Osimertinib as First-Line Treatment for Patients With Advanced EGFR Mutation-Positive Non-Small Cell Lung Cancer in a Real-World Setting: Updated Overall Survival Data (OSI-FACT-OS).

Background: Previously, we reported on osimertinib (OSI) as a first-line treatment for EGFR mutation-positive non-small cell lung cancer (EGFRm+ NSCLC) in a real-world setting. However, owing to the limited observation period, data on overall survival (OS) and long-term safety were not reported. Therefore, in this study, we aimed to assess the long-term efficacy and safety of OSI in patients with EGFRm+ NSCLC.

Patients and methods: We extended the observation period until July 2023 for 538 patients with EGFRm+ NSCLC who received OSI between August 2018 and December 2019.

Results: The median observation period was 37 months. The number of events was 392 (72.9%) for progression-free survival (PFS) and 285 (53%) for OS. The median PFS was 20.1 months (95% CI: 17.1-22.1) and median OS was 42.0 months (95% CI: 37.7-48.4). Safety data showed incidences of the following adverse events: pneumonitis (all grades/grade ≥ 3/grade 5), 90 (16.7%)/28 (5.2%)/5 (0.9%); grade ≥ 3 nonhematologic toxicity, 69 (12.8%); grade ≥ 3 hematologic toxicity, 34 (6.3%); QT prolongation (all grades/grade ≥ 3), 25 (4.6%)/8 (1.3%); and ejection fraction decrease and heart failure (all grades/grade ≥ 3), 14 (2.6%)/10 (1.9%). Regarding late adverse events manifesting after 1 year of treatment, 17 cases of pneumonitis and 7 cases of cardiotoxicity were recorded.

Conclusion: This study supports the long-term efficacy of OSI, with PFS and OS comparable to those in the FLAURA trial in a Japanese real-world setting. However, it highlights the need for careful and long-term safety monitoring throughout the treatment period.