Four-Year Survival With Durvalumab After Chemoradiotherapy in Stage III NSCLC-an Update From the PACIFIC Trial.

Introduction: In the Phase 3, placebo-controlled PACIFIC trial of patients with unresectable, stage III NSCLC without disease progression after concurrent chemoradiotherapy, consolidative durvalumab was associated with significant improvements in the primary end points of overall survival (OS) (hazard ratio [HR] = 0.68; 95% confidence interval [CI]: 0.53-0.87; p = 0.00251; data cutoff, March 22, 2018) and progression-free survival (PFS) (blinded independent central review; Response Evaluation Criteria in Solid Tumors version 1.1) (HR = 0.52; 95% CI: 0.42-65; p < 0.0001; February 13, 2017) with manageable safety. Here, we report updated analyses of OS and PFS, approximately 4 years after the last patient was randomized.

Methods: Patients with WHO performance status of 0 or 1 (and any tumor programmed death-ligand 1 status) were randomized (2:1) to intravenous durvalumab (10 mg/kg) or placebo, administered every 2 weeks (≤12 months), stratified by age, sex, and smoking history. OS and PFS were analyzed using a stratified log-rank test in the intent-to-treat population. Medians and 4-year OS and PFS rates were estimated by the Kaplan-Meier method.

Results: Overall, 709 of 713 randomized patients received durvalumab (n/N=473/476) or placebo (n/N=236/237). As of March 20, 2020 (median follow-up = 34.2 months; range: 0.2-64.9), updated OS (HR = 0.71; 95% CI: 0.57-0.88) and PFS (HR = 0.55; 95% CI: 0.44-0.67) remained consistent with the primary analyses. The median OS for durvalumab was reached (47.5 mo; placebo, 29.1 months). Estimated 4-year OS rates were 49.6% versus 36.3% for durvalumab versus placebo, and 4-year PFS rates were 35.3% versus 19.5% respectively.

Conclusion: These updated exploratory analyses demonstrate durable PFS and sustained OS benefit with durvalumab after chemoradiotherapy. An estimated 49.6% of patients randomized to durvalumab remain alive at 4 years (placebo, 36.3%), and 35.3% remain alive and progression-free (placebo, 19.5%).