Influence of EGFR mutation status and PD-L1 expression in stage III unresectable non-small cell lung cancer treated with chemoradiation and consolidation durvalumab

Background: Consolidation durvalumab after concurrent chemoradiation is the standard of care for unresectable stage III non-small cell lung cancer (NSCLC) based on the PACIFIC trial. However, there have been reports in the literature suggesting the efficacy of the treatment differs in patients whose tumors harbor epidermal growth factor receptor (EGFR) mutations and in those with low programed death ligand-1 (PD-L1) expression. This study describes the survival outcomes for patients with unresectable stage III NSCLC treated with chemoradiation followed by durvalumab with a specific focus on EGFR mutation status and PD-L1 expression.

Methods: This retrospective observational study was conducted across six sites in Greater Sydney, Australia. It included all patients diagnosed with unresectable stage III NSCLC treated with chemoradiation and who received at least one cycle of durvalumab between January 2018 and September 2021. Patients were stratified according to EGFR mutation status and PD-L1 tumor proportion score (TPS) of 1%.

Results: Of the 145 patients included in the analysis, 15/145 (10%) patients harbored an EGFR mutation and 61/145 (42%) patients had PD-L1 TPS of <1%. At a median follow-up of 15.1 months from the start of durvalumab, median progression-free survival (PFS) in EGFR mutant versus wild-type patients was 7.5 and 33.9 months, respectively (hazard ratio [HR]: 2.7; 95% confidence intervals [95% CI] 1.2-5.7; p = .01). Overall survival (OS) was not different between EGFR mutant and wild-type patients. There was no statistically significant difference in PFS (HR .7, 95% CI .4-1.7, p = .43) or OS (HR .5, 95% CI .4-4.7, p = .16) between patients with PD-L1 TPS of <1% versus PD-L1 TPS of ≥1%.

Conclusions: Our data adds to the growing evidence that suggests consolidation durvalumab after definitive chemoradiation may not be as efficacious in patients with EGFR-mutant tumors compared with EGFR wild-type NSCLC.