PD-L1 as a Biomarker for the Efficacy of Durvalumab in Stage III EGFR Mutant NSCLC.

Background/aim: Durvalumab consolidation is less effective in patients with epidermal growth factor receptor mutant (EGFR M+) NSCLC. Studies of durvalumab on EGFR M+ NSCLC as an expression of programmed death-ligand 1 (PD-L1) expression are limited. The purpose of this study was to determine the effect of durvalumab on PD-L1 expression in EGFR M+ patients.

Patients and methods: This study included 249 unresectable stage III NSCLC patients treated with durvalumab. The primary outcome was progression-free survival (PFS). Cox multivariate analysis was performed based on EGFR and PD-L1 statuses: EGFR M-, PD-L1 ≥50% (cohort A); EGFR M-, PD-L1 <50% (cohort B); EGFR M+, PD-L1 ≥50% (cohort C); and EGFR M+, PD-L1 <50% (cohort D).

Results: Overall, 31 of 249 (12.4%) and 218 of the 249 (87.6%) patients had EGFR M+ and EGFR M- NSCLC, respectively. Median PFSs and OSs did not differ (PFS: 16.6 vs. 18.7 months, p=0.591; OS: 37.4 vs. 35.7 months, p=0.271). Median PFS of cohort A did not significantly differ from the median PFSs of cohorts B and C, but it was significantly longer than the median PFS of cohort D (23.7 vs. 15.2 months, p=0.045). Cox multivariate analysis revealed that cohort D exhibited a worse PFS (adjusted hazard ratio=2.27, 95% confidence interval=1.11-4.66, p=0.025) compared with cohort A. Median OSs were not different between the four cohorts.

Conclusion: Durvalumab consolidation provided similar benefit in EGFR M+ patients with PD-L1 ≥50% compared with EGFR M- patients. A therapeutic role of durvalumab in patients with EGFR M+, high PD-L1 unresectable stage III NSCLC should be considered.