REC-163964

REC-163964 is a first-in-class, orally active small molecule toxin inhibitor developed by Recursion Pharmaceuticals for the prevention and treatment of recurrent Clostridioides difficile (C. difficile) infection. It was the first internally discovered new chemical entity (NCE) advanced to IND-enabling studies by Recursion’s machine learning-driven platform. The drug acts as a selective inhibitor of the glucosyltransferase activity of C. difficile toxin B (TcdB), suppressing toxin-induced glycosylation of Rho-GTPases in gut epithelial cells—a key pathogenic mechanism in C. difficile colitis and recurrence. Unlike antibiotics, REC-163964 targets bacterial toxins directly without disrupting normal gut flora, offering potential for both monotherapy and combination with standard-of-care antibiotics or other therapies[1][2][3][7]. Preclinical models demonstrated that oral administration improved survival in infected animals[7]. As of late 2024, it has progressed into Phase 2 clinical trials for recurrent C. difficile infection[2][5].