LEXINGTON, Mass. — Agenus Inc. said new clinical data show deep and durable responses with its investigational combination of botensilimab and balstilimab in women with heavily pretreated, treatment-refractory ovarian cancer, a population that has historically shown limited response to immunotherapy.
The results, from the ovarian cancer cohort of the Phase 1b C-800-01 trial, were published in The Journal for ImmunoTherapy of Cancer. The study evaluated the botensilimab and balstilimab combination, known as BOT+BAL, in patients with advanced disease who had exhausted standard treatment options.
In the heavily pretreated population, the combination achieved an overall response rate of 23 percent and a clinical benefit rate of 31 percent. Durable responses were observed, with a median duration of response of 9.7 months. Median overall survival reached 14.8 months, and an estimated 75 percent of patients were alive at 12 months.
Agenus said the findings build on previously presented results from the broader C-800-01 dataset, which showed activity across multiple refractory solid tumors. Collectively, the data suggest the BOT+BAL combination may be capable of generating meaningful immune responses in tumors traditionally considered resistant to immunotherapy.
Ovarian cancer remains a major cause of cancer-related mortality, with outcomes particularly poor once tumors become platinum-resistant or platinum-refractory. First-generation checkpoint inhibitors have produced modest results in this setting, leaving patients with limited treatment options.
The ovarian cancer cohort enrolled 44 women who had received multiple prior lines of therapy. Nearly three-quarters of participants were platinum-resistant or platinum-refractory, and most had high-grade serous tumors. Activity was observed in primary platinum-refractory patients, a high-risk group often excluded from clinical trials, as well as across multiple ovarian cancer subtypes, including high-grade serous, clear cell, and endometrioid disease.
The company said the safety profile of the combination was manageable and consistent with known CTLA-4 and PD-1 therapies. The most common treatment-related adverse events included diarrhea or colitis, fatigue, and nausea, which were generally reversible and managed using established guidelines. No treatment-related deaths were reported.
“These results offer a meaningful signal of clinical activity for women with platinum-refractory ovarian cancer, a group that has seen little therapeutic progress,” said Steven O’Day, M.D., chief medical officer of Agenus. “Botensilimab’s unique immune activation profile translated into clinically significant responses in a population long considered resistant to immunotherapy. These findings strengthen our confidence in the potential of this combination and support advancing it into larger, randomized studies.”
Rebecca Porter, M.D., Ph.D., lead author of the publication, said the results are encouraging given the severity of disease in the study population.
“These women faced some of the most treatment-resistant forms of ovarian cancer, yet several achieved meaningful and durable benefit,” Porter said. “Seeing this level of activity in such a heavily pretreated population provides important insights for patients with very limited remaining options.”
Agenus said the BOT+BAL combination continues to advance through global clinical development across multiple tumor types. In parallel, eligible patients may be able to access the therapy through regulatory-authorized early access programs in select countries where permitted. (Source: IANS)
