Pembrolizumab-programmed cell death protein 1 (PD-1) immune checkpoint inhibitor has been reported to elicit a 56% response rate in a 26-patient MCC cohort [12] and avelumab-programmed death-ligand 1 (PD-L1) inhibitor a 31.8% response rate in a heavily pretreated 88-patient MCC cohort, with a higher response rate in patients not previously exposed to chemotherapy [13]. Here, PDCD1 is linked to Merkel cell skin cancer.