Conflict of interest

Hiroshi Imamura has received honoraria from Taiho Pharmaceutical Co., Ltd. Kazuhiro Nishikawa has received honoraria from Bristol-Myers Squibb Co., Ltd., Daiichi Sankyo, Co., Ltd., EA Pharma Co., Ltd., Eli Lilly Japan K.K., MSD K.K., Ono Pharmaceutical Co., Ltd., and Taiho Pharmaceutical Co., Ltd. Hisato Kawakami has has received honoraria from BMS K.K., ONO Pharmaceutical Co., LTD., Eli Lilly Japan K.K., MSD K.K., and Daiichi Sankyo, Co., Ltd., fees for promotional materials from ONO Pharmaceutical Co., LTD., üMSD K.K., and Daiichi Sankyo, Co., Ltd., and research funding from BMS K.K., Eisai Co., Ltd., and Kobayashi Pharmaceutical Co. Ltd. Daisuke Sakai has received honoraria from Daiichi Sankyo Co. Ltd., and Chugai Pharmaceutical Co., Ltd., and research funding from Eli Lilly Japan K.K., Daiichi Sankyo Co., Ltd., and Taiho Pharmaceutical Co., Ltd. Yukinori Kurokawa has received lecture fees and research grant from Taiho Pharmaceutical Co., Ltd. Taroh Satoh has received honoraria from ONO Pharmaceutical Co., Yakult Honsha Co., Ltd., Chugai Pharmaceutical Co., Eli Lilly Japan K.K., Bristol-Myers Squibb Co. Ltd., MSD K.K., and Taiho Pharmaceutical Co., Ltd., research funding from ONO Pharmaceutical Co., Chugai Pharmaceutical Co., Eli Lilly Japan K.K., Bristol-Myers Squibb Co. Ltd., MSD K.K., Taiho Pharmaceutical Co., Ltd., and Hutch Med Co., Ltd., scholarship donations from Taiho Pharmaceutical Co., Ltd., and endowed chairs from ONO Pharmaceutical Co., Yakult Honsha Co., Ltd., and Chugai Pharmaceutical Co. All the remaining authors have no conflicts of interest to declare.

Ethical approval

All procedures in this study were conducted in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants before entry into the study.