Retrospective analysis of independent predictors of progression‐free survival in patients with EGFR mutation‐positive advanced non‐small cell lung cancer receiving first‐line osimertinib

BACKGROUND: Clinically measurable factors affecting the progression‐free survival (PFS) of patients receiving osimertinib as first‐line therapy for epidermal growth factor receptor (EGFR) mutation‐positive advanced non‐small cell lung cancer (NSCLC) have not yet been established. METHODS: We retrospectively reviewed the medical records of 61 patients treated with osimertinib as primary therapy for EGFR mutation‐positive advanced NSCLC at Yokohama City University Medical Center between August 2018 and March 2022. Our objective was to identify the independent predictors of PFS. RESULTS: The median age of participants was 74 years. Overall, 73.8% had good (0–1) Eastern Cooperative Oncology Group performance status (PS), and 98.4% had histology of adenocarcinoma. The EGFR mutation was exon19 deletion in 52.5% and exon21 L858R in 44.3% of patients. Programmed death‐ligand 1 tumor proportion score >50% was observed in 21.3% and liver metastasis in 9.9% of patients. Median PFS was 19.5 months (95% confidence interval [CI]: 10.6–31.6), and overall survival was not reached. The objective response rate was 68.9%, and disease control rate was 93.4%. Multivariate analysis showed that poor PS (2–4) negatively impacted PFS (hazard ratio, 3.79; 95% CI: 1.46–9.87; p = 0.006). Median PFS in the good PS and poor PS groups was 20.4 months (95% CI: 12.4‐not evaluable) and 7.2 months (95% CI: 7.2–19.5), respectively. Interstitial lung disease of all grades and grade 3 was observed as an adverse event in 6.6 and 4.9% of patients, respectively. CONCLUSION: Poor PS was associated with poor prognosis in patients with EGFR mutation‐positive advanced NSCLC treated with osimertinib as first‐line therapy.