Multicenter phase 2 trial of osimertinib for EGFR-mutated NSCLC with leptomeningeal metastases

After treatment of EGFR-mutated non-small cell lung cancer (NSCLC) with first- or second generation EGFR-TKIs there is a high incidence of leptomeningeal metastases (LMs). The phase 2 BLOSSOM study, at 6 centers in South Korea, evaluated osimertinib 80 mg once daily in NSCLC patients with LMs resistant to first- or second-generation EGFR TKIs. The median overall survival (primary endpoint) was 15.6 months (95% CI 11.5-20.2), while the LM objective response rate was 51.6% (complete response in 15.6%) and disease control rate was 81.3%. The median LM progression-free survival was 11.2 months (95% CI7.7-15.3) and the median duration of response was 12.6 months (95% CI 7.6-17.7). Moste adverse events were grade 1 or 2. The authors conclude that osimertinib demonstrated intracranial efficacy and survival benefit among NSCLC patients with LMs.