PDCD1 and melanoma: A population-based study conducted on 1435 melanoma patients from the SEER—Medicare database, treated with ICIs (ipilimumab, PD-1 inhibitors, or combination ipilimumab plus PD-1 inhibitor) in the period from 2012 to 2015, found that older melanoma patients treated with PD-1 inhibitors had prolonged survival compared to those treated with ipilimumab [80].