Use of Darvadstrocel (Allogenic Stem Cell Therapy) for Crohn's Fistulas in Real Clinical Practice: The National Project to Implement Mesenchymal Stem Cell for the Treatment of Perianal Crohn's Fistula (the PRIME Study).

BACKGROUND: Perianal fistulas may affect 15-50% of patients with Crohn's disease. Treatment is complex, requiring a multidisciplinary approach. Darvadstrocel (allogenic mesenchymal cells obtained from lipoaspirates) was approved in 2018 by the European and Spanish Agencies of Medicines and Medical Products as a treatment for fistulas in Crohn's disease. Recent European Crohn's and Colitis Organisation and Spanish Working Group on Crohn's Disease and Ulcerative Colitis guidelines state that darvadstrocel is effective with a favorable safety profile and a strong level of evidence (2).

OBJECTIVE: Presenting real-world effectiveness data for darvadstrocel in a Spanish population.

DESIGN: Observational retrospective cohort study with prospective data gathering.

SETTINGS: Fourteen institutions.

PATIENTS: From November 2019-April 2022, all patients (73) treated with darvadstrocel in these institutions were included, fulfilling the following criteria: 1) complex fistula/s in a patient with Crohn's disease; 2) failure of conventional and antitumor necrosis factor treatment; 3) absence of collections >2 cm confirmed by pelvic MRI scan at the time of surgery.

INTERVENTIONS: Darvadstrocel treatment.

MAIN OUTCOME MEASURES: Clinical response (closure of ≥50% of external openings), complete clinical closure (100% of external openings) and radiological closure (no fluid collection >2 cm, no edema or inflammation) evaluated 6 months after treatment.

RESULTS: Clinical response was observed in 63 patients (86.3%), complete clinical closure in 50 patients (68.5%) and radiological closure in 45 patients (69.2%). Combined clinical and radiological response was observed in 41 patients (63.1%). Not all clinically healed patients had radiological closure and vice versa. No serious adverse events were reported.

LIMITATIONS: Retrospective.

CONCLUSIONS: Study results were consistent with those reported in previous clinical trials, real-world efficacy findings from the INSPIRE study (assessing darvadstrocel effectiveness in Europe, Israel, Switzerland, UK, and Japan) and previously published literature. Darvadstrocel was effective and demonstrated a favorable safety profile when used in normal clinical practice for treatment of fistulas in Crohn's disease. See Video Abstract.