AGX87 - An IND-stage potent and selective next-generation NTRK/ROS1 inhibitor of WT and clinical resistant mutants with superiority over tyrosine kinase inhibitors currently approved or in development

Background: Fusions of the neurotrophic receptor tyrosine kinase (NTRK) genes NTRK1,2,3; and the ROS proto-oncogene 1 receptor tyrosine kinase gene (ROS1) are key driver mutations in several solid malignancies, including non-small cell lung cancers. While the 1st generation TKIs larotrectinib (LOXO101, LAR), entrectinib (ENT) and crizotinib (CRI) have provided effective initial treatment for patients with cancers harboring these mutations, acquired resistance including secondary kinase domain mutations invariably arise.

Methods: Kinase and cell proliferation inhibition and in vivo antitumor activity were determined using recombinant kinases and engineered NIH3T3 or Ba/F3 cells expressing WT or mutated TRKs and ROS1, respectively. Results: Superior efficacy of AGX87 was demonstrated in a series of NTRK and ROS1 tumor models. While both 1st and next generation inhibitors were effective against tumors with WT fusion mutations, AGX87 was the only compound that has significant in vivo efficacy in tumors that harbor the G667C TRKA or the ROS1 G2032R mutations; in both cases yielding antitumor activity greater than 1 log cell kill (LCK). In kinase assay, AGX87 was >10-fold more potent (IC50=0.5 nM) than LAR and ENT, and 6-fold more potent than LOX195 in WT TRKA. Against the resistant solvent-front (G595R) mutant AGX87 was >1000-fold more potent (IC50=0.2 nM) than LAR and ENT and 20-fold more potent than LOXO195. Against the glycine DFG (G667C) mutant, AGX87 was >20-fold more potent (IC50=8.5 nM) than all three TKIs. In cells, AGX87 was >30-fold more potent (IC50=0.7 nM) than LAR and ENT vs. WT TRKA and >30-fold more potent (IC50=29 nM) vs. the G667C mutant. Comparing with LOXO195, AGX87 was 8 and 4-fold more potent vs. the WT and G667C mutant, respectively. Against WT ROS1 and G2032R, the most important solvent-front mutation found in pretreated patients, AGX87 has IC50s of 0.3 and 0.7 nM, respectively. In contrast, ENT and CRI have similar IC50s in WT kinase, but were 42 and 58-folds less potent vs. the mutant kinase. In cell assay, AGX87 has comparable IC50 as ENT and CRI but was 100 and 20-fold more active in BAF/3 cells that harbor the resistant G2032R mutation. In nonclinical ADME studies, AGX87 has good bioavailability (F≥50% in mouse, rat and dog), acceptable metabolic stability, lack of significant drug-drug interaction liabilities (transporters, CYP inhibition, CYP induction).Conclusion: AGX87 demonstrated best-in-class activity against WT and mutated TRKs and ROS1 and exhibited excellent drug-like properties. IND enabling studies are in progress.

Citation Format: Francis Y.F. Lee, Wen-Lian Wu, Zhiqiang Yang, John Q. Tan. AGX87 - An IND-stage potent and selective next-generation NTRK/ROS1 inhibitor of WT and clinical resistant mutants with superiority over tyrosine kinase inhibitors currently approved or in development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1286.