Agenus (NASDAQ:AGEN) has published peer-reviewed results from the ovarian cancer cohort of its Phase 1b trial in The Journal for ImmunoTherapy of Cancer (JITC), highlighting a potential breakthrough for a patient population with historically limited options.
The study evaluated the combination of botensilimab (BOT), an Fc-enhanced anti-CTLA-4 antibody, and balstilimab (BAL), an anti-PD-1 antibody, in women with heavily pretreated, treatment-refractory ovarian cancer.
In this high-risk group—nearly three-quarters of whom were platinum-resistant or refractory—the BOT+BAL combination achieved an overall response rate (ORR) of 23% and a clinical benefit rate of 31%.
These figures significantly outperform the 8–10% response rates typically seen with first-generation checkpoint inhibitors in similar settings.
The responses were notably durable, with a median duration of 9.7 months and a median overall survival (OS) of 14.8 months.
The trial is particularly significant for its impact on "cold" tumors—cancers that generally do not respond to immunotherapy.
By utilizing an Fc-enhanced antibody (BOT), Agenus aims to "prime" the immune system more effectively than standard CTLA-4 blockers, inducing long-term memory responses even in late-line patients.
The publication comes as Agenus continues to build a "pan-tumor" case for the BOT+BAL doublet.
Data presented at ESMO 2025 earlier this quarter showed survival plateaus across multiple solid tumors, including colorectal and lung cancers.
With an estimated 75% of the ovarian cancer cohort alive at 12 months, the company is positioning BOT+BAL as a foundational therapy for the next generation of immuno-oncology.
Management noted that the safety profile remained manageable and consistent with known immune-mediated effects, primarily involving reversible gastrointestinal events.
As Agenus advances its Phase 3 BATTMAN trial in colorectal cancer, these ovarian results reinforce the combination's versatility across the most challenging-to-treat "cold" malignancies.