Multinational phase 3 trial of atezolizumab, bevacizumab and platinum-based therapy for late-relapsing ovarian cancer: final results

The multinational phase 3 ATALANTE/ENGOT-ov29 trial evaluated addition of atezolizumab to standard bevacizumab and platinum-based chemotherapy for late-relapsing recurrent ovarian cancer. Primary analysis of the trial did not find statistically improved progression-free survival (PFS) in the ITT population or the PD-L1-positive population. Final analysis of the trial has now been published. The trial included patients wit one or two prior chemotherapy lines and a platinum-free interval (PFI) longer than 6 months. Patients were randomized 2:1 to atezolizumab (n=410) or placebo (n=204) for up to 24 months, combined with bevacizumab and six cycles of investigator-selected platinum-based chemotherapy, stratified by PDI, PD-L1 status, and chemotherapy. At 5 year median follow-up, the median overall survival was 35.8 months in the atezolizumab group versus 30.6 months in the placebo group (HR 0.83; 95% CI 0.69-0.98) with 5-year overall survival rates 27% versus 17%, respectively. Time to subsequent therapy and PFS2 also showed consistent results favoring atezolizumab. There was no evidence of an enhanced treatment effect in the PD-L1-positive population. The authors conclude that at the final analysis of ATALANTE/ENGOT-ov29, a clinically meaningful 5-months improvement in median overall survival was observed with addition of atezolizumab to bevacizumab and platinum-based chemotherapy.