The receptor tyrosine kinase rearranged during transfection (RET) plays pivotal roles in several cancers, including thyroid carcinoma and non-small cell lung cancer (NSCLC). Currently, there are several FDA-approved RET inhibitors, but their indication is limited to thyroid cancer, and none can overcome their gatekeeper mutants (V804L and V804M). Here, we report the discovery of 9x representing a new chemotype of potent and selective RET inhibitors, using a rational design strategy of type II kinase inhibitors. 9x exhibited both superior antiproliferative activities against NSCLC-related carcinogenic fusions KIF5B-RET and CCDC6-RET and gatekeeper mutant-transformed Ba/F3 cells, with the lowest GI₅₀ of 9 nM, and substantial inhibitory activities against wild-type RET and RET mutant proteins, with the best IC₅₀ of 4 nM. More importantly, 9x also showed nanomole potency against RET-positive NSCLC cells LC-2/ad, but not against a panel of RET-negative cancer cells, such as A549, H3122, A375 or parental Ba/F3 cells, demonstrating its selective ‘on-target’ effect. In mouse xenograft models, 9x repressed tumor growth driven by both wild type KIF5B-RET-Ba/F3 and gatekeeper mutant KIF5B-RET(V804M)-Ba/F3 cells in a dose-dependent manner. Together, these data establish that 9x provides a good starting point for the development of targeted therapeutics against RET-positive cancers, especially NSCLC.

转染过程中重排的受体酪氨酸激酶（RET）在几种癌症中起关键作用，包括甲状腺癌和非小细胞肺癌（NSCLC）。当前，有几种FDA批准的RET抑制剂，但它们的适应症仅限于甲状腺癌，没有一个能克服其Gatekeeper突变体（V804L和V804M）。在这里，我们报告使用II型激酶抑制剂的合理设计策略，发现了9x代表有效和选择性RET抑制剂的新化学型的发现。9x对NSCLC相关致癌融合KIF5B-RET和CCDC6-RET以及关守突变体转化的Ba / F3细胞均显示出优异的抗增殖活性，且GI ₅₀最低9 nM，对野生型RET和RET突变蛋白具有显着的抑制活性，最佳IC ₅₀为4 nM。更重要的是，9x还显示出对RET阳性NSCLC细胞LC-2 / ad的纳摩尔效价，但对一组RET阴性癌细胞（如A549，H3122，A375或亲代Ba / F3细胞）没有纳摩尔效价，表明其选择性'目标上的效果。在小鼠异种移植模型中，9x抑制了野生型KIF5B-RET-Ba / F3和网守突变KIF5B-RET（V804M）-Ba / F3细胞驱动的肿瘤生长，呈剂量依赖性。总之，这些数据确定9x为针对RET阳性癌症（尤其是NSCLC）的靶向治疗药物的开发提供了良好的起点。