Data from A Novel, Selective, and Efficacious Nanomolar Pyridopyrazinone Inhibitor of <sup>V600E</sup>BRAF

Oncogenic BRAF is a critical driver of proliferation and survival and is thus a validated therapeutic target in cancer. We have developed a potent inhibitor, termed 1t (CCT239065), of the mutant protein kinase, ^V600EBRAF. 1t inhibits signaling downstream of ^V600EBRAF in cancer cells, blocking DNA synthesis, and inhibiting proliferation. Importantly, we show that 1t is considerably more selective for mutated BRAF cancer cell lines compared with wild-type BRAF lines. The inhibitor is well tolerated in mice and exhibits excellent oral bioavailability (F = 71%). Suppression of ^V600EBRAF-mediated signaling in human tumor xenografts was observed following oral administration of a single dose of 1t. As expected, the growth rate in vivo of a wild-type BRAF human tumor xenograft model is unaffected by inhibitor 1t. In contrast, 1t elicits significant therapeutic responses in mutant BRAF–driven human melanoma xenografts. Cancer Res; 70(20); 8036–44. ©2010 AACR.