IMpower131: Final OS Results of Carboplatin plus Nab-Paclitaxel +/- Atezolizumab in Advanced Squamous NSCLC

Abstract

Background: IMpower131 (NCT02367794) is a randomised Phase IIItrial of atezolizumab + chemotherapy vs chemotherapy alone asfirst-line therapy in Stage IV squamous NSCLC. Here we report thefinal OSresults (Arm B vs Arm C). Method: Enrolled patients were randomised1:1:1 to Arm A (atezolizumab 1200 mg q3w + carboplatin AUC 6 q3w +paclitaxel 200 mg/m2q3w), Arm B (atezolizumab + carboplatin + nab-paclitaxel 100 mg/m2qw) or Arm C (carboplatin + nab-paclitaxel) for 4or 6 cycles followed by atezolizumab maintenance therapy (Arms A andB) until loss of clinical benefit or progressive disease. Coprimary end-points were investigator-assessed PFS and OS in the ITT population.Data cutoff: October 3, 2018. Result: 1021 patients were enrolled, with343 in Arm B and 340 in Arm C. Median age was 65 years (range, 23-83[Arm B] and 38-86 [Arm C]) andz80% of patients were male. The proportion of patients with high (14% vs 13%), positive (39% vs 37%)or negative (47% vs 50%) PD-L1 expression was similar between arms.Median OS in the ITT population was 14.2 months in Arm B vs 13.5months in Arm C (HR, 0.88 [95% CI: 0.73, 1.05];P¼0.158; Table), notcrossing the boundary for statistical significance. In the PD-L1e high subgroup, median OS was 23.4 vs 10.2 months, respectively (HR, 0.48[95% CI: 0.29, 0.81]; not formally tested). Treatment-related Grade 3-4AEs and treatment-related SAEs occurred in 68.0% and 21.0% (Arm B)and 57.5% and 10.5% (Arm C) of patients; no new safety signals wereidentified, consistent with previous analyses. Conclusion: Final OS inArm B vs C did not cross the boundary for statistical significance. Clinically meaningful OS improvement was observed in the PD-L1ehigh subgroup, despite not being formally tested. No new or unex-pected safety signals were reported.