Epidermal growth factor receptor-Mutated Non-small-cell Lung Cancer with Intracranial Progressions and Stable Extracranial Diseases Benefit from Osimertinib Regardless of T790M Mutational Status

OBJECTIVES: Osimertinib has exhibited promising central nervous system (CNS) efficacy in Epidermal growth factor receptor (EGFR)-mutated advanced non-small-cell lung cancer (NSCLC) patients. In real-world clinical practice, patients would turn to plasma genotyping or take osimertinib blindly after CNS progression on previous tyrosine kinase inhibitors (TKIs). However, the efficacy of osimertinib in those patients according to their T790M mutational status has not been explored. MATERIALS AND METHODS: Twenty-five patients who received osimertinib due to intracranial progressions with stable extracranial diseases after early-generation EGFR-TKI treatment were collected from 1032 EGFR-mutated NSCLC. Plasma samples were analyzed for EGFR mutations using next-generation sequencing (NGS) or polymerase chain reaction (PCR). RESULTS: Among the 25 patients, 17 patients took plasma genotyping before osimertinib treatment with 8 patients EGFR T790M mutation-positive and the rest started osimertinib blindly. The median progression-free survival (PFS) was 8.0 months (95% confidence interval [CI]: 6.12-9.94) and median intracranial PFS (iPFS) was 14.4 months (95% CI: 7.27-21.59) for the total population. No statistical difference was found in PFS and iPFS among patients with different EGFR T790M mutational statuses. Intracranial disease control rate (DCR) was 100.0% for 14 patients with evaluable intracranial lesions despite different T790M mutational statuses. DCR for extracranial lesions and overall lesions were 100.0%, 66.7%, and 87.5% for patients with T790M, no T790M, and unknown T790M mutational status, respectively. CONCLUSION: For EGFR-mutated NSCLC patients with only intracranial progressions after previous TKI treatments, osimertinib is a promising treatment option regardless of T790M mutational status from plasma genotyping.