CTLA4 and melanoma: Interestingly, blockade of these immune checkpoints with antibodies, such as ipilimumab (anti-CTLA-4), nivolumab (anti-PD-1), and pembrolizumab (anti-PD-1), successfully demonstrated efficacy in various solid tumors, predominantly melanoma and non-small cell lung cancer (NSCLC), and prolonged the survival of patients with extracranial disease [14,15,16].