Nuvalent, Inc. (Nasdaq: NUVL), a clinical-stage biopharmaceutical company focused on creating precisely targeted therapies for clinically proven kinase targets in cancer, announced  which supports the rational molecular design of zidesamtinib, its novel and selective ROS1 inhibitor. Zidesamtinib is currently being evaluated in the ongoing ARROS-1 Phase 1/2 trial for patients with advanced ROS1-positive non-small cell lung cancer (NSCLC) and other solid tumors, which is designed with registrational intent for tyrosine kinase inhibitor (TKI) pre-treated and TKI-naïve patients with advanced ROS1-positive NSCLC.

"Zidesamtinib was specifically designed with the goal of addressing the combined medical needs of treating tumors that have developed resistance, treating brain metastases and avoiding off-target adverse events. Structural studies play a critical role in the development and optimization of novel therapeutics, particularly when aiming to solve for multiple, and at times competing, challenges. To date, structural studies for ROS1-positive cancers have been hindered by a lack of ROS1 G2032R crystal structures, despite G2032R being the most commonly occurring ROS1 resistance mutation," said first author Anupong Tangpeerachaikul, Ph.D., Director, Biology at Nuvalent. "With this publication in Molecular Cancer Therapeutics, we are pleased to have shared what is, to our knowledge, the first structure of ROS1 G2032R, or any ROS1 mutation, offering a framework for understanding ROS1 TKI activity against these important drivers of disease progression. This structure further illustrates the intentional design of zidesamtinib and adds to the growing body of preclinical data supporting its ROS1-selective and TRK-sparing design."

The manuscript explores the activity of zidesamtinib and other approved or investigational ROS1 TKIs at clinically relevant concentrations against ROS1 resistance mutations, including the most commonly occurring resistance mutation, ROS1 G2032R, in preclinical mutagenesis screens and an intracranial ROS1 G2032R xenograft model. Findings presented in the manuscript show that, at clinically relevant concentrations, zidesamtinib suppressed on-target resistance in ENU mutagenesis screens simulating first-line and later-line treatment and inhibited ROS1 G2032R brain tumors more effectively than the other ROS1 TKIs evaluated. This favorable preclinical activity suggests the potential for zidesamtinib to delay tumor progression, both peripherally and intracranially.

In addition, the manuscript details the first crystal structure of ROS1 G2032R in complex with zidesamtinib, which further supports zidesamtinib's molecular design and provides structural insights into how the ROS1 G2032R mutation affects TKI binding. Zidesamtinib was designed with the goal of being active against ROS1 and ROS1 resistance mutations while avoiding the inhibition of the structurally related tropomyosin receptor kinase (TRK) family in the central nervous system (CNS), which has been associated with neurological adverse events that can be dose limiting. The crystal structure elucidates zidesamtinib's preclinical affinity for ROS1 G2032R and selectivity for ROS1 over TRK.

The company expects to report pivotal clinical data for TKI pre-treated patients with advanced ROS1-positive NSCLC from the ARROS-1 Phase 1/2 trial in the first half of 2025 in support of an anticipated New Drug Application submission by mid-year 2025, with an initial target indication of TKI pre-treated patients with advanced ROS1-positive NSCLC.