifications. It is understood in the art that certain conservative sequence modification can be made which do not remove antigen binding. See, e.g., Brummell et al., (1993) Biochem 32: 1180-8; de Wildt et al., (1997) Prot. Eng. 10: 835-41; Komissarov et al., (1997) J. Biol. Chem. 272: 26864-26870; Hall et al., (1992) J. Immunol. 149: 1605-12; Kelley and O'Connell (1993) Biochem. 32: 6862-35; Adib-Conquy et al., (1998) Int. Immunol. 10: 341-6 and Beers et al., (2000) Clin. Can. Res. 6: 2835-43.

Accordingly, in one embodiment, the antibody comprises a heavy chain variable region comprising CDR1, CDR2, and CDR3 sequences and/or a light chain variable region comprising CDR1, CDR2, and CDR3 sequences, wherein:

(a) the heavy chain variable region CDR1 sequence comprises a sequence listed in Table 1 above, and/or conservative modifications thereof; and/or

(b) the heavy chain variable region CDR2 sequence comprises a sequence listed in Table 1 above, and/or conservative modifications thereof; and/or

(c) the heavy chain variable region CDR3 sequence comprises a sequence listed in Table 1 above, and conservative modifications thereof; and/or

(d) the light chain variable region CDR1, and/or CDR2, and/or CDR3 sequences comprise the sequence (s) listed in Table 1 above; and/or conservative modifications thereof; and

(e) the antibody specifically binds human FGFR2B.

The antibody or antigen binding portion thereof of the present disclosure possesses one or more of the following functional properties described above, such as high affinity binding to human FGFR2B, high blocking capability on FGF-FGFR2B interaction, high capability to induce ADCC and/or CDC against FGFR2B⁺ tumor cells.

In various embodiments, the antibody or antigen binding portion thereof of the disclosure can be, for example, mouse, chimeric or humanized.

As used herein, the term “conservative sequence modifications” is intended to refer to amino acid modifications that do not significantly affect or alter the binding characteristics of the antibody or antigen binding portion thereof containing the amino acid sequence. Such conservative modifications include amino acid substitutions, additions and deletions. Modifications can be introduced into an antibody of the disclosure by standard techniques known in the art, such as site-directed mutagenesis and PCR-mediated mutagenesis. Conservative amino acid substitutions are ones in which the amino acid residue is replaced with an amino acid residue having a similar side chain. Families of amino acid residues having similar side chains have been defined in the art. These families include amino acids with basic side chains (e.g., lysine, arginine, histidine) , acidic side chains (e.g., aspartic acid, glutamic acid) , uncharged polar side chains (e.g., glycine, asparagine, glutamine, serine, threonine, tyrosine, cysteine, tryptophan) , nonpolar side chains (e.g., alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine) , beta-branched side chains (e.g., threonine, valine, isoleucine) and aromatic side chains (e.g., tyrosine, phenylalanine, tryptophan, histidine) . Thus, one or more amino acid residues within the CDR regions of an antibody or an antigen binding portion thereof of the disclosure can be replaced with other amino acid residues from the same side chain family and the altered antibody can be tested for retained function (i.e., the functions set forth above) using the functional assays described herein.

The antibodies of the disclosure can be prepared using an antibody having one or more of the V_H/V_L sequences of the anti-FGFR2B antibody or an antigen binding portion thereof of the present disclosure as starting material. An antibody or an antigen binding portion thereof can be engineered by modifying one or more residues within one or both variable regions (i.e., V_H and/or V_L) , for example within one or more CDR regions and/or within one or more framework regions. Additionally or alternatively, an antibody or an antigen binding portion thereof can be engineered by modifying residues within the constant region (s) , for example to alter the effector function (s) of the antibody.

In certain embodiments, CDR grafting can be used to engineer variable regions of an antibody or an antigen binding portion thereof. The antibody or antigen binding portion thereof interacts with a target antigen predominantly through amino acid residues that are located in the six heavy and light chain complementarity determining regions (CDRs) . For this reason, the amino acid sequences within CDRs are more diverse between individual antibodies than sequences outside of CDRs. Because CDR sequences are responsible for most antibody-antigen interactions, it is possible to express recombinant antibodies or antigen binding portions thereof that mimic the properties of specific naturally occurring antibodies by constructing expression vectors that include CDR sequences from the specific naturally occurring antibody grafted onto framework sequences from a different antibody with different properties (see, e.g., Riechmann et al., (1998) Nature 332: 323-327; Jones et al., (1986) Nature 321: 522-525; Queen et al., (1989) Proc. Natl. Acad. See also U.S.A. 86: 10029-10033; U.S. Pat. Nos. 5,225,539; 5,530,101; 5,585,089; 5,693,762 and 6,180,370) .

Accordingly, another embodiment of the disclosure pertains to an isolated monoclonal antibody, or antigen binding portion thereof, comprising a heavy chain variable region comprising CDR1, CDR2, and CDR3 sequences comprising the sequences of the present disclosure, as described above, and/or a light chain variable region comprising CDR1, CDR2, and CDR3 sequences comprising the sequences of the present disclosure, as described above. While these antibodies contain the V_H and V_L CDR sequences of the monoclonal antibody or antigen binding portion thereof of the present disclosure, they can contain different framework sequences.

Such framework sequences can be obtained from public DNA databases or published references that include germline antibody gene sequences. For example, germline DNA sequences for human heavy and light chain variable region genes can be found in the “VBase” human germline sequence database (available on the Internet at www. mrc-cpe. cam. ac. uk/vbase) , as well as in Kabat et al., (1991) , cited supra; Tomlinson et al., (1992) J. Mol. Biol. 227: 776-798; and Cox et al., (1994) Eur. J. Immunol. 24: 827-836. As another example, the germline DNA sequences for human heavy and light chain variable region genes can be found in the Genbank database. For example, the following heavy chain germline sequences found in the HCo7 HuMAb mouse are available in the accompanying Genbank Accession Nos.: 1-69 (NG--0010109, NT--024637 &BC070333) , 3-33 (NG--0010109 &NT--024637) and 3-7 (NG--0010109 &NT--024637) . As another example, the following heavy chain germline sequences found in the HCo12 HuMAb mouse are available in the accompanying Genbank Accession Nos.: 1-69 (NG--0010109, NT--024637 &BC070333) , 5-51 (NG--0010109 &NT--024637) , 4-34 (NG--0010109 &NT--024637) , 3-30.3 (CAJ556644) &3-23 (AJ406678) .

Antibody protein sequences are compared against a compiled protein sequence database using one of the sequence similarity searching methods called the Gapped BLAST (Altschul et al., (1997) , supra) , which is well known to those skilled in the art.

Preferred framework sequences for use in the antibodies of the disclosure are those that are structurally similar to the framework sequences used by antibodies of the disclosure. The V_H CDR1, CDR2, and CDR3 sequences can be grafted onto framework regions that have the identical sequence as that found in the germline immunoglobulin gene from which the framework sequence derives, or the CDR sequences can be grafted onto framework regions that contain one or more mutations as compared to the germline sequences. For example, it has been found that in certain instances it is beneficial to mutate residues within the framework regions to maintain or enhance the antigen binding ability of the antibody (see e.g., U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762 and 6,180,370) .

Another type of variable region modification is to mutate amino acid residues within the V_H and/or V_L CDR1, CDR2 and/or CDR3 regions to thereby improve one or more binding properties (e.g., affinity) of the antibody or antigen binding portion thereof of interest. Site-directed mutagenesis or PCR-mediated mutagenesis can be performed to introduce the mutation (s) and the effect on antibody binding, or other functional property of interest, can be evaluated in in vitro or in vivo assays as known in the art. Particularly, conservative modifications (as known in the art) are introduced. The mutations can be amino acid substitutions, additions or deletions, but are preferably substitutions. Moreover, typically no more than one, two, three, four or five residues within a CDR region are altered.

Engineered antibodies of the disclosure include those in which modifications have been made to framework residues within V_H and/or V_L, e.g. to improve the properties of the antibody. The framework modification involves mutating one or more residues within the framework region, or even within one or more CDR regions, to remove T cell epitopes to thereby reduce the potential immunogenicity of the antibody. This approach is also referred to as “deimmunization” and is described in further detail in U.S. Patent Publication No. 20030153043.

In addition, or as an alternative to modifications made within the framework or CDR regions, antibodies of the disclosure can be engineered to include modifications within the Fc region, typically to alter one or more functional properties of the antibody, such as serum half- life, complement fixation, Fc receptor binding, and/or antigen-dependent cellular cytotoxicity. Furthermore, an antibody of the disclosure can be chemically modified (e.g., one or more chemical moieties can be attached to the antibody) or be modified to alter its glycosylation, again to alter one or more functional properties of the antibody.

In one embodiment, the hinge region of C_H1 is modified in such that the number of cysteine residues in the hinge region is altered, e.g., increased or decreased. This approach is described further in U.S. Pat. No. 5,677,425. The number of cysteine residues in the hinge region of C_H1 is altered to, for example, facilitate assembly of the light and heavy chains or to increase or decrease the stability of the antibody.

In another embodiment, the Fc hinge region of an antibody is mutated to decrease the biological half-life of the antibody. More specifically, one or more amino acid mutations are introduced into the C_H2-C_H3 domain interface region of the Fc-hinge fragment such that the antibody has impaired Staphylococcyl protein A (SpA) binding relative to native Fc-hinge domain SpA binding. This approach is described in further detail in U.S. Pat. No. 6,165,745.

In still another embodiment, the glycosylation of an antibody is modified. For example, a glycosylated antibody can be made (i.e., the antibody lacks glycosylation) . Glycosylation can be altered to, for example, increase the affinity of the antibody for antigen. Such carbohydrate modifications can be accomplished by, for example, altering one or more sites of glycosylation within the antibody sequence. For example, one or more amino acid substitutions can be made that result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site. Such aglycosylation may increase the affinity of the antibody for antigen. See, e.g., U.S. Pat. Nos. 5,714,350 and 6,350,861.

Additionally or alternatively, an antibody can be made that has an altered type of glycosylation, such as a hypofucosylated antibody having reduced amounts of fucosyl residues or an antibody having increased bisecting GlcNac structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies. Such carbohydrate modifications can be accomplished by, for example, expressing the antibody in a host cell with altered glycosylation machinery. Cells with altered glycosylation machinery have been described in the art, including, but not limited to, the slc35c1-knock out cell line, the fut8-knock out cell line, the variant Chinese hamster ovary cell line Lec13, the rat myeloma cell line YB2/0, a cell line containing small interfering RNAs against the fut8 gene, and a cell line co-expressing β-1, 4-acetylglucosaminyltransferase III and Golgi α-mannosidase II. These cell lines can be used as host cells in which to express recombinant antibodies of the disclosure to thereby produce an antibody with altered glycosylation. The slc35c1-knock out cell line may be prepared using the platform of MabWorks, and includes the CHO cell line having a deposit no. CGMCC No. 14287 as disclosed in US10377833B2.

Another modification of the antibodies herein that is contemplated by this disclosure is pegylation. An antibody can be pegylated to, for example, increase the biological (e.g., serum) half-life of the antibody. To pegylate an antibody, the antibody, or fragment thereof, typically is reacted with polyethylene glycol (PEG) , such as a reactive ester or aldehyde derivative of PEG, under conditions in which one or more PEG groups become attached to the antibody or antibody fragment.

Antibodies of the disclosure can be characterized by their various physical properties, to detect and/or differentiate different classes thereof.

For example, antibodies can contain one or more glycosylation sites in either the light or heavy chain variable region. Such glycosylation sites may result in increased immunogenicity of the antibody or an alteration of the pK of the antibody due to altered antigen binding (Marshall et al (1972) Annu Rev Biochem 41: 673-702; Gala and Morrison (2004) J Immunol 172: 5489-94; Wallick et al (1988) J Exp Med 168: 1099-109; Spiro (2002) Glycobiology 12: 43R-56R; Parekh et al (1985) Nature 316: 452-7; Mimura et al., (2000) Mol Immunol 37: 697-706) . Glycosylation has been known to occur at motifs containing an N-X-S/T sequence. In some instances, it is preferred to have an anti-FGFR2B antibody that does not contain glycosylation in the variable region (s) . This can be achieved either by selecting antibodies that do not contain the glycosylation motif in the variable region or by mutating residues within the glycosylation region.

In an embodiment, the antibodies do not contain asparagine isomerism sites. The deamidation of asparagine may occur on N-G or D-G sequences and result in the creation of an isoaspartic acid residue that introduces a kink into the polypeptide chain and decreases its stability (isoaspartic acid effect) .

In another aspect, the disclosure provides nucleic acid molecules that encode heavy and/or light chain variable regions, or CDRs, of an antibody or an antigen binding portion thereof of the disclosure. The nucleic acids can be present in whole cells, in a cell lysate, or in a partially purified or substantially pure form. A nucleic acid is “isolated” or “rendered substantially pure” when purified away from other cellular components or other contaminants, e.g., other cellular nucleic acids or proteins, by standard techniques. A nucleic acid of the disclosure can be, e.g., DNA or RNA and may or may not contain intronic sequences. In a preferred embodiment, the nucleic acid is a cDNA molecule.

Nucleic acids of the disclosure can be obtained using standard molecular biology techniques. For antibodies expressed by hybridomas (e.g., hybridomas prepared from transgenic mice carrying human immunoglobulin genes as described further below) , cDNAs encoding the light and heavy chains of the antibody made by the hybridoma can be obtained by standard PCR amplification or cDNA cloning techniques. For antibodies obtained from an immunoglobulin gene library (e.g., using phage display techniques) , a nucleic acid encoding such antibodies can be recovered from the gene library.

Monoclonal antibodies (mAbs) of the present disclosure can be produced using the well-known somatic cell hybridization (hybridoma) technique of Kohler and Milstein (1975) Nature 256: 495. Other embodiments for producing monoclonal antibodies include viral or oncogenic transformation of B lymphocytes and phage display techniques. Chimeric or humanized antibodies are also well known in the art. See e.g., U.S. Pat. Nos. 4,816,567; 5,225,539; 5,530,101; 5,585,089; 5,693,762 and 6,180,370.

Antibodies of the disclosure also can be produced in a host cell transfectoma using, for example, a combination of recombinant DNA techniques and gene transfection methods as is well known in the art (e.g., Morrison, S. (1985) Science 229: 1202) . In one embodiment, DNA encoding partial or full-length light and heavy chains obtained by standard molecular biology techniques is inserted into one or more expression vectors such that the genes are operatively linked to transcriptional and translational regulatory sequences. In this context, the term “operatively linked” is intended to mean that an antibody gene is ligated into a vector such that transcriptional and translational control sequences within the vector serve their intended function of regulating the transcription and translation of the antibody gene.

The term “regulatory sequence” is intended to include promoters, enhancers and other expression control elements (e.g., polyadenylation signals) that control the transcription or translation of the antibody genes. Such regulatory sequences are described, e.g., in Goeddel (Gene Expression Technology. Methods in Enzymology 185, Academic Press, San Diego, Calif. (1990) ) . Preferred regulatory sequences for mammalian host cell expression include viral elements that direct high levels of protein expression in mammalian cells, such as promoters and/or enhancers derived from cytomegalovirus (CMV) , Simian Virus 40 (SV40) , adenovirus, e.g., the adenovirus major late promoter (AdMLP) and polyoma. Alternatively, nonviral regulatory sequences can be used, such as the ubiquitin promoter or β-globin promoter. Still further, regulatory elements composed of sequences from different sources, such as the SRα promoter system, which contains sequences from the SV40 early promoter and the long terminal repeat of human T cell leukemia virus type 1 (Takebe et al., (1988) Mol. Cell. Biol. 8:466-472) . The expression vector and expression control sequences are chosen to be compatible with the expression host cell used.

The antibody light chain gene and the antibody heavy chain gene can be inserted into the same or separate expression vectors. In preferred embodiments, the variable regions are used to create full-length antibody genes of any antibody isotype by inserting them into expression vectors already encoding heavy chain constant and light chain constant regions of the desired isotype such that the V_H segment is operatively linked to the C_H segment (s) within the vector and the V_L segment is operatively linked to the C_L segment within the vector. Additionally or alternatively, the recombinant expression vector can encode a signal peptide that facilitates secretion of the antibody chain from a host cell. The antibody chain gene can be cloned into the vector such that the signal peptide is linked in-frame to the amino terminus of the antibody chain gene. The signal peptide can be an immunoglobulin signal peptide or a heterologous signal peptide (i.e., a signal peptide from a non-immunoglobulin protein) .

In addition to the antibody chain genes and regulatory sequences, the recombinant expression vectors of the disclosure can carry additional sequences, such as sequences that regulate replication of the vector in host cells (e.g., origins of replication) and selectable marker genes. The selectable marker gene facilitates selection of host cells into which the vector has been introduced (see, e.g., U.S. Pat. Nos. 4,399,216; 4,634,665 and 5,179,017) . For example, typically the selectable marker gene confers resistance to drugs, such as G418, hygromycin or methotrexate, on a host cell into which the vector has been introduced. Preferred selectable marker genes include the dihydrofolate reductase (DHFR) gene (for use in dhfr-host cells with methotrexate selection/amplification) and the neo gene (for G418 selection) .

For expression of the light and heavy chains, the expression vector (s) encoding the heavy and light chains is transfected into a host cell by standard techniques. The various forms of the term “transfection” are intended to encompass a wide variety of techniques commonly used for the introduction of exogenous DNA into a prokaryotic or eukaryotic host cell, e.g., electroporation, calcium-phosphate precipitation, DEAE-dextran transfection and the like. Although it is theoretically possible to express the antibodies of the disclosure in either prokaryotic or eukaryotic host cells, expression of antibodies in eukaryotic cells, and most preferably mammalian host cells, is the most preferred because such eukaryotic cells, and in particular mammalian cells, are more likely than prokaryotic cells to assemble and secrete a properly folded and immunologically active antibody.

Mammalian host cells for expressing the recombinant antibodies of the disclosure include the slc35c1-knock out cell line, the fut8-knock out cell line, the variant Chinese hamster ovary cell line Lec13, the rat myeloma cell line YB2/0, a cell line containing small interfering RNAs against the fut8 gene, and a cell line co-expressing β-1, 4-acetylglucosaminyltransferase III and Golgi α-mannosidase II, Chinese Hamster Ovary (CHO cells) (including dhfr-CHO cells, described in Urlaub and Chasin, (1980) Proc. Natl. Acad. Sci. USA 77: 4216-4220, used with a DHFR selectable marker, e.g., as described in R. J. Kaufman and P. A. Sharp (1982) J. Mol. Biol. 159: 601-621) , NSO myeloma cells, COS cells and SP2 cells. In particular for use with NSO myeloma cells, another preferred expression system is the GS gene expression system disclosed in WO 87/04462, WO 89/01036 and EP 338, 841. When recombinant expression vectors encoding antibody genes are introduced into mammalian host cells, the antibodies are produced by culturing the host cells for a period of time sufficient to allow for expression of the antibody in the host cells or, more preferably, secretion of the antibody into the culture medium in which the host cells are grown. Antibodies can be recovered from the culture medium using standard protein purification methods.

Antibodies of the disclosure can be conjugated to a therapeutic agent to form an immunoconjugate such as an antibody-drug conjugate (ADC) . Suitable therapeutic agents include cytotoxins, alkylating agents, DNA minor groove binders, DNA intercalators, DNA crosslinkers, histone deacetylase inhibitors, nuclear export inhibitors, proteasome inhibitors, topoisomerase I or II inhibitors, heat shock protein inhibitors, tyrosine kinase inhibitors, antibiotics, and anti-mitotic agents. In the ADC, the antibody and therapeutic agent preferably are conjugated via a linker cleavable such as a peptidyl, disulfide, or hydrazone linker.

In another aspect, the present disclosure features bispecific molecules comprising one or more antibodies of the disclosure linked to at least one other functional molecule, e.g., another peptide or protein (e.g., another antibody or ligand for a receptor) to generate a bispecific molecule that binds to at least two different binding sites or target molecules. Thus, as used herein, “bispecific molecule” includes molecules that have three or more specificities.

Bispecific molecules may be in many different formats and sizes. At one end of the size spectrum, a bispecific molecule retains the traditional antibody format, except that, instead of having two binding arms of identical specificity, it has two binding arms each having a different specificity. At the other extreme are bispecific molecules consisting of two single-chain antibody fragments (scFv's) linked by a peptide chain, a so-called Bs (scFv) ₂ construct. Intermediate-sized bispecific molecules include two different F (ab) fragments linked by a peptidyl linker. Bispecific molecules of these and other formats can be prepared by genetic engineering, somatic hybridization, or chemical methods. See, e.g., Kufer et al, cited supra; Cao and Suresh, Bioconjugate Chemistry, 9 (6) , 635-644 (1998) ; and van Spriel et al., Immunology Today, 21 (8) , 391-397 (2000) , and the references cited therein.

The present disclosure further provides a chimeric antigen receptor containing an anti-FGFR2B scFv, wherein the anti-FGFR2B scFv contains the heavy/light chain variable regions and/or CDRs of the disclosure.

The chimeric antigen receptor of the disclosure may comprise (a) an extracellular antigen binding domain containing an anti-FGFR2B scFv; (b) a transmembrane domain; and (c) an intracellular domain containing a signaling domain and/or a costimulatory domain.

An oncolytic virus preferentially infects and kills cancer cells. The antibody or antigen binding portion thereof of the disclosure may be used in conjunction with the oncolytic virus. Alternatively, an oncolytic virus encoding antibody or antigen binding portion thereof of the disclosure may be introduced into human bodies.

In another aspect, the present disclosure provides a pharmaceutical composition comprising the antibody or antigen binding portion thereof, immuneconjugate, the bispecific molecule, the immune cell, the oncolytic virus, the nucleic acid molecule, the expression vector, or the host cell, of the present disclosure, formulated together with a pharmaceutically acceptable carrier. The composition may optionally contain one or more additional pharmaceutically active ingredients, such as another antibody or a drug, such as an ant-tumor antibody, or an antibody for enhancing immune response, or another non-antibody therapeutic agent, such as an anti-tumor agent, or a costimulatory agent. The pharmaceutical composition of the disclosure also can be administered in a combination therapy with, for example, an anti-tumor agent, or a costimulatory agent.

The pharmaceutical composition can comprise any number of excipients. Excipients that can be used include carriers, surface active agents, thickening or emulsifying agents, solid binders, dispersion or suspension aids, solubilizers, colorants, flavoring agents, coatings, disintegrating agents, lubricants, sweeteners, preservatives, isotonic agents, and combinations thereof. The selection and use of suitable excipients is taught in Gennaro, ed., Remington: The Science and Practice of Pharmacy, 20th Ed. (Lippincott Williams &Wilkins 2003) .

The pharmaceutical composition may be suitable for intravenous, intramuscular, subcutaneous, parenteral, spinal or epidermal administration (e.g., by injection or infusion) . Depending on the route of administration, the active ingredient can be coated in a material to protect it from the action of acids and other natural conditions that may inactivate it. The phrase “parenteral administration” as used herein means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal, epidural and intrasternal injection and infusion. Alternatively, an antibody of the disclosure can be administered via a non-parenteral route, such as a topical, epidermal or mucosal route of administration, e.g., intranasally, orally, vaginally, rectally, sublingually or topically.

Pharmaceutical compositions can be in the form of sterile aqueous solutions or dispersions. They can also be formulated in a microemulsion, liposome, or other ordered structure suitable to high drug concentration.

The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will vary depending upon the subject being treated and the particular mode of administration and will generally be that amount of the composition which produces a therapeutic effect. Generally, out of one hundred percent, this amount will range from about 0.01%to about 99%of active ingredient in combination with a pharmaceutically acceptable carrier.

Dosage regimens are adjusted to provide the optimum desired response (e.g., a therapeutic response) . It is especially advantageous to formulate parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subjects to be treated; each unit contains a predetermined quantity of active ingredient calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. Alternatively, antibody can be administered as a sustained release formulation, in which case less frequent administration is required.

For administration of the antibody or the antigen binding portion thereof, the dosage may range from about 0.0001 to 100 mg/kg of the host body weight. An exemplary treatment regime entails administration once per week.

A “therapeutically effective dosage” of an anti-FGFR2B antibody or antigen binding portion thereof of the disclosure results in a decrease in severity of disease symptoms, an increase in frequency and duration of disease symptom-free periods, or prevention of impairment or disability due to the disease affliction. For example, for the treatment of tumor- bearing subjects, a “therapeutically effective dosage” preferably inhibits tumor growth by at least about 20%, more preferably by at least about 40%, even more preferably by at least about 60%, and still more preferably by at least about 80%relative to untreated subjects. A therapeutically effective amount of a therapeutic antibody can decrease tumor size, or otherwise ameliorate symptoms in a subject, which is typically a human or can be another mammal.

The pharmaceutical composition can be a controlled release formulation, including implants, transdermal patches, and microencapsulated delivery systems. Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid.

In certain embodiments, the monoclonal antibodies of the disclosure can be formulated to ensure proper distribution in vivo. For example, to ensure that the therapeutic antibody of the disclosure cross the blood-brain barrier, they can be formulated in liposomes, which may additionally comprise targeting moieties to enhance selective transport to specific cells or organs.

The pharmaceutical compositions of the present disclosure have numerous in vitro and in vivo utilities, including, for example, in vitro detection of the FGFR2B protein, and treatment of FGFR2B associated cancers. The pharmaceutical compositions can be administered to human subjects, e.g., in vivo, to inhibit tumor growth.

Given the ability of the pharmaceutical compositions of the disclosure to inhibit proliferation and survival of cancer cells, the disclosure provides methods for inhibiting growth of tumor cells in a subject in need thereof, comprising administering to the subject a pharmaceutical composition of the disclosure such that growth of the tumor is inhibited in the subject. Non-limiting examples of tumors that can be treated by the pharmaceutical compositions of the disclosure include, but not limited to, gastric cancer, gastroesophageal junction cancer, lung cancer (e.g., non-small cell lung cancer, such as squamous cell lung cancer) , breast cancer (e.g., three negative breast cancer) , ovarian cancer, pancreatic cancer, biliary duct cancer (e.g., intrahepatic cholangiocarcinoma) , cervical cancer, or endometrial cancer, original and/or metastatic. Additionally, the pharmaceutical compositions of the disclosure may also apply to refractory or recurrent malignancies whose growth may be inhibited by the composition of the disclosure.

In another aspect, the disclosure provides methods of combination therapy in which a pharmaceutical composition of the present disclosure is co-administered with one or more additional antibodies or non-antibody agents that are effective in inhibiting tumor growth in a subject. In one embodiment, the disclosure provides a method for inhibiting tumor growth in a subject comprising administering to the subject a pharmaceutical composition of the disclosure and one or more additional antibodies, such as an anti-PD-L1 antibody, and/or an anti-PD-1 antibody. In certain embodiments, the subject is human. In certain embodiments, the pharmaceutical composition of the disclosure may be further combined with standard cancer treatments. For example, a chemotherapeutic agent can be administered with the pharmaceutical composition of the disclosure, which may be a cytotoxic agent.

The combination of therapeutic agents discussed herein can be administered concurrently as a single composition in a pharmaceutically acceptable carrier, or concurrently as separate compositions with each agent in a pharmaceutically acceptable carrier. In another embodiment, the combination of therapeutic agents can be administered sequentially.

Furthermore, if more than one dose of the combination therapy is administered sequentially, the order of the sequential administration can be reversed or kept in the same order at each time point of administration, sequential administrations can be combined with concurrent administrations, or any combination thereof.

The present disclosure is further illustrated by the following examples, which should not be construed as further limiting. The contents of all figures and all references, Genbank sequences, patents and published patent applications cited throughout this application are expressly incorporated herein by reference.

Examples

Example 1. Construction of CHO cells stably expressing human FGFR2B, monkey FGFR2B, mouse FGFR2B, human FGFR2C, or human FGFR2B variant

CHO cells were used to construct cell lines stably expressing the human FGFR2B protein, the monkey FGFR2B protein, the mouse FGFR2B protein, the human FGFR2C protein, or the human FGFR2B variant.

Briefly, cDNA sequences encoding human FGFR2Bα, human FGFR2Bβ, monkey FGFR2B, mouse FGFR2B (amino acid sequences set forth in SEQ ID NO: 23 (the 252^th residue being S) , 27, 24 and 25, respectively) , human FGFR2C (amino acid sequence set forth in SEQ ID NO: 26) and human FGFR2Bα variant (human FGFR2B-S252W, amino acid sequence set forth in SEQ ID NO: 23 (the 252^th residue being W) ) were synthesized, respectively, and then subcloned into the pLV-EGFP (2A) -Puro vector (Beijing Inovogen, CN) between EcoRI and BamHI. Lentiviruses were generated in HEK293T cells (Cobioer, NJ, CN) by co-transfection of the resultant pLV-EGFP (2A) -Puro-FGFR2B or pLV-EGFP (2A) -Puro-FGFR2C, as well as psPAX and pMD2. G plasmids, according to the instruction in Lipofectamine 3000 kit (Thermo Fisher Scientific, USA) . Three days post co-transfection, the lentiviruses were harvested from the HEK293T cell culture supernatants (the culture medium containing DMEM (Cat#: SH30022.01, Gibco) with 10%FBS (Cat#: FND500, Excell) ) , and then used to infect CHO cells (Cobioer, NJ, CN) , to generate CHO/human FGFR2B cells, CHO/human FGFRβ2B cells, CHO/monkey FGFR2B cells, CHO/mouse FGFR2B cells, CHO/human FGFR2C cells and CHO/human FGFR2B-S252W cells. These CHO cells were cultured in DMEM containing 10%FBS and 0.2 μg/ml puromycin (Cat#: A11138-03, Gibco) for 7 days. The expressions of the FGFR2B proteins, including the variant, were confirmed by FACS using commercially available anti-FGFR2 antibodies (Cat#: 13042-1-AP, Thermo Fisher, US) .

Example 2. Generation of monoclonal anti-human FGFR2B antibodies

Table 2. Immunization scheme

The monoclonal mouse anti-human FGFR2B antibodies were obtained by the conventional hybridoma fusion technology with 4 different schemes as shown in Table 2, with the antigen information summarized in Table 3. One week after each boost, 50 μl of murine serum was collected from each mouse for binding capability determination by ELISA using the recombinant human FGFR2B-α-his (Cat#: FGR-HM1BD, Kactus Biosystems, CN) , and for titer determination by FACS using the CHO cells as prepared in Example 1 that expressed human, monkey or mouse FGFR2B proteins.

Based on the ELISA and FACS analysis results after the final boost, the mice with highest serum titers were chosen for the hybridoma cell line preparation.

Table 3. Antigens used in mouse immunization

Generation of hybridoma cell lines

Hybridoma cell lines were generated using the conventional hybridoma fusion technology with minor modifications.

Four days after the final boost, mice were sacrificed, and spleens were collected and prepared as single cell suspensions in PBS. The spleenocytes were washed for three times with DMEM medium (Hyclone, Cat#: SH30243.01B) . Viable myeloma cells SP2/0 (ATCC, CRL-1581) at the log-phase were mixed with the murine spleenocytes in a ratio of 1: 4. The cells were then washed twice with DMEM, and then cell fusion was performed with PEG (Sigma, Cat#: P7181) . The post-fusion cells were washed with DMEM medium for three times and suspended in cell culture medium RPMI 1640 (Gibco, Cat#: C22400500CP) supplemented with 10%FBS and 1X HAT (Sigma, H0262) . The cell suspension was plated onto 96 well cell culture plates, 200 μl per well (5×10⁴ cells/well) , and incubated in a 37℃humidified 5%CO₂ incubator for 7 days. Then, the culture medium was replaced by fresh medium supplemented with 10%FBS+ 1X HT. Two to three days later, the hybridoma cells were screened by ELISA and FACS.

Screening of hybridoma cell lines by ELISA

High-throughput ELISA binding assay was firstly used to screen for hybridoma clones producing monoclonal antibodies binding to the full-length human FGFR2B protein using the recombinant human FGFR2B-α-his (Cat#: FGR-HM1BD, Kactus Biosystems, CN) .

The hybridoma clones as selected were further tested for their binding capability to the full-length human FGFR2C protein, using an ELISA kit (Cat#: FGR-HM1BC, Kactus Biosystems, CN) .

With the ELISA assays, 5 hybridoma clones were identified that had specific binding activity to the FGFR2B protein and did not bind the FGFR2C protein.

Screening of hybridoma cell lines by FACS

The 5 hybridoma clones were further tested for their binding capacity to CHO cells expressing human, monkey or mouse FGFR2B proteins, or the human FGFR2C protein, using the CHO/human FGFR2B cells, CHO/monkey FGFR2B cells, CHO/mouse FGFR2B cells, and CHO/human FGFR2C cells prepared in Example 1.

Based on the FACS screening, 5 hybridoma clones were obtained that displayed high binding capacity to the CHO/human FGFR2B cells, CHO/monkey FGFR2B cells, and CHO/mouse FGFR2B cells, but showed no binding to CHO/human FGFR2C cells.

Subcloning of hybridoma clones producing anti-FGFR2B antibodies

The 5 hybridoma clones were subject to 2 rounds of subcloning. During the subcloning, multiple subclones (n>3) from each parent clone were selected and confirmed by ELISA and FACS assays as described above. The subclones selected through this process were defined as hybridoma cells producing monoclonal antibodies. Finally, 5 subclones (one subclone from each parent clone) having high binding capacity to the human FGFR2B protein were obtained.

Example 3. Purification and isotyping of monoclonal anti-FGFR2B antibodies

The 5 monoclonal mouse antibodies as obtained in Example 2 were purified. Briefly, the cells of each hybridoma clone were cultured in the T175 flask containing 100 ml fresh serum-free culture medium (Cat#: 12045-076, Gibco, US) with 1%HT supplement (Cat#: 11067-030, Gibco, US) in an incubator at 37℃ under 5%CO₂ for 10 days, collected by centrifugation at 3500 rpm for 5 min, and flowed through a 0.22 μm film filter to remove the cell debris. The monoclonal antibodies were purified using pre-equilibrated Protein-A affinity columns (Cat#: 17040501, GE, USA) and eluted with the elution buffer (20 mM citric acid, pH 3.0-3.5) . The antibodies as obtained were kept in PBS (pH 7.0) and measured for the concentrations using a NanoDrop analyzer.

The purified antibodies were determined for their isotypes using the isotyping kits (Cat#: 26179, Thermal, US; Cat#: IS02-1KT, Sigma, US) , following the protocol in the instruction of the kits.

Most of the hybridoma clones, including 113F4 and B18B6, produced IgG1/κantibodies, while a few others produced IgG2a/κ antibodies.

Example 4. Binding capability of monoclonal anti-FGFR2B antibodies to FGFR2B- expressing CHO cells

The anti-FGFR2B antibodies were tested for their binding capability to the human, monkey or mouse FGFR2B protein on CHO cells, by FACS, using the CHO cells prepared in Example 1. Briefly, 10⁵ CHO cells were plated onto 96 well plates in 100 μl culture medium, and the plates were added with 50 μl serially diluted anti-FGFR2B antibodies. The plates were incubated for 1 h at 4℃, washed by PBST for three times, and added with 1: 500 diluted APC-goat-anti-mouse IgG antibodies (Cat#: 405308, BioLegend, US) . After 1-h incubation at 4℃, the plates were washed by PBS for three times, and subjected to cell fluorescence measurement in an FACS analyzer (BD) . FPA144 was prepared using the heavy and light chain sequences in WO2015017600A1 (the SEQ ID NOs: 2 and 3 in WO2015017600A1) and used as the positive control.

The EC₅₀ values of two representative antibodies were summarized in Table 4. The data indicated that all the mouse anti-FGFR2B antibodies bound to human, monkey and mouse FGFR2B proteins with high binding capabilities, but did not bind the human FGFR2C protein.

Table 4. Binding capability of anti-FGFR2B antibodies to human, monkey and mouse FGFR2B proteins

Example 5. Expression and purification of chimeric anti-FGFR2B antibodies

The antibodies 113F4 and B18B6 were further studied. The heavy/light chain variable region sequences of the two mouse antibodies were cloned from hybridoma cells using PCR with a set of the primers as described in literatures (Juste et al., (2006) , Anal Biochem. 1;349 (1) : 159-61) and then sequenced. The sequence information was set forth in Table 1 and Table 10. Expression vectors were constructed by inserting the sequence encoding the heavy chain variable region plus human IgG1 constant region (amino acid sequence set forth in SEQ ID NO: 21, the 97^th residue being K for 113F4 and R for B18B6) or the sequence encoding the light chain variable region plus human kappa constant region (amino acid sequences set forth in SEQ ID NO: 22) into pCDNA3.1 (Invitrogen, Carlsbad, USA) between XhoI and BamHI, wherein the C-terminus of the heavy chain variable region was linked to the N-terminus of the human IgG1 constant region, and the C-terminus of the light chain variable region was linked to the N-terminus of the human kappa constant region.

The expression vectors were PEI transfected into HEK-293F cells (Cobioer, NJ, China) . In specific, the HEK-293F cells were cultured in Free Style^TM 293 Expression Medium (Gibco, Cat#: 12338-018) and transfected with the expression vectors using polyethyleneinimine (PEI) at a DNA: PEI ratio of 1: 3, 1.5 μg of DNAs per millimeter of cell medium. The transfected HEK-293F cells were cultured in an incubator at 37℃ under 5%CO₂ with shaking at 120 RPM. After 10-12 days, the culture supernatants were collected, and monoclonal antibodies were purified from the supernatants as described in Example 3.

Example 6. Binding capability of chimeric anti-FGFR2B antibodies to FGFR2B-expressing CHO cells

Following the protocol of Example 4, the obtained chimeric antibodies were tested for their binding capability to the CHO/human FGFR2B cells, CHO/monkey FGFR2B cells, CHO/mouse FGFR2B cells and CHO/human FGFR2C cells. The results were shown in FIG. 1.

As shown in FIG. 1, the chimeric antibodies bound to human FGFR2B (A) , monkey FGFR2B (B) and mouse FGFR2B (C) with high binding capability, and did not bind human FGFR2C (D) .

Example 7. Humanization of anti-FGFR2B antibodies

Based on the assays above, the antibodies 113F4 and B18B6 were humanized and further investigated. Humanization of the mouse antibodies was conducted using the well-established CDR-grafting method (U.S. Pat. No. 5,225,539) as described in detail below.

To select the acceptor frameworks for humanization of the two mAbs, the heavy chain and light chain variable region sequences were blasted against the human immunoglobulin gene database in NCBI website (http: //www. ncbi. nlm. nih. gov/igblast/) . The human germline IGVH and IGVK with the highest homology to the two mAbs were selected as the acceptors for humanization. For 113F4, the human heavy chain acceptor IGHV1-46*01 and the human light chain acceptor IGKV3-11*01 were selected. And for B18B6, the human heavy and light chain acceptors IGHV1-46*01 and IGKV3-11*01 were selected.

The three dimensional structures were simulated for the variable domains of the two mAbs, in order to identify key framework residues that might be playing important roles in supporting CDR loop structures, thus designing back mutations in the humanized antibodies.

Six (6) residues were identified for the back mutation of the heavy chain of 113F4, i.e., M48I, V68A, M70L, R72A, T74K, and V79A, and 2 residues were for the back mutation of the light chain of 113F4, i.e., I2N and F70Y. For B18B6, 6 residues were identified for the back mutation of the heavy chain variable region, i.e., M48I, V68A, M70L, R72A, V79A, and A97T, and 2 residues were for the back mutation of the light chain variable region, L46W and F70Y. Based on these back mutations, frameworks were designed for the humanization.

As shown in Table 5, 4 exemplary humanized heavy chain variable region and 2 exemplary humanized light chain variable region were designed for the antibody 113F4.

Table 5. Back mutations for antibody 113F4

As shown in Table 6, 4 exemplary humanized heavy chain variable region and 2 exemplary humanized light chain variable region were designed for the antibody B18B6.

Table 6. Back mutations for antibody B18B6

Seven (7) exemplary humanized antibodies were obtained for 113F4, and 7 humanized antibodies were obtained for B18B6. The sequence information was set forth in Table 1 and Table 10.

The nucleotide sequence encoding a humanized heavy chain variable region and a human IgG constant region (amino acid sequence set forth in SEQ ID NO: 21, the 97^th residue being K for 113F4 and R for B18B6) , and the nucleotide sequence encoding a humanized light chain variable region plus human kappa constant region (amino acid sequences set forth in SEQ ID NO: 22) were chemically synthesized and then subcloned into GS expression vectors (Invitrogen, USA) using the EcoRI/XhoI and ClaI/HindIII restriction sites. All expression constructs were checked by DNA sequencing. Fourteen (14) humanized anti-FGFR2B antibodies were expressed in CHO-K1-AF cells whose slc35c1 gene had been knocked out, using the EXPiCHO expression systems (Invitrogen, USA) , The slc35c1-knock out CHO-K1-AF cells were prepared in house according to US10377833B2, the antibodies expressed from such a cell line contained almost no fucose. The antibodies were expressed and purified according to the protocol in Example 5.

Example 8. Binding capability of humanized anti-FGFR2B antibodies to CHO cells expressing human, monkey or mouse FGFR2B, human FGFR2B variant, human FGFR2C, or FGFR2B⁺ tumor cells

According to the protocol of Example 4, the humanized antibodies were tested for their binding capability to CHO cells prepared in Example 1, including CHO/human FGFR2B cells, CHO/monkey FGFR2B cells, CHO/mouse FGFR2B cells, CHO/human FGFR2C cells, CHO/human FGFRβ2B cells, and CHO/human FGFR2B-S252W cells, and three FGFR2B⁺tumor cells, including SNU-16 cells, KATOIII cells and OCUM-1 cells. The results were shown in FIG. 2.

According to FIG. 2, the chimeric and humanized antibodies of the disclosure showed high binding capability to CHO cells expressing human FGFR2Bα (A, B) , human FGFR2Bβ(C) , human FGFR2Bα-S252W variant (D) , monkey FGFR2B (E) , or mouse FGFR2B (F) , as well as the SUN-16 cells (G) , low binding capability to KATOIII cells (H) and OCUM-1 cells (I) , and no binding capability to CHO cells expressing human FGFR2C (J) .

Example 9. Binding affinity ofhumanized anti-FGFR2B antibodies to human, monkey and mouse FGFR2B protein

The humanized antibodies were measured for their binding affinity to recombinant human, monkey and mouse FGFR2B proteins by BIAcore^TM 8K (GE Life Sciences, USA) .

Briefly, 100-200 response units (RUs) of human FGFR2B (ECD) -his (Cat#: FGR-HM1BD, Kactus Biosystems, CN) , monkey FGFR2B (ECD) -hFc (Cat#: FGB-C52H6, ACRO, CN) and mouse FGFR2B (ECD) -hFc (Cat#: FGB-M52H5, ACRO, CN) were respectively coupled to CM5 biosensor chips (Cat#: BR-1005-30, GE Life Sciences, US) . The un-reacted groups in the chips were blocked with 1 M ethanolamine.

The serially diluted antibodies of the disclosure at concentrations ranging from 0.3 μM to 10 μM were injected into the SPR running buffer (HBS-EP buffer, pH7.4, Cat#: BR-1006-69, GE Life Sciences, US) at 30 μL/min. The binding affinity was calculated with the RUs of blank controls subtracted, and the association rate (k_a) and dissociation rate (k_d) were determined using the one-to-one Langmuir binding model (BIA Evaluation Software, GE Life Sciences, US) . The equilibrium dissociation constant K_D was calculated as the k_d/k_a ratio.

Table 7. Binding affinity of anti-FGFR2B antibodies to human FGFR2B

Table 8. Binding affinity of anti-FGFR2B antibodies to monkey FGFR2B

The binding affinity of the humanized antibodies were summarized in Table 7, Table 8 and Table 9. The humanized antibodies showed comparable high binding affinity to human, monkey and mouse FGFR2B proteins.

Table 9. Binding affinity of anti-FGFR2B antibodies to mouse FGFR2B

Example 10. Antibody dependent cell mediated cytotoxicity induced by humanized anti- FGFR2B antibodies

The humanized antibodies were further measured for their capability to induce antibody dependent cell mediated cytotoxicity (ADCC) against CHO/human FGFR2B cells, CHO/human FGFR2C cells and SNU-16 cells.

Briefly, the CHO/human FGFR2B cells, CHO/human FGFR2C cell, SNU-16 cells, used as the target cells, and the NK92MI-CD16a (Huabo Bio) , as the effector cells, were centrifuged at 1200 rpm for 5 min, and re-suspended in MEM culture medium (Cat#: 12561-056, Gibco) with 1%FBS (Cat#: FND500, EX-cell) and 1%BSA (Cat#: V900933-1KG, VETEC) . The cell viability was about 90%. Then, 50 μl target cells at the density of 4×10⁵/ml and 50 μl effector cells at the density of 2×10⁶/ml were plated onto 96-well plates, at the effector-to-target ratio of 5: 1. The plates were added with the antibodies of the disclosure, with the working concentration of the antibodies 5-fold diluted starting at 10 μg/ml, incubated at 37℃ for 4 h, and added with 100 μl LDH color developing solution (Cytotoxicity detection kit+ (LDH) , Cat#: 04744926001, Roche) . The plates were kept in dark at room temperature for 20 min, and subjected to absorbance measurement in MD SpectraMax i3. The anti-HEL isotype antibody (Cat#: LT12031, LifeTein, LLC) was used as the negative control, and FPA144 as expressed by slc35c1-knock out CHO-K1-AF cells was used as the positive control.

As shown in FIG. 3, all the humanized antibodies of the disclosure induced NK92 cell mediated CHO/human FGFR2B cell death and SNU-16 cell death (A, C) with the activity comparable to that of FPA144. Further, none of the antibodies induced death of CHO/human FGFR2C cells (B) , indicating the antibodies of the disclosure had binding specificity to the FGFR2B protein.

Example 11. Complement dependent cytotoxicity induced by humanized anti-FGFR2B antibodies

The humanized antibodies of the disclosure were measured for their capability to induce complement dependent cytotoxicity (CDC) against FGFR2B⁺ cells using the cytotoxicity detection kit⁺ (LDH) , Cat#: 04744926001, Roche) .

The CHO/human FGFR2B cells and CHO/human FGFR2C cells, as the target cells, were centrifuged at 1200 rpm for 4 min, and re-suspended in DMEM culture medium with 1%FBS. Then, 100 μl target cell suspension at the cell density of 3×10⁵/ml was added to the 96-well plates, and the plates were added with serially diluted antibodies of the disclosure, the working concentration of the antibodies were 5-fold diluted starting at 100 μg/ml. The plates were added with normal human serum complement (Cat#: A113, Quidel) at the final concentration of 5%, and incubated at 37℃ for 2 h. After addition of 100 μl LDH color develpment solution, the plates were incubated in dark at room temperature for 20 min, The plates were subjected to absorbance measurement in MD SpectraMax i3. The anti-HEL isotype antibody (Cat#: LT12031, LifeTein, LLC) was used as the negative control, and FPA144 was used as the positive control.

FIG. 4 showed that all antibodies of the disclosure induced potent CDC against FGFR2B⁺ cells in a concentration dependent manner, with the capability comparable to that of FPA144 (A) , but failed to induce CDC against FGFR2C⁺ cells (B) . The data indicated that the antibodies of the disclosure had binding specificity to the FGFR2B protein.

Example 12. Internalization ofhumanized anti-FGFR2B antibodies

Whether the humanized antibodies can be internalized into the FGFR2B⁺ cells were tested using SNU-16 cells, with FPA144 used as the positive control.

The humanized anti-FGFR2B antibodies of the disclosure were mixed with pHAb labelled goat-anti-human IgG1 Fc antibodies (Cat#: SSA015, Sino Biological, CN) as the secondary antibody, at 1: 1 concentration ratio. The 96-well plates were added with 20000 SNU-16 cells in 100 μl solution containing 25 μg/mL antibody-secondary complexes, with human IgG1 used in the blank control wells. The plates were incubated in dark on ice for 1 h, washed with cold FACS buffer (90%DMEM+10%FBS) by centrifugation for 3 times, added with 100 μl warm RPMI1640 culture medium (Cat#: 12-115F, Lonza) supplemented with 10%FBS (Cat#: FND500, Excell) and 1%penicillin/streptomycin (Cat#: SV30010, Hyclone) , and incubated in a 37℃-5%CO₂ incubator. The cell cultures were collected 24 h later, and kept in dark on ice. The collected cell cultures were centrifuged at low temperature at 1200 rpm for 3 min, supernatants discarded, washed with PBS once, and subjected to flow cytometry. The fluoresce MFI of the cells into which the antibodies were internalized was calculated from the raw data.

The results were shown in FIG. 5. It can be seen all antibodies of the disclosure were internalized into the SNU-16 cells, with 113F4VH3VL0 having the highest internalization rate.

Example 13. Epitope binning

The antibodies were further tested for their competition with FPA144 over epitope binding by FACS using the CHO/human FGFR2B cells generated in Example 1.

Briefly, the 96-well plates were plated with 10⁵ CHO cells in 100 μl culture medium, added with 50 μl 1 μg/ml FPA144-mFc (containing mIgG2a Fc of SEQ ID NO: 28 as the heavy chain constant region) or anti-HEL-mFc (mIgG2a) , incubated at 4℃ for 1 h, and washed with PBST for three times. The plates were then added with serially diluted humanized antibodies of the disclosure containing hIgG1 (SEQ ID NO: 21) as the heavy chain constant region (with 97^th residue being K for the 113F4 antibodies and R for the B18B6 antibodies) , with the working concentrations of the antibodies 5-fold diluted starting at 40 μg/ml. The plates were incubated at 4℃ for 1 h, washed with PBST for three times, and added with 1: 500 diluted APC-goat-anti-mouse IgG antibodies (Cat#: 405308, BioLegend, US) . The plates were incubated at 4℃ for 1 h, washed with PBS for three times, and subjected to fluoresce measurement by a FACS analyzer (BD) .

The results were shown in FIG. 6. The humanized anitbodies of the disclosure, including 113F4VH3VL0 (A) , 113F4VH4VL0 (B) , B18B6VH4VL0 (C) and B18B6VH4VL2 (D) , competed with FPA144 over epitope binding, suggesting these antibodies might bind to the same or similar epitope as the FPA144 did.

Example 14. Humanized anti-FGFR2B antibodies blocked FGF7 or FGF10-induced signaling

The humanized anti-FGFR2B antibodies of the disclosure were tested for their blocking capability on FGFR2 signaling activation.

Briefly, SNU-16 cells in 100 μl culture medium at the cell density of 2×10⁵/ml were plated onto the 96-well plates. The culture medium in each well was discarded, and the plates were added with RPMI 1640 medium (Cat#: 61870036, Gibco, US) with 0.05%bovine serum albumin (Cat#: 15260037, Life Technologies, US) and incubated at 37℃, 5%CO₂ for 4 h. The plates were then added with the antibodies, with the working concentration of these antibodies 10-fold diluted starting at 100 μg/ml, incubated for 30 min, added with FGF7 (Cat#: 100-19, Peprotech, US) or FGF10 (Cat#: 100-26, Peprotech, US) at the final concentration of 100 ng/ml as well heparin sodium (Cat#: S1346, Selleck, US) at the final concentration of 1 μg/mL, incubated for 5 min, added with ice-cold RIPA lysis buffer (Cat#: P0013B, Beyotime, CN) , and incubated on ice for 10 min. After centrifugation at 3000 g, the supernatant from each well was collected and measured for the FGFR2 phosphorylation level using an ELISA kit (Cat#: DYC684-2, R&D Systems, US) , with absorbance read in MD SpectraMax i3. FPA144 was used as the positive control.

The results were shown in FIG. 7. All the antibodies of the disclosure inhibited FGF7 induced FGFR2B phosphorylation (A) , with some antibodies’ inhibitory effects being higher, or significantly higher, than the positive control at certain concentrations. Further, all antibodies inhibited FGF10 induced FGFR2B phosphorylation to some extent (B) .

Example 15. In vivo anti-tumor effect of humanized anti-FGFR2B antibodies

The antibodies of the disclosure, including 113F4VH3VL0, 113F4VH3VL2, B18B6VH3VL0, and B18B6VH4VL0, were tested for their in vivo anti-tumor effect in comparison to FPA144. All these antibodies contained human IgG1 heavy chain constant region (SEQ ID NO: 21, the 97^th residue being K for the 113F4 antibodies and R for the B18B6 antibodies and FPA144) and human κ light chain constant region (SEQ ID NO: 22) , and were defucosylated via expression in CHO-K1-AF cells. The gastric tumor cell line OCUM-2M (RRID: CVCL_8383, Yicon (Beijing) BioMedical Technology Inc., CN) was implanted into BALB/c mice (GemPharmatech Co. Ltd, CN) to establish the animal model.

Briefly, the mice were subcutaneously injected with 1×10⁷ OCUM-2M cells at the left or right flank. When the average tumor size reached 40-60 mm³, the animals were allocated into 6 groups, 10 animals per group, this day was designated as Day 0. The mice from Group 1 to Group 6 were intraperitoneally administered with FPA144, 113F4VH3VL0, 113F4VH3VL2, B18B6VH3VL0, B18B6VH4VL0 and PBS, respectively, at the dose of 10 mg/kg body weight, on Day 0, 3, 7 and 10. The tumor size and mouse body weight were monitored. The tumor size was determined by measuring by a caliper the length (the longest diameter) and the width (the diameter perpendicular to the length) of the tumors and calculating the volumes as 0.5×D×d². The test was terminated when tumor remission was observed in most antibody administration groups, and one-way ANOVA was used to identify tumor size differences among groups.

As shown in FIG. 8 (A, B) , all the anti-FGFR2B antibodies significantly inhibited tumor growth in the animals, and 113F4VH3VL0, B18B6VH3VL0 and B18B6VH4VL0 showed higher in vivo anti-tumor efficacy than FPA144.

Example 16. Immunochemiscal staining specificity of anti-FGFR2B antibodies

The chimeric antibodies 113F4-CM and B18B6-CM as generated in Example 5 were used for immunochemical staining of some FGFR2B⁺ samples.

Briefly, the CHO/human FGFR2B cells and the CHO/human FGFR2C cells, prepared in Example 1, and the CHO cells, were fixed for 1 h in 10%formalin, centrifuged at 2000 rpm for 15 min at 4℃ to remove the formalin, and mixed with HistoGel^TM specimen processing gel (Cat#: HG-4000-012, Thermo, US) at a volume ratio of 1: 1. The cell/gel mixtures were vortexed gently, cooled down on ice for 2 min to solidify, wrapped in lens paper, and put into an embedding cassette. The cells were dehydrated in an automatic machine (HistoCore PEARL, Leica) , embedded into paraffin blocks using a paraffin embedding station (EG1150, Leica) . The paraffin blocks were sectioned in a semi-automatic microtome (HistoCore Mμlticμt, Leica) to get 4 μm sections. The sections were stained in an automatic IHC stainer (Bond RX, Leica) , following the instruction of the stainer, using an immunochemical detection kit (DS9800, Leica) with the working concentration of the detection antibody at 0.25 μg/ml. After color developing, the sections were scanned using a 3D scanner (3DHistech, Pannoramic SCAN.

The results were shown in FIG. 9. It can be seen the chimeric 113F4 and B18B6 antibodies specifically stained the CHO/human FGFR2B cells, as there was no staining on neither the CHO cells nor the CHO/human FGFR2C cells, which indicated these two antibodies may be used for the immunochemical staining of the FGFR2B protein.

The sequences in the present application are summarized in Table 10 below.

Table 10. Sequences

***

Having thus described in detail preferred embodiments of the present invention, it is to be understood that the invention defined by the above paragraphs is not to be limited to particular details set forth in the above description as many apparent variations thereof are possible without departing from the spirit or scope of the present invention.

Claims

An isolated monoclonal antibody or an antigen binding portion thereof, capable of binding FGFR2B, comprising:

i) a heavy chain variable region comprising a VH CDR1, a VH CDR2 and a VH CDR3, and

ii) a light chain variable region comprising a VL CDR1, a VL CDR2 and a VL CDR3,

wherein the VH CDR1, the VH CDR2, the VH CDR3, the VL CDR1, the VL CDR2 and the VL CDR3 comprise amino acid sequences having at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to (1) SEQ ID NOs: 1, 2, 3, 4, 5 and 6, respectively; or (2) SEQ ID NOs: 7, 8, 9, 10, 11 and 12, respectively.
The isolated monoclonal antibody or antigen binding portion thereof of claim 1, wherein the heavy chain variable region comprises an amino acid sequence having at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to SEQ ID NOs: 13, 15, 17 or 19,

wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively; M, A, L, R, T and V, respectively; M, A, L, A, K and V, respectively; or I, A, L, A, K and A, respectively,

wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively; M, A, L, R, V and A, respectively; M, A, L, A, V and T, respectively; or I, A, L, A, A and T, respectively.
The isolated monoclonal antibody or antigen binding portion thereof of claim 1, wherein the light chain variable region comprises an amino acid sequence having at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to SEQ ID NOs: 14, 16, 18 or 20,

wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively; or N and Y, respectively,

wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or W and Y, respectively.
The isolated monoclonal antibody or antigen binding portion thereof of claim 2, wherein the heavy chain variable region and the light chain variable region respectively comprise amino acid sequences having at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%or 100%sequence identity to

(1) SEQ ID NOs: 13 and 14;

(2) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(3) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(4) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(5) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(6) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(7) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(8) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(9) SEQ ID NOs: 17 and 18;

(10) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(11) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(12) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively;

(13) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(14) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively;

(15) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or

(16) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively.
An isolated monoclonal antibody or an antigen binding portion thereof, capable of binding FGFR2B, comprising:

i) a heavy chain variable region comprising a VH CDR1, a VH CDR2 and a VH CDR3, and

ii) a light chain variable region comprising a VL CDR1, a VL CDR2 and a VL CDR3,

wherein the VH CDR1, the VH CDR2, the VH CDR3, the VL CDR1, the VL CDR2 and the VL CDR3 are from a heavy chain variable region and a light chain variable region respectively comprising the amino acid sequences of

(1) SEQ ID NOs: 13 and 14;

(2) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, V, M, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(3) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(4) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, R, T and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(5) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(6) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are M, A, L, A, K and V, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(7) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are I and F, respectively;

(8) SEQ ID NOs: 15 and 16, wherein the 48^th, 68^th, 70^th, 72^th, 74^th and 79^th amino acid residues in SEQ ID NO: 15 are I, A, L, A, K and A, respectively, wherein the 2^rd and 70^th amino acid residues in SEQ ID NO: 16 are N and Y, respectively;

(9) SEQ ID NOs: 17 and 18;

(10) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, V, M, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(11) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(12) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, R, V and A, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively;

(13) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively;

(14) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are M, A, L, A, V and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively;

(15) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are L and F, respectively; or

(16) SEQ ID NOs: 19 and 20, wherein the 48^th, 68^th, 70^th, 72^th, 79^th and 97^th amino acid residues in SEQ ID NO: 19 are I, A, L, A, A and T, respectively, wherein the 46^th and 70^th amino acid residues in SEQ ID NO: 20 are W and Y, respectively.
The isolated monoclonal antibody or antigen binding portion thereof of claim 1 or 5, comprising a heavy chain constant region and a light chain constant region, wherein the heavy chain constant region is human IgG1 constant region, the light chain constant region is human κ light chain constant region.
The isolated monoclonal antibody or antigen binding portion thereof of claim 1 or 5, which is defucosylated.
The isolated monoclonal antibody or antigen binding portion thereof of claim 1 or 5, which (a) is able to bind human FGFR2B, (b) is able to bind monkey FGFR2B, (c) is able to bind mouse FGFR2B, (d) is not able to bind FGFR2C, (e) is able to bind a FGFR2B⁺ cell, (f) is able to induce antibody dependent cell mediated cytotoxicity (ADCC) against a FGFR2B⁺ cell, (g) is able to induce complement dependent cytotoxicity (CDC) against a FGFR2B⁺ cell, (h) is able to be internalized into a FGFR2B⁺ cell, (i) is able to block FGF7 induced FGFR2B signaling, (j) is able to block FGF10 induced FGFR2B signaling, and/or (k) has in vivo anti-tumor effect.
A bispecific molecule, an immuneconjugate, a chimeric antigen receptor, an engineered T cell receptor, or an oncolytic virus, comprising the isolated monoclonal antibody or antigen binding portion thereof of claim 1 or 5.
A nucleic acid molecule, encoding the isolated monoclonal antibody or antigen binding portion thereof of any one of claims 1 to 8.
An expression vector, comprising the nucleic acid molecule of claim 10.
A host cell, comprising the expression vector of claim 11, or having the nucleic acid molecule of claim 10 integrated into its genome.
A pharmaceutical composition comprising the isolated monoclonal antibody or antigen binding portion thereof of any one of claims 1 to 8, the nucleic acid molecule of claim 10, the expression vector of claim 11, or the host cell of claim 12, and a therapeutically acceptable carrier.
Use of the pharmaceutical composition of claim 13 in preparation of a medicament for treating a FGFR2B related tumor.
The use of claim 14, wherein the tumor is gastric cancer, gastroesophageal junction cancer, lung cancer, breast cancer, ovarian cancer, pancreatic cancer, biliary duct cancer, cervical cancer, or endometrial cancer.
A detection kit, comprising the isolated monoclonal antibody or antigen binding portion thereof of any one of claims 1 to 8.