Results of a multicenter prospective clinical study in Japan for evaluating efficacy and safety of desensitization protocol based on rituximab in ABO-incompatible kidney transplantation.

Background: Deceased organ donations are rare in Japan, with most kidney transplants performed from a limited number of living donors. Researchers have thus developed highly successful ABO-incompatible transplantation procedures, emphasizing preoperative desensitization and postoperative immunosuppression. A recent open-label, single-arm, multicenter clinical study prospectively examined the efficacy and safety of rituximab/mycophenolate mofetil desensitization in ABO-incompatible kidney transplantation without splenectomy.

Methods: Mycophenolate mofetil and low dose steroid were started 28 days pretransplant, followed by two doses of rituximab 375 mg/m at day -14 and day -1, and postoperative immunosuppression with tacrolimus or ciclosporin and basiliximab. The primary endpoint was the non-occurrence rate of acute antibody-mediated rejection. Patient survival and graft survival were monitored for 1 year posttransplant.

Results: Eighteen patients received rituximab and underwent ABO-incompatible kidney transplantation. CD19-positive peripheral B cell count decreased rapidly after the first rituximab infusion and recovered gradually after week 36. The desensitization protocol was tolerable, and most rituximab-related infusion reactions were mild. No anti-A/B antibody-mediated rejection occurred with this series. One patient developed anti-HLA antibody-mediated rejection (Banff 07 type II) on day 2, which was successfully managed. Patient and graft survival were both 100 % after 1 year.

Conclusion: Our desensitization protocol was confirmed to be clinically effective and with acceptable toxicities for ABO-I-KTx (University Hospital Medical Information Network Registration Number: UMIN000006635).