Key Moments
- Recursion Pharmaceuticals (NASDAQ:RXRX) shares climbed 7% after reporting positive Phase 2 data for REC-4881 in familial adenomatous polyposis (FAP).
- REC-4881 led to a 75% response rate among evaluable patients, with a 43% median reduction in total polyp burden at 12 weeks and durable effects after treatment cessation.
- The company aims to engage with the FDA in the first half of 2026 to discuss a potential registration pathway for REC-4881 in FAP.
FAP Study Results Drive Market Reaction
Recursion Pharmaceuticals (NASDAQ:RXRX) saw its stock advance 7% on Monday after unveiling encouraging results from a Phase 2 clinical study of its investigational therapy REC-4881 in patients with familial adenomatous polyposis (FAP), a rare inherited condition that currently has no approved treatments.
In the trial, REC-4881 demonstrated rapid clinical activity. The company reported that 75% of evaluable participants experienced a reduction in total polyp burden, with a 43% median decrease after 12 weeks of treatment. The company highlighted the durability of this effect, noting that 82% of patients sustained polyp burden reductions 12 weeks after discontinuing therapy, corresponding to a 53% median reduction from baseline.
Efficacy Versus Natural History and Disease Progression
The announced findings were framed against natural history data for FAP, which indicate that 87% of untreated patients generally show an increase in polyp burden over time. By contrast, REC-4881 not only reduced polyp burden in most treated patients but also demonstrated broader clinical benefit.
According to Recursion, 40% of patients achieved a clinically meaningful improvement in Spigelman stage, a scale used to assess the severity of upper gastrointestinal disease in FAP.
| Metric | REC-4881 Outcome | Comparator / Context |
|---|---|---|
| Stock price reaction | +7% | Following Phase 2 data release |
| Patients with reduced total polyp burden (evaluable) | 75% | After 12 weeks of treatment |
| Median reduction in total polyp burden | 43% | At Week 12 on therapy |
| Patients with durable reductions after stopping therapy | 82% | 12 weeks post-treatment (Week 25) |
| Median reduction from baseline at Week 25 | 53% | 12 weeks after completing therapy |
| Untreated FAP patients with increased polyp burden over time | 87% | Natural history data |
| Patients with clinically meaningful Spigelman stage improvement | 40% | Upper GI disease severity measure |
Investigator Perspective
“The durable polyp burden reduction demonstrated by REC-4881—especially the sustained effect seen at Week 25, 12 weeks after completing therapy—is highly encouraging for the FAP community,” said Jessica Stout, Principal Investigator of the TUPELO study and Assistant Clinical Professor at University of Utah School of Medicine.
Mechanism, Discovery Platform, and Safety Profile
REC-4881 is described as an allosteric MEK1/2 inhibitor that was discovered using Recursion’s in-house artificial intelligence-enabled discovery system, known as the Recursion OS. The company stated that the therapy’s safety findings were consistent with MEK1/2 inhibition. Most treatment-related adverse events were reported as Grade 1 or 2, and there were no Grade 4 or higher treatment-related events.
Regulatory Path and Development Plans
Recursion indicated that it intends to meet with the U.S. Food and Drug Administration in the first half of 2026 to discuss a potential registration pathway for REC-4881 in FAP. As part of its development strategy, the company plans to broaden the eligible patient population and refine the dosing regimen.
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