Osimertinib retreatment for patients with advanced EGFR-mutated non-small cell lung cancer.

Resistance to osimertinib, a third-generation EGFR tyrosine kinase inhibitor, remains a key challenge in the treatment of EGFR-mutated non-small cell lung cancer (NSCLC). Although retreatment with earlier-generation EGFR tyrosine kinase inhibitors has been studied, data on osimertinib rechallenge are limited. We conducted a single institution retrospective analysis of patients with EGFR-mutated NSCLC who were rechallenged with osimertinib following progression on prior osimertinib and interim systemic therapy, including chemotherapy. Seventeen patients met inclusion criteria, all with adenocarcinoma histology and either EGFR exon 19 deletions or L858R mutations. Median interval between osimertinib treatments was 10.5 months. Osimertinib retreatment resulted in a partial response in 18 % (3/17) and stable disease in 35 % of patients (6/17), for a disease control rate of 53 % (9/17). Median retreatment duration was 4.3 months, and median overall survival following retreatment initiation was 8.9 months. Among patients with central nervous system involvement, several experienced intracranial stability without additional radiation. Duration of initial osimertinib therapy did not strongly predict retreatment benefit. These findings suggest that osimertinib rechallenge may provide clinically meaningful disease control in a subset of patients, especially given its tolerability and oral formulation. Further research is needed to identify biomarkers of sensitivity and to optimize patient selection for osimertinib retreatment following interval chemotherapy.