OSE Immunotherapeutics has shared phase 2 data on its neo-epitope vaccine candidate and Keytruda in ovarian cancer, linking maintenance use of the combination to improvements over best supportive care.
Investigators at ARCAGY-GINECO, a French cooperative that performs clinical trials in women’s cancers, ran the study. The researchers enrolled 185 recurrent ovarian cancer patients who either responded to platinum therapy or had stable disease after the treatment. Participants received best supportive care, OSE2101 as a monotherapy or the neo-epitope vaccine in combination with Merck & Co.’s Keytruda.
Progression-free survival (PFS) on the OSE2101-Keytruda cocktail was 4.1 months, versus 2.8 months for best supportive care. The difference, which was statistically significant, was particularly pronounced among patients who had partial or complete responses to platinum therapy.
The researchers linked the addition of Keytruda to OSE2101 to a non-statistically significant, 28% drop in the risk of progression or death over the single-agent treatment. Adverse events including cytokine release syndrome were more common in the combination arm than the single-agent cohort. OSE2101 monotherapy had a numerical PFS edge over best supportive care.
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The lack of a Keytruda monotherapy cohort makes it hard to tease out OSE2101’s contribution to the combination data. Keytruda is approved as a treatment for platinum-resistant ovarian cancer, but not in the platinum-sensitive, maintenance setting studied in the clinical trial.
OSE2101 is designed to turn immunogenically “cold” tumors “hot,” reversing the immunosuppressive microenvironment that limits the efficacy of checkpoint inhibitors such as Keytruda. The vaccine targets five tumor-associated antigens—TP53, MAGE2, MAGE3, CEA and HER2—to induce T-cell responses.
OSE is running a phase 3 study of OSE2101 in metastatic non-small cell lung cancer. Outside of its lead indication, the biotech is relying on investigator-sponsored trials to assess OSE2101-based combinations in ovarian, pancreatic and lung cancers. OSE expects the studies to generate more data this year.
