Agenus trial results announced on October 25, 2026, showed that 72% of 18 patients with locally advanced, mismatch repair-deficient colon cancer had no cancer remaining in examined tumor tissue or nearby lymph nodes at surgery after a six-week immunotherapy course. The early Phase 2 findings support further investigation of botensilimab plus balstilimab, but do not establish a cure or superiority to existing treatment.
Key Takeaways
- The NEOASIS cohort met its primary endpoint, with 83% achieving a major pathologic response.
- All 18 patients were alive at a median follow-up of 15 months; 16 remained free of recurrence.
- Investigators are enrolling a rectal cancer cohort to explore whether selected patients can avoid surgery.
Table of Contents
- Agenus trial results meet the primary response endpoint
- Safety and follow-up qualify the early findings
- Rectal cancer enrollment extends the development program
- Conclusion
Agenus trial results meet the primary response endpoint
The Netherlands Cancer Institute sponsored the investigator-initiated NEOASIS study, with the colon cancer findings presented at the European Society for Medical Oncology Congress in Madrid. Participants had non-metastatic, resectable disease with mismatch repair deficiency, known as dMMR.
Agenus’ NEOASIS Phase 2 announcement defines major pathologic response as 10% or less viable tumor remaining at surgery. The 83% response rate met the cohort’s primary endpoint, while 72% achieved a pathologic complete response, meaning no cancer remained in the examined tumor or nearby lymph nodes.
The distinction matters: these results measure response in surgically examined tissue, not proof that cancer will never return. Nearly all participants, 17 of 18, had some degree of pathologic response.
| Item | Details |
|---|---|
| Study design | Single-center Phase 2 platform study. |
| Botensilimab dose | 50 mg on Day 1. |
| Balstilimab doses | 450 mg on Days 1 and 22. |
| Tumor stage | All tumors were at least T3; 67% were T4. |
| Lymph node involvement | 72% of patients had cancer in nearby lymph nodes. |
Safety and follow-up qualify the early findings
Immune-related side effects were mostly Grade 1 or 2 and manageable, Agenus said. One patient developed Grade 3 colitis, which resolved with treatment.
All patients proceeded to surgery. Seventeen underwent surgery as planned; one had an earlier operation on Day 41 because of a bowel obstruction and achieved a pathologic complete response.
All 18 patients were alive at a median follow-up of 15 months, but two had experienced recurrence. The small cohort and absence of a control arm limit conclusions about comparative effectiveness, long-term recurrence prevention and safety.
Rectal cancer enrollment extends the development program
Netherlands Cancer Institute investigators are now enrolling a dMMR rectal cancer cohort to assess whether a short course of the combination can allow selected patients to avoid surgery. That is an investigational goal, not an established treatment outcome.
Agenus is also advancing the short-course approach in microsatellite-stable colon cancer, a different disease subgroup from the dMMR cohort described here. The reported response rates should not be assumed to apply to that population.
For Agenus, the announcement is a clinical-development milestone rather than a new U.S. marketing authorization. Botensilimab and balstilimab remain investigational outside Armenia and are not approved by the U.S. Food and Drug Administration.
Conclusion
The Agenus trial results establish an early tissue-response signal in a narrowly defined colon cancer population, not a proven long-term survival benefit. The next confirmed development step is enrollment in the dMMR rectal cancer organ-preservation cohort.
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