“These results add to the growing body of data showing deep and durable efficacy signals for botensilimab across nine cold and treatment-resistant cancers,” said Steven O’Day, M.D., Chief Medical Officer of Agenus. “Botensilimab is designed with a unique mechanism of action that stimulates both innate and adaptive immune responses against cancer, resulting in an improved benefit compared to what has been reported for other checkpoint therapies.“

“The combination of botensilimab and balstilimab in platinum-resistant ovarian cancer shows promise for a substantial improvement in efficacy compared to existing therapies, which typically only yield single-digit response rates,” said Bruno Bockorny, M.D., Harvard Medical School, Beth Israel Deaconess Medical Center, and principal investigator for the study. “The remarkable efficacy and manageable tolerability profile of this combination suggest a transformative potential for ovarian cancer patients.”

The ovarian cancer cohort is part of a large study evaluating the safety, efficacy, and dose optimization of botensilimab alone and in combination with balstilimab in multiple solid tumors. Agenus is currently enrolling in Global Phase 2 ACTIVATE trial programs in metastatic microsatellite stable colorectal cancer, melanoma and pancreatic cancers. Based on recent positive findings presented at SITC, Agenus is also expanding enrollment of its anti-PD-(L)1 relapsed/refractory non-small cell lung cancer cohort of the Phase 1b study and planning additional NSCLC studies.

Study Design and Highlights

A total of 24 evaluable patients with recurrent platinum resistant/refractory ovarian cancer received either 1 or 2 mg/kg botensilimab every 6 weeks and 3 mg/kg balstilimab every 2 weeks.

Patient Demographics

• 79% were high grade serous, which has a poor prognosis
• Patients were heavily pre-treated, with a median of 4 prior lines of therapy including 21% with prior immunotherapy
• Majority of patients had biomarkers associated with poor response to immunotherapy:
  • 90% had a low tumor mutation burden (<10 mutations per megabase)
  • Over half of patients were PD-L1 negative by IHC

Clinical Findings

• 33% overall response rate (1 complete response, 7 partial responses)
  • Other PD-(L)1 + CTLA-4 combinations in other trials reported 3-10% response rates in a comparable patient population.^1,2
• 67% disease control rate
• Median duration of response not reached
• Manageable tolerability profile

Presentation Details

Abstract Title: Botensilimab, a Novel Innate/Adaptive Immune Activator, plus Balstilimab (Anti-PD-1) in Patients with Recurrent Platinum Refractory/Resistant Ovarian Cancer (NCT03860272)

Presenting Author: Bruno Bockorny, MD, Harvard University, Beth Israel Deaconess Medical Center

Data presented will be available to view in the Publications section of the Agenus website (https://agenusbio.com/publications) following the SGO Conference.