C-RAF mutations confer resistance to RAF inhibitors

R Antony, CM Emery, AM Sawyer, LA Garraway - Cancer research, 2013 - AACR
R Antony, CM Emery, AM Sawyer, LA Garraway
Cancer research, 2013AACR
Melanomas that contain B-RAFV600E mutations respond transiently to RAF and MEK
inhibitors; however, resistance to these agents remains a formidable challenge. Although B-
or C-RAF dysregulation represents prominent resistance mechanisms, resistance-
associated point mutations in RAF oncoproteins are surprisingly rare. To gain insights
herein, we conducted random mutagenesis screens to identify B-or C-RAF mutations that
confer resistance to RAF inhibitors. Whereas bona fide B-RAFV600E resistance alleles were …
Abstract
Melanomas that contain B-RAFV600E mutations respond transiently to RAF and MEK inhibitors; however, resistance to these agents remains a formidable challenge. Although B- or C-RAF dysregulation represents prominent resistance mechanisms, resistance-associated point mutations in RAF oncoproteins are surprisingly rare. To gain insights herein, we conducted random mutagenesis screens to identify B- or C-RAF mutations that confer resistance to RAF inhibitors. Whereas bona fide B-RAFV600E resistance alleles were rarely observed, we identified multiple C-RAF mutations that produced biochemical and pharmacologic resistance. Potent C-RAF resistance alleles localized to a 14-3-3 consensus binding site or a separate site within the P loop. These mutations elicited paradoxical upregulation of RAF kinase activity in a dimerization-dependent manner following exposure to RAF inhibitors. Knowledge of resistance-associated C-RAF mutations may enhance biochemical understanding of RAF-dependent signaling, anticipate clinical resistance to novel RAF inhibitors, and guide the design of “next-generation” inhibitors for deployment in RAF- or RAS-driven malignancies. Cancer Res; 73(15); 4840–51. ©2013 AACR.
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