<prompt> Pembrolizumab is used for which conditionMetastatic MelanomaBasal cell carcinoma skinSquamous cell carcinoma of skinPemphigus vulgaris  <response>: PD-1 inhibitors pembrolizumab, nivolumab Ipilimumab was the first checkpoint inhibitor to improve overall survival in randomized phase III trials of advanced melanoma; however, checkpoint inhibitors that target the Programmed cell death-1 PD-1 receptor have quickly become the preferred approach to immunotherapy since they are more effective and have fewer side effects PD-1 is an immune checkpoint receptor expressed by activated T cells Normally functions as a brake on the immune response PD-1 on activated T cells binds to its ligands PD1-L1 B7-H1 and PD1-L2 B7-DC, which are expressed on tumor cells - deactivation of T cells - loss of immune response against tumor Nivolumab and pembrolizumab Monoclonal antibodies that target PD-1 - prevent T cell deactivation - immune-mediated tumoricidal activity Both are FDA approved for advanced melanoma Phase 3 RCTs in patients wadvanced melanoma have demonstrated overall survival, progression-free survival, and fewer side effects with either agent when compared to ipilimumab or conventional chemotherapy Some patients have durable responses even after completion of treatment Efficacy improved when used in combination with ipilimumab main disadvantage immune mediated side effects Most common adverse events: fatigue, pruritus, and rash Less common far less common than w ipilimumab: pneumonitis, colitis, hepatitis, nephritis and renal dysfunction, and thyroid dysfunction. Ref:- Review of Dermatology by Alikhan; pg num:-41 