• The objective response rate (ORR) in patients with PD-L1 positive tumors: 20.0% and included 3 patients (3/85, 3.5%) with a complete response and 14 patients (14/85, 16.5%) with a partial response.
• The median duration of response (DoR): Not reached after a 14.6-month median follow-up.
• Responses were also observed in the PD-L1 negative population with an ORR of 7.9%.
• The confirmed ORR for both PD-L1 positive and negative tumors was 15.0% and included 5 patients (3.6%) with a complete response and 16 patients (11.4%) with a partial response.
• The median DoR was 15.4 months and the disease control rate was ~50%. Notably, responses were observed across histologies, with responses in the squamous cell histology (ORR 17.6%) and in the more difficult to treat adenocarcinoma histology (ORR 12.5%).
• The safety profile was manageable and consistent with that of currently approved anti-PD-1 antibodies; it also compared favorably to the safety profiles of chemotherapies used in this population. Data from this trial continue to mature.

As discussed in the publication, these data suggest that balstilimab may be a differentiated anti-PD-1 antibody as compared to currently approved PD-1 inhibitors.

In the KEYNOTE-158 trial of pembrolizumab – an anti-PD-1 antibody, in the same setting, an ORR of 14.6% was observed in the PD-L1 positive population and no responses were observed in the PD-L1 negative population.

The noted 12.5% response rate of balstilimab in patients with cervical adenocarcinoma is significant as this subpopulation typically does not respond to immunotherapy and represents a growing proportion of advanced cervical cancer cases.

Balstilimab thus provides the potential for therapeutic benefit to patient populations that do not typically respond to currently available immunotherapy, both alone and in combination with other therapies, such as Agenus’ anti-CTLA-4 antibodies zalifrelimab and AGEN1181.

Final results from a Phase 2 trial of balstilimab in combination with zalifrelimab in advanced cervical cancer will be presented in a Mini Oral Session at the European Society for Medical Oncology (ESMO) Congress 2021 on September 19 from 11:35 – 11:40 am ET by David O’Malley, MD.

From Ohio State University College of Medicine

David O’Malley, MD, Professor, Department of Obstetrics and Gynecology, The Ohio State University College of Medicine; Director, Division of Gynecologic Oncology, OSUCCC – James; and lead author on the publication said, “The efficacy and safety of balstilimab provide additional evidence of the importance of immune checkpoint blockade in the treatment of recurrent, advanced cervical cancer patients,” “Furthermore, responses to balstilimab were seen in patients who were PD-L1 positive, PD-L1-negative, bevacizumab pre-treated, and squamous cell and adenocarcinoma histologies. Balstilimab clearly provides clinical benefit in a broad range of cervical cancer patients.”

Study Design (NCT03104699)

This was an open-label, single-arm, global Phase 2 clinical trial conducted at 60 sites throughout the United States, Europe, South America, and Australia. Patients were enrolled from November 20, 2017, to April 16, 2020, and received intravenous balstilimab at a dose of 3 mg/kg once every two weeks, given as a 60-minute infusion. Treatment was permitted for up to 24 months, or until disease progression, intolerable toxicity, or investigator/patient decision. 

Balstilimab is a novel, fully human monoclonal immunoglobulin G4 (IgG4) designed to block PD-1 (programmed cell death protein 1) from interacting with its ligands PD-L1 and PD-L2. PD-1 is a negative regulator of immune activation that is considered a foundational target within the immuno-oncology market. Agenus announced it had submitted a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) on April 19, 2021, for use in patients with recurrent or metastatic cervical cancer, and the application is under priority review with a target action date of December 16, 2021. 

About Agenus

Agenus is a clinical-stage immuno-oncology company focused on the discovery and development of therapies that engage the body’s immune system to fight cancer. The Company’s vision is to expand the patient populations benefiting from cancer immunotherapy by pursuing combination approaches that leverage a broad repertoire of antibody therapeutics, adoptive cell therapies (through its MiNK Therapeutics subsidiary), adjuvants and proprietary cancer vaccine platforms. The Company is equipped with a suite of antibody discovery platforms and a state-of-the-art GMP manufacturing facility with the capacity to support clinical programs. Agenus is headquartered in Lexington, MA.

Information that may be important to investors will be routinely posted on the Company’s website and its Twitter handle @agenus_bio.

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