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.