Immunophenotyping of Melanoma Patients on Treatment With Pembrolizumab

Immunotherapy is a new approach to treating cancers and the major side effects are classed as autoimmune because the immune system is targeting itself. Currently doctors are not able to identify patients at higher risk of developing such autoimmune toxicities and nor are doctors able to identify patients more likely to respond to such treatment. Markers in the immune system have already been identified which are associated with naturally occurring autoimmune diseases. In this study the investigators will examine immune cells from patients with advanced malignant melanoma receiving immunotherapy treatment with Pembrolizumab to see if similar immune system markers can be identified and if such markers may be related to the development of autoimmune side effects or response to treatment. This would enable better selection of patients for treatment with immunotherapy.