Osimertinib, a third‐generation EGFR tyrosine kinase inhibitor: A retrospective multicenter study of its real‐world efficacy and safety in advanced/recurrent non‐small cell lung carcinoma

BACKGROUND: Osimertinib is recommended for T790M mutation‐positive advanced non‐small cell lung cancer (NSCLC) resistant to first‐ and second‐generation epidermal growth factor receptor (EGFR)‐tyrosine kinase inhibitors (TKIs). Recently, some reports exist on the real‐world use of osimertinib; however, reports involving third/later‐line use are few. Hence, this study was conducted to evaluate the efficacy and safety of osimertinib used in various treatment lines for T790M‐positive NSCLC patients. METHODS: This retrospective, observational, multicenter study included T790M‐positive advanced/recurrent NSCLC patients treated with osimertinib from May 2016 to March 2018. The clinical characteristics, efficacy, and adverse events were retrospectively investigated. The Kaplan‐Meier method was used to analyze progression‐free survival (PFS) and overall survival (OS). PFS‐associated clinical characteristics were evaluated using the Cox proportional hazards model. RESULTS: The objective response rate (ORR) and disease control rate (DCR) were 60.7% and 91.1%, respectively; the median PFS was 11.0 months. There were no significant differences in the median PFS for patients treated with osimertinib as second‐line and third−/later‐line (14.5 vs. 11.0 months respectively, P = 0.327). Analysis using the Cox proportional hazards model for clinical features affecting PFS also revealed no significant factors. Adverse events of grade ≥ 3 were reported in 15 patients (26.8%); the most common were anemia (n = 3) and cutaneous toxicity (n = 3). Grade 4 neutropenia was observed in one patient; any‐grade pneumonitis was observed in six patients (10.7%), including one with grade 3 pneumonitis. CONCLUSIONS: Osimertinib demonstrated efficacy even when administered as third−/later‐line treatment to NSCLC patients. Osimertinib‐related pneumonitis was observed more frequently than previously reported. KEY POINTS: SIGNIFICANT FINDINGS OF THE STUDY: Osimertinib shows efficacy even as later‐line treatment in T790M mutation‐positive NSCLC patients previously treated with EGFR‐TKIs. However, the incidence of ≥ grade 3 adverse events, especially pneumonitis, was higher than that previously reported by other studies. WHAT THIS STUDY ADDS: Osimertinib was approved for previously EGFR‐TKI‐treated EGFR T790M‐positive NSCLC. With the increasing frequency of its use as first‐line treatment, this study provides valuable evidence for the efficacy and safety of osimertinib for previously EGFR‐TKI‐treated NSCLC.