BRAF inhibitor resistance mechanisms in metastatic melanoma

Spectrum and clinical impact

Helen Rizos*, Alexander M. Menzies, Gulietta M. Pupo, Matteo S. Carlino, Carina Fung, Jessica Hyman, Lauren E. Haydu, Branka Mijatov, Therese M. Becker, Suzanah C. Boyd, Julie Howle, Robyn Saw, John F. Thompson, Richard F. Kefford, Richard A. Scolyer, Georgina V. Long

*Corresponding author for this work

Research output: Contribution to journalArticle

276 Citations (Scopus)

Abstract

Purpose: Multiple BRAF inhibitor resistance mechanisms have been described, however, their relative frequency, clinical correlates, and effect on subsequent therapy have not been assessed in patients with metastatic melanoma. Experimental Design: Fifty-nine BRAFV600-mutant melanoma metastases from patients treated with dabrafenib or vemurafenib were analyzed. The genetic profile of resistance mechanisms and tumor signaling pathway activity was correlated with clinicopathologic features and therapeutic outcomes. Results: Resistance mechanisms were identified in 58% progressing tumors and BRAF alterations were common. Gene expression analysis revealed that mitogen-activated protein kinase (MAPK) activity remained inhibited in 21% of resistant tumors, and the outcomes of patients with these tumors were poor. Resistance mechanisms also occurred in pretreatment biopsies and heterogeneity of resistance mechanisms occurred within patients and within tumors. There were no responses to subsequent targeted therapy, even when a progressing tumor had a resistance mechanism predicted to be responsive. Conclusions: Selecting sequential drugs based on the molecular characteristics of a single progressing biopsy is unlikely to provide improved responses, and first-line therapies targeting multiple pathways will be required.

Original languageEnglish
Pages (from-to)1965-1977
Number of pages13
JournalClinical Cancer Research
Volume20
Issue number7
DOIs
Publication statusPublished - 1 Apr 2014
Externally publishedYes

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