Cemiplimab Plus Chemotherapy Versus Chemotherapy Alone in Advanced NSCLC: 2-Year Follow-Up From the Phase 3 EMPOWER-Lung 3 Part 2 Trial

Introduction: EMPOWER-Lung 3 part 2 (NCT03409614), a double-blind, placebo-controlled phase 3 study, investigated cemiplimab (antiprogrammed cell death protein 1) plus chemotherapy versus placebo plus chemotherapy in patients with advanced NSCLC without EGFR, ALK, or ROS1 aberrations, with either squamous or nonsquamous histology, irrespective of programmed death-ligand 1 levels. At primary analysis, after 16.4 months of follow-up, cemiplimab plus chemotherapy improved median overall survival (OS) versus chemotherapy alone (21.9 versus 13.0 mo, hazard ratio [HR] = 0.71, 95% confidence interval [CI]: 0.53-0.93, p = 0.014). Here, we report protocol-specified final OS and 2-year follow-up results.

Methods: Patients (N = 466) were randomized 2:1 to receive histology-specific platinum-doublet chemotherapy, with 350 mg cemiplimab (n = 312) or placebo (n = 154) every 3 weeks for up to 108 weeks. Primary end point was OS; secondary end points included progression-free survival and objective response rates.

Results: After 28.4 months of median follow-up, median OS was 21.1 months (95% CI: 15.9-23.5) for cemiplimab plus chemotherapy versus 12.9 months (95% CI: 10.6-15.7) for chemotherapy alone (HR = 0.65, 95% CI: 0.51-0.82, p = 0.0003); median progression-free survival was 8.2 months (95% CI: 6.4-9.0) versus 5.5 months (95% CI: 4.3-6.2) (HR = 0.55, 95% CI: 0.44-0.68, p < 0.0001), and objective response rates were 43.6% versus 22.1%, respectively. Safety was generally consistent with previously reported data. Incidence of treatment-emergent adverse events of grade 3 or higher was 48.7% with cemiplimab plus chemotherapy and 32.7% with chemotherapy alone.

Conclusions: At protocol-specified final OS analysis with 28.4 months of follow-up, the EMPOWER-Lung 3 study continued to reveal benefit of cemiplimab plus chemotherapy versus chemotherapy alone in patients with advanced squamous or nonsquamous NSCLC, across programmed death-ligand 1 levels.