Discovery and Characterization of 2,5-Substituted Benzoic Acid Dual Inhibitors of the Anti-apoptotic Mcl‑1 and Bfl‑1 Proteins

Anti-apoptotic Bcl-2 family proteins are overexpressed in a wide spectrum of cancers and have become well validated therapeutic targets. Cancer cells display survival dependence on individual or subsets of anti-apoptotic proteins that could be effectively targeted by multimodal inhibitors. We designed a 2,5-substituted benzoic acid scaffold that displayed equipotent binding to Mcl-1 and Bfl-1. Structure-based design was guided by several solved cocrystal structures with Mcl-1, leading to the development of compound 24, which binds both Mcl-1 and Bfl-1 with Ki values of 100 nM and shows appreciable selectivity over Bcl-2/Bcl-xL. The selective binding profile of 24 was translated to on-target cellular activity in model lymphoma cell lines. These studies lay a foundation for developing more advanced dual Mcl-1/Bfl-1 inhibitors that have potential to provide greater single agent efficacy and broader coverage to combat resistance in several types of cancer than selective Mcl-1 inhibitors alone.抗凋亡Bcl-2家族蛋白（anti-apoptotic Bcl-2 family proteins）在多种癌症中广泛过表达，且已被充分验证为治疗靶点。癌细胞对单个或特定亚型的抗凋亡蛋白存在生存依赖性，此类蛋白可通过多模式抑制剂实现有效靶向。我们设计了一种2,5-取代苯甲酸骨架（2,5-substituted benzoic acid scaffold），其对Mcl-1与Bfl-1可实现等效结合。基于结构的药物设计以多个已解析的Mcl-1共晶结构为指导，最终开发出化合物24：该化合物对Mcl-1和Bfl-1的结合抑制常数（Ki）均为100 nM，且相较于Bcl-2/Bcl-xL展现出显著的选择性。化合物24的选择性结合特征在淋巴瘤模型细胞系中转化为靶向细胞活性。本研究为开发更先进的双靶点Mcl-1/Bfl-1抑制剂奠定了基础；相较于单一选择性Mcl-1抑制剂，此类抑制剂有望实现更强的单药疗效，并能更广泛地覆盖多种癌症的耐药情况。