Targeted molecular therapy in melanoma

Abstract

Immunotherapy and chemotherapy benefit few patients with metastatic melanoma, and even fewer experience durable survival benefit. These poor results may come from treating all melanomas as though they are biologically homogeneous. Recently, it has been shown that targeting specific activated tyrosine kinases (oncogenes) can have striking clinical benefits in patients with melanoma. In 2002, a V600E mutation of the BRAF serine/threonine kinase was described as present in more than 50% of all melanomas. The mutation appeared to confer a dependency by the melanoma cancer cell on activated signaling through mitogen-activated protein kinase pathway. The frequency and focality of this mutation (>95% of all BRAF mutations being at V600 position) suggested its importance in melanoma pathophysiology and potential as a target for therapy. The recent results of a phase 1 study with PLX4032/RG7204, a small molecule RAF inhibitor, confirm this hypothesis. Mucosal and acral-lentiginous melanomas, comprising 3% of all melanomas, frequently harbor activating mutations of c-kit and drugs targeting this mutation seem to confer similar benefits for these types of tumors. Here we provide an overview of the targeted therapy development in melanoma with emphasis on BRAF inhibition because of its prevalence and possibility of transforming the care of many melanoma patients.