The Genetic Landscape of Clinical Resistance to RAF Inhibition in Metastatic Melanoma
Menée sur des échantillons tumoraux prélevés sur 45 patients atteints d'un mélanome métastatique présentant la mutation V600E du gène BRAF et ayant été traités à l'aide de vémurafenib ou dabrafenib, cette étude met en évidence un ensemble d'anomalies dans des gènes associés à la résistance aux inhibiteurs de RAF
Most patients with BRAFV600-mutant metastatic melanoma develop resistance to selective RAF kinase inhibitors. The spectrum of clinical genetic resistance mechanisms to RAF inhibitors and options for salvage therapy are incompletely understood. We performed whole-exome sequencing on formalin-fixed, paraffin-embedded tumors from 45 patients with BRAFV600-mutant metastatic melanoma who received vemurafenib or dabrafenib monotherapy. Genetic alterations in known or putative RAF inhibitor resistance genes were observed in 23 of 45 patients (51%). Besides previously characterized alterations, we discovered a “long tail” of new mitogen-activated protein kinase (MAPK) pathway alterations (MAP2K2, MITF) that confer RAF inhibitor resistance. In three cases, multiple resistance gene alterations were observed within the same tumor biopsy. Overall, RAF inhibitor therapy leads to diverse clinical genetic resistance mechanisms, mostly involving MAPK pathway reactivation. Novel therapeutic combinations may be needed to achieve durable clinical control of BRAFV600-mutant melanoma. Integrating clinical genomics with preclinical screens may model subsequent resistance studies. SIGNIFICANCE: The use of RAF inhibitors for BRAFV600-mutant metastatic melanoma improves patient outcomes, but most patients demonstrate early or acquired resistance to this targeted therapy. We reveal the genetic landscape of clinical resistance mechanisms to RAF inhibitors from patients using whole-exome sequencing, and experimentally assess new observed mechanisms to define potential subsequent treatment strategies. Cancer Discov; 4(1); 1–16. ©2013 AACR.