Notably, in the small but relevant subgroup of patients with microsatellite instability, which is characterized by high tumour mutational burden and CD8-positive T-cell infiltrates and is susceptible to immune-checkpoint inhibition25,28–30, longer overall survival and higher ORR were observed with nivolumab plus ipilimumab versus chemotherapy in CheckMate 649. This evidence concerns the gene CD8A and neoplasm.