Final Results From the ATALANTE/ENGOT-ov29 Randomized Phase III Trial of Atezolizumab, Bevacizumab, and Platinum-Based Therapy for Late-Relapsing Recurrent Ovarian Cancer

PURPOSE Previously reported results from the placebo-controlled double-blind randomized phase III ATALANTE/ENGOT-ov29 trial (ClinicalTrials.gov identifier: NCT02891824 ) showed that progression-free survival improvement with the addition of atezolizumab to standard bevacizumab and platinum-based chemotherapy for late-relapsing recurrent ovarian cancer did not reach statistical significance in the intention-to-treat (ITT; hazard ratio [HR] 0.83 [95% CI, 0.69 to 0.99]; two-sided P = .041) or PD-L1–positive populations (dual primary end points). Here we report the final analysis, including overall survival (OS). PATIENTS AND METHODS Patients with recurrent epithelial ovarian cancer, one or two prior chemotherapy lines, and platinum-free interval (PFI) >6 months were randomly assigned 2:1 to atezolizumab or placebo for up to 24 months, combined with bevacizumab and six cycles of investigator-selected platinum-based chemotherapy, stratified by PFI, PD-L1 status, and chemotherapy regimen. OS was a secondary end point. RESULTS At 5 years' median follow-up, the median OS was 35.8 months with atezolizumab-containing therapy (n = 410) and 30.6 months with standard therapy (n = 204) in the ITT population (HR, 0.83 [95% CI, 0.69 to 0.98]); 5-year OS rates were 27% versus 17%, respectively. Time to second subsequent therapy showed consistent results favoring atezolizumab. There was no evidence of an enhanced treatment effect in the PD-L1–positive population. CONCLUSION At the final analysis, a clinically meaningful 5-month improvement in median OS was observed with atezolizumab added to bevacizumab and a platinum doublet.