Excellent Results With High-Dose Mizoribine Combined With Cyclosporine, Corticosteroid, and Basiliximab in Renal Transplant Recipients: Multicenter Study in Japan

Prediction of mizoribine pharmacokinetic parameters by serum creatinine in renal transplant recipients

PURPOSE

Mizoribine (MZR) is an immunosuppressive agent with extensive inter-individual differences in pharmacokinetics (PK). Here, we investigated the PK characteristics of MZR in renal transplant recipients and gave equations for prediction of some critical PK parameters.

METHODS

A total of 40 renal transplant recipients participated in this prospective study and were administered MZR orally twice daily in the range of 1.1-8.9 mg kg^-1 day^-1. Steady-state concentrations of MZR were detected before (0 h) and 0.5, 1, 2, 3, 4, 5, 6, 8, and 12 h after administration by high-performance liquid chromatography method. Another 38 patients with newly detected trough concentration (C₀) were enrolled to validate the obtained C₀ predictive equation.

RESULTS

Significant inter-individual differences in MZR PK parameters were observed. Patients with decreasing creatinine clearance rate (CCr) had significantly decreased terminal elimination rate constant (k_el) and apparent total body clearance (Cl/F), while other PK parameters including apparent terminal half-life (t_1/2), peak time (T_max), peak concentration (C_max), area under the curve (AUC_0-12h), apparent volume of distribution (V/F), and mean residence time (MRT) were significantly increased. Correlation coefficients between AUC_0-12h and C₀/C_max were 0.894 and 0.916, respectively (both p < 0.001). A serum creatinine (SCr)-based predictive C₀ equation [C₀ = (2.160 × SCr - 54.473) × Dose] was established and validated by C₀ from another 38 patients. Besides, significant linear correlations between k_el/t_1/2 and CCr were also found (r² = 0.668 and 0.484, respectively), and equations predicting k_el/t_1/2 were also obtained (k_el = 0.015 + 0.002 × CCr, t_1/2 = 13.601 - 0.139 × CCr).

CONCLUSIONS

Renal function plays as an essential factor that contributes to great inter-individual MZR PK variation. Both C₀ and C_max are suitable for evaluating MZR exposure in the body. SCr could be applied to predict C₀ and t_1/2 of MZR.

Hyperuricemia and Acute Renal Failure in Renal Transplant Recipients Treated With High-Dose Mizoribine

BACKGROUND

Hyperuricemia is a common adverse event frequently found in renal transplant recipients with mizoribine (MZ). Hyperuricemia itself will be a cause of renal dysfunction, and renal dysfunction also will be a cause of hyperuricemia simultaneously. This study investigates frequency of hyperuricemia and renal failure in renal transplant recipients treated with high-dose MZ.

PATIENTS AND METHODS

From December 2007 to October 2015, there was a total of 32 living related renal transplant recipients treated with high-dose MZ. Of the 32 patients, 28 were treated with urate-lowering medications.

RESULTS

One patient received allopurinol (AP) and 13 patients received benzbromarone (BB). For 6 of them, their urate-lowering medications were converted to febuxostat (FX) form AP or BB. In the remaining 14 patients, FX was administered from the beginning. In 2 cases of ABO-incompatible living related renal transplant recipients who were maintained with high-dose MZ and BB, severe hyperuricemia and acute renal failure occurred. One patient was a 48-year-old man, and his creatinine (Cr) level increased to 8.14 mg/dL and his serum uric acid (UA) was 24.6 mg/dL. Another patient was a 57-year-old man, and his Cr level increased to 3.59 mg/dL and his UA was 13.2 mg/dL. In both cases Cr and UA were improved, and no finding of acute rejection and drug toxicity was observed in graft biopsy specimens. BB was switched to FX and discontinuance or reduction of MZ was done.

CONCLUSION

Combination of MZ and BB has the risk of acute renal dysfunction after renal transplantation. Latent renal dysfunction should be watched for in renal transplant recipients receiving high-dose MZ.

A Prospective Randomized, Comparative Trial of High-Dose Mizoribine Versus Mycophenolate Mofetil in Combination With Tacrolimus and Basiliximab for Living Donor Renal Transplant: A Multicenter Trial

OBJECTIVES

Our objectives were to compare the clinical outcomes of mizoribine (12 mg/kg/d) and mycophenolate mofetil (2000 mg/d) in combination with tacrolimus, basiliximab, and corticosteroids.

MATERIALS AND METHODS

We enrolled 83 recipients of living-donor renal transplant (performed between 2008 and 2013) in this study. This prospective multi-institutional randomized comparative study compared mizoribine (n = 41) and mycophenolate mofetil (n = 42) in combination with tacrolimus, basiliximab, and corticosteroids for living-donor renal transplant recipients. We compared the acute rejection and graft survival rates and adverse event rates within 1 year of renal transplant between the 2 groups using intention-to-treat analyses.

RESULTS

During the 1-year observation period, patient and graft survival rates were 100%. The acute rejection rate was 17.1% in the mizoribine group and 19% in the mycophenolate mofetil group. The incidence rate of cytomegalovirus infection seropositivity (recipient and donor with positive cytomegalovirus antibody status) was higher in the mycophenolate mofetil group than in the mizoribine group, although the difference in these rates was not statistically significant. The incidence of leukopenia was higher in the mizoribine group than in the mycophenolate mofetil group.

CONCLUSIONS

High-dose mizoribine at 12 mg/kg/day was a safe and efficacious immunosuppressive alternative to mycophenolate mofetil in living-donor renal transplant recipients. Leukopenia should be closely monitored in the initial period of insufficient kidney function after renal transplant.

Mizoribine versus mycophenolate mofetil in combination therapy with tacrolimus for de novo kidney transplantation: evaluation of efficacy and safety

The present study compared the efficacy and safety of mizoribine (MZR) with mycophenolate mofetil (MMF) in kidney transplantation. This multicenter, randomized clinical trial. Employed doses of study drug tailored to the immunosuppressive need. The primary efficacy outcome was the incidence of biopsy-proven acute rejection episodes (BPAR). The safety of the study drug was assessed using the incidences of adverse events, drug discontinuations, and abnormal laboratory results. The 7 (6.4%) BPARs above grade II were observed in the MZR group noninferior to the 2 (1.8%) in the MMF group (95% confidence interval, -0.007-0.097 > noninferiority limit [-0.2]). BPAR was significantly decreased in the MZR group after the dose change (17/41 [41.4%] vs 8/69 [11.6%]; P < .0001) and the incidence of BPAR was similar between the MZR and MMF groups after the dose change (P = .592). The uric acid level was significantly elevated in the MZR group (P = .002). In conclusion, the efficacy and safety of MZR were similar and statistically noninferior to MMF in combination therapy with tacrolimus.

The argument for the use of mizoribine in renal transplantation: a meta-analysis and systemic review

OBJECTIVE

The aim of this study is to evaluate the efficacy and safety of mizoribine (MZR) for immunosuppressive therapy in renal transplantation.

METHODS

A systematic search of the eligible studies that compared MZR with azathioprine (AZA) for post renal transplant immunosuppressive therapy was performed by using MEDLINE, EMBASE, and the Cochrane Library. Meta-analyses were performed to study the pooled effects of relative risk (RR) and weighted mean difference with 95% confidence intervals (CI).

RESULTS

A total of 486 participants from seven clinical trials were included. MZR demonstrated comparable efficacy in terms of acute rejection, patient/graft survival, and serum creatinine. However, MZR was associated with a significantly lower incidence of adverse events as compared with AZA (RR 0.39, CI 0.21-0.73, p=0.003). Specifically, recipients receiving MZR suffered from significantly fewer episodes of myelosuppression (RR 0.12, CI 0.02-0.54, p=0.006) and leukopenia (RR 0.20, CI 0.06-0.70, p=0.01). Also, MZR seemed to offer more favorable outcomes in terms of hepatic dysfunction, infection and diabetes, although the differences were not statistically significant.

CONCLUSIONS

MZR is a safe, well-tolerated and effective immunosuppressive agent that can be recommended as an alternative to AZA in renal transplant recipients, although further studies are needed to balance its effect with mycophenolate mofetil.