Yang JCH, Kim SW, Kim DW, et al. - Researchers undertook this phase I study (BLOOM) to assess osimertinib [a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI)] among patients who developed leptomeningeal metastases (LMs) from EGFR-mutated (EGFRm) advanced non–small-cell lung cancer (NSCLC) that progressed on previous EGFR-TKI therapy. They administered osimertinib 160 mg once daily to patients having cytologically confirmed LM. In this study enrolling 41 patients, investigator-detected objective response rate was 41%, and median duration of response was 8.3 months. Median investigator-evaluated progression-free survival and median overall survival were 8.6 months with 78% maturity and 11.0 months with 68% maturity, respectively. In 11 of 40 patients, CSF tumor cell clearance was verified. In 12 (57%) of 21 patients with an abnormal evaluation at baseline, an improved neurologic function was observed. The observed adverse event and pharmacokinetics profiles were found to be compatible with earlier reports for osimertinib. Findings revealed meaningful therapeutic efficacy of osimertinib in the CNS as well as a manageable safety profile demonstrated by osimertinib when administered 160 mg once daily in patients with EGFRm NSCLC and LM.