CTLA4 and melanoma: Recent studies indicate that pembrolizumab or nivolumab are more effective than ipilimumab in advanced melanoma [5, 8], yet ipilimumab could further improve anti-tumor immune responses induced by nivolumab [8], indicating α-PD-1 and α-CTLA-4 antibodies have (partially) distinct mechanisms of action and we are currently awaiting long-term benefits of these (combined) treatment modalities.