Allogenic stem cells for anal Crohn’s fistula: treating early improves the deep response rate

Abstract Purpose: The aim of this study was to evaluate the real-life clinical and radiological efficacy of darvadstrocel injection into complex perianal fistulas in Crohn’s disease. Secondary endpoints were to assess symptomatic efficacy, outcomes and factors associated with complete combined clinical-radiological response (deep response). Methods: After marketing the product in France, all patients treated consecutively were included. A complete clinical response was defined by a complete closure of all external openings with no discharge on pressure. A partial response was defined by closure of ≥ 50% of external openings with no discharge on pressure. A complete radiological response (MRI), evaluated at least after six months of follow-up, was defined by a completely fibrotic sequela without abscess. Results: Forty-three patients were included (M/F: 22/21, median age 37 [26-45] years). The fistulas of all patients were already drained with seton(s) and were on biologic treatment. After a median follow-up of 383 [359-505] days, 28 (65%) patients showed a clinical response (22 complete and 6 partial). Only 16 (37%) achieved a deep response. The PDAI decreased significantly after treatment: 39 (91%) patients reported symptomatic improvement in terms of discharge, pain, and induration, and 28 (65%) no longer had any perineal symptoms. Only a short history of Crohn’s disease < 3 years was significantly associated with deep response (OD 4.5 [1.0-19.1], p = 0.04). Conclusion: Darvadstrocel injection resulted in a clinical response for two thirds of patients and deep response for one third. A shorter duration of Crohn’s disease was associated with deep response.