New Data on Botensilimab/Balstilimab in MSS CRC at 2024 ASCO Meeting

Agenus Inc., a prominent player in the field of immuno-oncology, has unveiled a groundbreaking analysis from the Phase 1b trial of botensilimab (BOT) combined with balstilimab (BAL) in patients with relapsed/refractory microsatellite stable colorectal cancer (r/r MSS CRC) without active liver metastases (NLM). This new analysis, set to be presented at the 2024 American Society of Clinical Oncology (ASCO) Annual Meeting on June 1, 2024, reveals that BOT/BAL demonstrates efficacy in metastatic sites beyond the lungs and lymph nodes, including the peritoneum, soft tissue, and brain.

Dr. Steven O'Day, Chief Medical Officer at Agenus, emphasized the significance of these findings, noting that the activity observed in traditionally unresponsive metastatic sites is a rare achievement for immunotherapy in MSS mCRC. This positions BOT/BAL as a distinctive treatment option, potentially offering durable long-term benefits for cancer patients.

Patient Demographics

The study involved 77 patients with NLM MSS mCRC who were administered 1 or 2 mg/kg BOT every six weeks, along with 3 mg/kg BAL every two weeks. These patients had undergone extensive prior treatments, with a median of four previous therapy lines. Notably, 21% of participants had been treated with prior PD-(L)1/CTLA-4 therapy.

Regarding the distribution of NLM sites, 81% of patients had lung involvement, 43% had peritoneal involvement, 42% had lymph node involvement, 19% had soft tissue involvement, and 23% had other metastatic sites, including the bone and brain.

Clinical Findings

The clinical outcomes across different NLM sites showcased encouraging results. The overall response rates (ORR) ranged from 18-33%, while the disease control rates (DCR) spanned 67-82%. Overall survival (OS) remained consistent, fluctuating between 20.7 months to not reached (NR). Importantly, no new safety concerns were identified during the trial.

The analysis will be formally presented under the abstract titled "Botensilimab plus balstilimab in microsatellite stable metastatic colorectal cancer: Assessing efficacy in non-liver metastatic sites." The abstract, numbered 3556, will be presented by Dr. Marwan Fakih, Division Head of GI Medical Oncology at City of Hope Comprehensive Cancer Center, during a poster session in the Gastrointestinal Cancer – Colorectal and Anal category on June 1, 2024, from 1:30 p.m. to 4:30 p.m. CT.

Botensilimab: A Novel Immunotherapy Agent

Botensilimab is a human Fc-enhanced CTLA-4 blocking antibody designed to enhance both innate and adaptive anti-tumor immune responses. Its innovative design aims to extend the benefits of immunotherapy to "cold" tumors that typically respond poorly to standard care or are refractory to existing PD-1/CTLA-4 therapies. Botensilimab boosts immune responses across diverse tumor types by priming and activating T cells, downregulating intratumoral regulatory T cells, activating myeloid cells, and inducing long-term memory responses.

To date, approximately 900 patients have participated in Phase 1 and Phase 2 clinical trials involving botensilimab. The agent, either alone or in combination with Agenus’ investigational PD-1 antibody, balstilimab, has demonstrated clinical responses in nine metastatic, late-line cancers.

About Agenus

Agenus is a leading company in the field of immuno-oncology, focusing on cancer and infectious diseases. The company’s mission is to broaden the patient population benefiting from cancer immunotherapy through combination approaches, utilizing a wide array of antibody therapeutics, adoptive cell therapies via MiNK Therapeutics, and adjuvants through SaponiQx. Headquartered in Lexington, MA, Agenus is dedicated to advancing its comprehensive pipeline of immunological agents.

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