In the phase III ATALANTE/ENGOT-ov29 trial reported in the Journal of Clinical Oncology, Kurtz et al found that the addition of atezolizumab to bevacizumab and platinum-based doublets did not significantly improve progression-free survival among patients with platinum-sensitive ovarian cancer.

Study Details

The double-blind trial included 614 patients with recurrent epithelial ovarian cancer from sites in Europe and Israel. They were randomly assigned 2:1 between September 2016 and October 2019 to receive atezolizumab at 1,200 mg every 3 weeks (n = 410) or placebo (n = 204) for up to 24 months combined with bevacizumab and six cycles of an investigator-selected platinum-based  doublet, followed by bevacizumab maintenance. Patients could have received one or two prior chemotherapy lines and had to have a platinum-free treatment interval of longer than 6 months. A total of 38% of patients—156 in the atezolizumab group and 77 in the control group—had PD-L1–positive tumors. The co-primary endpoints of the study were investigator-assessed progression-free survival in the intention-to-treat (ITT) and PD-L1–positive populations, with a significance level of .025 in each analysis.

Progression-Free Survival

Median follow-up was 36.6 months (95% confidence interval [CI] = 35.1–38.7 months).

In the ITT population, median-progression free survival was 13.5 months (95% CI = 12.2–14.2 months) in the atezolizumab group vs 11.3 months (95% CI = 11.0–13.5 months) in the control group (hazard ratio [HR] = 0.83, 95% CI = 0.69–0.99, P = .041). Rates at 1 and 2 years were 56% vs 46% and 20% vs 12%, respectively.

In the PD-L1–positive population, median progression-free survival was 15.2 months (95% CI = 13.6–17.3 months) in the atezolizumab group vs 13.1 months (95% CI = 11.3–16.5 months) in the control group (HR = 0.86, 95% CI = 0.63–1.16, P = .30). Rates at 1 and 2 years were 64% vs 55% and 28% vs 19%, respectively.

Overall survival data were immature. At time of analysis in the ITT population, median overall survival was 35.5 months in the atezolizumab group vs 30.6 months in the control group (HR = 0.81, 95% CI = 0.65–1.01), with 1-, 2- , and 3-year rates of 89% vs 87%, 67% vs 62%, and 49% vs 38%, respectively. In the PD-L1–positive population, median overall survival was 40.7 months in the atezolizumab group vs 33.6 months in the control group (HR = 0.90, 95% CI = 0.61–1.32).

Adverse Events

Grade ≥ 3 adverse events occurred in 88% of patients in the atezolizumab group vs 87% of the control group and were considered related to treatment in 33% vs 35%. Adverse events led to the discontinuation of atezolizumab in 25% of patients and placebo in 18%; adverse events led to the discontinuation of bevacizumab in 34% vs 27% of patients and to the discontinuation of chemotherapy in 15% vs 15%. Potential immune-related adverse events occurred in 27% vs 15% of patients (grade ≥ 3 in 13% vs 8%). Fatal adverse events considered related to treatment occurred in three patients in the atezolizumab group (cardiac arrest, peritonitis, and acute myeloid leukemia) and in two patients in the control group (pulmonary embolism and bowel perforation).

The investigators concluded, “ATALANTE/ENGOT-ov29 did not meet its coprimary progression-free survival objectives in the ITT or PD-L1–positive populations. Overall survival follow-up continues. Further research on biopsy samples is warranted to decipher the immunologic landscape of late-relapsing ovarian cancer.”

Jean-Emmanuel Kurtz, MD, PhD, of the Department of Medical and Surgical Oncology & Hematology, ICANS, Strasbourg, France, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by F. Hoffmann-La Roche, Ltd. For full disclosures of the study authors, visit ascopubs.org.