Gainor JF, Curigliano G, Kim DW, et al. - In this multi-cohort, open-label, phase 1/2 study (ARROW), researchers tested pralsetinib (a highly potent, oral, selective RET inhibitor) for its safety, tolerability, and antitumour activity in patients with RET fusion-positive non-small-cell lung cancer (NSCLC). Phase 2 involved administration of 400 mg once-daily oral pralsetinib to patients, and treatment could be continued until disease progression, intolerance, withdrawal of consent, or investigator decision. In 53 of 87 patients with previous platinum-based chemotherapy, overall responses were recorded, including a complete response in five (6%) patients; and among 27 treatment-naive patients, overall responses were recorded in 19 patients, including three (11%) with a complete response. Findings demonstrated good tolerability as well as promising efficacy of pralsetinib as a new once-daily oral treatment choice for RET fusion-positive NSCLC cases.