This is a phase II, randomized study which will enroll participants given 4 to 6 cycles of first-line platinum-based chemotherapy treatment for advanced penile SCC not amenable by curative surgical treatment (stages III-IV as per American Joint Committeeon Cancer - AJCC - 8th) recurrent and who did not progress at the end of these 4 to 6 cycles. Participants eligible for the study will be randomized between 4 and 8 weeks after the last chemotherapy cycle to receive: - Cemiplimab maintenance plus best supportive care: cemiplimab 350 mg IV every 3 weeks until week 24, disease progression, unacceptable toxicity or consent withdrawal. patients who continue to derive clinical benefit on the experimental arm may continue to receive treatment until week 48. - Best supportive care.