Different Survival Benefit of Osimertinib in Different Sequences: A Real‐World Outcome of Osimertinib Treatment in Pretreated T790M-Positive Advanced NSCLC in Taiwan

Background: To investigate the relationships among the clinical characteristics, different EGFR-TKIs, and osimertinib treatment in different treatment lines.Methods: We retrospectively screened a total of 3807 patients diagnosed between 2013 and 2019 at Kaohsiung Chang Gung Memorial Hospital. Furthermore, 98 patients after re-biopsy or liquid with EGFR T790M mutation who received osimertinib were enrolled for analysis. Results: Among all 98 patients, the median PFS of those who received osimertinib therapy was 10.48 months, and the median OS of those who received osimertinib therapy was 42.21 months. The OS of those who received osimertinib therapy after previous gefitinib, afatinib, or erlotinib therapy was 87.93, 49.00, and 42.00 months, respectively (P=0.006). There was a significant difference in disease control rate between those who received osimertinib treatment after previous chemotherapy (Group A) or immediately following EGFR-TKI therapy (Group B) (93.3% vs. 77.4%, P=0.029). There was also a significant difference in PS between those who received osimertinib as a second-line treatment and those who received it as a third-line treatment (10.83 vs. 17.33 months, P=0.044). In addition, COPD tended to be a poor prognostic factor for PFS and OS.Conclusion: In this retrospective real‐world analysis, it was determined that pretreatment with gefitinib and previous chemotherapy could affect the treatment outcomes of NSCLC patients treated with osimertinib. Furthermore, COPD tended to a poor prognostic factor for PFS and OS in such patients.