Recursion presented updated results from TUPELO, its Phase 1b and 2 trial of REC-4881 in familial adenomatous polyposis, at the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer meeting in Denver. REC-4881 is an oral MEK1 and MEK2 inhibitor dosed at 4 milligrams once daily, studied over 12 weeks on treatment and 12 weeks off treatment.
In the expanded adult efficacy population, 13 of 15 patients, or 87 percent, had a reduction in total polyp burden after 12 weeks, with a median reduction of 47 percent, and about one in three achieved reductions of 65 percent or more. Twelve weeks after stopping treatment, 85 percent of evaluable patients remained below baseline. Reductions appeared in both the upper gastrointestinal tract, where the median reduction was 55 percent, and the lower tract, where it was 50 percent among patients with measurable burden.
The higher risk detail is the part clinicians will weigh most. Six of eight patients with polyps larger than 5 millimetres at baseline had fewer such polyps after 12 weeks, four had reductions of 80 percent or more, and two saw counts of larger polyps fall from more than 90 to one. On safety, the highest grade treatment related adverse event was Grade 1 or 2 in 21 of 26 patients and Grade 3 in four, with no Grade 4 or 5 treatment related events and no new safety signals reported.
The limits matter as much as the headline. TUPELO is open label, the evaluable groups are small and vary by measure, and polyp reduction has not yet been shown to prevent cancer or avoid surgery. Recursion said it is in ongoing discussions with the FDA and, subject to alignment, targets a registrational trial in the second half of 2027, with more detail on the path due later this year.