PDCD1 and cancer: These findings may suggest that GISTs progressed on IM and treated with SU or REG are the better potential candidates for future clinical trials of ICIs against advanced GISTs, as high PD-L1 expression of tumour or immune cells was correlated with better efficacy with anti-PD-1 or anti-PD-L1 inhibitors in other cancer types.16,17 Based on the design of the current study, our results do not preclude the possibility that these changes are a result of natural course of disease progression.