0000000000066524
AUTHOR
Levi A. Garraway
The Genetic Landscape of Clinical Resistance to RAF Inhibition in Metastatic Melanoma.
Abstract 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 (…
Acquired BRAF inhibitor resistance: A multicenter meta-analysis of the spectrum and frequencies, clinical behaviour, and phenotypic associations of resistance mechanisms.
BackgroundAcquired resistance to BRAF inhibitors (BRAFi) is a near-universal phenomenon caused by numerous genetic and non-genetic alterations. In this study, we evaluated the spectrum, onset, pattern of progression, and subsequent clinical outcomes associated with specific mechanisms of resistance.MethodsWe compiled clinical and genetic data from 100 patients with 132 tissue samples obtained at progression on BRAFi therapy from 3 large, previously published studies of BRAFi resistance. These samples were subjected to whole-exome sequencing and/or polymerase chain reaction-based genetic testing.ResultsAmong 132 samples, putative resistance mechanisms were identified in 58%, including NRAS o…
AKT-independent signaling downstream of oncogenic PIK3CA mutations in human cancer.
SummaryDysregulation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway occurs frequently in human cancer. PTEN tumor suppressor or PIK3CA oncogene mutations both direct PI3K-dependent tumorigenesis largely through activation of the AKT/PKB kinase. However, here we show through phosphoprotein profiling and functional genomic studies that many PIK3CA mutant cancer cell lines and human breast tumors exhibit only minimal AKT activation and a diminished reliance on AKT for anchorage-independent growth. Instead, these cells retain robust PDK1 activation and membrane localization and exhibit dependency on the PDK1 substrate SGK3. SGK3 undergoes PI3K- and PDK1-dependent activation in PI…
The genetic landscape of clinical resistance to RAF inhibition in melanoma.
11009 Background: Although single-agent RAF inhibition has proved effective in metastatic BRAFV600-mutant melanoma, most patients relapse and some are intrinsically resistant. While several genetic resistance effectors have been identified, a comprehensive assessment of the genetic resistance spectrum in a large patient cohort may further inform resistance patterns and treatment strategies. Methods: Pre-treatment and post-relapse biopsies were obtained from BRAFV600melanoma patients treated with vemurafenib or dabrafenib. Whole exome sequencing of tumor and normal samples was performed to identify exome-wide mutations, insertion/deletions, and chromosomal copy number alterations. Since som…