Advances and future directions in ROS1 fusion-positive lung cancer

ROS1 gene fusions are an established oncogenic driver comprising 1%-2% of non-small cell lung cancer (NSCLC). Successful targeting of ROS1 fusion oncoprotein with oral small-molecule tyrosine kinase inhibitors (TKIs) has revolutionized the treatment landscape of metastatic ROS1 fusion-positive (ROS1+) NSCLC and transformed outcomes for patients. The preferred Food and Drug Administration-approved first-line therapies include crizotinib, entrectinib, and repotrectinib, and currently, selection amongst these options requires consideration of the systemic and CNS efficacy, tolerability, and access to therapy. Of note, resistance to ROS1 TKIs invariably develops, limiting the clinical benefit of these agents and leading to disease relapse. Progress in understanding the molecular mechanisms of resistance has enabled the development of numerous next-generation ROS1 TKIs, which achieve broader coverage of ROS1 resistance mutations and superior CNS penetration than first-generation TKIs, as well as other therapeutic strategies to address TKI resistance. The approach to subsequent therapy depends on the pace and pattern of progressive disease on the initial ROS1 TKI and, if known, the mechanisms of TKI resistance. Herein, we describe a practical approach for the selection of initial and subsequent therapies for metastatic ROS1+ NSCLC based on these clinical considerations. Additionally, we explore the evolving evidence for the optimal treatment of earlier-stage, non-metastatic ROS1+ NSCLC, while, in parallel, highlighting future research directions with the goal of continuing to build on the tremendous progress in the management of ROS1+ NSCLC and ultimately improving the longevity and well-being of people living with this disease. This article describes a practical approach for the selection of initial and subsequent therapies for metastatic ROS1+ non-small cell lung cancer, explores the evolving evidence for optimal treatment of early-stage disease, and highlights areas for future research.