ESMO 2023

Agenus’ Botensilimab/Balstilimab Combination Delivers Durable Responses across Multiple Sarcoma Subtypes

Agenus Inc. (Nasdaq:AGEN), a leader in developing novel immunological agents to treat various cancers, today announced expanded data from the company’s phase 1b study of botensilimab (BOT, multifunctional immune activator) in combination with balstilimab (BAL, anti-PD-1) in patients with advanced sarcomas. The results were presented in an oral presentation at the European Society for Medical Oncology (ESMO) Congress 2023.

Relapsed/refractory sarcoma represents a significant unmet medical need where existing standard of care options and previous immunotherapies have shown limited activity. At present, available treatments for advanced soft tissue sarcoma patients only have modest activity. The sarcoma cohort presented is part of a larger phase 1b study evaluating the safety, efficacy, and dose optimization of BOT alone and in combination with BAL in multiple advanced solid tumors.

"These results reinforce the promising potential of BOT+BAL in multiple cold, treatment-resistant solid tumors," said Dr. Steven O’Day, Chief Medical Officer. "Notably, we observed several durable responses extending past one year, including patients with visceral angiosarcoma, which is traditionally unresponsive to immunotherapy, as well as other cold subtypes like leiomyosarcoma. As we expand the study, we aim to focus on key subsets and dosing strategies to maximize benefit for patients.”

“As the study has advanced, BOT+BAL continues to demonstrate encouraging results in a larger population of patients with difficult to treat sarcomas, with a median response duration of 19.4 months and a 40% 6-month progression-free survival rate. We're also seeing a dose-dependent effect, with a 29% objective response rate at 2 mg/kg,” said Dr. Breelyn Wilky, MD, Director of Sarcoma Medical Oncology at the University of Colorado, and study investigator.

Study Design and Highlights

A total of 41 evaluable patients received either 1 or 2 mg/kg BOT every 6 weeks and 3 mg/kg BAL every 2 weeks.

Patient Demographics

• Majority of patients had either angiosarcoma (29%) or leiomyosarcoma (39%) subtypes
• Patients were heavily pre-treated, with a median of three prior lines of therapy, including 16% who received prior PD-(L)1 therapy
• Majority of patients had biomarkers associated with poor response to immunotherapy:
  • 87% had a low tumor mutation burden (<10 mutations per megabase)
  • 74% of patients were PD-L1 negative by immunohistochemistry

Clinical Findings