The Effects of Treatment With Vemurafenib on the Immune System in Advanced Melanoma

Approximately 40-60 % of cutaneous melanomas select for a mutation in a protein called BRAF which is part of a signaling pathway called the Mitogen Activated Protein Kinase (MAPK) pathway. When BRAF is mutated the MAPK pathway remains active allowing for melanoma to grow. Vemurafenib is an oral treatment which blocks the activity of BRAF which leads to decreasing the activity of the MAPK pathway. When patients with melanoma expressing specific mutation in BRAF are treated with vemurafenib approximately 50% will develop a response to treatment with shrinkage of tumor. When compared to a standard chemotherapy called dacarbazine used to treat melanoma, treatment with vemurafenib leads to a statistically significant overall survival or living longer benefit. Because of this survival benefit vemurafenib was Food and Drug Administration (FDA) approved for the treatment of metastatic melanoma expressing a BRAF mutation called V600E BRAF. There is increasing evidence that the immune system can also be important in affecting melanoma growth and survival and there are immune treatments FDA approved for the treatment of metastatic melanoma. There is some limited evidence that blocking BRAF with vemurafenib may affect the activity of components of the immune system. It is important to better characterize and understand the effects of vemurafenib treatment on various components of the immune system. The purpose of this study is to systematically evaluate the effects of vemurafenib treatment (at FDA approved dosing regimen) on parts of the immune systems called the innate and adaptive immune systems. The hypothesis is that vemurafenib treatment will affect the immune system.