DC reports research grants from Roche, and 4SC, and provision of investigational medicinal product from Merck and Leap Therapeutics to support academic trials assessing anti-PD-L1 antibodies in gastrointestinal cancer; grants from Clovis, Eli Lilly, Bayer, and Celgene, unrelated to the topic of this Comment; and is on the scientific advisory board of OVIBIO, unrelated to the topic of this Comment. DC receives funding as the Director of the National Institute for Health Research Biomedical Research Centre at the Royal Marsden Hospital and the Institute of Cancer Research. The views expressed are those of the authors and not necessarily those of the UK National Institute for Health Research or the Department of Health and Social Care. SS declares no competing interests.