Real-world evidence of first-line osimertinib effectiveness in Bulgarian patients: a retrospective analysis.

Background: Third-generation EGFR tyrosine kinase inhibitor (EGFR-TKI) osimertinib is approved as a first-line treatment against non-small-cell lung cancer (NSCLC) harboring sensitizing EGFR mutations. Herein, we perform a retrospective analysis of real-world data on first-line osimertinib treatment among Bulgarian patients with NSCLC, comparing treatment outcomes to FLAURA results.

Research design and methods: Patient data were obtained from electronic health records over a 4-year period. Baseline characteristics and endpoints (progression-free survival [PFS], objective response rate [ORR], and clinical benefit rate [CBR]) were compared. Iterative proportional fitting was performed to balance patient characteristics prior to survival analysis.

Results: A total of 365 patients on first-line osimertinib were included. Partial responses were more frequent in the RWE cohort (24% vs 13%), while the opposite was noted for stable disease (63% vs 80%). Complete response frequency was comparable (2% vs 1%). The ORR was higher in the real world compared to in FLAURA (26% vs 14%), whereas CBR was slightly higher in the trial (89% vs 94%). The real-world PFS was higher than reported in FLAURA (19.1 vs 18.9 months), with more favorable outcomes in the RWE cohort beyond 18 months.

Conclusion: RWE closely aligns with FLAURA results, suggesting even greater benefit of first-line osimertinib in the real-world setting.