P0795Efficacy of Granulocyte and Monocyte Apheresis (GMA) for Pouchitis Following Colectomy in Ulcerative Colitis Patients” Abstract

Background Despite advances in biologic therapies since the early 2000s, surgery remains necessary for refractory ulcerative colitis (UC) and UC-associated neoplasia (UCAN). After colectomy with ileal pouch–anal anastomosis (IPAA), pouchitis is a common complication. Its pathogenesis involves altered microbiota and immune dysregulation, with neutrophil infiltration in acute cases and lymphocyte/plasma cell infiltration in chronic cases. Antibiotics are first-line therapy, but refractory cases require alternative approaches.This study aimed to evaluate the efficacy and safety of leukocyte apheresis (GMA: granulocyte and monocyte apheresis) in patients who developed pouchitis after colectomy for UC. Methods Between June 2020 and August 2025, 22 patients with UC who developed pouchitis after IPAA and underwent GMA were retrospectively analyzed. The primary endpoint was remission induction rate. Secondary endpoints included comparison of background factors between remission and non-remission groups (sex, age, acute vs. chronic pouchitis, time to onset, ciprofloxacin resistance, prior GMA use, drug allergies, baseline modified Pouchitis Disease Activity Index [mPDAI], hemoglobin, albumin, C-reactive protein levels), improvement in urgency, and adverse events. Results The remission induction rate following GMA was 82%, and improvement in urgency was observed in 91% of cases. Comparison between remission and non-remission groups revealed a significant difference in the presence of extraintestinal complications. Adverse events were minimal: one patient experienced fever and headache, while no other serious events were reported.Although the etiology of pouchitis is multifactorial, histological findings suggest that neutrophil-dominated leukocyte infiltration plays a pivotal role, particularly in the acute phase. The favorable outcomes observed in this study indicate that GMA may exert therapeutic benefit by removing activated inflammatory leukocytes, thereby attenuating mucosal inflammation. Given the high remission and symptom improvement rates, GMA may represent a promising treatment option, especially in patients with antibiotic-refractory pouchitis. The low incidence of adverse events further supports its clinical applicability. Future studies with larger cohorts and prospective designs are warranted to confirm these findings and to clarify the role of GMA in combination with antibiotics or biologic agents. Conclusion Leukocyte apheresis appears to be an effective and safe therapeutic option for pouchitis following colectomy in UC patients. These results suggest that GMA could serve as a valuable adjunctive treatment in the management of postoperative pouchitis, particularly in refractory cases. Conflict of interest: Dr. Ito, Ayumi: No conflict of interest Miki, Koroku: No conflict of interest Yonezawa, Maria: No conflict of interest Nakamura, Shinichi: No conflict of interest Nakai, Yousuke: No conflict of interest