Impact of Pleural Effusion on Outcomes of Patients Receiving Osimertinib for NSCLC Harboring EGFR T790M.

Background/Aim: Osimertinib has demonstrated promising efficacy in patients with epidermal growth factor receptor (EGFR) T790M-positive non-small cell lung cancer (NSCLC). We investigated the efficacy of osimertinib in such patients presenting with pleural effusion, which has been unclear to date. Patients and Methods: The medical records of all patients treated with osimertinib for advanced NSCLC with EGFR T790M between April 2016 and July 2017 at our Institution were retrospectively reviewed. Time to treatment failure (TTF) and overall survival (OS) were determined as endpoints. Results: Twenty-three patients (seven with pleural effusions) were treated with osimertinib. Patients with pleural effusion had significantly shorter median TTF than those without (3.7 vs. 12.8 months, respectively, p=0.021), as well as shorter median OS (7.8 months vs. not attained, respectively, p=0.002). Metastasis to the brain, bone, and liver did not significantly influence our endpoints. Conclusion: Osimertinib monotherapy is less effective in patients with NSCLC with pleural effusions.