High-dose alectinib for RET fusion-positive non-small cell lung cancer in the Blood First Assay Screening Trial

Introduction: This paper presents results from Cohort B (rearranged during transfection [RET], fusion-positive) of the Blood First Assay Screening Trial in patients with advanced non-small cell lung cancer (NSCLC) screened for genetic alterations using blood-based next-generation sequencing. Material and methods: Adults with advanced RET fusion-positive NSCLC received alectinib 900 mg twice daily (BID) in Phase I. Enrolment closed prematurely with Phase II uninitiated. Results: Among eight treated patients, confirmed best overall responses in evaluable patients were stable disease (4/5) and progressive disease (1/5). One dose-limiting toxicity (death, unknown cause) was considered by the investigator to be related to treatment and underlying disease. Serious adverse events (SAEs) occurred in five patients, and SAEs that may be related to treatment occurred in two patients. Conclusions: Alectinib showed limited activity in advanced RET fusion-positive NSCLC, and further investigation was not conducted due to the development of selective RET inhibitors pralsetinib and selpercatinib. No new safety signals were observed, and the safety profile of alectinib was in line with previous reports at the 600 mg BID dose.