The final study results of the AGO-OVAR 2.29 (ENGOT-ov34) study were published in December 2025.

This large international Phase III study investigated whether the additional administration of the immunotherapy drug atezolizumab together with bevacizumab and non-platinum-based chemotherapy can prolong the survival of patients with recurrent ovarian cancer. This form of cancer recurs despite platinum-based chemotherapy and is considered particularly difficult to treat.

A total of 574 patients were randomised in the study and received either the standard treatment (chemotherapy + bevacizumab + placebo) or atezolizumab in addition.

What did the study show?

➡️ No clear survival benefit was found with the addition of atezolizumab:

• The median overall survival (OS) was approximately 14.2 months with atezolizumab and 13.0 months in the control group – this difference was not statistically significant, i.e. not clear enough to speak of a reliable advantage.

• The median progression-free survival (PFS) – i.e. the time during which the tumour does not grow again – was practically the same with atezolizumab at 6.4 months compared to 6.7 months in the control group, and likewise without any statistically significant advantage.

💡 This means that immunotherapy with atezolizumab did not lead to a clear improvement in disease control or prolongation of life in this study when given in addition to bevacizumab and chemotherapy.

What about side effects?

Serious side effects (grade ≥ 3) occurred slightly more frequently in patients receiving atezolizumab (72% vs. 69%), but overall the safety profile was comparable to that already known for the individual drugs.

Was any difference observed depending on PD-L1 status?

The study also investigated whether patients with PD-L1-positive tumours (a possible indication of a better response to immunotherapy) benefited more from atezolizumab. This was not the case – the results were similar regardless of whether the tumour was PD-L1-positive or -negative.

Important contribution to research
Even if these specific results are negative, large-scale studies such as this are important for understanding exactly which therapies really help in which situations – and where we still need new approaches.

💡 Standards remain unchanged
For patients with platinum-resistant recurrence, established treatment options such as chemotherapy with bevacizumab or other effective combinations remain the recommended standard. Immunotherapy such as atezolizumab is not currently proven to be more effective than standard treatment in this setting.

Source: Publication at ASCO