Lambrolizumab (MK-3475) is a humanized anti–PD-1 monoclonal antibody that has demonstrated significant benefit for those patients with advanced Malignant Melanoma regardless of their prior therapy with anti-CTLA 4 antibody, YERVOY® (Ipilimumab). The programmed death 1 (PD-1) receptor is an inhibitory receptor expressed on activated T-cells in the tumor micro environment. The anti–PD-1 antibody by blocking the PD-1 receptor essentially unleashes the immune system to fight off cancer cells. This information published in the NEJM in June 2013 and presented at the 2013 ASCO annual meeting gives an additional option for patients with advanced Malignant Melanoma.