Discovery of Novel Mcl‑1 Inhibitors with a 3‑Substituted‑1<i>H</i>‑indole-1-yl Moiety Binding to the P1–P3 Pockets to Induce Apoptosis in Acute Myeloid Leukemia Cells

Mcl-1 is a main antiapoptotic protein in acute myeloid leukemia (AML) and is used as a target to develop inhibitors. Currently, potent Mcl-1 inhibitors primarily interact with the P2–P4 pockets of Mcl-1, but pharmacological modulation by targeting the P1 pocket is less explored. We designed a series of 1H-indole-2-carboxylic acid compounds as novel Mcl-1 inhibitors occupying the P1–P3 pockets and evaluated their Mcl-1 inhibition and apoptosis induction in AML cells. Two-dimensional 15N-HSQC spectroscopy indicated that 47 (Ki = 24 nM) bound to the BH3 binding groove, occupied the P1 pocket in Mcl-1, and formed interactions with Lys234 and Val249. 47 exhibited good microsomal stability and pharmacokinetic profiles, with low potential risk of cardiotoxicity. 47 inhibited tumor growth in HL-60 and THP-1 xenograft models with growth inhibition rate of 63.7% and 57.4%, respectively. Collectively, 47 represents a novel Mcl-1 inhibitor targeting the P1–P3 pockets with excellent antileukemia effects.髓系细胞白血病1蛋白（Mcl-1）是急性髓系白血病（acute myeloid leukemia, AML）中主要的抗凋亡蛋白，亦是开发靶向抑制剂的核心靶点。当前强效Mcl-1抑制剂主要靶向结合Mcl-1的P2-P4口袋，而通过靶向P1口袋实现药理学调控的研究尚待深入探索。本研究设计了一系列1H-吲哚-2-羧酸类化合物作为新型Mcl-1抑制剂，这类化合物可占据Mcl-1的P1-P3口袋，并在AML细胞中评估了其Mcl-1抑制活性与凋亡诱导能力。二维15N-异核单量子相干谱实验结果显示，化合物47的抑制常数Ki为24 nM，可结合Mcl-1的BH3结合凹槽，占据其P1口袋，并与Lys234（赖氨酸234）、Val249（缬氨酸249）形成特异性相互作用。化合物47展现出良好的微粒体稳定性与药代动力学特性，且心脏毒性潜在风险较低。在HL-60与THP-1异种移植瘤模型中，化合物47可显著抑制肿瘤生长，肿瘤生长抑制率分别达63.7%与57.4%。综上，化合物47是一类靶向P1-P3口袋的新型Mcl-1抑制剂，具备优异的抗白血病活性。