A Prospective, Single-Arm Study to Evaluate the Safety and Efficacy of RD2-Ver.02, an Autologous Blood Clot, in the Treatment of Anal Fistula

Abstract

BACKGROUND: Surgical treatment of complex perianal fistula is technically challenging, associated with risk of failure, and may require multiple procedures. In recent years, several biologic agents have been developed for the purpose of permanently eradicating anal fistulous disease with variable success. RD2-Ver.02 treatment is an autologous whole blood product created from the patients’ blood, which forms a provisional matrix that was found to be safe and effective in healing acute and chronic cutaneous wounds. OBJECTIVE: To assess the efficacy and safety of RD2-Ver.02 as a treatment for transsphincteric perianal fistulas. DESIGN: A prospective single-arm study. SETTINGS: A single tertiary medical center. PATIENTS: Patients with simple or complex transsphincteric fistulas confirmed by magnetic resonance imaging were included in the study. Etiology was either cryptoglandular or Crohn’s related (in the absence of active luminal bowel disease). INTERVENTION: The outpatient procedure was performed under general anesthesia and consisted of: 1) physical debridement and cleansing of the fistula tract; 2) suture closure of the internal opening; and 3) instillation of RD2-Ver.02 into the entire tract. MAIN OUTCOME MEASURES: Safety and efficacy at 6- and 12-months following surgery. RESULTS: Fifty-three patients (77% male) with a median age of 42 (20-72) years were included in the study. Three patients withdrew consent, and 1 patient was lost to follow-up. At the time of this interim analysis, 49 and 33 patients completed the 6 and 12 months follow-up period, respectively. Thirty-four (34) patients achieved complete healing (69%) at 6 months while 20 patients out of 33 (60%) achieved healing after 1 year. All patients who achieved healing at 6 months remained healed at the 1 year mark. In a subgroup analysis of Crohn’s patients, 7 of 9 patients completed 1-year follow-up, with 5 patients (71%) achieving clinical remission. No major side effects or postoperative complications were noted, while 2 adverse events occurred (admission for pain control and COVID-19 infection). LIMITATIONS: Noncomparative single-arm pilot study. CONCLUSIONS: Treatment with RD2-Ver.02 in perianal fistular disease was found to be feasible and safe, with an acceptable healing rate in both cryptoglandular and Crohn’s fistula in ano. Further comparative assessment is required to determine its potential role in the treatment paradigm of fistula-in-ano. See Video Abstract.