Effects of long-term treatment with mizoribine in patients with proliferative lupus nephritis

Lupus Nephritis in Children: Novel Perspectives

Childhood-onset systemic lupus erythematosus is an inflammatory and autoimmune condition characterized by heterogeneous multisystem involvement and a chronic course with unpredictable flares. Kidney involvement, commonly called lupus nephritis, mainly presents with immune complex-mediated glomerulonephritis and is more frequent and severe in adults. Despite a considerable improvement in long-term renal prognosis, children and adolescents with lupus nephritis still experience significant morbidity and mortality. Moreover, current literature often lacks pediatric-specific data, leading clinicians to rely exclusively on adult therapeutic approaches. This review aims to describe pediatric lupus nephritis and provide an overview of the novel perspectives on the pathogenetic mechanisms, histopathological classification, therapeutic approach, novel biomarkers, and follow-up targets in children and adolescents with lupus nephritis.

Giant Cell Arteritis with Generalized Granuloma Annulare

We report the case of an 80-year-old man with generalized granuloma annulare (GGA) who subsequently developed giant cell arteritis (GCA). Steroid treatment was effective for both diseases in this case. Although cases of concomitant GGA and GCA have rarely been reported, previous studies suggest that common histological characteristics underlie the two diseases. It is therefore necessary to recognize that GGA can be complicated by GCA, particularly when typical symptoms, such as headache and visual disturbance, are present.

Study protocol: high-dose mizoribine with prednisolone therapy in short-term relapsing steroid-sensitive nephrotic syndrome to prevent frequent relapse (JSKDC05 trial)

Background

Eighty percent of children with steroid-sensitive nephrotic syndrome (SSNS) relapse within 2 years and 40–50% patients show frequently-relapsing nephrotic syndrome (FRNS). Patients showing a relapse within 6 months after initial remission are at high risk of FRNS. Since frequent prednisolone treatment for FRNS induces severe prednisolone side effects, development of a treatment to prevent patients from shifting to FRNS is desirable. Mizoribine is an immunosuppressive drug with fewer side effects than prednisolone. Recent studies reported the efficacy of high-dose mizoribine in children with FRNS.

Methods/design

We conduct a multicenter, open, randomized controlled trial to investigate the efficacy and safety of standard prednisolone plus high-dose mizoribine therapy in children with SSNS showing a relapse within 6 months after an initial remission. Patients are allocated to either standard prednisolone alone treatment group, or standard prednisolone plus high-dose mizoribine group. For the former group, mizoribine is administered at a dose of 10 mg/kg/day once daily and continued for 2 years. The primary endpoint is the duration to frequent relapse.

Discussion

The results provide important data on use of high-dose mizoribine to prevent SSNS patients from shifting to FRNS. Since blood concentrations of mizoribine have not been investigated in detail until now, there is a possibility that mizoribine is underestimated in favor of other immunosuppressive drugs. In future, high-dose mizoribine therapy may lead to prevention of relapse in children at high risk of FRNS, and to decreased total dose of prednisolone.

Trial registration

UMIN000005103, (Prospectively registered 1st March 2011).

Post-marketing surveillance study of the long-term use of mizoribine for the treatment of lupus nephritis: 2-Year results

OBJECTIVES

To understand the status of mizoribine use in patients with lupus nephritis (LN) and to collect safety- and efficacy-related data on 2-year treatment with mizoribine.

METHODS

A continuous survey was conducted between March 2010 and July 2015.

RESULTS

The analysis set included 559 patients (mean age 39.5 years, females 82.6%, mean duration of systemic lupus erythematosus (SLE) 8.4 years, mean duration of LN 5.9 years). Renal function was satisfactory for 6 months, but worsened from 12 months, with significant worsening at 24 months. By the ACR 2006 remission criteria (eGFR >60), at 24 months, 26.5% of patients achieved complete remission, and 63.3% achieved complete or partial remission. The urine protein to creatinine ratio decreased significantly. The SLE Disease Activity Index 2000 score decreased significantly at 12 and 24 months. Overall, 98 (17.5%) patients experienced 124 adverse drug reactions (ADRs); 3.6% experienced serious ADRs. Mizoribine was used with a steroid in 99.3% and an immunosuppressant in 51.2%; tacrolimus was used in 43.8%. The oral steroid dosage decreased from baseline to 24 months. The incidence of ADRs was not significantly different with concomitant tacrolimus use.

CONCLUSIONS

The results suggest that long-term mizoribine is safe and effective, even when used with tacrolimus.

Safety and efficacy of mizoribine treatment in nephrotic syndrome complicated with hepatitis B virus infection: a clinical study

Objective The objective of this study is to explore the efficacy and safety of mizoribine (MZR) in treating nephrotic syndrome patients afflicted with hepatitis B virus (HBV). Methods The present study included 36 nephrotic syndrome patients accompanied with HBV infection. A draft of MZR (150-200 mg/d), methylprednisolone (0.6-0.8 mg/kg·d), and entecavir (0.5 mg/d) was administered to study patients over 24 weeks. The serum albumin (AlB), 24-h urine protein (24-U-TP), liver and renal functions, and HBV-DNA were quantified before and at 2, 4, 8, 12, 16, 20, and 24 weeks after the treatment. The adverse responses were recorded. Results The AlB levels of patients increased gradually after comprehensive treatment, while the 24-U-TP, serum cholesterol, and triglyceride (TG) levels declined gradually. The changes at 24 weeks post-treatment were statistically significant. Compared with the levels before treatment, the HBV-DNA, transaminase, and renal functions of the patients were not significantly altered after the treatment. No evident adverse response was found. Conclusion Treatment using MZR in combination with methylprednisolone and entecavir in HBV-positive nephrotic syndrome patients displays significant efficacy with a low incidence of adverse reactions.

Population pharmacokinetics of mizoribine in pediatric patients with kidney disease

BACKGROUND

The present study aimed to obtain information enabling optimisation of the clinical effect of mizoribine (MZR) in pediatric patients with kidney disease.

METHODS

A total of 105 pediatric patients with kidney disease treated at our institutions were enrolled. Kidney transplant patients were excluded. Population pharmacokinetic analysis of MZR was performed based on serum concentration data. Area under the curve from time zero to infinity (AUC_∞) and maximal concentration (C _max) were calculated by Bayesian analysis.

RESULTS

In children, the appearance of MZR in the blood tended to be slower and the subsequent rise in blood concentration tended to be more sluggish, compared to healthy adults. Apparent volume of distribution and oral clearance were also higher in children compared to adults. A significant positive correlation was observed between patient age and AUC_∞. There were significant differences of AUC_∞ and C _max by age group. No relationship was observed between the administration method of MZR and serum concentration.

CONCLUSION

The pharmacokinetics of MZR was different in children compared to adults. To obtain the expected clinical efficacy, the regular MZR dosage schedule (2-3 mg/kg/day) might be insufficient for pediatric patients. In particular, younger patients might require a higher dosage of MZR per unit body weight.

Lupus Nephritis in Asia: Clinical Features and Management

BACKGROUND

Lupus nephritis (LN) is a common and severe organ involvement manifesting itself in systemic lupus erythematosus (SLE). There is a considerable difference in prevalence, severity, treatment response and outcomes between Asian LN patients and LN patients from other racial backgrounds.

SUMMARY

Asian SLE patients have a higher prevalence of LN than Caucasian SLE patients and often present with a more severe disease. Increasing data from genetic studies, accompanied by progress in high-throughput genotyping, have advanced our knowledge about genetic predispositions that might partly contribute to the clinical variations observed. Corticosteroids combined with either cyclophosphamide (CYC) or mycophenolic acid (MPA) is the current standard-of-care induction regimen for severe LN irrespective of race or ethnicity. However, the preference for MPA or CYC, and possibly the optimum dose for MPA, is influenced by the patient's origin. Also, there is an insufficient evidence base for reduced-dose intravenous CYC in Asian patients. Health economics and access to prompt diagnosis and treatment are still challenging issues in some Asian regions. The former represents a significant obstacle limiting the access of patients to MPA despite the proven efficacy of the drug as an induction agent and its superiority over azathioprine (AZA) in preventing disease flares when used for long-term maintenance immunosuppression. Calcineurin inhibitors such as tacrolimus deserve further investigation in view of their additional effect on podocytes by reducing proteinuria and the promising data from Asian patients. Despite considerable advances in the clinical management of LN over the past few decades with resultant improvements in patients' outcomes, there are still knowledge gaps and unmet clinical needs. Asia has made substantial contributions to the evidence base that guides clinical management and continues to offer invaluable opportunities for research pursuits.

KEY MESSAGES

Treatment responses and clinical outcomes in Asian patients with LN compare favorably with patients from other parts of the world. The prevention and treatment of infective complications remain significant challenges in managing LN in Asia.

FACTS FROM EAST AND WEST

(1) The prevalence of SLE is lower among Caucasians than other ethnicities. A higher prevalence is observed among Asians and African Americans, while the highest prevalence is found in Caribbean people. The prevalence of LN in Asian SLE patients is much higher than in Caucasians as well. However, the 10-year renal outcome and renal survival rate appear to be better in Asians. (2) Polymorphisms of genes involved in the immune response, such as Fcγ receptor, integrin alpha M, TNF superfamily 4, myotubularin-related protein 3 and many others, might be partly responsible for the differences in prevalence between the different ethnic groups. European ancestry was shown to be associated with a decrease in the risk of LN even after adjustment for genes most associated with renal disease. (3) Access to health care is a key determinant of disease progression, treatment outcome and the management of complications such as infections, particularly in South Asia, and might also explain disparities between clinical outcomes. (4) The efficacy of low-dose CYC combined with corticosteroids for induction treatment of LN was proved in European Caucasian patients. This treatment is also used in Asia, although no formal evaluation of efficacy and safety in comparison with other treatment regimens exists in this population. The efficacy of mycophenolate mofetil (MMF) is similar to that of CYC, and similar between Asians and Caucasians. MMF may be more effective than CYC in inducing response in high-risk populations such as African American or Hispanic patients. MMF might cause less infection-related events in Asians, but its high cost prevents broader usage at present. (5) For maintenance therapy, corticosteroid combined with AZA or MMF is used worldwide, with a broadly similar efficacy of both treatments, although there are data suggesting that in high-risk populations (e.g. African Americans) MMF may be more effective in preventing renal flares. AZA is often preferred in Asia due to economic constraints and because of its safety in pregnancy. (6) Alternative therapies under investigation include rituximab, which might be more efficient in Caucasians, as well as belimumab. Recent Japanese and Chinese studies have indicated a potential benefit of tacrolimus as a substitute for or in addition to CYC or MMF (dual or triple immunosuppression). Mizoribine is used in Japan exclusively.

Mizoribine in the treatment of pediatric-onset glomerular disease

BACKGROUND

Mizoribine (MZR) is a selective inhibitor of inosine monophosphate dehydrogenase, a key enzyme in the pathway responsible for de novo synthesis of guanine nucleotides. As an immunosuppressant, MZR has been used successfully without any serious adverse effects in the treatment of renal diseases in children as well as adults. Besides its immunosuppressive effect, MZR has been reported to ameliorate tubulointerstitial fibrosis in rats via suppression of macrophage infiltration.

DATA SOURCES

In this review, we summarize reported possible benefits of MZR in the treatment of pediatriconset glomerular disease.

RESULTS

We recently observed that MZR itself selectively attenuates the expression of monocyte chemoattractant protein-1 at both the mRNA and protein levels in human mesangial cells. Since MZR binds specifically to 14-3-3 proteins and heat shock protein 60, both of which are reportedly expressed in inflamed glomeruli, MZR may bind directly to inflamed glomerular cells, thereby possibly preventing progressive damage from glomerulonephritis through a suppressive effect on activated macrophages and intrinsic renal cells. Moreover, it has recently been reported that MZR directly prevents podocyte injury through correction of the intracellular energy balance and nephrin biogenesis in cultured podocyte and rat models, suggesting a direct anti-proteinuric effect of MZR.

CONCLUSIONS

These beneficial mechanisms of action of MZR as well as its immunosuppressive effect would warrant its use in the treatment of pediatric-onset glomerular disease. Although further studies remain to be done, we believe that MZR may be an attractive treatment of choice for children with glomerular diseases from a histologic as well as clinical standpoint.

Long-term post-marketing surveillance of mizoribine for the treatment of lupus nephritis: Safety and efficacy during a 3-year follow-up

OBJECTIVE

To determine the safety and efficacy of long-term use of mizoribine by undertaking a 3-year post-marketing surveillance study.

METHODS

Subjects were all lupus nephritis patients newly treated with mizoribine between 1 October 2003 and 30 September 2005 at contracted study sites.

RESULTS

Mizoribine was administered to 881 lupus nephritis patients in the safety analysis set consisting of 946 patients recruited from 281 contracted study sites after satisfying the eligibility criteria. There were 301 events of adverse drug reactions that were observed in 196 (20.7%) of the 946 subjects. There were 34 events of serious adverse drug reactions in 31 patients (3.2%). No deterioration in hematological and biochemical test values was observed, but immunological testing showed significant improvements in C3, CH50, and anti-DNA antibody titers. The negative rate of proteinuria also increased over time. The median steroid dosage was 15 mg/day at the commencement of treatment, but was reduced to 10 mg/day at 12 months and 8 mg/day at 36 months.

CONCLUSION

The findings of the 3-year long-term drug use surveillance study indicated that mizoribine can be used over the long term with relatively few adverse drug reactions, suggesting its suitability for use in maintenance drug therapy.

Refractory Proliferative Lupus Nephritis

Objective: To review the literature available regarding treatment of lupus nephritis (LN) refractory to cyclophosphamide, mycophenolate mofetil, azathioprine, and glucocorticoids. Data Sources: PubMed-MEDLINE and SCOPUS databases were searched through June 2013 using the terms lupus nephritis, refractory, induction, systemic lupus erythematosus, diffuse proliferative glomerulonephritis, rituximab, cyclosporine, tacrolimus, leflunomide, mizoribine, intravenous immunoglobulin, and belimumab. Study Selection and Data Extraction: Included studies were limited to human studies that evaluated clinical efficacy and English language articles. Articles assessing treatment with first-line agents such as glucocorticoids, cyclophosphamide, mycophenolate, and azathioprine were excluded from this review. Data Synthesis: There are an increasing number of medications being used in refractory LN, making the selection of an appropriate agent more difficult. Thirty studies evaluating the treatment of LN with alternative agents were identified. Although rituximab and calcineurin inhibitors have demonstrated the ability to induce remission in approximately 60% of patients with LN, large randomized trials have not confirmed these results. Leflunomide, mizoribine, and intravenous immunoglobulin have revealed potential benefits in some patient populations; however, there is not enough data to support the regular use of these agents for refractory LN. Conclusions: Rituximab and calcineurin inhibitors have the most evidence to support their use and should be the preferred agents in the treatment of refractory LN at this time. Further studies may elucidate the efficacy of other agents for refractory LN.

Treatment of young patients with lupus nephritis using calcineurin inhibitors

Recent advances in the management of lupus nephritis, together with earlier renal biopsy and selective use of aggressive immunosuppressive therapy, have contributed to a favorable outcome in children and adolescents with systemic lupus erythematosus (SLE). Nevertheless, we believe that a more effective and less toxic treatment is needed to attain an optimal control of the activity of lupus nephritis. Recent published papers and our experiences regarding treatment of young patients with lupus nephritis using calcineurin inhibitors are reviewed. Although it has been reported that intermittent monthly pulses of intravenous cyclophosphamide (IVCY) are effective for preserving renal function in adult patients, CPA is a potent immunosuppressive agent that induces severe toxicity, including myelo- and gonadal toxicity, and increases the risk of secondary malignancy. Thus, treatment for controlling lupus nephritis activity, especially in children and adolescents, remains challenging. Cyclosporine A (CsA) and tacrolimus (Tac) are T-cell-specific calcineurin inhibitors that prevent the activation of helper T cells, thereby inhibiting the transcription of the early activation genes of interleukin (IL)-2 and suppressing T cell-induced activation of tumor necrosis factor-α, IL-1β and IL-6. Therefore, both drugs, which we believe may be less cytotoxic, are attractive therapeutic options for young patients with lupus nephritis. Recently, a multidrug regimen of prednisolone (PDN), Tac, and mycophenolate mofetile (MMF) has been found effective and relatively safe in adult lupus nephritis. Since the mechanisms of action of MMF and Tac are probably complementary, multidrug therapy for lupus nephritis may be useful. We propose as an alternative to IVCY, a multidrug therapy with mizoribine, which acts very similarly to MMF, and Tac, which has a different mode of action, combined with PDN for pediatric-onset lupus nephritis. We also believe that a multidrug therapy including CsA and Tac may be an attractive option for young patients with SLE and lupus nephritis.

Efficacy and safety of multitarget therapy with mizoribine and tacrolimus for systemic lupus erythematosus with or without active nephritis

The prognosis of lupus nephritis (LN) has improved since the introduction of immunosuppressant therapies, but the safety and effectiveness of treatments can also be improved. We retrospectively assessed the treatment courses of 12 patients with systemic lupus erythematosus who were treated with glucocorticoid, mizoribine (MZR) and tacrolimus. This regimen was used as initial therapy for active LN in six patients (mean glucocorticoid dose, 66.6 mg); four of these six patients also received pulse methylprednisolone therapy. The starting doses of MZR and tacrolimus were 150 and 3 mg, respectively, and they were titrated as required. Five of six patients achieved complete remission and one achieved partial remission at 6 months. Five patients who completed 12-month analysis achieved complete remission. Another six patients were given the combination regimen for treating minor flares or for steroid sparing. The mean prednisolone doses were reduced from 11.0 mg at baseline to 6.6 mg at 12 months. Six patients experienced minor adverse events, including three minor infections. One patient stopped tacrolimus because of suspected toxicity. All 12 patients were successfully treated, and none experienced severe adverse events. Multitarget therapy combining glucocorticoid, MZR and tacrolimus may have the potential to become a treatment option which is effective and safe.

Mizoribine for crescentic glomerulonephritis with sarcoidosis: effectiveness not only for urinalysis abnormalities but also for hilar lymph node enlargement

Sarcoidosis is a multisystem disease related to helper T cell responses. We recently experienced the case of a 57-year-old woman with sarcoidosis complicated by crescentic glomerulonephritis with low levels of myeloperoxidase-antineutrophil cytoplasmic antibody. We herein describe the details of her clinical course and discuss the effectiveness of mizoribine, which has an immunosuppressive effect equivalent to that of mycophenolate mofetil, not only for urinalysis abnormalities but also for hilar lymph node enlargement.

Recent advances in the treatment of lupus nephritis

Lupus nephritis is a common complication of systemic lupus erythematosus (SLE) which is associated with significant morbidity and mortality. The concept of two phases of therapy for lupus nephritis, such as an induction phase and a maintenance phase, is widely accepted. Since the renal involvement in SLE is heterogeneous, the treatment of lupus nephritis is governed by its pathological type and ranges from nonspecific measures, such as maintenance of adequate blood pressure control and blockade of the renin-angiotensin-aldosterone system, to the use of immunosuppressive agents. Cyclophosphamide (CYC) in combination with prednisone has been the standard method of treatment of the proliferative forms of lupus nephritis. However, the high rates of progression to end-stage renal disease coupled with the adverse effects of CYC and prednisone have led to an intensive search for more effective and less toxic therapies for lupus nephritis. We review the options available for the treatment of proliferative and membranous lupus nephritis and summarize the results of recently published clinical trials that add new perspectives to the management of kidney disease in SLE.

Methylprednisolone pulse plus mizoribine in children with Henoch-Schoenlein purpura nephritis

We evaluated whether methylprednisolone and urokinase pulse therapy combined with mizoribine (MUPM) was effective in children with severe Henoch-Schoenlein purpura nephritis (HSPN). We studied 12 patients who had been diagnosed with HSPN of at least ISKDC type III. All patients were treated with MUPM. Clinical features, pathological findings, and prognosis were prospectively investigated. Ten patients (responders; nine with ISKDC grade IIIb and one with grade IVb) were treated with MUPM, whereas MUPM was discontinued due to the lack of response in two patients (non-responders; two with grade IVb). Among responders, urinary protein excretion had decreased significantly from 99.7 ± 37.8 to 25.9 ± 33.4 mg/m(2) per hour after 3 months of therapy. The acute index and tubulointerstitial scores decreased significantly from 5.8 ± 1.5 and 3.8 ± 0.6 at the first biopsy to 2.3 ± 1.3 and 1.0 ± 0.8 at the second biopsy, respectively. At the most recent follow-up, eight of the responders had normal urine, and two had minor urinary abnormalities. Non-responders demonstrated continued high levels of urinary protein excretion after 3 months of therapy, and MUPM was discontinued. Our study suggests that MUPM is effective in ameliorating the proteinuria and the histological severity of HSPN in patients with <50% crescents but is not so effective for HSPN in patients with >50% crescents.

Mizoribine: a new approach in the treatment of renal disease

Mizoribine (MZB) is an imidazole nucleoside and an immunosuppressive agent. The immunosuppressive effect of MZB has been reported to be due to the inhibition of DNA synthesis in the S phase of the cell cycle. Because of its relative lack of toxicity, during the past decade MZB has been frequently used instead of azathioprine as a component of immunosuppressive drug regimens. MZB is being used to treat renal transplantation patients, IgA nephropathy, lupus erythematosus, and childhood nephrotic syndrome (NS), and some recent studies have assessed the efficacy of oral MZB pulse therapy for severe lupus nephritis, steroid-resistant NS, and frequently relapsing-steroid-dependent NS. This review summarizes the published findings on the efficacy of MZB for renal disease including IgA nephropathy, lupus nephritis, and NS, as well as of oral MZB pulse therapy for severe lupus nephritis and NS, and also the mechanism of the effect of oral MZB pulse therapy on the lymphocyte cell cycle.

[The efficacy of mycophenolate mofetil for systemic lupus erythematosus]

Systemic lupus erythematosus (SLE) is usually treated with corticosteroids and immunosuppressive agents. However, some patients are refractory to these agents, others show adverse effects. Usefulness of mycophenolate mofetil (MMF) in SLE has been reported in several studies. In this study, we evaluated the clinical efficacy and adverse effects of MMF in SLE. Sixteen cases which were difficult to reduce the dose of corticosteroid, resistant to immunosuppressive agents or could not use them for adverse effects were treated with MMF. Thirteen cases were females and three were males. Mean age was 44.4+/-9.2 year-old. Mean duration of SLE was 12.5+/-6.9 years. Mean observational duration was 12.0+/-5.5 months. Mean maintenance dose of MMF was 1.95+/-0.61 g/day. Good clinical response was obtained in 69% of total cases. In laboratory data, serum IgG (p<0.05) decreased and the levels of serum albumin (p<0.01) and complement (p<0.05) increased significantly. Adverse effects, mainly infections, were observed, but severe infection was not experienced. This study suggests that MMF is effective and relatively safe for SLE.

Successful treatment of refractory polymyositis with the immunosuppressant mizoribine: case report

We describe a patient who presented with polymyositis with anti-Jo-1 antibodies at 18 years after the onset of rheumatoid arthritis and was successfully treated with the immunosuppressive drug mizoribine at the time of exacerbation. She had developed diabetes mellitus, cerebral infarction, and myocardial infarction after high-dose steroid therapy was initiated. Therefore, an immunosuppressant was preferred as the second-line agent. Treatment with 150 mg/day of mizoribine and 8 mg/day of prednisolone resulted in eventual normalization of muscle enzyme levels. Mizoribine is a purine antimetabolite that inhibits T cell activation/proliferation and B cell proliferation. The potential efficacy of mizoribine for polymyositis was suggested by this case.

A sudden onset of diabetic ketoacidosis and acute pancreatitis after introduction of mizoribine therapy in a patient with rheumatoid arthritis

Mizoribine has been recognized to have an acceptable toxicity profile compared with other immunosuppressants. In this study, however, we report a case of diabetic ketoacidosis and acute pancreatitis that suddenly occurred in a rheumatoid arthritis patient 2 weeks after introduction of mizoribine therapy. To the best of our knowledge, this is the first case in the literature to show mizoribine-induced diabetic ketoacidosis. Through prompt diagnosis and treatment, the patient recovered from these extremely rare but potentially lethal complications.

Mizoribine intermittent pulse protocol for induction therapy for systemic lupus erythematosus in children: an open-label pilot study with five newly diagnosed patients

The objective of the current work is to report our preliminary experience with the mizoribine (MZR) intermittent pulse protocol for induction therapy for newly diagnosed pediatric-onset systemic lupus erythematosus (SLE). Five consecutive patients who were newly diagnosed as having SLE with biopsy-proven lupus nephritis were recruited for an open-label trial of prednisolone (PDN) and MZR intermittent pulse therapy (10 mg/kg for 2 days of the week for 12 months). Data on the renal response and serologic lupus activity were collected prospectively. The baseline characteristics of the patients were: mean age, 11 years; urinary protein/creatinine ratio (U-prot./cre.), 0.99 +/- 0.91; serum complement hemolytic activity (CH50), 10.6 +/- 1.3 (normal, 23-46 U/ml); serum anti-dsDNA antibody titer, 258.6 +/- 125.5 IU/ml (normal, <12.0 IU/ml); serum creatinine, 0.5 +/- 0.1 mg/dl; European Consensus Lupus Activity Measurement index (ECLAM), 7.4 +/- 1.1. The primary endpoint was the interval until the development of a flare of SLE. Despite gradual tapering of the PDN dose, significant improvement as compared to the baseline values was observed in all the parameters examined at 3, 6, and 12 months of treatment. After 12 months therapy, complete response was achieved in all of the patients, except for 1 patient who showed poor drug compliance. In two patients who had severe lupus nephritis at the first renal biopsy, marked histologic improvement was confirmed at the second renal biopsy. No serious adverse effects were observed. We believe that the MZR pulse protocol combined with PDN for induction therapy may be the treatment of choice in selected young patients with SLE. Further studies to confirm the long-term efficacy and safety of our current protocol in larger numbers of patients are, however, needed.

Prophylactic treatment of antibody-mediated rejection with high-dose mizoribine and pharmacokinetic study

Although mizoribine (MZ), which inhibits inosine monophosphate dehydrogenase in the same way as mycophenolate mofetil, recently proved more effective when higher doses were administered than previously approved, neither the optimal dosage nor blood concentration has yet been clarified. We aimed at investigating the effect of high-doses of MZ on prevention of anti-donor antibody (Ab) production and acute Ab-mediated rejection (AMR) on the basis of the pharmacokinetic profile in a pig kidney transplantation model. Group 1 (n = 5) received cyclosporin microemulsion (6 mg/kg) and prednisolone (0.1 mg/kg). Groups 2, 3 and 4 (each n = 5) were treated, respectively, with 30, 10 and 3 mg/kg of MZ in addition to cyclosporin and prednisolone. The incidences of AMR in groups 1, 2, 3 and 4 were 5/5, 1/5, 3/5 and 5/5, respectively. Anti-donor IgG/IgM Ab levels (relative to pretransplantation levels) on day 14 in groups 1, 2, 3 and 4 were 10.3/9.3, 1.8/1.0, 2.3/1.8 and 6.5/3.5, respectively. While only 2 (28.6%) of seven pigs with Cmax > 3 microg/ml during the first 2 weeks had AMR, 7 (87.5%) of eight pigs with Cmax < 3 microg/ml elicited anti-donor Abs and experienced AMR (P = 0.0406). Effective Cmax seemed to be over 3 microg/ml at minimum. Higher doses of MZ efficiently prevented AMR. However, therapeutic drug monitoring is essential before clinical application.

Long-term mizoribine intermittent pulse therapy for young patients with flare of lupus nephritis

Mizoribine (MZR) is a novel purine synthesis inhibitor that was developed in Japan. We previously reported the efficacy and safety of oral MZR intermittent pulse therapy, which is associated with elevated peak serum MZR levels, in selected patients with lupus nephritis. However, the efficacy and safety of long-term MZR intermittent pulse therapy (administered for over 24 months) in lupus nephritis patients at high risk for relapse has not yet been reported. Our study included five patients with a long history of systemic lupus erythematosus (SLE), including four patients with proliferative lupus nephritis (WHO class IV) and one patient with WHO class II lupus nephritis, in whom remission had been achieved through treatment with high-dose corticosteroids combined with cytotoxic agents. For the most recent flares, all the patients were treated with MZR intermittent pulse therapy without increase in the dose of corticosteroids. MZR was administered at 5-10 mg/kg per day (up to 500 mg) as a single daily dose on two days of the week (Monday and Thursday) for over 24 months. Concomitantly administered corticosteroid dose was gradually reduced or continued unchanged. At presentation, the urinary protein excretion, serum complement hemolytic activity (CH50) and serum anti-dsDNA antibody titer were 1.7+/-1.0 g/day, 16.6+/-3.8 U/mL (normal, 23-46 U/mL) and 143.7+/-151.1 IU/mL (normal,<12.0 IU/mL), respectively. At the latest observation point, after a mean interval of 31 months (24-34 months) after the initiation of MZR pulse therapy, the urinary protein excretion and serum anti-dsDNA antibody titer were significantly decreased (0.3+/-0.2 g/day and 18.5+/-19.1 IU/mL, respectively; P<0.05), and the serum CH50 value had returned to within normal range (33.6+/-7.8 U/mL, P<0.05). Despite the reduced minimum dose of prednisolone required to maintain clinical remission at the time of the post-treatment evaluation after MZR pulse therapy as compared with that at the time of the pretreatment evaluation (9.0+/-4.5 vs. 17.5+/-7.9 mg/day; P=0.0656), the calculated flare rate was significantly decreased (0.15+/-0.2 vs. 0.6+/-0.11 times per year; P<0.05). The serum creatinine level remained within normal range in all the study participants. Furthermore, the platelet count increased following the MZR pulse therapy in two patients who had suffered from chronic thrombocytopenia. No serious adverse effects were observed. From the view point of the balance between suppression of disease activity and the adverse effects of treatment, we believe that long-term MZR pulse therapy may be the treatment of choice in selected patients with lupus nephritis at high risk for relapse. However, this was only a pilot study conducted on a small number of subjects, without a control group. Further studies to confirm the long-term efficacy and safety of oral MZR intermittent pulse therapy in larger numbers of patients are needed.

Combination therapy of prednisolone and mizoribine improves cryoglobulinemic vasculitis with purpura and skin ulcers

Conventional treatment is not standardized for hepatitis C virus-negative cryoglobulinemia, but corticosteroids, immunosuppressive agents, and plasma exchange typically improved the symptoms. Mizoribine is an immunosuppressive agent that was developed in Japan and has been found to inhibit the proliferation of lymphocytes, especially B cells. We have encountered an elder patient who had hepatitis C virus-negative, type II cryoglobulinemic vasculitis with leg purpura and skin ulcers. Her symptoms improved and cryoglobulin disappeared by the combination therapy of prednisolone and mizoribine. We speculate the action mechanism of this therapy is due to immunosuppressive effects including up-regulation of the efficacy of prednisolone by mizoribine.