Abstract 828: ANS03, a novel, orally bioavailable small-molecule type II ROS1/NTRK inhibitor, effectively overcomes clinically relevant ROS1/NTRK resistance mutations and exhibits potent antitumor activity in preclinical tumor models

Background: ROS1 and NTRK are critical driver genes for tumorigenesis and progression, and inhibitors targeted towards their tyrosine kinases (TKIs) are clinically proven anti-cancer agents. Although Type I ROS1/NTRK TKIs like Repotrectinib show clinical benefit, on-target resistance mutations inevitably develop. Hence there is an unmet clinical need for novel Type II ROS1/NTRK TKIs capable of overcoming on-target acquired resistance mutations. Methods: A comprehensive panel of IND-enabling non-clinical studies was conducted to evaluate the mechanism of action, pharmacologic activity, pharmacokinetics, and the safety profile of ANS03. Results: ANS03 is a novel Type II TKI targeting both ROS1 and NTRK. Unlike type I TKIs, which engage the active “DFG-in” conformation of the kinase, type II TKIs engage the inactive “DFG-out” conformation of the kinase and also extend into an adjacent allosteric pocket. As a result, ANS03 shows a broad and potent inhibitory spectrum for ROS1/NTRK drug-resistance mutations with IC50’s ranging from 0.324 nM to 4.88 nM. In cellular systems, ANS03 showed outstanding antitumor effects against wild-type fusions and diverse acquired drug-resistance mutations, with IC50’s ranging from 0.1 nM to 26 nM. For ROS1 SF mutations (G2032R, D2033N), ANS03 was 22.2x and 30.6x more active than Repotrectinib, respectively. ANS03 showed a 104x enhancement against ROS1 Cβ6 mutation (L2086F), a 52.5x enhancement against NTRK1 xDFG mutation (G667C), and a 104.4x enhancement against NTRK1 compound mutation (G595R-G667C) vs. Repotrectinib. ANS03 also had better activity against the ROS1 L2086F mutation when compared to both Repotrectinib and NVL-520. In vivo, ANS03 exhibited antitumor effects in BALB/c nude mouse subcutaneous xenotransplantation models that were as good- or better than- those of the ROS1/NTRK TKIs Repotrectinib or NVL-520. Notably, it achieved complete tumor regression in Ba/F3-ROS1-G2032R models at a dose of 10 mg/kg and triggered tumor regression in LU-01-0414 (ROS1 wild-type fusion) and KM12-Luc (NTRK wild-type fusion) models at a dose of 3 mg/kg. Moreover, ANS03 significantly improved the survival rates of tumor bearing mice in a dose-dependent manner. Concurrent pharmacokinetic (PK) studies in mice positively correlated plasma exposures of ANS03 to administered doses, with ANS03 showing favorable tumor distribution and detectable brain penetration. Conclusion: Non-clinical studies of ANS03 showed it is a potent, orally bioavailable Type II ROS1/NTRK inhibitor with remarkable activity against various pathogenetic ROS1/NTRK alterations and with favorable absorption, distribution, pharmacokinetics, efficacy, and tolerability profiles in vivo. The compound will enter Phase 1 clinical development in the US and China soon. Citation Format: Gong Li, Alexander Drilon, Shengxiang Ren, Peilong Zhang, Xiangqiu Li, Linna Li, Ruiya Zhang, Wenli Lan, Di Han, Weizhe Xue, Peipei Yang, Shutan Liao, Kevin Schaab, Brendan Putz, Hepeng Shi. ANS03, a novel, orally bioavailable small-molecule type II ROS1/NTRK inhibitor, effectively overcomes clinically relevant ROS1/NTRK resistance mutations and exhibits potent antitumor activity in preclinical tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 828.