Agenus' Neoadjuvant Immunotherapy Shows Deep Responses in Colon Cancer — Agenus Inc.

Event summary

Agenus published updated Phase 2 NEST trial results showing 59% pathologic response rate in pMMR/MSS colon cancer patients with no observed recurrences after median 32.2 months follow-up.
41% of patients achieved major pathologic response, 32% pathologic complete response in historically immunotherapy-resistant pMMR/MSS tumors.
NEST3 Phase 2 trial actively enrolling 100 patients across 11 US sites, first patient dosed in July 2026.
ROBBIN Phase 3 trial planned to evaluate neoadjuvant BOT+BAL vs standard of care in high-risk Stage II/III MSS colon cancer.

The big picture

Agenus' results challenge the historical limitation of immunotherapy in mismatch repair proficient (pMMR/MSS) colon cancers, which represent 85% of early-stage cases. The neoadjuvant approach aims to leverage the intact tumor microenvironment for more effective immune activation. If confirmed in larger trials, this could reshape treatment paradigms for a significant portion of colorectal cancer patients.

What we're watching

Clinical Validation: Whether the deep pathologic responses and recurrence-free survival observed in NEST will translate to the larger Phase 3 ROBBIN trial population.
Regulatory Pathway: The pace at which Agenus can advance BOT+BAL through the neoadjuvant setting, potentially establishing a new standard of care for MSS colon cancer.
Competitive Positioning: How Agenus' Fc-enhanced CTLA-4 antibody differentiates from conventional checkpoint inhibitors in remodeling the tumor microenvironment.