JAK1 and neoplasm: The presence of two JAK1 mutations and the significantly lower IFN-γ expression both suggest complete loss of function of JAK1. We therefore considered these JAK1 frameshift mutations as a possible route for primary resistance mechanism to ICI, which may suggest that patients with dMMR/MSI-H tumours harbouring these JAK1 frameshift mutations are possibly not good candidates for ICI treatment and should be excluded from this treatment.