Footnotes

• Contributors HJK and S-HK had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: HJK, S-HK. Acquisition of data: HJK, S-HK, GK, NYP, H-MJ, H-JS, J-WH. Analysis and interpretation of data: HJK, S-HK, GK, NYP, H-MJ, H-JS, J-WH. Drafting of the manuscript: S-HK, HJK. Critical revision of the manuscript for important intellectual content: HJK, S-HK, GK, NYP, H-MJ, H-JS, J-WH. Statistical analysis: S-HK. Study supervision: HJK.

• Funding This work was supported by the National Research Foundation of Korea (Grant No NRF-2016R1D1A1A09916480) and by the Bio and Medical Technology Develop­ment Program (M3A9B6069339) through the Ministry of Science and ICT, Republic of Korea.

• Competing interests S-HK has received a grant from the National Research Foundation of Korea. S-HK has lectured, consulted and received honoraria from Bayer Schering Pharma, Biogen, Celltrion, Eisai, Genzyme, HanAll BioPharma, MedImmune, Merck Serono, Novartis, Teva-Handok and UCB; received a grant from the Ministry of Science and ICT; accepted research funding from Genzyme, Kael-GemVax, Merck Serono, Teva-Handok and UCB; serves on a steering committee for MedImmune; is a coeditor for the Multiple Sclerosis Journal-Experimental, Translational and Clinical, and an associated editor for the Journal of Clinical Neurology.

• Patient consent Obtained.

• Ethics approval This study was approved by the Institutional Review Board of the National Cancer Center.

• Provenance and peer review Not commissioned; externally peer reviewed.