BRAF^V600E is the most common activating mutation in melanoma and patients treated with BRAF^V600E inhibitors all develop resistance within one year. A significant resistance pathway is paradoxical activation (transactivation) involving BRAF dimers, whereby an inhibitor bound protein subunit allosterically activates the other subunit. We recently reported on dimeric BRAF^V600E -selective vemurafenib inhibitors that stabilize an inactive αC-out/αC-out homodimeric conformation with improved inhibitor potency and selectivity in vitro. We set out to extend this strategy to target RAF homo- and heterodimers with the pan-RAF inhibitor TAK632 in dimeric configuration. Surprisingly, we find that monomeric TAK632 induces an active αC-in/αC-in BRAF dimer conformation, while dimeric TAK inhibitors cannot promote BRAF dimers and have significantly compromised potency in vitro. These studies uncover the intimate connection between BRAF dimerization and TAK632 mode of inhibition and highlight the importance of understanding the impact of BRAF inhibitors on kinase dimerization.

中文翻译：

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N-（7-氰基-6-（4-氟-3-（2-（3-（三（三氟甲基）苯基）乙酰胺基）苯氧基）苯并[d]噻唑-2-基）环丙烷甲酰胺（TAK632）通过抑制BRAF抑制二聚体的诱导

BRAF ^V600E是黑色素瘤中最常见的激活突变，接受BRAF ^V600E抑制剂治疗的患者均在一年内产生耐药性。一个重要的抗性途径是涉及BRAF二聚体的反常激活（反式激活），由此抑制剂结合的蛋白亚基变构地激活其他亚基。我们最近报道了BRAF ^V600E二聚体选择性维罗非尼抑制剂，可稳定无活性的αC-out/αC-out同型二聚体构象，并在体外具有增强的抑制剂效价和选择性。我们着手将这一策略扩展为以二聚体构型的pan-RAF抑制剂TAK632靶向RAF同型和异二聚体。出乎意料的是，我们发现单体TAK632诱导了活跃的αC-in/αC-inBRAF二聚体构象，而二聚体TAK抑制剂则不能促进BRAF二聚体，并且在体外具有显着降低的效能。这些研究揭示了BRAF二聚化与TAK632抑制模式之间的密切联系，并强调了理解BRAF抑制剂对激酶二聚化影响的重要性。