Osimertinib in the treatment of leptomeningeal disease in T790M-negative, epidermal growth factor receptor-mutated non-small cell lung cancer: a case report.

Leptomeningeal carcinomatosis (LMC) is a terminal event in advanced cancer, its incidence in epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is increasing due to recent advances in systemic therapy and prolongation of survival. Osimertinib is a third generation EGFR-tyrosine kinase inhibitor (TKI) with preclinical and early clinical studies showing activity against LMC resistant to previous TKI treatments and acquired T790M mutation. We report a case of osimertinib in the treatment of LMC in a T790M-negative, EGFR-mutated NSCLC with significant clinical benefit and no toxicity. Osimertinib is a potentially effective treatment for LMC associated with EGFR-mutated NSCLC regardless of T790M status and a well-tolerated treatment for poor performance status patients.