Method for treating EGFR-TKI-resistant non-small-cell lung cancer by anti her3 antibody-drug conjugate administration

Abstract

To provide a therapeutic agent and a method for treating EGFR-TKI-resistant non-small cell lung cancer.SOLUTION: There is provided a therapeutic agent containing anti HER3 antibody-drug conjugate as an active ingredient, or a treatment method of administering anti HER3 antibody-drug conjugate.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a therapeutic agent and method for EGFR-TKI-resistant non-small cell lung cancer, which is characterized by administering an anti-HER3 antibody-drug conjugate. [Background technology]

[0002] In the treatment using EGFR tyrosine kinase inhibitors (EGFR-TKIs) that are effective against epidermal growth factor receptor (EGFR) gene mutation-positive non-small cell lung cancer, in many cases, drug resistance to the inhibitors in the treated cancer is enhanced as the treatment continues, resulting in progression of the disease. It is known that about half of the cancers that are resistant to the first generation EGFR-TKIs Gefitinib and Erlotinib, and the second generation EGFR-TKI Afatinib have a T790M mutation in the EGFR gene. Osimertinib, a third generation EGFR-TKI, is known as a drug that is effective against non-small cell lung cancer confirmed to be positive for the EGFR T790M mutation (Non-Patent Document 1). However, an optimal drug for non-small cell lung cancer resistant to osimertinib has not yet been approved. In addition, no optimal drug has yet been approved for non-small cell lung cancer that is resistant to EGFR-TKIs and has been confirmed to be negative for EGFR T790M mutation.

[0003] Human epidermal growth factor receptor 3 (HER3, also known as ErbB3) is a transmembrane receptor that belongs to the epidermal growth factor receptor subfamily of receptor protein tyrosine kinases. It is known that an increase in the expression level of HER3 in cancer cells is associated with the acquisition of resistance to EGFR-TKI (Non-Patent Document 2). In addition, research is being conducted to verify the effect of anti-HER3 antibodies on non-small cell lung cancer (Non-Patent Document 3).

[0004] Antibody-drug conjugates (ADCs), which combine a cytotoxic drug with an antibody that binds to an antigen expressed on the surface of cancer cells and can be internalized into the cells, are expected to be able to selectively deliver the drug to cancer cells, thereby accumulating the drug within the cancer cells and killing the cancer cells (Non-Patent Documents 4 to 8).

[0005] As one type of antibody-drug conjugate, an antibody-drug conjugate containing an anti-HER3 antibody and exatecan, a topoisomerase I inhibitor, as components is known (Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 155998 [Non-patent literature]

[0007] [Non-Patent Document 1] I. Sullivan et al. Ther Adv Respir Dis 2016, Vol. 10(6) 549-565. [Non-Patent Document 2] NV Sergina et al. Nature 2007 January 25; 445(7126): 437-441. [Non-Patent Document 3] K Yonesaka et al., Oncogene (2016) 35, 878-886. [Non-Patent Document 4] Ducry, L., et al., Bioconjugate Chem. (2010) 21, 5-13. [Non-Patent Document 5] Alley, SC, et al., Current Opinion in Chemical Biology (2010) 14, 529-537. [Non-Patent Document 6] Damle NK Expert Opin. Biol. Ther. (2004) 4, 1445-1452. [Non-Patent Document 7] Senter PD, et al., Nature Biotechnology (2012) 30, 631-637. [Non-Patent Document 8] Howard A. et al., J Clin Oncol 29: 398-405. Summary of the Invention [Problem to be solved by the invention]

[0008] An objective of the present invention is to provide a therapeutic agent and a therapeutic method for EGFR-TKI-resistant non-small cell lung cancer. [Means for solving the problem]

[0009] The present inventors discovered that an anti-HER3 antibody-drug conjugate exhibits excellent antitumor effects against EGFR-TKI-resistant non-small cell lung cancer.

[0010] That is, the present invention provides [1] A therapeutic agent for EGFR-TKI-resistant non-small cell lung cancer, containing an anti-HER3 antibody-drug conjugate as an active ingredient.

[0011] [2] The therapeutic agent according to [1], wherein the non-small cell lung cancer is EGFR T790M mutation-negative non-small cell lung cancer.

[0012] [3] The therapeutic agent according to [1] or [2], wherein the EGFR-TKI is gefitinib, erlotinib, afatinib, or osimertinib.

[0013] [4] The therapeutic agent according to [1] or [2], wherein the EGFR-TKI is osimertinib.

[0014] [5] The therapeutic agent according to [2], wherein the EGFR-TKI is gefitinib, erlotinib, or afatinib.

[0015] [6] The therapeutic agent according to [2], wherein the EGFR-TKI is gefitinib or erlotinib.

[0016] [7] The therapeutic agent according to any one of [1] to [6], wherein the non-small cell lung cancer expresses HER3.

[0017] [8] The anti-HER3 antibody-drug conjugate has the formula

[0018] [ka] (In the formula, A represents the binding site for the anti-HER3 antibody.) The therapeutic agent according to any one of [1] to [7], which is an anti-HER3 antibody-drug conjugate in which a drug linker represented by the following formula (I) is linked to the anti-HER3 antibody via a thioether bond.

[0019] [9] The therapeutic agent according to any one of [1] to [8], wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising CDRH1 consisting of the amino acid sequence shown in SEQ ID NO: 1, CDRH2 consisting of the amino acid sequence shown in SEQ ID NO: 2, and CDRH3 consisting of the amino acid sequence shown in SEQ ID NO: 3, and a light chain comprising CDRL1 consisting of the amino acid sequence shown in SEQ ID NO: 4, CDRL2 consisting of the amino acid sequence shown in SEQ ID NO: 5, and CDRL3 consisting of the amino acid sequence shown in SEQ ID NO: 6.

[0020]

[10] The therapeutic agent according to any one of [1] to [8], wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising a heavy chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 7, and a light chain comprising a light chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 8.

[0021]

[11] The therapeutic agent according to any one of [1] to [8], wherein the anti-HER3 antibody is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10.

[0022]

[12] The therapeutic agent according to

[11] , wherein the lysine residue at the carboxyl terminus of the heavy chain of the anti-HER3 antibody is deleted.

[0023]

[13] The therapeutic agent according to any one of [1] to

[12] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7 to 8.

[0024]

[14] The therapeutic agent according to any one of [1] to

[12] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7.5 to 8.

[0025]

[15] The therapeutic agent according to any one of [1] to

[14] , which is administered in combination with a second drug.

[0026]

[16] The therapeutic agent according to

[15] , wherein the second drug is gefitinib, erlotinib, afatinib, or osimertinib.

[0027]

[17] The therapeutic agent according to

[16] , wherein the second drug is erlotinib.

[0028]

[18] The therapeutic agent according to

[16] , wherein the second drug is osimertinib.

[0029]

[19] A method for treating EGFR-TKI-resistant non-small cell lung cancer, comprising administering an anti-HER3 antibody-drug conjugate.

[0030]

[20] The treatment method according to

[19] , wherein the non-small cell lung cancer is EGFR T790M mutation-negative non-small cell lung cancer.

[0031] [twenty one] The treatment method according to

[19] or

[20] , wherein the EGFR-TKI is gefitinib, erlotinib, afatinib, or osimertinib.

[0032] [twenty two] The treatment method according to

[19] or

[20] , wherein the EGFR-TKI is osimertinib.

[0033] [twenty three] The treatment method according to

[20] , wherein the EGFR-TKI is gefitinib, erlotinib, or afatinib.

[0034] [twenty four] The treatment method described in

[20] , wherein the EGFR-TKI is gefitinib or erlotinib.

[0035] [twenty five] The method for treatment according to any one of

[19] to

[24] , wherein the non-small cell lung cancer expresses HER3.

[0036]

[26] The anti-HER3 antibody-drug conjugate has the formula

[0037] [ka] (In the formula, A represents the binding site for the anti-HER3 antibody.) The method for treating HER3 is an anti-HER3 antibody-drug conjugate in which the drug linker represented by the following formula (I) is linked to the anti-HER3 antibody via a thioether bond.

[0038]

[27] The treatment method according to any one of

[19] to

[26] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising CDRH1 consisting of the amino acid sequence shown in SEQ ID NO: 1, CDRH2 consisting of the amino acid sequence shown in SEQ ID NO: 2, and CDRH3 consisting of the amino acid sequence shown in SEQ ID NO: 3, and a light chain comprising CDRL1 consisting of the amino acid sequence shown in SEQ ID NO: 4, CDRL2 consisting of the amino acid sequence shown in SEQ ID NO: 5, and CDRL3 consisting of the amino acid sequence shown in SEQ ID NO: 6.

[0039]

[28] The treatment method according to any one of

[19] to

[26] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising a heavy chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 7, and a light chain comprising a light chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 8.

[0040]

[29] The treatment method according to any one of

[19] to

[26] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10.

[0041]

[30] The treatment method described in

[29] , wherein the lysine residue at the carboxyl terminus of the heavy chain of the anti-HER3 antibody is deleted.

[0042]

[31] The treatment method according to any one of

[19] to

[30] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7 to 8.

[0043]

[32] The treatment method according to any one of

[19] to

[30] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7.5 to 8.

[0044]

[33] The method of treatment according to any one of

[19] to

[32] , wherein the anti-HER3 antibody-drug conjugate is administered in combination with a second drug.

[0045]

[34] The method of treatment according to

[33] , wherein the second drug is gefitinib, erlotinib, afatinib, or osimertinib.

[0046]

[35] The method of treatment according to

[34] , wherein the second drug is erlotinib.

[0047]

[36] The treatment method according to

[34] , wherein the second drug is osimertinib.

[0048]

[37] Anti-HER3 antibody-drug conjugate for the treatment of EGFR-TKI-resistant non-small cell lung cancer.

[0049]

[38] The anti-HER3 antibody-drug conjugate according to

[37] , wherein the non-small cell lung cancer is EGFR T790M mutation-negative non-small cell lung cancer.

[0050]

[39] The anti-HER3 antibody-drug conjugate according to

[37] or

[38] , wherein the EGFR-TKI is gefitinib, erlotinib, afatinib, or osimertinib.

[0051]

[40] The anti-HER3 antibody-drug conjugate according to

[37] or

[38] , wherein the EGFR-TKI is osimertinib.

[0052]

[41] The anti-HER3 antibody-drug conjugate according to

[38] , wherein the EGFR-TKI is gefitinib, erlotinib, or afatinib.

[0053]

[42] The anti-HER3 antibody-drug conjugate according to

[38] , wherein the EGFR-TKI is gefitinib or erlotinib.

[0054]

[43] The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[42] , wherein the non-small cell lung cancer expresses HER3.

[0055]

[44] The anti-HER3 antibody-drug conjugate has the formula

[0056] [ka] (In the formula, A represents the binding site for the anti-HER3 antibody.) The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[43] , wherein the anti-HER3 antibody-drug conjugate is an anti-HER3 antibody-drug conjugate in which a drug linker represented by the following formula (I) is linked to the anti-HER3 antibody via a thioether bond.

[0057]

[45] The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[44] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising CDRH1 consisting of the amino acid sequence shown in SEQ ID NO: 1, CDRH2 consisting of the amino acid sequence shown in SEQ ID NO: 2, and CDRH3 consisting of the amino acid sequence shown in SEQ ID NO: 3, and a light chain comprising CDRL1 consisting of the amino acid sequence shown in SEQ ID NO: 4, CDRL2 consisting of the amino acid sequence shown in SEQ ID NO: 5, and CDRL3 consisting of the amino acid sequence shown in SEQ ID NO: 6.

[0058]

[46] The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[44] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising a heavy chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 7, and a light chain comprising a light chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 8.

[0059]

[47] The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[44] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10.

[0060]

[48] An anti-HER3 antibody-drug conjugate described in

[47] , in which the lysine residue at the carboxyl terminus of the heavy chain of the anti-HER3 antibody is deleted.

[0061]

[49] An anti-HER3 antibody-drug conjugate according to any one of

[37] to

[48] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7 to 8.

[0062]

[50] An anti-HER3 antibody-drug conjugate according to any one of

[37] to

[48] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7.5 to 8.

[0063]

[51] The anti-HER3 antibody-drug conjugate according to any one of

[37] to

[50] , which is administered in combination with a second drug.

[0064]

[52] The anti-HER3 antibody-drug conjugate according to

[51] , wherein the second drug is gefitinib, erlotinib, afatinib, or osimertinib.

[0065]

[53] The anti-HER3 antibody-drug conjugate of

[52] , wherein the second drug is erlotinib.

[0066]

[54] The anti-HER3 antibody-drug conjugate of

[52] , wherein the second drug is osimertinib.

[0067]

[55] Use of an anti-HER3 antibody-drug conjugate for the manufacture of a medicament for the treatment of EGFR-TKI-resistant non-small cell lung cancer.

[0068]

[56] The use according to

[55] , wherein the non-small cell lung cancer is EGFR T790M mutation-negative non-small cell lung cancer.

[0069]

[57] The use according to

[55] or

[56] , wherein the EGFR-TKI is gefitinib, erlotinib, afatinib, or osimertinib.

[0070]

[58] The use described in

[55] or

[56] , wherein the EGFR-TKI is osimertinib.

[0071]

[59] The use described in

[56] , wherein the EGFR-TKI is gefitinib, erlotinib, or afatinib.

[0072]

[60] The use described in

[56] , wherein the EGFR-TKI is gefitinib or erlotinib.

[0073]

[61] The use described in any one of

[55] to

[60] , wherein the non-small cell lung cancer expresses HER3.

[0074]

[62] The anti-HER3 antibody-drug conjugate has the formula

[0075] [ka] (In the formula, A represents the binding site for the anti-HER3 antibody.) The use according to any one of

[55] to

[61] , wherein the anti-HER3 antibody-drug conjugate is an anti-HER3 antibody-drug conjugate in which the drug linker represented by the formula:

[0076]

[63] The use described in any one of

[55] to

[62] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising CDRH1 consisting of the amino acid sequence shown in SEQ ID NO: 1, CDRH2 consisting of the amino acid sequence shown in SEQ ID NO: 2, and CDRH3 consisting of the amino acid sequence shown in SEQ ID NO: 3, and a light chain comprising CDRL1 consisting of the amino acid sequence shown in SEQ ID NO: 4, CDRL2 consisting of the amino acid sequence shown in SEQ ID NO: 5, and CDRL3 consisting of the amino acid sequence shown in SEQ ID NO: 6.

[0077]

[64] The use described in any one of

[55] to

[62] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain comprising a heavy chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 7, and a light chain comprising a light chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 8.

[0078]

[65] The use described in any one of

[55] to

[62] , wherein the anti-HER3 antibody is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10.

[0079]

[66] The use described in

[65] , wherein the lysine residue at the carboxyl terminus of the heavy chain of the anti-HER3 antibody is deleted.

[0080]

[67] The use described in any one of

[55] to

[66] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7 to 8.

[0081]

[68] The use described in any one of

[55] to

[66] , wherein the average number of drug linkers bound per antibody in the anti-HER3 antibody-drug conjugate is in the range of 7.5 to 8.

[0082]

[69] The use described in any one of

[55] to

[68] , wherein the anti-HER3 antibody-drug conjugate is administered in combination with a second drug.

[0083]

[70] The use according to

[69] , wherein the second drug is gefitinib, erlotinib, afatinib, or osimertinib.

[0084]

[71] The use according to

[70] , wherein the second drug is erlotinib.

[0085]

[72] The use according to

[70] , wherein the second agent is osimertinib. Regarding. Effect of the Invention

[0086] The present invention can provide a therapeutic agent and method for EGFR-TKI-resistant non-small cell lung cancer, which is characterized by administering an anti-HER3 antibody-drug conjugate. [Brief description of the drawings]

[0087] [Figure 1] FIG. 1 shows the heavy chain amino acid sequence of anti-HER3 antibody (1). [Diagram 2] FIG. 1 shows the amino acid sequence of the light chain of anti-HER3 antibody (1). [Diagram 3] 1 shows the cell proliferation inhibitory activity of HER3-ADC(1) against HCC827 and HCC827GR5 cell lines, with error bars indicating standard error (n=6). [Figure 4] FIG. 1 shows the amount of HER3 mRNA in HCC827 and HCC827GR5 cell lines. [Diagram 5] 1 shows the cell proliferation inhibitory activity of HER3-ADC(1) alone, erlotinib alone, or a combination of HER3-ADC(1) and erlotinib against the HCC827GR5 cell line. Error bars in the figure show standard error (n=6). [Figure 6] 1 shows the antitumor effect of single-agent HER3-ADC(1), single-agent erlotinib, or combination treatment of HER3-ADC(1) and erlotinib on the HCC827GR5 cell line implanted in nude mice. Error bars in the figure show standard deviation (n=10). [Figure 7] FIG. 1 shows the cytostatic activity of osimertinib against PC9 and PC9AZDR7 cell lines. Error bars in the figure indicate standard error (n=6). [Figure 8] 1 shows the protein levels of HER3 in PC9 and PC9AZDR7 cell lines, with error bars indicating standard deviation (n=3). [Figure 9] This is a graph showing the antitumor effect of HER3-ADC(1) alone against PC9 cell lines implanted in nude mice. The error bars in the graph show standard error (control group, n=8; HER3-ADC(1) group, n=9), and the arrows show drug administration. [Figure 10] This is a diagram showing the antitumor effect of HER3-ADC(1) alone against the PC9AZDR7 cell line implanted in nude mice. The error bars in the diagram indicate standard error (control group, n=8; HER3-ADC(1) group, n=9), and the arrows indicate administration of the drug. [Figure 11] This is a diagram showing the antitumor effect of the combination of HER3-ADC(1) and osimertinib against the PC9AZDR7 cell line transplanted into nude mice. The error bars in the diagram indicate standard error (control group n = 11, HER3-ADC(1) single agent group n = 12, osimertinib single agent group n = 12, HER3-ADC(1) and osimertinib combination group n = 10), and the arrows indicate the administration of the drugs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0088] A preferred embodiment for carrying out the present invention will be described below. Note that the embodiment described below is an example of a typical embodiment of the present invention, and the scope of the present invention is not to be interpreted narrowly by this embodiment.

[0089] In the present invention, "EGFR-TKI" refers to an EGFR tyrosine kinase inhibitor, and examples thereof include gefitinib, erlotinib, afatinib, and osimertinib.

[0090] In the present invention, gefitinib and erlotinib are sometimes referred to as first-generation EGFR-TKIs, afatinib as second-generation EGFR-TKIs, and osimertinib as third-generation EGFR-TKIs.

[0091] In the present invention, "EGFR-TKI-resistant non-small cell lung cancer" refers to non-small cell lung cancer that has been confirmed to be resistant to EGFR-TKI, as well as non-small cell lung cancer that can be reasonably recognized or predicted to be resistant to EGFR-TKI.

[0092] In the present invention, the term "EGFR T790M mutation" refers to a mutation in which the 790th amino acid threonine located in the gatekeeper region of the ATP binding site of the EGFR tyrosine kinase domain is converted to methionine (Pao W, et al., PLoS Med. 2(3):e73, 2005; Kobayashi S, et al., N Engl J Med. 352(8):786-792, 2005). The presence or absence of the EGFR T790M mutation can be confirmed by collecting tissue or plasma samples from patients with non-small cell lung cancer and using a method such as real-time PCR.

[0093] In the present invention, "EGFR T790M mutation-positive non-small cell lung cancer" refers to non-small cell lung cancer that has been confirmed to be positive for EGFR T790M mutation, as well as non-small cell lung cancer that can be reasonably recognized or predicted to be positive for EGFR T790M mutation.

[0094] EGFR T790M mutation-positive non-small cell lung cancer is thought to be resistant to first-generation EGFR-TKIs and second-generation EGFR-TKIs due to steric hindrance and other mechanisms caused by changes in the three-dimensional structure of the EGFR ATP binding site, and is observed in approximately half of the cases of resistance to first-generation EGFR-TKIs and second-generation EGFR-TKIs. Osimertinib, a third-generation EGFR-TKI, is known as an effective drug for EGFR T790M mutation-positive non-small cell lung cancer.

[0095] The optimal drug has not yet been approved for osimertinib-resistant non-small cell lung cancer, and there is an unmet medical need.

[0096] An example of a cell line corresponding to osimertinib-resistant non-small cell lung cancer is the PC9AZDR7 cell line. The PC9AZDR7 cell line is a cell line that has acquired resistance to osimertinib from PC9, a human non-small cell lung cancer cell line, as a parent line, and can be established by the method described in Example 3-1 of the present specification.

[0097] The antitumor effect of the drug against osimertinib-resistant non-small cell lung cancer can be confirmed by testing the in vitro cell growth inhibitory activity against the above cell lines, and the in vivo tumor growth inhibition rate in a model in which the above cell lines are transplanted into nude mice.

[0098] In the present invention, "EGFR T790M mutation-negative non-small cell lung cancer" refers to non-small cell lung cancer that has been confirmed to be negative for EGFR T790M mutation, as well as non-small cell lung cancer that can be reasonably recognized or predicted to be negative for EGFR T790M mutation.

[0099] In cases of EGFR-TKI resistance, cases other than EGFR T790M mutation-positive non-small cell lung cancer correspond to EGFR T790M mutation-negative non-small cell lung cancer. Such EGFR T790M mutation-negative non-small cell lung cancer is thought to have acquired resistance due to mutations other than EGFR T790M mutation (e.g., amplification of the MET gene), but the existence of unknown resistance mechanisms has also been suggested.

[0100] There is an unmet medical need for an optimal drug that has not yet been approved for EGFR T790M mutation-negative non-small cell lung cancer that is resistant to EGFR-TKIs.

[0101] An example of a cell line corresponding to EGFR T790M mutation-negative non-small cell lung cancer that is resistant to EGFR-TKI is the HCC827GR5 cell line (Engelman JA et al., Science 2007, 316(5827), 1039-1043). The HCC827GR5 cell line is a cell line that has acquired resistance to EGFR-TKI gefitinib, using HCC827, a human non-small cell lung cancer cell line, as a parent line. In addition, the 11-18 cell line (Proc Natl Acad Sci US A. 2012 Jul 31;109(31):E2127-33) and the Ma70GR cell line (K Yonesaka et al., Oncogene (2016) 35, 878-886) can also be used as cell lines corresponding to EGFR T790M mutation-negative non-small cell lung cancer that is resistant to EGFR-TKIs.

[0102] The antitumor effect of a drug against EGFR T790M mutation-negative non-small cell lung cancer that is resistant to EGFR-TKI can be confirmed by testing the in vitro cell growth inhibitory activity against the above cell lines, and the in vivo tumor growth inhibition rate in a nude mouse model in which the above cell lines are transplanted.

[0103] In the present invention, "HER3" is synonymous with human epidermal growth factor receptor 3 (sometimes called ErbB3), and is a transmembrane receptor that belongs to the epidermal growth factor receptor subfamily of receptor protein tyrosine kinases along with HER1, HER2, and HER4. HER3 is expressed in several types of cancer, such as breast cancer, gastrointestinal cancer, and pancreatic cancer, and is known to form a heterodimer with tyrosine kinase receptors such as EGFR and HER2, thereby being phosphorylated and inducing cancer cell proliferation and apoptosis inhibitory signals.

[0104] The HER3 protein used in the present invention can be directly purified from human HER3-expressing cells, or when used as an antigen, the cell membrane fraction of the cells can be used as the HER3 protein. Also, HER3 can be obtained by synthesizing in vitro or by producing it in a host cell by genetic engineering. Specifically, in genetic engineering, HER3 cDNA is incorporated into an expression vector, and then the vector is incubated in a solution containing enzymes, substrates, and energy substances required for transcription and translation to synthesize HER3. Alternatively, the protein can be obtained by transforming other prokaryotic or eukaryotic host cells with the vector and expressing HER3. In addition, the HER3-expressing cells by genetic engineering or cell lines expressing HER3 can be used as HER3 protein antigens.

[0105] The RNA sequence, cDNA sequence, and amino acid sequence of HER3 are published in public databases and can be referenced by accession numbers such as AAA35979 (precursor including a signal sequence consisting of 19 amino acid residues at the amino terminus) and M34309 (NCBI).

[0106] Furthermore, HER3 also includes proteins that have an amino acid sequence in which 1 to 10 amino acids have been substituted, deleted, added and / or inserted in the amino acid sequence of the above-mentioned HER3 and have biological activity equivalent to that of the said protein.

[0107] In the present invention, "anti-HER3 antibody" refers to an antibody that specifically binds to HER3, and preferably has the activity of being internalized into HER3-expressing cells upon binding to HER3, in other words, an antibody that has the activity of migrating into HER3-expressing cells after binding to HER3.

[0108] The anti-HER3 antibody used in the present invention can be obtained by known means. For example, it can be obtained by immunizing an animal with the antigen HER3 or any polypeptide selected from the amino acid sequence of HER3 using a method commonly used in this field, and collecting and purifying the antibody produced in the body. The origin of the antigen is not limited to humans, and animals can also be immunized with antigens derived from animals other than humans, such as mice and rats. In this case, anti-HER3 antibodies applicable to human diseases can be selected by testing the cross-reactivity of the obtained antibody that binds to a heterologous antigen with a human antigen.

[0109] Alternatively, a hybridoma can be established by fusing an antibody-producing cell that produces an antibody against an antigen with a myeloma cell according to known methods (e.g., Kohler and Milstein, Nature (1975) 256, p. 495-497; Kennet, R. ed., Monoclonal Antibodies, p. 365-367, Plenum Press, NY (1980)), thereby obtaining a monoclonal antibody.

[0110] The antigen can be obtained by genetically engineering a gene encoding an antigen protein in a host cell to produce it. Specifically, a vector capable of expressing an antigen gene is prepared, introduced into a host cell to express the gene, and the expressed antigen is purified. Antibodies can also be obtained by immunizing an animal with the above-mentioned genetically engineered antigen-expressing cells or cell lines expressing the antigen.

[0111] The anti-HER3 antibody used in the present invention is preferably a genetically engineered antibody that has been artificially modified for the purpose of reducing heterologous antigenicity against humans, such as a chimeric antibody or a humanized antibody, or is preferably an antibody having only the genetic sequence of an antibody derived from humans, i.e., a human antibody. These antibodies can be produced using known methods.

[0112] Chimeric antibodies include antibodies whose variable and constant regions are of different species, such as chimeric antibodies in which the variable region of an antibody derived from a mouse or rat is joined to a constant region derived from a human (Proc. Natl. Acad. Sci. USA, 81, 6851-6855, (1984)).

[0113] Examples of humanized antibodies include antibodies in which only the complementarity determining region (CDR) of a heterologous antibody has been incorporated into an antibody of human origin (Nature (1986) 321, p. 522-525), antibodies in which not only the CDR sequence of a heterologous antibody but also some framework amino acid residues of the heterologous antibody have been grafted onto a human antibody by CDR grafting (WO 90 / 07861), and antibodies humanized using a gene conversion mutagenesis strategy (U.S. Pat. No. 5,821,337).

[0114] Examples of human antibodies include antibodies produced using human antibody-producing mice having a human chromosome fragment containing the heavy and light chain genes of a human antibody (see, for example, Tomizuka, K. et al., Nature Genetics (1997) 16, p.133-143; Kuroiwa, Y. et al., Nucl. Acids Res. (1998) 26, p.3447-3448; Yoshida, H. et al., Animal Cell Technology: Basic and Applied Aspects vol.10, p.69-73 (Kitagawa, Y., Matsuda, T. and Iijima, S. eds.), Kluwer Academic Publishers, 1999; Tomizuka, K. et al., Proc. Natl. Acad. Sci. USA (2000) 97, p.722-727). Alternatively, antibodies obtained by phage display selected from a human antibody library can also be used (see, for example, Wormstone, IM et. al, Investigative Ophthalmology & Visual Science. (2002) 43 (7), p. 2301-2308; Carmen, S. et. al., Briefings in Functional Genomics and Proteomics (2002), 1 (2), p. 189-203; Siriwardena, D. et. al., Ophthalmology (2002) 109 (3), p. 427-431).

[0115] The anti-HER3 antibody used in the present invention also includes modified antibodies. The modified antibody means an antibody according to the present invention that has been chemically or biologically modified. Chemical modifications include those having a chemical moiety bonded to the amino acid backbone, or a chemical moiety bonded to an N- or O-linked carbohydrate chain. Biological modifications include those that have been post-translationally modified (e.g., addition of an N- or O-linked glycan, processing of the N- or C-terminus, deamidation, isomerization of aspartic acid, oxidation of methionine, etc.), and those that have been expressed using a prokaryotic host cell to add a methionine residue to the N-terminus. In addition, those labeled to enable detection or isolation of the anti-HER3 antibody or antigen used in the present invention, such as enzyme-labeled, fluorescent-labeled, and affinity-labeled antibodies, are also included in the meaning of such modifications. Such modified anti-HER3 antibodies used in the present invention are useful for improving the stability and blood retention of the antibody, reducing antigenicity, and detecting or isolating the antibody or antigen.

[0116] In addition, antibody-dependent cellular cytotoxicity can be enhanced by regulating the sugar chain modification bound to the anti-HER3 antibody used in the present invention (glycosylation, defucosylation, etc.). Techniques for regulating the sugar chain modification of antibodies are known, including, but not limited to, WO 99 / 54342, WO 00 / 61739, and WO 02 / 31140. The anti-HER3 antibody used in the present invention also includes antibodies in which the sugar chain modification has been regulated.

[0117] It is known that antibodies produced in cultured mammalian cells have a deletion of the lysine residue at the carboxyl terminus of their heavy chains (Journal of Chromatography A, 705: 129-134 (1995)), and also have a deletion of two amino acid residues, glycine and lysine, at the carboxyl terminus of the heavy chain, and amidation of the proline residue at the carboxyl terminus (Analytical Biochemistry, 360: 75-83 (2007)). However, these deletions and modifications of the heavy chain sequence do not affect the antigen-binding ability and effector functions (complement activation, antibody-dependent cellular cytotoxicity, etc.) of the antibody. Therefore, the anti-HER3 antibody used in the present invention also includes antibodies and functional fragments of the antibodies that have been modified in this way, including deletions in which one or two amino acids have been deleted at the carboxyl terminus of the heavy chain, and deletions that have been amidated (for example, heavy chains in which the proline residue at the carboxyl terminus has been amidated). However, as long as the antigen-binding ability and effector function are maintained, the deletion of the carboxyl terminus of the heavy chain of the anti-HER3 antibody used in the present invention is not limited to the above types. The two heavy chains constituting the anti-HER3 antibody used in the present invention may be any one of heavy chains selected from the group consisting of full-length and the above deletions, or may be a combination of any two of them. The quantitative ratio of each deletion may be influenced by the type and culture conditions of the cultured mammalian cells producing the anti-HER3 antibody used in the present invention, but the anti-HER3 antibody used in the present invention preferably includes one in which one amino acid residue is deleted at the carboxyl terminus of both of the two heavy chains.

[0118] The isotype of the anti-HER3 antibody used in the present invention can be, for example, IgG (IgG1, IgG2, IgG3, IgG4), and preferably IgG1 or IgG2. Modified versions of these antibodies can also be used as the anti-HER3 antibody of the present invention.

[0119] Anti-HER3 antibodies that can be used in the present invention include Patritumab (U3-1287), U1-59 (WO 2007 / 077028), AV-203 (WO 2011 / 136911), LJM-716 (WO 2012 / 022814), Duligotumab (MEHD-7945A) (WO 2010 / 108127), Istiratumab (MM-141) (WO 2011 / 047180), Lumretuz ... b(RG-7116) (WO 2014 / 108484), Setibantumab (MM-121) (WO 2008 / 100624), REGN-1400 (WO 2013 / 048883), ZW-9 (WO 2013 / 063702), and variants, active fragments, modified forms, etc. thereof can be mentioned, and preferably, Patritumab and U1-59 can be mentioned. These anti-HER3 antibodies can be produced by the methods described in the above documents.

[0120] In the present invention, the term "antibody-drug conjugate" refers to a complex in which a cytotoxic drug is bound to an antibody via a linker. Examples of the antibody-drug conjugate include those described in U.S. Pat. No. 6,214,345, WO 2002 / 083067, WO 2003 / 026577, WO 2004 / 054622, WO 2005 / 112919, WO 2006 / 135371, WO 2007112193, WO 2008 / 033891, WO 2009 / 100194, WO 2009 / 134976, WO 2009 / 134977, WO 2010 / 093395, WO 2011 / 093396, WO 2012 / 093397, WO 2013 / 093398, WO 2014 / 093399, WO 2015 / 093399, WO 2016 / 093391, WO 2017 / 093392, WO 2018 / 093393, WO 2019 / 093394, WO 2019 / 093395, WO 2019 / 093396, WO 2019 / 093397, WO 2019 / 093398, WO 2019 / 093399, WO 2019 / 093396, WO 2019 / 093399, WO 2019 / 093399, WO 2019 / 093399, WO 20 Examples of the antibody-drug conjugates include those described in International Publication Nos. 11 / 130613, 2011 / 130616, 2013 / 055993, 2014 / 057687, 2014 / 061277, 2014 / 107024, 2014 / 134457, and 2014 / 145090, preferably those described in International Publication Nos. 2014 / 057687 and 2014 / 061277, and more preferably those described in International Publication No. 2014 / 057687. These antibody-drug conjugates can be produced by the methods described in the above-mentioned documents.

[0121] The cytotoxic drug is not particularly limited as long as it has an antitumor effect and has a substituent or partial structure that can be bound to a linker, and examples of the cytotoxic drug include camptothecin, calicheamicin, doxorubicin, daunorubicin, mitomycin C, bleomycin, cyclocytidine, vincristine, vinblastine, methotrexate, cisplatin, auristatin E, and the like. E), Maytansine, Paclitaxel, Pyrrolobenzodiazepine, and derivatives thereof, preferably camptothecin derivatives, and more preferably exatecan derivatives. The topoisomerase I inhibitor exatecan (IUPAC name: (1S,9S)-1-amino-9-ethyl-5-fluoro-1,2,3,9,12,15-hexahydro-9-hydroxy-4-methyl-10H,13H-benzo[de]pyrano[3',4':6,7]indolizino[1,2-b]quinoline-10,13-dione, (chemical name: (1S,9S)-1-amino-9-ethyl-5-fluoro-2,3-dihydro-9-hydroxy-4-methyl-1H,12H-benzo[de]pyrano[3',4':6,7]indolizino[1,2-b]quinoline-10,13(9H,15H)-dione)) has the formula

[0122] [ka] It is a compound represented by the formula:

[0123] In the present invention, the term "drug linker" refers to the drug and linker moiety in an antibody-drug conjugate, in other words, a partial structure other than the antibody in an antibody-drug conjugate.

[0124] In the present invention, the term "anti-HER3 antibody-drug conjugate" refers to an antibody-drug conjugate in which the antibody in the antibody-drug conjugate is an anti-HER3 antibody. Examples of the anti-HER3 antibody-drug conjugate include those described in WO 2012 / 019024, WO 2012 / 064733, and WO 2015 / 155998, and preferably those described in WO 2015 / 155998. These anti-HER3 antibody-drug conjugates can be produced by the methods described in the above documents.

[0125] The anti-HER3 antibody-drug conjugate more preferably used in the present invention is represented by the formula

[0126] [ka] (In the formula, A represents the binding site for the anti-HER3 antibody.) The anti-HER3 antibody-drug conjugate is an anti-HER3 antibody-drug conjugate in which the drug linker shown in Figure 1 is linked to the anti-HER3 antibody via a thioether bond. This drug linker is linked to a thiol group (in other words, a sulfur atom of a cysteine ​​residue) generated at the disulfide bond site between the antibody chains (between two heavy chains and between two heavy chains and light chains).

[0127] The above-mentioned anti-HER3 antibody-drug conjugate, which is more preferably used in the present invention, can also be represented by the following formula:

[0128] [ka]

[0129] Here, the drug linker is bound to the antibody via a thioether bond, and n is synonymous with the so-called average drug binding number (DAR; Drug-to-Antibody Ratio), and indicates the average number of drug linkers bound per antibody.

[0130] The anti-HER3 antibody-drug conjugate more preferably used in the present invention is one in which the linker moiety is cleaved after the antibody is transferred into a tumor cell, and the antibody is represented by the formula

[0131] [ka] The compound represented by the formula:

[0132] The above compound is considered to be the main component of the antitumor activity of the above anti-HER3 antibody-drug conjugate, which is more preferably used in the present invention, and has been confirmed to have a topoisomerase I inhibitory effect (Ogitani Y. et al., Clinical Cancer Research, 2016, Oct 15;22(20):5097-5108, Epub 2016 Mar 29).

[0133] The anti-HER3 antibody portion of the anti-HER3 antibody-drug conjugate used in the present invention is preferably an antibody comprising a heavy chain comprising CDRH1 consisting of the amino acid sequence shown in SEQ ID NO: 1, CDRH2 consisting of the amino acid sequence shown in SEQ ID NO: 2, and CDRH3 consisting of the amino acid sequence shown in SEQ ID NO: 3, and a light chain comprising CDRL1 consisting of the amino acid sequence shown in SEQ ID NO: 4, CDRL2 consisting of the amino acid sequence shown in SEQ ID NO: 5, and CDRL3 consisting of the amino acid sequence shown in SEQ ID NO: 6, More preferably, it is an antibody comprising a heavy chain comprising a heavy chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 7, and a light chain comprising a light chain variable region consisting of the amino acid sequence shown in SEQ ID NO: 8, Even more preferably, the antibody is an antibody comprising a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10, or an antibody in which the lysine residue at the carboxyl terminus of the heavy chain of the above antibody is deleted.

[0134] The drug linker intermediate used in the preparation of the above anti-HER3 antibody-drug conjugates is represented by the following formula:

[0135] [ka]

[0136] The above drug linker intermediate can be represented by the chemical name N-[6-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)hexanoyl]glycylglycyl-L-phenylalanyl-N-[(2-{[(1S,9S)-9-ethyl-5-fluoro-9-hydroxy-4-methyl-10,13-dioxo-2,3,9,10,13,15-hexahydro-1H,12H-benzo[de]pyrano[3',4':6,7]indolizino[1,2-b]quinolin-1-yl]amino}-2-oxoethoxy)methyl]glycinamide, and can be produced with reference to the descriptions in WO 2014 / 057687 and WO 2015 / 155998.

[0137] The anti-HER3 antibody-drug conjugate preferably used in the present invention can be produced by reacting the above-mentioned drug linker intermediate with an anti-HER3 antibody having a thiol group (also called a sulfhydryl group).

[0138] An anti-HER3 antibody having a sulfhydryl group can be obtained by a method well known to those skilled in the art (Hermanson, G. T, Bioconjugate Techniques, pp.56-136, pp.456-493, Academic Press (1996)). For example, a reducing agent such as tris(2-carboxyethyl)phosphine hydrochloride (TCEP) can be used in an amount of 0.3 to 3 molar equivalents per intra-chain disulfide of the antibody, and reacted with the anti-HER3 antibody in a buffer containing a chelating agent such as ethylenediaminetetraacetic acid (EDTA), to obtain an anti-HER3 antibody having a sulfhydryl group in which the intra-chain disulfide of the antibody has been partially or completely reduced.

[0139] Additionally, 2 to 20 molar equivalents of drug linker intermediate can be used per anti-HER3 antibody bearing a sulfhydryl group to produce anti-HER3 antibody-drug conjugates with 2 to 8 drugs attached per antibody.

[0140] The average number of drugs bound per antibody molecule of the produced anti-HER3 antibody-drug conjugate can be calculated, for example, by a method in which the UV absorbance of the anti-HER3 antibody-drug conjugate and its conjugation precursor are measured at two wavelengths, 280 nm and 370 nm (UV method), or by a method in which the antibody-drug conjugate is treated with a reducing agent, and each of the resulting fragments is quantified by HPLC measurement and then calculated (HPLC method).

[0141] Conjugation of the anti-HER3 antibody to the drug linker intermediate, and calculation of the average number of drugs bound per antibody molecule of the anti-HER3 antibody-drug conjugate can be performed with reference to the descriptions in WO 2015 / 155998, etc.

[0142] The average number of drug linker bonds per antibody in the anti-HER3 antibody-drug conjugate used in the present invention is preferably 2 to 8, more preferably 3 to 8, even more preferably 7 to 8, even more preferably 7.5 to 8, and even more preferably about 8.

[0143] The therapeutic agent and method of the present invention are characterized by administering an anti-HER3 antibody-drug conjugate and can be used to treat EGFR-TKI-resistant non-small cell lung cancer. The "non-small cell lung cancer" may be EGFR T790M mutation-negative non-small cell lung cancer or EGFR T790M mutation-positive non-small cell lung cancer.

[0144] The "EGFR-TKI" in the "EGFR-TKI-resistant non-small cell lung cancer" is preferably gefitinib, erlotinib, afatinib, or osimertinib, more preferably osimertinib. When the "non-small cell lung cancer" in the "EGFR-TKI-resistant non-small cell lung cancer" is EGFR T790M mutation-negative non-small cell lung cancer, the "EGFR-TKI" is preferably gefitinib, erlotinib, or afatinib, more preferably gefitinib or erlotinib.

[0145] The "EGFR-TKI-resistant non-small cell lung cancer" preferably expresses HER3, more preferably highly expresses HER3. The expression of HER3 can be confirmed, for example, by detection at the level of the HER3 gene product (protein) by immunohistochemistry (IHC), flow cytometer, western blot method, etc., or by detection at the level of gene transcription by in situ hybridization (ISH) or quantitative PCR (q-PCR). Whether HER3 is highly expressed can be determined using a method well known to those skilled in the art.

[0146] The therapeutic agent and method of the present invention may contain one or more other drugs (e.g., a second drug) other than the anti-HER3 antibody-drug conjugate used in the present invention. That is, the therapeutic agent of the present invention or the anti-HER3 antibody-drug conjugate used in the present invention may be administered in combination with other drugs, thereby enhancing the anti-cancer effect. The other drugs used for such purposes may be administered to an individual simultaneously, separately, or consecutively with the anti-HER3 antibody-drug conjugate used in the present invention, or may be administered at different administration intervals. The other drug or second drug is preferably a cancer therapeutic agent. Such a cancer therapeutic agent is not limited as long as it is a drug having antitumor activity, but is, for example, at least one selected from the group consisting of EGFR-TKI, cisplatin, carboplatin, oxaliplatin, paclitaxel, docetaxel, gemcitabine, capecitabine, irinotecan (CPT-11), etoposide, cyclophosphamide, doxorubicin, vinblastin, and vincristine, and is preferably an EGFR-TKI.

[0147] The above-mentioned EGFR-TKI is preferably gefitinib, erlotinib, afatinib, or osimertinib, more preferably erlotinib or osimertinib, and even more preferably osimertinib.

[0148] The therapeutic agent and method of the present invention can be selected and used as a drug for drug therapy, which is the main method of cancer treatment, and as a result, it can delay the growth of cancer cells, suppress their proliferation, and even destroy them. These actions can relieve cancer patients from symptoms caused by cancer and improve their QOL, and the therapeutic effect can be achieved while preserving the life of the cancer patient. Even if the destruction of cancer cells is not achieved, the inhibition and control of the proliferation of cancer cells can help cancer patients achieve a higher QOL and a longer life.

[0149] In addition to being used alone in such drug therapy, the therapeutic agent and method of the present invention can also be used as a drug to be combined with other therapies in adjuvant therapy, and can be combined with surgery, radiation therapy, hormone therapy, etc. Furthermore, it can also be used as a drug for drug therapy in neoadjuvant therapy.

[0150] In addition to the above therapeutic uses, the therapeutic agent and method of the present invention can be expected to have a preventive effect of suppressing and even destroying the proliferation of minute metastatic cancer cells. For example, it can be expected to have an effect of suppressing and destroying cancer cells in body fluids during the metastasis process, and an effect of suppressing and destroying minute cancer cells immediately after implantation in any tissue. Therefore, it can be expected to have an effect of suppressing and preventing cancer metastasis, especially after surgical removal of cancer.

[0151] The therapeutic agent and method of the present invention can be applied to patients as a systemic therapy, and also can be expected to have a therapeutic effect when applied locally to cancer tissue.

[0152] The therapeutic agent and method of the present invention can be suitably used for mammals, and more suitably used for humans.

[0153] The therapeutic agent of the present invention may be administered as a pharmaceutical composition containing one or more pharma- ceutical compatible ingredients. The substances used in the pharmaceutical composition of the present invention may be appropriately selected from formulation additives and other substances commonly used in this field in terms of dosage amount and administration concentration and applied. For example, the pharmaceutical composition typically contains one or more pharmaceutical carriers (e.g., a sterile liquid). Here, the liquid includes, for example, water and oil (petroleum, animal, vegetable, or synthetic oils). The oil may be, for example, peanut oil, soybean oil, mineral oil, sesame oil, etc. Water is a more typical carrier when the pharmaceutical composition is administered intravenously. Saline solution, and aqueous dextrose and glycerol solutions may also be used as liquid carriers, particularly for injectable solutions. Suitable pharmaceutical excipients may be appropriately selected from those known in the art. The pharmaceutical composition may also contain minor amounts of wetting or emulsifying agents, or pH buffering agents, if desired. Examples of suitable pharmaceutical carriers are described in "Remington's Pharmaceutical Sciences" by EW Martin. The formulation corresponds to the mode of administration.

[0154] Various delivery systems are known and can be used to administer the pharmaceutical composition of the present invention. Routes of introduction can include, but are not limited to, intradermal, intramuscular, intraperitoneal, intravenous, and subcutaneous routes. Administration can be, for example, by infusion or bolus injection. In certain preferred embodiments, administration of the antibody-drug conjugate is by infusion. Parenteral administration is the preferred route of administration.

[0155] In a representative embodiment, the pharmaceutical composition is formulated according to routine procedures as a composition adapted for intravenous administration to humans. Typically, compositions for intravenous administration are solutions in sterile isotonic aqueous buffer. If necessary, the pharmaceutical composition may also include a solubilizing agent and a local anesthetic (e.g., lignocaine) to ease pain at the site of injection. Generally, the ingredients are supplied either separately or mixed together in unit dosage form, e.g., as a dry lyophilized powder or water-free concentrate in a hermetically sealed container, such as an ampule or sachette indicating the quantity of active agent. When the pharmaceutical composition is in a form to be administered by injection, it can be dispensed, for example, in an infusion bottle containing sterile pharmaceutical grade water or saline. When the medicament is administered by injection, an ampoule of sterile water for injection or saline can be provided, for example, so that the ingredients can be mixed prior to administration.

[0156] The single dose of the anti-HER3 antibody-drug conjugate used in the present invention is preferably in the range of 1.6 mg / kg to 12.4 mg / kg, more preferably 3.2 mg / kg, 4.8 mg / kg, 6.4 mg / kg, 8 mg / kg, 9.6 mg / kg, or 12.4 mg / kg, and even more preferably 4.8 mg / kg, 6.4 mg / kg, 8 mg / kg, 9.6 mg / kg, or 12.4 mg / kg.

[0157] Furthermore, when the anti-HER3 antibody-drug conjugate used in the present invention is used in combination with a second drug (preferably an EGFR-TKI, more preferably erlotinib or osimertinib, and even more preferably osimertinib), the dose of the anti-HER3 antibody-drug conjugate used in the present invention per administration is preferably in the range of 0.8 mg / kg to 12.4 mg / kg, more preferably 1.6 mg / kg, 3.2 mg / kg, 4.8 mg / kg, 6.4 mg / kg, 8 mg / kg, 9.6 mg / kg, or 12.4 mg / kg, and even more preferably 3.2 mg / kg, 4.8 mg / kg, 6.4 mg / kg, 8 mg / kg, 9.6 mg / kg, or 12.4 mg / kg.

[0158] The administration interval of the anti-HER3 antibody-drug conjugate used in the present invention is preferably once every week (q1w), once every two weeks (q2w), once every three weeks (q3w), or once every four weeks (q4w), and more preferably once every three weeks (q3w). EXAMPLES

[0159] The present invention will be specifically described with reference to the following examples, but the present invention is not limited thereto. Furthermore, the examples should not be construed as being limiting in any sense.

[0160] Example 1: Preparation of antibody-drug conjugates According to the production method described in WO 2015 / 155998, an anti-HER3 antibody (referred to as "anti-HER3 antibody (1)" in the present invention) having a heavy chain consisting of the amino acid sequence shown in SEQ ID NO: 9 ( FIG. 1 ) and a light chain consisting of the amino acid sequence shown in SEQ ID NO: 10 ( FIG. 2 ) is used to produce a HER3 antibody having the formula

[0161] [ka] (wherein A represents the binding site to the antibody) An anti-HER3 antibody-drug conjugate (referred to as "HER3-ADC(1)" in the present invention) was produced in which the drug linker represented by the formula: is linked to the anti-HER3 antibody via a thioether bond. The average number of drugs bound per antibody in HER3-ADC(1) is 7.6.

[0162] Example 2: Sensitivity test of HER3-ADC (1) against HCC827GR5 cell line

[0163] Example 2-1: Cytostatic activity against HCC827 cell line and HCC827GR5 cell line The HCC827 cell line was cultured in RPMI1640 medium (Sigma) containing R10 medium (10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.)). The HCC827GR5 cell line was cultured in the above medium containing gefitinib at a final concentration of 1 μM. It has been reported that the HCC827GR5 cell line does not show strong sensitivity to single-agent erlotinib or single-agent treatment with anti-HER3 antibody (1) (the antibody portion of HER3-ADC (1)) (K Yonesaka et al., Oncogene (2016) 35, 878-886). After culturing the HCC827 cell line and the HCC827GR5 cell line, they were detached by trypsin treatment, the cells were collected, the number of cells in the cell suspension was measured, and the cells were suspended in RPMI1640 medium containing 10% fetal bovine serum to prepare a concentration of 100,000 cells / mL. 50 μL of each cell suspension was added to each well of a Sumilon 96-well plate (manufactured by Sumitomo Bakelite) (5,000 cells / well) and cultured. Three days after the start of culture, a dilution of HER3-ADC(1) dissolved in R10 medium or R10 medium containing no drug as a negative control was added and cultured (the final solution volume was 100 μl per well, and the final concentration of the culture solution was 0, 0.0033, 0.01, 0.033, 0.1, 0.33, 1, 3.3, and 10 μg / mL). On the 7th day after the start of treatment, 50 μL of CellTiter Glo (Promega) was added to each well, stirred for 2 minutes with a plate mixer, and left to stand for 30 minutes under light-shielded conditions. 120 μL of each well was taken and transferred to a black microplate, and the luminescence value was measured with a luminometer.

[0164] The cytostatic activity of each drug (% Control) was calculated using the following formula.

[0165] % Control = (mean luminescence value in wells containing samples ÷ mean luminescence value in negative control wells) x 100

[0166] The experiment was carried out in 6 wells for each group.

[0167] The results are shown in Figure 3. The HER3-ADC(1) groups containing 10, 3.3, and 1 μg / mL of HER3-ADC(1) showed 41.3, 40.0, and 50.0% cell growth inhibitory activity, respectively, against the HCC827GR5 cell line. On the other hand, no cell growth inhibitory activity was observed against the HCC827 cell line at concentrations of 3.3 μg / mL or less.

[0168] These results demonstrated that HER3-ADC(1) exhibited cell proliferation inhibitory activity against the HCC827GR5 cell line.

[0169] Example 2-2: HER3 mRNA expression in HCC827 and HCC827GR5 cell lines 1. Preparation of Total RNA Total RNA was prepared using Rneasy Mini Kit (Qiagen). HCC827 cell line was cultured in RPMI1640 medium (Sigma) containing R10 medium (10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.)). HCC827GR5 cell line was cultured in the above medium containing gefitinib at a final concentration of 1 μM. After culturing HCC827 cell line and HCC827GR5 cell line, they were detached by trypsin treatment, the cells were collected, the number of cells in the cell suspension was measured, and the cells were suspended in RPMI1640 medium containing 10% fetal bovine serum. 5 million cells of each type were collected, centrifuged, and then 600 μL of Buffer RLT (containing β-mercaptoethanol at 100:1) was added and stirred for 30 seconds, and then stored at -80 ° C. After dissolving the prepared solution, it was added to a QIA Shredder and centrifuged at 15000 rpm for 2 minutes, and 600 μL of 70% ethanol was added to the extract and stirred. This solution was added to a spin column and centrifuged at 12000 rpm for 15 seconds. 80 μL of DNase(+) (70 μL BufferRDD, 10 μL DNaseI stock solution) was added to the spin column and left at room temperature for 15 minutes, then 700 μL of BufferRW was added and centrifuged at 10000 rpm or more for 15 seconds. The collection tube was replaced, 500 μL of Buffer RPE was added, and the column was centrifuged at 10000 rpm or more for 15 seconds, and the extract was discarded. 500 μL of Buffer RPE was added again and centrifuged for 2 minutes, then the tube was replaced with a recovery tube, 100 μL of Rnase-free water was added to the spin column and left to stand for 5 minutes. After centrifugation at 12,000 rpm or more for 15 seconds, the amount of total RNA in the recovery tube was measured.

[0170] 2. cDNA Preparation cDNA was prepared using a High Capacity RNA-to-cDNA Kit (Applied Biosystems). 2 μg of the RNA prepared above was added to a solution prepared with 2x RT Buffer, 20x RT Enzyme Mix, and Nuclease-free H20 to prepare a solution with a total volume of 20 μL. After centrifugation to remove air bubbles, the mixture was placed in a thermal cycler and reacted at 37°C for 60 minutes and at 95°C for 5 minutes, and then cooled to 4°C to perform reverse transcription and prepare cDNA.

[0171] 3. Quantitative PCR Reaction Quantitative polymerase chain reaction (qPCR) reactions were performed using a MicroAmp Optical 96-well Reaction Plate. 50 ng of the cDNA prepared above was added to the plate, followed by 12.5 μL of Soraris qPCR Master Mix (2x) (Thermo Fisher Scientific), 12.5 μL of Soraris Primer / Probe set (20x) (Thermo Fisher Scientific) for HER3 mRNA amplification, and distilled water. To create a standard curve for calculating the amount of mRNA, the same procedure was performed on 200, 100, and 20 ng of cDNA prepared by the same method from human colon cancer cells HCT116. The plates containing the various samples were loaded into an ABI 7900HT (Applied Biosystems) and incubated at 95°C for 15 minutes, followed by 60 cycles of incubation at 95°C for 15 seconds and 60°C for 60 seconds. After cooling at 4°C for 10 minutes, the fluorescence intensity of each well was measured and the amount of PCR product was quantified to measure the amount of mRNA in each sample.

[0172] The results are shown in Figure 4. The amount of HER3 mRNA in the HCC827GR5 cell line was significantly higher than the amount of HER3 mRNA derived from the HCC827 cell line (student t-test, p<0.05).

[0173] Example 2-3: Cytostatic activity against HCC827GR5 cell line The HCC827GR5 cell line was cultured in RPMI1640 medium (Sigma) containing R10 medium (10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.)) containing gefitinib at a final concentration of 1 μM. After culturing the HCC827GR5 cell line, the cells were detached by trypsin treatment, and the cells were collected, the number of cells in the cell suspension was measured, and the cells were suspended in RPMI1640 medium containing 10% fetal bovine serum and adjusted to a concentration of 100,000 cells / mL. 50 μL of the cell suspension was added to each well of a Sumilon 96-well plate (Sumitomo Bakelite Co., Ltd.) (5,000 cells / well) and cultured. After 3 days of culture, HER3-ADC(1) diluted solution (final concentration of culture solution: 0, 0.0033, 0.01, 0.033, 0.1, 0.33, 1, 3.3, 10 μg / mL) dissolved in R10 medium, erlotinib diluted solution (final concentration of culture solution: 0, 0.0033, 0.01, 0.033, 0.1, 0.33, 1, 3.3, 10 μM), erlotinib (final concentration of culture solution 1 μM) dissolved in R10 medium (final concentration of culture solution: 0, 0.0033, 0.01, 0.033, 0.1, 0.33, 1, 3.3, 10 μg / mL), and R10 medium containing no drug as a negative control were added, and the final culture volume of each well was 100 μL, and culture was performed. On the 7th day after the start of treatment, 50 μL of CellTiter Glo (Promega) was added to each well, stirred for 2 minutes with a plate mixer, and left to stand for 30 minutes under light-shielded conditions. 120 μL of each well was taken and transferred to a black microplate, and the luminescence value was measured with a luminometer.

[0174] The cell proliferation inhibitory activity (% Control) of each drug against the HCC827GR5 cell line was calculated using the following formula.

[0175] % Control = (mean luminescence value in wells containing samples ÷ mean luminescence value in negative control wells) x 100

[0176] The experiment was carried out in 6 wells for each group.

[0177] The results are shown in Figure 5. For the HCC827GR5 cell line, 41.3, 40.0, and 50.0% cell growth inhibitory activity was observed in the HER3-ADC(1) 10, 3.3, and 1 μg / mL groups, respectively, and 31.7, 52.6, and 69.2% cell growth inhibitory activity was observed in the erlotinib 10, 3.3, and 1 μg / mL groups, respectively. On the other hand, 3.1, 3.2, and 3.0% cell growth inhibitory activity was observed in the combination groups of erlotinib 1 μM and HER3-ADC(1) 10, 3.3, and 1 μg / mL, respectively.

[0178] From the above results, HER3-ADC(1) showed higher cell proliferation inhibitory activity in combination with erlotinib against the HCC827GR5 cell line compared to treatment with HER3-ADC(1) or erlotinib alone.

[0179] Example 2-4: Antitumor effect against HCC827GR5 cell line transplanted into nude mice The HCC827GR5 cell line was cultured in R10 medium (10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.)) and RPMI1640 medium (Sigma) containing erlotinib at a final concentration of 1 μM, then the cells were detached by trypsin treatment, collected, the number of cells in the cell suspension was measured, and the cells were suspended in R10 medium to prepare a concentration of 75,000,000 cells / mL. After transplanting 100 μL (7,500,000 cells) of the prepared cell suspension subcutaneously into the ventral side of 6-week-old female nude mice (BALB / cAJcl-nu / nu), the average estimated tumor volume of the transplanted tumor was 110 mm 3After tumor transplantation, the mice were divided into groups 7 days after tumor transplantation, and drug administration was started (day 0). HER3-ADC(1) was dissolved in phosphate-buffered saline (PBS) and adjusted to a concentration of 1 mg / mL. Erlotinib was dissolved in hydroxypropyl methylcellulose (HPMC) solution and adjusted to 2.75 mg / mL. In the monotherapy groups, the prepared HER3-ADC(1) was administered intraperitoneally at 200 μL / mouse (10 mg / kg) once a week (total of 7 times) from day 0 to a maximum of day 49, and the prepared erlotinib was administered orally at 0.18 mL / mouse (25 mg / kg) six times a week (total of 19 times). In the combination treatment group, HER3-ADC(1) and erlotinib were administered at the same dose and schedule as the monotherapy group from day 0. A group that did not receive administration was set as a control group. Each group consisted of 10 mice. After the start of administration, tumor diameters (long diameter, short diameter) were measured twice a week (days 0, 3, 7, 10, 14, 17, 21, 24, 28, 31, 35, 38, 41, 45, and 49), and the estimated tumor volume for each group was calculated according to the formula shown below. Then, the average estimated tumor volume for each group was calculated.

[0180] Estimated tumor volume (Volume, mm 3 ) = major axis (mm) × minor axis (mm) 2 ÷2

[0181] In addition, the tumor growth inhibition rate of each group compared with the control group was calculated according to the formula shown below.

[0182] Tumor growth inhibition rate (%) = 100 - (mean estimated tumor volume of treatment group ÷ mean estimated tumor volume of control group × 100)

[0183] In the control group and the erlotinib monotherapy group, the estimated tumor volume was between 1200 and 1500 mm on the 21st day. 3 Therefore, from the viewpoint of animal ethics, the measurement was terminated. Accordingly, the calculation of the tumor growth inhibition rate (%) was limited to the 21st day.

[0184] The results are shown in Tables 1, 2, and 6. Erlotinib was not effective against the HCC827GR5 cell line. In contrast, a significant antitumor effect was observed in the HER3-ADC(1) treatment group and the treatment group in which HER3-ADC(1) was combined with erlotinib (Dunnet's Multiple Comparison test p<0.001 at Day 21).

[0185] Based on the above results, HER3-ADC(1) showed significantly higher antitumor effects against the HCC827GR5 cell line implanted in nude mice, when used alone or in combination with erlotinib, compared with no treatment or treatment with erlotinib alone (Dunnet's Multiple Comparison test p<0.001 on Day 21).

[0186] [Table 1] TIFF2025026600000013.tif57165

[0187] [Table 2]

[0188] The results of Example 2 confirmed the antitumor effect of HER3-ADC (1) on the HCC827GR5 cell line. The HCC827GR5 cell line is a cell line that has acquired resistance to EGFR-TKI using HCC827, a human non-small cell lung cancer cell line, as a parent line, and corresponds to non-small cell lung cancer negative for EGFR T790M mutation.

[0189] These results demonstrate that administration of an anti-HER3 antibody-drug conjugate can provide a therapeutic agent and method for EGFR-TKI-resistant, EGFR T790M mutation-negative non-small cell lung cancer.

[0190] Example 3: Sensitivity test of HER3-ADC (1) against PC9 cell line and PC9AZDR7 cell line

[0191] Example 3-1: Creation of osimertinib-resistant PC9 cell line PC9, a non-small cell lung cancer line, was cultured in RPMI-1640 medium (Sigma) containing 10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.). After adding 1 nM osimertinib to the culture medium, the cells were cultured, and the concentration of osimertinib was gradually increased for subculture. Finally, the cells were cultured in a medium containing 100 nM osimertinib to establish an osimertinib-resistant PC9 cell line (PC9AZDR7).

[0192] Example 3-2: Cytostatic activity against PC9 and PC9AZDR7 cell lines PC9 and PC9AZDR7 cell lines were cultured in RPMI1640 medium (Sigma) containing 10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.). PC9AZDR7 was cultured with the addition of 100 nM osimertinib. After culturing PC9 and PC9AZDR7 cell lines, they were detached by trypsin treatment, the cells were collected, the number of cells in the cell suspension was measured, and the cells were suspended in RPMI1640 medium containing 2% fetal bovine serum. 50 μL of each cell suspension was added to each well of a Sumilon 96-well plate (Sumitomo Bakelite Co., Ltd.) (10,000 cells / well) and cultured. One day after the start of culture, osimertinib dilutions prepared to various concentrations or RPMI-1640 medium containing no drug as a negative control were added and cultured. The final concentrations of osimertinib were 0, 0.001, 0.0033, 0.01, 0.033, 0.1, 0.33, 1, and 3.3 μM. On the third day of treatment, 50 μL of CellTiter Glo (Promega) was added to each well, stirred for 2 minutes with a plate mixer, and left to stand for 30 minutes under light-shielded conditions. 120 μL was taken from each well and transferred to a black microplate, and the luminescence value was measured with a luminometer.

[0193] The cell proliferation inhibitory activity (% of control) of each drug was calculated using the following formula.

[0194] % of Control = (mean luminescence value in wells containing samples ÷ mean luminescence value in negative control wells) x 100

[0195] The experiment was carried out in 6 wells for each group.

[0196] The results are shown in Figure 7. A strong cell growth inhibitory activity was observed in the PC9 cell line when osimertinib was added at 0.01 μM or more. On the other hand, no cell growth inhibitory activity was observed in the PC9AZDR7 cell line at concentrations of 1 μM or less.

[0197] These results demonstrated that PC9AZDR7 exhibits drug resistance to osimertinib.

[0198] Example 3-3: Expression of HER3 protein in PC9 cell line and PC9AZDR7 cell line The expression of HER3 protein in each of the PC9 and PC9AZDR7 cell lines was measured using QIFIKIT (Dako). After culturing PC9 and PC9AZDR7, mouse anti-human HER3 antibody (Clone 1B4C3, Dako) or mouse IgG2a isotype control antibody was added and then cultured, followed by incubation with FITC-conjugated anti-mouse IgG antibody (Dako). The expression level of HER3 protein in each cell line was measured by measuring the fluorescence intensity of each sample using LSRFortessaX-20 (BD Biosciences).

[0199] The results are shown in Figure 8. The expression level of HER3 protein in PC9 was 5,088 cells / cell, whereas the expression level in PC9AZDR7 was 15,469 cells / cell, indicating that the expression of HER3 protein was more than three times higher than that in PC9 (unpaired T test, p<0.001).

[0200] These results demonstrated that the expression level of HER3 protein in PC9AZDR7, which was established from the non-small cell lung cancer cell line PC9 and shows resistance to osimertinib, is significantly higher than that of the parent cell line PC9.

[0201] Example 3-4: Antitumor effect of HER3-ADC (1) on PC9 and PC9AZDR7 cell lines transplanted into nude mice PC9 and PC9AZDR7 cell lines were cultured in RPMI1640 medium (Sigma) containing 10% fetal bovine serum and 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.). PC9AZDR7 cell line was cultured in medium containing osimertinib at a final concentration of 100 nM. After culture, cells were detached by trypsin treatment, collected, and the number of cells in the cell suspension was measured to prepare each cell suspension. After transplanting 100 μL (5,000,000 cells) of each prepared cell suspension subcutaneously into the ventral side of 6-week-old female nude mice (BALB / cAJcl-nu / nu), the average estimated tumor volume of the transplanted tumor was approximately 200 mm. 3 When the tumor volume reached 100 μL / mouse, the mice were divided into groups and drug administration was started (day 0). HER3-ADC(1) was dissolved in phosphate-buffered saline (PBS) and adjusted to a concentration of 0.6 mg / mL. The prepared HER3-ADC(1) was administered intraperitoneally once on Day 0 at 100 μL / mouse (3 mg / kg). A control group was administered with PBS only. The control group consisted of 8 mice, and the HER3-ADC(1) group consisted of 9 mice. After the start of administration, the tumor diameters (long diameter, short diameter) were measured twice a week, and the estimated tumor volume of each group was calculated according to the formula shown below. The average estimated tumor volume of each group was then calculated.

[0202] Estimated tumor volume (Volume, mm 3 ) = major axis (mm) × minor axis (mm) 2 ÷2

[0203] In addition, the tumor growth inhibition rate of each group compared with the control group was calculated according to the formula shown below.

[0204] Tumor growth inhibition rate (%) = 100 - (mean estimated tumor volume of treatment group ÷ mean estimated tumor volume of control group × 100)

[0205] The antitumor effect of HER3-ADC(1) on the PC9 cell line is shown in Table 3 and Figure 9, and the antitumor effect of HER3-ADC(1) on the PC9AZDR7 cell line is shown in Table 4 and Figure 10. HER3-ADC(1) was not effective against the PC9 cell line (tumor growth inhibition rate on Day 21: 17%). In contrast, a significant antitumor effect (tumor growth inhibition rate on Day 18: 72%) was observed in the HER3-ADC(1) treatment group of PC9AZDR7 (unpaired t test p<0.05 on Day 18).

[0206] [Table 3]

[0207] [Table 4]

[0208] These results demonstrated that HER3-ADC(1) exhibited a significantly higher antitumor effect against the PC9AZDR7 cell line implanted in nude mice compared to the control group.

[0209] From the above, it has been demonstrated that administration of an anti-HER3 antibody-drug conjugate can provide a therapeutic agent and method for osimertinib-resistant non-small cell lung cancer.

[0210] Example 3-5: Antitumor effect of HER3-ADC(1) in combination with osimertinib against PC9AZDR7 cell line transplanted in nude mice The PC9AZDR7 cell line was cultured in RPMI1640 medium (Sigma) containing 10% fetal bovine serum, 1% penicillin-streptomycin B (Wako Pure Chemical Industries, Ltd.), and 100 nM osimertinib. After culturing the PC9AZDR7 cell line, it was detached by trypsin treatment, the cells were collected, the number of cells in the cell suspension was measured, and each cell suspension was prepared. After transplanting 100 μL (34 million cells) of each prepared cell suspension subcutaneously into the ventral side of 6-week-old female nude mice (BALB / cAJcl-nu / nu), the average estimated tumor volume of the transplanted tumor was approximately 60 mm. 3 When the mice reached this age, they were divided into groups (Day 0), and drug administration began the day after group division (Day 1). HER3-ADC(1) was dissolved in phosphate-buffered saline (PBS) and adjusted to a concentration of 0.1 mg / mL. Osimertinib was dissolved in distilled water for injection containing 0.1% dimethyl sulfoxide and 30% polyethylene glycol 300 and adjusted to a concentration of 0.2 mg / mL. In the single-agent groups, HER3-ADC(1) was administered intraperitoneally at 200 μL / mouse (1 mg / kg) on ​​Day 1, and osimertinib was administered orally at 100 μL / mouse (1 mg / kg) on ​​Days 1, 2, 3, 4, 5, 8, 9, 10, 11, 12, 15, 16, 17, 18, and 19. In the HER3-ADC(1) and osimertinib combination group, each drug was administered at the same dose and schedule as in the single-agent groups. A group that did not receive any administration was set up as a control group. The control group consisted of 11 mice, the HER3-ADC(1) single-agent group consisted of 12 mice, the osimertinib single-agent group consisted of 12 mice, and the HER3-ADC(1) and osimertinib combination group consisted of 10 mice. After the start of administration, tumor diameters (long diameter, short diameter) were measured twice a week, and the estimated tumor volume of each group was calculated according to the formula shown below. The average estimated tumor volume of each group was then calculated.

[0211] Estimated tumor volume (Volume, mm 3 ) = major axis (mm) × minor axis (mm) 2 ÷2

[0212] In addition, the tumor growth inhibition rate of each group compared with the control group was calculated according to the formula shown below.

[0213] Tumor growth inhibition rate (%) = 100 - (mean estimated tumor volume of treatment group ÷ mean estimated tumor volume of control group × 100)

[0214] The results are shown in Table 5 and Figure 11. The HER3-ADC(1) 1 mg / kg and osimertinib 1 mg / kg monotherapy groups did not show high efficacy against the PC9AZDR7 cell line (tumor growth inhibition rate on Day 21: HER3-ADC(1), 25.3%, osimertinib, 27.7%). In contrast, the combination treatment group of HER3-ADC(1) 1 mg / kg and osimertinib 1 mg / kg showed a significant antitumor effect (tumor growth inhibition rate on Day 21: 66.6%, p = 0.0057 for the HER3-ADC(1) monotherapy group on Day 21, p = 0.0092 for the osimertinib monotherapy group, Dunnett's test).

[0215] [Table 5]

[0216] [Table 6]

[0217] These results demonstrate that combined treatment with HER3-ADC(1) and osimertinib exhibits significantly greater antitumor effects against the PC9AZDR7 cell line implanted in nude mice than treatment with HER3-ADC(1) alone or osimertinib alone. [Sequence List Free Text]

[0218] SEQ ID NO: 1: Amino acid sequence of CDRH1 of anti-HER3 antibody (1) SEQ ID NO: 2: Amino acid sequence of CDRH2 of anti-HER3 antibody (1) SEQ ID NO: 3: Amino acid sequence of CDRH3 of anti-HER3 antibody (1) SEQ ID NO: 4: Amino acid sequence of CDRL1 of anti-HER3 antibody (1) SEQ ID NO: 5: Amino acid sequence of CDRL2 of anti-HER3 antibody (1) SEQ ID NO: 6: Amino acid sequence of CDRL3 of anti-HER3 antibody (1) SEQ ID NO: 7: Amino acid sequence of the heavy chain variable region of anti-HER3 antibody (1) SEQ ID NO: 8: Amino acid sequence of the light chain variable region of anti-HER3 antibody (1) SEQ ID NO: 9: Amino acid sequence of the heavy chain of anti-HER3 antibody (1) SEQ ID NO: 10: Amino acid sequence of the light chain of anti-HER3 antibody (1)

Claims

[Claim 1] The invention described herein.

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