Yefarchoan and colleagues evaluated the correlation between TMB and the objective response rate (ORR) in 27 tumour types among patients, receiving anti-PD-1 or anti-PDL-1 therapy, and observed that some cancers such as MCC responded to therapy better than what was predicted by TMB, suggesting that the emergence of viral antigens on some tumours may increase the response to anti-PD-1 therapy [112]. This evidence concerns the gene PDCD1 and Merkel cell skin cancer.