PDCD1 and melanoma: A landmark clinical trial called the CheckMate 067 clinical trial (ClinicalTrials.gov NCT01844505) used a combination CPI therapy with an anti-CTLA-4 antibody and an anti-PD-1 antibody This study was carried out on 945 patients with stage III or IV melanoma and evaluated the median overall survival under treatment with nivolumab plus ipilimumab or with nivolumab or ipilimumab monotherapy.