NVL-520 is a selective, TRK-sparing, and brain-penetrant inhibitor of ROS1 fusions and secondary resistance mutations


 ROS1 tyrosine kinase inhibitors (TKIs) have been approved (crizotinib and entrectinib) or explored (lorlatinib, taletrectinib, and repotrectinib) for the treatment of ROS1 fusion-positive cancers, although none simultaneously address the need for broad resistance coverage, avoidance of clinically dose-limiting TRK inhibition, and brain penetration. NVL-520 is a rationally designed macrocycle with >50-fold ROS1 selectivity over 98% of the kinome tested. It is active in vitro against diverse ROS1 fusions and resistance mutations and exhibits 10-to-1,000-fold improved potency for the ROS1 G2032R solvent-front mutation over crizotinib, entrectinib, lorlatinib, taletrectinib, and repotrectinib. In vivo, it induces tumor regression in G2032R-inclusive intracranial and patient-derived xenograft models. Importantly, NVL-520 has a ~100-fold increased potency for ROS1 and ROS1 G2032R over TRK. As clinical proof-of-concept, NVL-520 elicited objective tumor responses in three patients with TKI-refractory ROS1 fusion-positive lung cancers, including two with ROS1 G2032R and one with intracranial metastases, with no observed neurological toxicities.