Usefulness and safety of high-dose mizoribine on ABO-incompatible living related kidney transplantation using anti-CD20 and anti-CD25 antibodies without splenectomy: 3-year results.

BACKGROUND: Mizoribine (MZR) has been developed as an immunosuppressive agent in Japan, but has a less potent immunosuppressive effect up to 3 mg/kg/d. We previously reported that high-dose MZR, at 6 mg/kg/d, would be effective and safe for ABO-incompatible(ABO-i) living donor kidney transplantation (LDKT) patients when combined with cyclosporine (CsA) or tacrolimus(FK), anti-CD20 and anti-CD25 monoclonal antibodies, and corticosteroid without splenectomy in a 1-year study. Therefore, we observed these patients for 3 years.

METHODS: From 2007 to 2010, we encountered 24 cases of ABO-i LDKT using anti-CD20 and anti-CD25 monoclonal antibodies without splenectomy. The pretransplantation immunosuppressive regimen consisted of two doses of anti-CD20 antibody, mycophenolate mofetil (MMF, 25 mg/kg/d), prednisolone, calcineurin inhibitor (CNI; CsA 7 mg/kg or (FK 0.2 mg/kg) and two doses of anti-CD25 antibody. Antibody removal by plasmapheresis was performed before LDKT up to several times according to the antibody titer. The post-transplantation regimen consisted of high-dose MZR (6 mg/kg/d) instead of MMF (MZR group, N = 12) .

RESULTS: The 3-year graft survival rates for the MZR and MMF groups were 91.7% and 100%, respectively. Serum creatinine levels for the MZR and MMF groups were 1.44 mg/dL and 1.31 mg/dL at 1 year, 1.55 mg/dL and 1.41 mg/dL at 2 years, and 1.51 mg/dL and 1.48 mg/dL at 3 years, respectively (not significant [NS]). The MZR group did not show a higher rate of elevated serum uric acid values. The percentage of patients who were administered anti-uric medication was 42.5% (5/12) in the MZR group and 50% (6/12) in the MMF group (P = NS) at the third year. Severe infection, such as cytomegalovirus, herpes zoster, was not observed at the second and third years in both groups.

CONCLUSION: A high-dose MZR regimen including CNI (CsA or FK), steroid, and anti-CD20 and anti-CD25 antibodies without splenectomy was effective and safe in ABO-i renal transplantation.