HSP90 is ubiquitously overexpressed in a broad spectrum of human cancers and has been recognized as an attractive target for cancer treatment. Here, we described the fragment screening, synthesis and structure-activity relationship studies of small molecule inhibitors with 4,5-diarylisoxazole scaffold targeting HSP90. Among them, the compound N-(3-(2,4-dihydroxy-5-isopropylphenyl)-4-(4-((4-morpholinopiperidin-1-yl)methyl)phenyl)isoxazol-5-yl)cyclopropanecarboxamide (108) showed high affinity for binding to HSP90 (FP binding assay, IC₅₀ = 0.030 μM) and inhibited the proliferation of various human cancer cell lines with averaging GI₅₀ about 88 nM. Compound 108 exhibited its functional inhibition of HSP90 by depleting key signaling pathways and concomitantly elevating of HSP70 and HSP27 in U-87MG cells. Further in vivo studies showed that compound 108 strongly suppressed the tumor growth of human glioblastoma xenograft model U-87MG with T/C = 18.35% at 50 mg/kg q3w/2.5w. Moreover, compound 108 also exhibited good pharmacokinetic properties. Together, our study implicates that compound 108 is a promising candidate of HSP90 inhibitor and is currently advanced to preclinical study.

HSP90在广泛的人类癌症中普遍存在过表达，并且已被公认为是癌症治疗的诱人靶标。在这里，我们描述了靶向HSP90的4,5-二芳基异恶唑支架的小分子抑制剂的片段筛选，合成和构效关系研究。其中，化合物N-（3-（2,4-二羟基-5-异丙基苯基）-4-（4-（（4-吗啉代哌啶-1-基）甲基）苯基）异恶唑-5-基）环丙烷甲酰胺（108）显示出与HSP90结合的高亲和力（FP结合测定，IC ₅₀  = 0.030μM），并以GI ₅₀平均约为88 nM抑制了各种人类癌细胞系的增殖。化合物108通过消耗关键信号通路并同时升高U-87MG细胞中的HSP70和HSP27，其对HSP90的功能受到抑制。进一步体内研究表明，化合物108强烈抑制人成胶质细胞瘤异种移植物型号U-87MG与T / C = 18.35％的肿瘤生长，在50毫克/公斤Q3W /2.5瓦特 此外，化合物108还表现出良好的药代动力学性质。总之，我们的研究表明化合物108是HSP90抑制剂的有希望的候选者，目前已进入临床前研究。