UPDATE: New results from the ongoing TUPELO trial show that REC-4881, an investigational drug, has achieved astonishing success in treating patients with Familial Adenomatous Polyposis (FAP). The clinical data, announced December 8, 2025, reveals that 82% of patients maintained significant reductions in polyp burden even after stopping therapy for 12 weeks.
This groundbreaking data is crucial for the FAP community, where patients face a near 100% lifetime risk of colorectal cancer if left untreated. The trial results provide a beacon of hope for individuals suffering from this debilitating condition, which impacts over 50,000 people in the US and EU.
In the Phase 1b/2 trial, REC-4881 demonstrated rapid clinical activity, with a 43% median reduction in total polyp burden observed after just 12 weeks of treatment among evaluable patients. At the 25-week mark, which is 12 weeks after discontinuation of the drug, 82% of patients still showed reductions, indicating the treatment’s durable efficacy.
Patients in the study reported a substantial improvement, with 40% achieving a clinically significant increase in Spigelman stage, a key measure of upper gastrointestinal disease severity. These findings stand in stark contrast to a natural history analysis of untreated FAP patients, which showed that 87% experienced an increase in polyp burden annually.
Dr. Jessica Stout, Principal Investigator of the TUPELO study, emphasized the importance of this trial for patients: “The durable polyp burden reduction demonstrated by REC-4881 is highly encouraging. Given the absence of approved therapies, these results provide a meaningful basis for hope.”
The safety profile of REC-4881 aligns with previous MEK1/2 inhibitors, with 94.7% of patients experiencing treatment-related adverse events, primarily mild (Grade 1/2). No severe (Grade ≥4) adverse events have been reported to date.
This trial not only marks a pivotal moment for FAP treatment but also validates the innovative approach of Recursion Pharmaceuticals. “These results represent a meaningful validation of our technology platform,” stated Chris Gibson, Co-Founder and CEO of Recursion. “We believe this is just the beginning of our journey in developing transformative therapies.”
Moving forward, Recursion plans to engage with the FDA in the first half of 2026 to discuss potential registration pathways for REC-4881. The company also intends to expand eligibility for the trial to include patients aged 18 and older, further widening access to this promising treatment.
As the trial progresses, the medical community and patients alike will be watching closely for further developments. This ground-breaking data not only sheds light on a previously underserved population but also raises hopes for a non-surgical option to manage FAP, significantly improving quality of life for those affected.
Stay tuned for more updates as Recursion continues to pave the way in innovative cancer therapies.
