OSE’s Tedopi-Keytruda combo clears Phase II ovarian cancer hurdle

The Nantes-based company said the TEDOVA/GINECO-OV244b/ENGOT-ov58 trial met its primary endpoint in patients with platinum-sensitive recurrent ovarian cancer who had progressed after, or were ineligible for, PARP inhibitors and bevacizumab. In the study, Tedopi combined with Keytruda improved median progression-free survival to 4.1 months, compared with 2.8 months for best supportive care.

The trial enrolled 185 patients whose disease had achieved complete response, partial response or stable disease following platinum-based chemotherapy. Participants were randomised to one of three maintenance strategies: best supportive care, Tedopi alone, or Tedopi in combination with Keytruda. The primary endpoint compared the combination arm with best supportive care.

The design is important for interpreting the result. TEDOVA does not show that Tedopi alone is superior to Keytruda, nor does it isolate the full contribution of Keytruda in the combination. What it does show is that the Tedopi-Keytruda maintenance regimen outperformed best supportive care in a post-PARP, post-bevacizumab recurrent ovarian cancer population. When the two investigational arms were compared, adding Keytruda to Tedopi reduced the risk of progression or death by 28%.

Ovarian cancer has been a challenging field for immunotherapy. Checkpoint inhibitors have transformed treatment in several cancers, but ovarian tumours have generally been less responsive to single-agent PD-1 or PD-L1 blockade. More recently, pembrolizumab-based combinations have generated stronger data in recurrent disease, including the Phase III KEYNOTE-B96 trial in platinum-resistant recurrent ovarian cancer. TEDOVA adds a different angle: rather than combining Keytruda with chemotherapy, the study tested whether a therapeutic cancer vaccine could help prime or amplify an anti-tumour immune response during maintenance treatment.

Tedopi, also known as OSE2101, is an off-the-shelf T-cell epitope-based cancer vaccine developed for HLA-A2-positive patients. It targets five tumour-associated antigens and is designed to activate tumour-specific T lymphocytes. The rationale for combining it with Keytruda is that a vaccine may help generate or expand anti-tumour T-cell responses, while PD-1 blockade may prevent these immune cells from being switched off in the tumour microenvironment.

According to OSE, the combination was associated with more adverse events than Tedopi alone, including immune-related events, consistent with the known mechanism of checkpoint inhibition. The company did not provide detailed safety tables in the press release.

The study was sponsored by the French academic cooperative group ARCAGY-GINECO and conducted within the ENGOT network. Full data are scheduled for presentation by Alexandra Leary of Gustave Roussy at the American Society of Clinical Oncology annual meeting in Chicago on 30 May 2026.

For OSE, the ovarian cancer result strengthens the broader development case for Tedopi, whose most advanced programme remains in non-small cell lung cancer. The company is currently advancing Tedopi in the Phase III ARTEMIA trial in HLA-A2-positive NSCLC patients with secondary resistance to immune checkpoint inhibitors, while also exploring the vaccine in investigator-sponsored trials across ovarian, pancreatic and lung cancers.

The immediate clinical question for TEDOVA will be whether the PFS signal can translate into a more durable benefit, and whether future studies can define which patients are most likely to benefit from the vaccine-checkpoint combination.