Agenus Inc. reported no recurrences of colorectal cancer in a Phase 2 study evaluating its botensilimab and balstilimab combination as neoadjuvant therapy for resectable colon cancer.
The mid-stage trial, published in Clinical Cancer Research, included 24 patients with 26 resectable tumors, with a median follow-up of 32.2 months in the NEST-1 cohort and 23.5 months in NEST-2. All participants proceeded to planned surgical resection without treatment-related delays, with pre-surgical treatment intervals of approximately four weeks in NEST-1 and eight weeks in NEST-2.
Among tumors with proficient mismatch repair/microsatellite stable (pMMR/MSS) status—representing roughly 85% of early-stage colorectal cancers—the combination therapy achieved a pathological response rate of 59%, including a major pathological response in 41% and complete pathological response in 32%. For the four tumors with deficient mismatch repair/microsatellite instability-high (dMMR/MSI-H) status, all achieved a major pathological response, with two complete responses and two near-complete regressions of 98% and 99%, respectively.
Circulating tumor DNA (ctDNA) analysis showed that 88% of patients with detectable ctDNA at baseline cleared it before surgery. ctDNA remained undetectable after resection in all evaluated cases. No Grade 4 treatment-related adverse events, deaths, or study discontinuations were reported.
Agenus is advancing toward ROBBIN, a planned randomized global Phase 3 trial comparing neoadjuvant botensilimab and balstilimab followed by standard of care against standard of care alone in untreated high-risk stage II or stage III MSS colon cancer patients.
