Treatment Patterns and Clinical Outcomes in Patients With EGFR-Mutated Non-Small-Cell Lung Cancer After Progression on Osimertinib

Introduction: For patients with advanced epidermal growth factor receptor (EGFR)-mutated non-small-cell lung cancer (NSCLC) who progress on first-line osimertinib, the optimal second-line treatment regimen after progression is not known. We sought to assess practice patterns and evaluate the association between different therapies and survival in patients with EGFR-mutated NSCLC following progression on first-line osimertinib. Methods: Retrospective cohort study of patients who received first-line treatment with osimertinib using a population-based, multicenter nationwide electronic health record-derived deidentified database. Results: We identified 2373 patients who received first-line osimertinib. The majority (n = 2279) received osimertinib monotherapy. A total of 538 patients received first-line osimertinib and had second-line treatment data available. Second-line treatment regimens were varied: 65% (n = 348) included chemotherapy, 37% (n = 197) included an immune checkpoint inhibitor (ICI), and 44% (n = 234) included an EGFR tyrosine kinase inhibitor (TKI). We then analyzed the 333 patients with performance status 0-2 who received chemotherapy with osimertinib (n = 107, 32%) versus chemotherapy without osimertinib (n = 226, 68%). The continuation of osimertinib with chemotherapy was associated with superior progression-free survival (PFS; median: 10.1 versus 5.9 months, Hazard Ratio [HR]: 0.48, 95% Confidence Interval [CI]: [0.34, 0.68], P < .001) and overall survival (OS; median: 17.0 versus 12.8 months, HR: 0.64, 95% CI: [0.44, 0.93], P = .018) compared to other chemotherapy approaches without osimertinib. This effect was most pronounced in patients with an EGFR exon 19 deletion. Conclusions: Following progression on osimertinib, a wide variety of treatment regimens were used. The continuation of osimertinib with chemotherapy in the second line was associated with increased PFS and OS.