Structural Optimization and Structure–Activity Relationship Studies of 6,6-Dimethyl-4-(phenylamino)-6<i>H</i>-pyrimido[5,4-<i>b</i>][1,4]oxazin-7(8<i>H</i>)-one Derivatives as A New Class of Potent Inhibitors of Pan-Trk and Their Drug-Resistant Mutants
Shulei Pan, Liting Zhang, Xinling Luo, Jinshan Nan, Wei Yang, Huachao Bin, Li Yang, Qiao Huang, Tianqi Wang, Zhiling Pan, Bo Mu, Falu Wang, Chenyu Tian, Yang Liu, Linli Li, Shengyong Yang
Abstract
Tropomyosin receptor kinases (TrkA, TrkB, and TrkC) are attractive therapeutic targets for multiple cancers. Two first-generation small-molecule Trks inhibitors, larotrectinib and entrectinib, have just been approved to use clinically. However, the drug-resistance mutations of Trks have already emerged, which calls for new-generation Trks inhibitors. Herein, we report the structural optimization and structure–activity relationship studies of 6,6-dimethyl-4-(phenylamino)-6H-pyrimido[5,4-b][1,4]oxazin-7(8H)-one derivatives as a new class of pan-Trk inhibitors. The prioritized compound 11g exhibited low nanomolar IC50 values against TrkA, TrkB, and TrkC and various drug-resistant mutants. It also showed good kinase selectivity. 11g displayed excellent in vitro antitumor activity and strongly suppressed Trk-mediated signaling pathways in intact cells. In in vivo studies, compound 11g exhibited good antitumor activity in BaF3-TEL-TrkA and BaF3-TEL-TrkCG623R allograft mouse models without exhibiting apparent toxicity. Collectively, 11g could be a promising lead compound for drug discovery targeting Trks and deserves further investigation.