Targeted protein degradation of neosubstrates plays a crucial role in hematological cancer treatment involving immunomodulatory imide drugs (IMiDs) therapy. Nevertheless, the persistence of inevitable drug resistance and hematological toxicities represents a significant obstacle to their clinical effectiveness. Phenotypic profiling of a small molecule compounds library in multiple hematological cancer cell lines was conducted to screen for hit degraders. Molecular dynamic-based rational design and cell-based functional assays were conducted to develop more potent degraders. Multiple myeloma (MM) tumor xenograft models were employed to investigate the antitumor efficacy of the degraders as single or combined agents with standard of care agents. Unbiased proteomics was employed to identify multiple therapeutically relevant neosubstrates targeted by the degraders. MM patient-derived cell lines (PDCs) and a panel of solid cancer cell lines were utilized to investigate the effects of candidate degrader on different stage of MM cells and solid malignancies. Unbiased proteomics of IMiDs-resistant MM cells, cell-based functional assays and RT-PCR analysis of clinical MM specimens were utilized to explore the role of BRD9 associated with IMiDs resistance and MM progression. We identified a novel cereblon (CRBN)-dependent lead degrader with phthalazinone scaffold, MGD-4, which induced the degradation of Ikaros proteins. We further developed a novel potent candidate, MGD-28, significantly inhibited the growth of hematological cancer cells and induced the degradation of IKZF1/2/3 and CK1α with nanomolar potency via a Cullin-CRBN dependent pathway. Oral administration of MGD-4 and MGD-28 effectively inhibited MM tumor growth and exhibited significant synergistic effects with standard of care agents. MGD-28 exhibited preferentially profound cytotoxicity towards MM PDCs at different disease stages and broad antiproliferative activity in multiple solid malignancies. BRD9 modulated IMiDs resistance, and the expression of BRD9 was significant positively correlated with IKZF1/2/3 and CK1α in MM specimens at different stages. We also observed pronounced synergetic efficacy between the BRD9 inhibitor and MGD-28 for MM treatment. Our findings present a strategy for the multi-targeted degradation of Ikaros proteins and CK1α against hematological cancers, which may be expanded to additional targets and indications. This strategy may enhance efficacy treatment against multiple hematological cancers and solid tumors.

中文翻译：

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通过多种新底物降解，针对广泛的血液癌细胞系的新型有效分子胶降解剂


新底物的靶向蛋白质降解在涉及免疫调节酰亚胺药物 (IMiD) 治疗的血液癌症治疗中发挥着至关重要的作用。然而，不可避免的耐药性和血液学毒性的持续存在对其临床有效性构成了重大障碍。对多种血液癌细胞系中的小分子化合物库进行表型分析，以筛选命中降解剂。进行了基于分子动力学的合理设计和基于细胞的功能测定，以开发更有效的降解剂。采用多发性骨髓瘤 (MM) 肿瘤异种移植模型来研究降解剂作为单一药物或与标准护理药物组合的抗肿瘤功效。采用无偏见的蛋白质组学来识别降解剂靶向的多种治疗相关的新底物。利用 MM 患者来源的细胞系 (PDC) 和一组实体癌细胞系来研究候选降解剂对不同阶段的 MM 细胞和实体恶性肿瘤的影响。利用 IMiDs 耐药性 MM 细胞的无偏蛋白质组学、基于细胞的功能测定和临床 MM 标本的 RT-PCR 分析来探索 BRD9 与 IMiDs 耐药性和 MM 进展相关的作用。我们鉴定了一种新型 cereblon (CRBN) 依赖性铅降解剂，具有二氮杂萘酮支架 MGD-4，它能诱导 Ikaros 蛋白的降解。我们进一步开发了一种新的有效候选药物 MGD-28，它能够通过 Cullin-CRBN 依赖性途径显着抑制血液癌细胞的生长，并以纳摩尔级的效力诱导 IKZF1/2/3 和 CK1α 的降解。 口服 MGD-4 和 MGD-28 可有效抑制 MM 肿瘤生长，并与标准护理药物表现出显着的协同效应。 MGD-28 在不同疾病阶段对 MM PDC 优先表现出深刻的细胞毒性，并在多种实体恶性肿瘤中表现出广泛的抗增殖活性。 BRD9调节IMiDs耐药性，不同阶段MM标本中BRD9的表达量与IKZF1/2/3和CK1α呈显着正相关。我们还观察到 BRD9 抑制剂和 MGD-28 在 MM 治疗中具有显着的协同功效。我们的研究结果提出了一种针对血液癌症的 Ikaros 蛋白和 CK1α 多靶点降解策略，该策略可能会扩展到其他靶点和适应症。该策略可能会增强针对多种血液癌症和实体瘤的疗效。