In this episode of JCO Article Insights, host Dr. Melis Canturk summarizes the article, "Atezolizumab With Bevacizumab and Nonplatinum Chemotherapy for Recurrent Ovarian Cancer: Final Results From the Placebo-Controlled AGO-OVAR 2.29/ENGOT-ov34 Phase III Trial," by Harter et al.
TRANSCRIPT
Melis Canturk: Hello, and welcome to the JCO Article Insight. I'm your host, Melis Canturk, and today we will be discussing the JCO article, "Atezolizumab With Bevacizumab and Nonplatinum Chemotherapy for Recurrent Ovarian Cancer: Final Results From the Placebo-Controlled AGO-OVAR 2.29/ENGOT-ov34 Phase III Trial."
While integrating immune checkpoint inhibitors has revolutionized the treatment of various gynecologic cancers, these agents have historically shown limited single agent activity in ovarian cancer. Despite a strong biological rationale for combining immunotherapy with chemotherapy and bevacizumab to enhance T-cell infiltration and normalized tumor vasculature, several phase III trials have failed to demonstrate a significant survival benefit in this setting.
The AGO-OVAR 2.29/ENGOT-ov34 trial was launched to definitely evaluate whether adding the PD-L1 inhibitor atezolizumab to this combination could improve long-term outcomes for patients experiencing early relapse. This international, double-blind, randomized phase III trial enrolled 574 patients with epithelial ovarian, fallopian tube, or peritoneal cancer. Eligible participants had to be in their first or second relapse within 6 months of completing platinum therapy or in their third relapse regardless of the treatment-free interval. All patients received bevacizumab and an investigator selected chemotherapy backbone, either paclitaxel or doxorubicin. They were randomly assigned to receive either 840 mg of atezolizumab or a placebo every 2 weeks until disease progression or for a maximum of 2 years.
The study population was an all-comer group, though patients were stratified by their PD-L1 status, previous bevacizumab use, and the number of prior treatment lines. The trial did not meet its primary end points, as the addition of atezolizumab failed to significantly improve overall survival or progression-free survival in the intention-to-treat population. For the primary end point of overall survival, the median was 14.2 months with atezolizumab compared to 13 months with the placebo. Progression-free survival was similarly insignificant, with a median of 6.4 months in the experimental arm versus 6.7 months in the control arm. Furthermore, the objective response rates were nearly identical between the groups, recorded at 40% for atezolizumab and 44% for the placebo.
Interestingly, exploratory subgroup analyses revealed potential signals of benefit in specific populations, even though the overall trial was negative. Patients who had been previously treated with bevacizumab appeared to derive a greater benefit from the addition of atezolizumab than those who were bevacizumab-naïve. Additionally, outcomes seemed more favorable for patients receiving a paclitaxel chemotherapy backbone compared to those receiving doxorubicin. However, PD-L1 status did not appear to be a predictive marker for success, as hazard ratios for survival were similar regardless of whether the tumor was PD-L1 positive or negative.
The safety profile of the triple combination was consistent with the known toxicities of the individual drugs. Grade 3 or higher adverse events occurred in 73% of the atezolizumab group and 70% of the placebo group. While the experimental arm saw higher incidences of immune-mediated events, such as thyroid-related issues, these were generally manageable. Serious adverse events were more frequent in the atezolizumab arm than in the placebo arm, but discontinuation rates due to toxicity were relatively low and comparable between the two groups.
In conclusion, the AGO-OVAR 2.29 trial confirms that adding atezolizumab to bevacizumab and nonplatinum chemotherapy does not provide a statistically significant survival advantage for patients who receive nonplatinum chemotherapy for recurrent ovarian cancer. This study contributes to the growing body of evidence showing that immune checkpoint inhibitors have yet to find a definitive role in the standard treatment of recurrent ovarian cancer. Future research will likely focus on more sophisticated molecular stratification and the use of novel agents, such as bispecific antibodies, to overcome the challenging tumor microenvironment of low-grade serous ovarian cancer.
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