Long-term safety and efficacy of darvadstrocel for complex perianal fistulas in Japanese adults with Crohn's disease: 3-year follow-up results.

Background/Aims: Darvadstrocel is a 1-time local injection for treatment-refractory complex perianal fistulas in patients with Crohn's disease. Here we present 3-year (week 156) follow-up results from a Japanese phase 3, multicenter, open-label study of darvadstrocel. Methods: Adult Japanese patients with Crohn's disease and complex perianal fistulas refractory to previous treatment were treated with darvadstrocel after fistula curettage and seton placement. In this long-term follow-up extension, treatment-emergent adverse events, including serious treatment-emergent adverse events, were recorded through week 156. The proportions of patients with combined remission (clinical remission plus magnetic resonance imaging confirmation of fistula closure) and clinical remission were recorded at week 104 and week 156. Results: In total, 22 patients were treated with darvadstrocel; 19 patients completed assessment at week 156. Through week 156, treatment-emergent adverse events were experienced by 21/22 patients (95.5%); most treatment-emergent adverse events were moderate (40.9%) or mild (31.8%). Serious treatment-emergent adverse events were reported in 11 patients (50.0%). At week 104 and week 156, 77.3% of patients (17/22) and 68.2% of patients (15/22), respectively, achieved both combined and clinical remission. Mean maximum short axis diameter of the fistula tract at the time of remission was shortest in patients who maintained combined remission until week 156. Conclusions: No new safety signals for darvadstrocel were identified during the 3-year follow-up period. Combined and clinical remission of complex perianal fistulas was sustained up to 156 weeks. ClinicalTrialsgov registration: NCT03706456.