Lazarus effect in a patient initially empirically treated with osimertinib for EGFR L858R mutant non-small cell lung cancer with leptomeningeal disease: a case report.

Osimertinib has been shown to be effective for patients with non-small cell lung cancer (NSCLC) with activating EGFR mutations, and these patients are at risk for leptomeningeal disease. In this report, we present a patient of East Asian descent whose initial presentation included severe, progressive leptomeningeal carcinomatosis and a small lung mass, with limited tissue available for molecular testing. She responded to empiric, urgent initiation of osimertinib, repeat tissue sampling revealed an EGFR L858R mutation, and she has experienced durable disease improvement for 18 months on osimertinib monotherapy.