On the basis of remarkable antitumor activity, programmed death receptor-1 (PD-1) inhibitors pembrolizumab and nivolumab were approved for the treatment of advanced melanoma in the second-line setting following progression on either CTLA-4 inhibitor ipilimumab or BRAF/MEK inhibitors (for BRAF mutated melanoma). The gene discussed is CTLA4; the disease is melanoma.