ROS1 is a proto-oncogene that encodes the receptor tyrosine kinase ROS1, which can be aberrantly activated by gene rearrangement to drive tumor cell proliferation, survival, and metastasis. In non-small cell lung cancer (NSCLC), ROS1 rearrangements are detected in up to 3% of patients with up to 40% of these patients also presenting with accompanying central nervous system (CNS) metastases. Although various tyrosine kinase inhibitors (TKI) have been approved or are under development for treating ROS1-positive patients, these therapies are associated with one or more of the following significant challenges: 1. emergence of ROS1 mutations that confer disease resistance, including the G2032R solvent front mutation, 2. disease progression into the CNS, and 3. treatment-related adverse events (AEs) associated with off-target kinase inhibition, notably TRKB in the CNS. NVL-520 was developed to address the challenges listed above. Preclinical studies have shown that NVL-520 inhibits wild-type and drug resistance mutants of the ROS1 kinase and demonstrated activity against CNS disease with minimal kinase off-target activity, suggesting an opportunity for durable responses for patients with ROS1-positive disease. Here we report detailed characterization of cellular and antitumor activity of NVL-520 in patient-derived models of ROS1-driven NSCLC. Methods: Cellular and antitumor activity of NVL-520 were evaluated in patient-derived models of NSCLC representing ROS1 and ROS1-G2032R driven disease. For in vivo studies, treatments were administered orally. Western blotting, immunohistochemistry, and gene expression analyses were used to measure pharmacodynamic (PD) effects in tumor tissue. Pharmacokinetic (PK) analyses were also performed. Results: In patient-derived cell (PDC) models of EZR-ROS1 and CD74-ROS1 G2032R, NVL-520 treatment resulted in antiproliferative activity, with IC50 values < 10 nM, and reduced levels of phospho-ROS1 and markers of downstream signaling. Studies in patient-derived xenograft (PDX) models demonstrated that NVL-520 was well-tolerated and resulted in dose-dependent antitumor activity, including tumor regression in all models. Analysis of PD biomarkers showed that NVL-520 suppressed ROS1 phosphorylation and significantly impacted ROS1-dependent signaling pathways. PK analysis demonstrated dose-dependent differences in NVL-520 exposure. PD-Efficacy correlation analysis showed that changes in PD were consistent with dose-dependent antitumor activity of NVL-520 with distinct changes observed at doses that induce tumor stasis versus tumor regression. Conclusion: NVL-520 exhibits antiproliferative and antitumor activity in NSCLC models driven by ROS1 and ROS1-G2032R solvent front mutation. We believe the findings presented here support evaluation of NVL-520 for the treatment of patients with ROS1-driven disease.

Citation Format: Amit M. Deshpande, Satoshi Yoda, Anupong Tangpeerachaikul, Nancy E. Kohl, Joshua C. Horan, Aaron N. Hata, Henry E. Pelish. Preclinical antitumor activity of NVL-520 in patient-derived models harboring ROS1 fusions, including G2032R solvent front mutation [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P249.