P581 Allogeneic expanded adipose-derived mesenchymal stem cell therapy for perianal fistulas in Crohn’s disease: First real-life experiences

Abstract Background Since treatment of perianal fistulas in patients with Crohn’s disease (CD) has low durable fistula closure rates even with optimal medical and surgical therapy, new therapies are needed. According to a pivotal phase 3 study program, darvadstrocel, a mesenchymal stem cell therapy, appears to be a promising new treatment option after failure or incomplete response to biologics and immunosuppressive agents. However, until now, no data on the real-life efficacy of darvadstrocel is available. Methods A total of 7 CD patients with complex perianal fistulas without luminal disease were treated with local injection of 120 million allogenic adipose-derived stem cells at our academic tertiary referral centre on an outpatient basis. MRI and fistula conditioning with seton loop placement were performed at least 6 weeks pre-operatively. Furthermore, CD remission was confirmed endoscopically in advance. Results The mean age of patients was 39.4 years, 86% were male and 29% smokers. The mean duration of fistula manifestation was 8.1 years. All patients (except one treated with tacrolimus) had previously received anti-TNF treatment without fistula healing. One patient had CD of an ileoanal pouch following restorative proctocolectomy. Postoperatively, the secretion from the wounds stopped after a few days and in 2 patients clinically fistula healing occurred already after 4 weeks. In 3 patients the fistulas healed after 6 weeks. One patient developed repeated abscesses without fistula healing. Another patient showed improvement of symptoms but without healing of the fistula at 8 weeks. Interestingly, symptomatic CMV viremia occurred two weeks after darvadstrocel injection in one patient, but his two fistulas healed. Conclusion Our initial experience of seven patients treated with darvadstrocel for perianal CD fistulas demonstrates promising results with rapid resolution of local complaints and full clinical healing in five patients until now. Taken together, darvadstrocel appears to be a promising therapeutic option for the challenging group of patients suffering from complex perianal CD fistulas.