Conflict of interest

TN has received personal fees from Chugai Pharmaceutical Co., Ltd., Eli Lilly Japan K.K., Daiichi Sankyo Co., Ltd., AstraZeneca K.K., Taiho Pharmaceutical Co., Ltd., Eisai Co., Ltd., Pfizer Japan Inc., MSD K.K., Novartis Pharma K.K., Sandoz K.K., and Celltrion Inc. NN reports consulting or advisory roles for AstraZeneca K.K., Chugai Pharmaceutical Co., Ltd., and Daiichi Sankyo Co., Ltd.; and has received lecture fees from AstraZeneca K.K., Eisai Co., Ltd., Pfizer Japan Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eli Lilly Japan K.K., and Nippon Kayaku Co., Ltd.; and has received research funding from Pfizer Japan Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eli Lilly Japan K.K., and Nippon Kayaku Co., Ltd. TY has received lecture fees from AstraZeneca K.K., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo Co., Ltd., Eisai Co., Ltd., Eli Lilly Japan K.K., Kyowa Kirin Co., Ltd., Novartis Pharma K.K., and Pfizer Japan Inc. KI has received research funding from Daiichi Sankyo Co., Ltd., AstraZeneca K.K., Chugai Pharmaceutical Co., Ltd., MSD K.K., and Ono Pharmaceutical Co., Ltd. M Yamaguchi has received speakers’ bureau from Pfizer Japan Inc., Novartis Pharma K.K., Taiho Pharmaceutical Co., Ltd., Eli Lilly Japan K.K., Medicon, Inc., Kyowa Kirin Co., Ltd., Chugai Pharmaceutical Co., Ltd., and Daiichi Sankyo Co., Ltd. TA has received speakers’ bureau from Chugai Pharmaceutical Co., Ltd., Pfizer Japan Inc., Eli Lilly Japan K.K., and AstraZeneca K.K. NS reports consulting or advisory roles for Kyowa Kirin Co., Ltd. and Chugai Pharmaceutical Co., Ltd.; and has received speakers’ bureau from Daiichi Sankyo Co., Ltd., Kyowa Kirin Co., Ltd., Pfizer Japan Inc., Eisai Co., Ltd., Yakult Honsha Co., Ltd., Taiho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Co., Ltd., AstraZeneca K.K., Merck Biopharma Co., Ltd., Bayer Yakuhin, Ltd., Eli Lilly Japan K.K., Ono Pharmaceutical Co., Ltd., and Nippon Kayaku Co., Ltd.; and has received research funding from Daiichi Sankyo Co., Ltd., Ono Pharmaceutical Co., Ltd., and MSD K.K. JT reports consulting or advisory roles for Daiichi Sankyo Co., Ltd., AstraZeneca K.K., Eisai Co., Ltd., Eli Lilly Japan K.K., and Seagen Inc.; and has received speakers’ bureau from Daiichi Sankyo Co., Ltd., Eisai Co., Ltd., Eli Lilly Japan K.K., and Kyowa Kirin Co., Ltd.; and has received research funding from Daiichi Sankyo Co., Ltd., AstraZeneca K.K., Eisai Co., Ltd., Eli Lilly Japan K.K., Seagen Inc., Kyowa Kirin Co., Ltd., Sant Joan de Déu Research Foundation, and West Japan Oncology Group. DT, TT, AB, and KS are employees of Daiichi Sankyo Co., Ltd. M Yamamoto, KM, ST, HN, SK, AS, YO, and SS have no conflicts of interest to disclose.

Ethical approval

This study was approved by the centralized authority (the ethics review committee at Tokeikai Kitamachi Clinic, reference number: DSY08309), as well as by the individual ethics committees at each study center. The study was conducted in accordance with the Declaration of Helsinki and adhered to local ethical guidelines.

Informed consent

This study was conducted using an opt-out approach. As the study was non-interventional and non-invasive, the need to obtain informed consent from patients was waived as per local ethical guidelines.