Bruton's Tyrosine Kinase (BTK) functions as a key regulator of B-cell receptor (BCR) signaling pathway, which is frequently hyperactivated in a variety of lymphoma cancers. Using Proteolysis Targeting Chimera (PROTAC) technology, we have recently discovered a highly potent ARQ-531-derived BTK PROTAC 6e, inducing effective degradation of both wild type (WT) and C481S mutant BTK proteins. However, the poor metabolic stability of PROTAC 6e have limited its further in vivo studies. Herein, we present our structure-activity relationship (SAR) studies on modifying PROTAC 6e using linker rigidification strategy to identify a novel cereblon (CRBN)-recruiting compound 3e that induced BTK degradation in a concentration-dependent manner but had no effect on reducing the level of CRBN neo-substrates. Moreover, compound 3e suppressed the cell growth more potently than the small molecule inhibitors ibrutinib and ARQ-531 in several cells. Furthermore, compound 3e with the rigid linker displayed a significantly improved metabolic stability profile with the T_1/2 increased to more than 145 min. Overall, we discovered a highly potent and selective BTK PROTAC lead compound 3e, which could be further optimized as potential BTK degradation therapy for BTK-associated human cancers and diseases.

Bruton 酪氨酸激酶 (BTK) 作为 B 细胞受体 (BCR)信号通路的关键调节剂发挥作用，该通路在多种淋巴瘤癌症中经常过度激活。使用蛋白水解靶向嵌合体 (PROTAC) 技术，我们最近发现了一种高效的 ARQ-531 衍生的 BTK PROTAC6e，可诱导野生型 (WT) 和 C481S 突变体 BTK 蛋白的有效降解。然而，PROTAC 6e较差的代谢稳定性限制了其进一步的体内研究。在此，我们介绍了我们的构效关系 (SAR) 研究，即使用连接基刚性化策略修饰 PROTAC6e以鉴定新型大脑 (CRBN) 募集化合物3e以浓度依赖性方式诱导 BTK 降解，但对降低 CRBN 新底物的水平没有影响。此外，在几种细胞中，化合物3e比小分子抑制剂 ibrutinib 和 ARQ-531 更有效地抑制细胞生长。此外，具有刚性接头的化合物3e显示出显着改善的代谢稳定性特征，T _1/2增加到超过 145 分钟。总的来说，我们发现了一种高效且具有选择性的 BTK PROTAC 先导化合物3e，它可以进一步优化为 BTK 相关人类癌症和疾病的潜在 BTK 降解疗法。