Gene expression profiling of B9 cells in response to two classes of BRAF inhibitors

Selective RAF inhibitors including vemurafenib (PLX4032) have demonstrated clinical efficacy in mutant BRAF driven metastatic melanoma. The clinical effectiveness of RAF inhibitors depends on near complete abolition of the MAPK pathway output in tumors harboring BRAF mutations. However these compounds paradoxically activate the MAPK pathway in cells bearing oncogenic RAS or elevated upstream receptor signaling. This paradox can promote cellular proliferation and can manifest clinically with progression of secondary malignancies such as cutaneous squamous cell carcinomas (cuSCC). We have identified next generation RAF inhibitors (paradox breakers, e.g. PLX7904) that inhibit mutant BRAF cells without activating the MAPK pathway in cells bearing upstream activation.

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Zhang C, Spevak W, Zhang Y, Burton EA, Ma Y, Habets G, Zhang J, Lin J, Ewing T, Matusow B, Tsang G, Marimuthu A, Cho H, Wu G, Wang W, Fong D, Nguyen H, Shi S, Womack P, Nespi M, Shellooe R, Carias H, Powell B, Light E, Sanftner L, Walters J, Tsai J, West BL, Visor G, Rezaei H, Lin PS, Nolop K, Ibrahim PN, Hirth P, Bollag G