Maribavir for treatment of cytomegalovirus infection in a liver-transplanted patient

Cytomegalovirus infection (CMV) can be fatal for organ transplant recipients as shown in this case report. Maribavir is a recently approved drug, which can be used for therapy-refractory CMV infection or when other treatment options cannot be used. The patient in this case report was a CMV-infected liver transplant recipient, who developed a severe erythema and high CMV DNA during valganciclovir therapy. Toxic epidermal necrolysis was suspected. The patient was treated with maribavir, and both CMV DNA and the skin normalised. This case illustrates that maribavir is a useful alternative to other antiviral drugs for CMV infection.

Effects of Maribavir on P-Glycoprotein and CYP2D6 in Healthy Volunteers

Maribavir is an investigational drug being evaluated in transplant recipients with cytomegalovirus infection. To understand potential drug-drug interactions, we examined the effects of multiple doses of maribavir on cytochrome P450 (CYP) 2D6 and P-glycoprotein (P-gp) activity using probe substrates in healthy volunteers. During this phase 1 open-label study (NCT02775240), participants received the probe substrates digoxin (0.5 mg) and dextromethorphan (30 mg) before and after maribavir (400 mg twice daily for 8 days). Serial plasma samples were analyzed for digoxin, dextromethorpha, dextrorphan, and maribavir concentrations. Pharmacokinetic parameters were calculated (noncompartmental analysis) and analyzed with a linear mixed-effects model for treatment comparison to estimate geometric mean ratios (GMRs) and 90% confidence intervals (CIs). CYP2D6 polymorphisms were genotyped using polymerase chain reaction. Overall, 17 of 18 participants (94.4%) completed the study. All participants were genotyped as CYP2D6 intermediate/extensive metabolizers. GMR (90%CI) of digoxin Cmax , AUClast , and AUC0-∞ with and without maribavir was 1.257 (1.139-1.387), 1.187 (1.088-1.296), and 1.217 (1.110-1.335), respectively, outside the "no-effect" window (0.8-1.25). GMR (90%CI) of dextromethorphan AUClast and AUClast ratio of dextromethorphan/dextrorphan were 0.877 (0.692-1.112) and 0.901 (0.717-1.133), respectively, marginally outside the no-effect window, although large variability was observed in these pharmacokinetic parameters. Pharmacokinetic parameters of dextrorphan were unaffected. Maribavir inhibited P-gp activity but did not affect CYP2D6 activity. Maribavir's effect on the pharmacokinetics of P-gp substrates should be evaluated individually, and caution should be exercised with P-gp substrates with narrow therapeutic windows.

In Vitro and in Vivo Antiviral Activity of Mizoribine Against Foot-And-Mouth Disease Virus

Foot-and-mouth disease (FMD) is a highly contagious viral disease of cloven-hoofed animals, which has significant economic consequences in affected countries. As the currently available vaccines against FMD provide no protection until 4–7 days post-vaccination, the only alternative method to control the spread of FMD virus (FMDV) during outbreaks is the application of antiviral agents. Hence, it is important to identify effective antiviral agents against FMDV infection. In this study, we found that mizoribine has potent antiviral activity against FMDV replication in IBRS-2 cells. A time-of-drug-addition assay demonstrated that mizoribine functions at the early stage of replication. Moreover, mizoribine also showed antiviral effect on FMDV in vivo. In summary, these results revealed that mizoribine could be a potential antiviral drug against FMDV.

First successful perinatal management of pregnancy after ABO-incompatible liver transplantation

Many papers have reported on pregnancy and delivery after liver transplantation, but there have been no reports on pregnancy after ABO-incompatible liver transplantation. This paper reports the first successful pregnancy and delivery of a newborn after ABO-incompatible liver transplantation for fulminant hepatic failure. The patient was a 39-year-old female. She had an ABO-incompatible liver transplantation, donated from her husband, due to subacute fulminant hepatitis of unknown etiology. She was taking tacrolimus, methylprednisolone, and mizoribine orally for the maintenance of immunosuppression at the time of discharge. She was discharged uneventfully on postoperative day 38 without any rejection episodes. At 1 year and 6 mo after transplantation, she indicated a wish to become pregnant. Therefore, treatment with mycophenolate mofetil was interrupted at that time. After two miscarriages, she finally became pregnant and delivered transvaginally 3 years after the transplantation. All of the pregnancies were conceived naturally. The newborn was female with a birth weight of 3146 g; the Apgar scores were 9 and 10. Delivery was performed smoothly, and the newborn exhibited no malformations. The mother and the newborn were discharged uneventfully. We suggest that pregnancy is possible for recipients after ABO-incompatible liver transplantation.

Mizoribine Synchronized Methotrexate Therapy should be Considered when Treating Rheumatoid Arthritis Patients with an Inadequate Response to Various Combination Therapies

Objective The objective of this study was to confirm the efficacy of low-dose mizoribine (MZR), an inhibitor of inosine monophosphate dehydrogenase, as part of synchronized methotrexate (MTX) therapy for rheumatoid arthritis (RA) patients with an inadequate response to various combination therapies of MTX, other synthetic disease-modifying anti-rheumatic drugs (DMARDs) and biological DMARDs. Methods Low-dose MZR was administered to 56 uncontrolled RA patients being treated with MTX and various biological DMARDs. The observation period was 12 months, and the disease activity was evaluated based on the Disease Activity Score in 28 joints (DAS28)-ESR, Simplified Disease Activity Index (SDAI) and serum MMP-3 level. Results All of the disease activity indices were significantly improved within three months, and the serum MMP-3 levels were also significantly decreased around four months after starting low-dose MZR therapy. No patients experienced any adverse effects. Conclusion The present preliminary findings suggest that low-dose MZR therapy with MTX should be considered for the treatment of RA patients with an inadequate response to various combination therapies including MTX, other synthetic DMARDs and biological DMARDs or in whom increasing the dose of MTX is difficult for reasons such as adverse effects and complications.

Mizoribine therapy combined with steroids and mizoribine blood concentration monitoring for idiopathic membranous nephropathy with steroid-resistant nephrotic syndrome

Background

We designed a prospective and randomized trial of mizoribine (MZR) therapy combined with prednisolone (PSL) for idiopathic membranous nephropathy (IMN) with steroid-resistant nephrotic syndrome (SRNS).

Methods

Patients with IMN were divided into 2 groups, and MZR combined with PSL was administered for 2 years. PSL was initially prescribed at 40 mg/day and tapered. MZR was given once-a-day at 150 mg and 3-times-a-day at 50 mg each to groups 1 and 2. Serum MZR concentrations from 0 to 4 h after administration were examined within one month of treatment. The concentration curve and peak serum level (C_max) of MZR were estimated by the population pharmacokinetic (PPK) parameters of MZR.

Results

At 2 years, 10 of 19 patients (52.6 %) in group 1 and 7 of 18 patients (38.9 %) in group 2 achieved complete remission (CR). The time-to-remission curve using the Kaplan–Meier technique revealed an increase in the cumulative CR rate in group 1, but no significant difference between the groups. Meanwhile, there was a significant difference in C_max between groups 1 and 2 (mean ± SD: 1.20 ± 0.52 vs. 0.76 ± 0.39 μg/mL, p = 0.04), and C_max levels in CR cases were significantly higher than those in non-CR cases. Receiver operating characteristic analysis showed that C_max more than 1.1 µg/mL was necessary for CR in once-a-day administration.

Conclusion

Administration of MZR once a day is useful when combined with PSL for treatment of IMN with SRNS. In addition, it is important to assay the serum concentration of MZR and to determine C_max, and more than 1.1 µg/mL of C_max is necessary for CR.

The effectiveness of new triple combination therapy using synthetic disease-modifying anti-rheumatic drugs with different pharmacological function against rheumatoid arthritis: the verification by an in vitro and clinical study

The study aims to confirm the feasibility of new oral triple combination therapy using methotrexate (MTX), mizoribine (MZR), and tacrolimus (TAC) in patients with rheumatoid arthritis (RA) by in vitro and clinical analyses. Triple therapy with a combination of MTX, MZR, and TAC was used for an in vitro study with osteoclasts and a prospective clinical study in order to show the efficacy of these agents against refractory RA. In particular, low-dose TAC or MZR was added to treat 14 patients with RA that was resistant to MTX + MZR or MTX + TAC dual therapy. The combination of three pharmacological agents showed statistically significant differences to reduce differentiation induction and activity of osteoclasts compared with single and double agents. In clinical use, triple therapy showed a statistically significant difference in the improvement of Disease Activity Score-28-erythrocyte sedimentation rate and the Simple Disease Activity Index score at around 8 months. Additionally, the serum matrix metalloproteinase-3 level significantly decreased. No patients dropped out because of adverse effects. Based on this in vitro and prospective clinical study, oral triple therapy might be effective against refractory RA. Furthermore, this therapy might be safe and economical for clinical practice.

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.

Urocortin attenuates myocardial fibrosis in diabetic rats via the Akt/GSK-3β signaling pathway

OBJECTIVE

Urocortin, a novel identified corticotropin-releasing factor-related endocrinal peptide, has been shown to play an essential role in cardioprotection. Until recently, whether urocortin can protect the heart against diabetic cardiomyopathy (DCM) remained unclear. Herein, we evaluated the cardioprotective effect of urocortin on cardiac dysfunction, inflammation, and fibrosis and demonstrated the potential mechanism in a diabetic rat model.

METHODS

Diabetic rats were randomly divided into 4 groups: diabetic control group, urocortin, urocortin + astressin (a selective CRF receptor 2 antagonist) and urocortin + triciribine (an Akt pathway blocker). Cardiac catheterization was performed to evaluate cardiac function. The levels of creatine phosphokinase isoenzyme (CK-MB), plasma brain natriuretic peptide (BNP), myocardial collagen volume fraction (CVF) and left ventricular mass index (LVWI) were measured. Inflammatory factors (transforming growth factor beta 1, TGF-β1; connective tissue growth factor, CTGF) and activation of signaling proteins (Akt, GSK-3β) were also detected using western blot.

RESULTS

DCM was successfully induced by the injection of streptozotocin (STZ) as evidenced by abnormal heart mass and cardiac function as well as the imbalance of extracellular matrix homeostasis. Rats in the DCM group showed increased mRNA and protein levels of LVWI, BNP, CK-MB, CVF, TGF-β1 and CTGF compared to the control group, which were accompanied with diminished phosphorylation of Akt and GSK-3β. Interestingly, myocardial dysfunction, cardiac fibrosis, and inflammation were suppressed by urocortin in the heart of diabetic rats. Moreover, inhibition of phosphorylation of Akt and GSK-3β was also reversed by urocortin. These effects of urocortin were suppressed by astressin. In addition, triciribine partially reduced the effects of urocortin on myocardial dysfunction, inflammation, and cardiac fibrosis.

CONCLUSIONS

These results suggest that urocortin exhibits a therapeutic benefit in the treatment of DCM by attenuating fibrosis and inflammation. Furthermore, inhibition of the Akt/GSK-3β signaling pathway may be partially responsible for these effects.

Improvement in Severe Mycophenolic Acid-associated Gastrointestinal Symptoms after Changing Enteric-coated Mycophenolate Sodium to Mizoribine in Renal Transplant Recipients: Two Case Reports

Clinical results point to a better gastrointestinal tolerability with enteric-coated mycophenolate sodium as compared to mycophenolate mofetil. However, some transplant recipients who are treated with enteric-coated mycophenolate sodium still experience gastrointestinal symptoms. We herein present two cases of renal transplant recipients with severe gastrointestinal symptoms who were switched from enteric-coated mycophenolate sodium to mizoribine, and the symptom reversal effects were evaluated using the Gastrointestinal Symptom Rating Scale. The results of this study showed a significant improvement in severe gastrointestinal symptoms in renal transplant recipients after converting from enteric-coated mycophenolate sodium to mizoribine.

[Natural purine compounds as radioprotective agents]

Purine compounds xanthosine, caffeine, inosine-5'-monophosphate and guanosine-5'-monophosphate in the concentration range of 0.02-1 mmol/L exhibit antioxidant properties in vitro, significantly reducing the formation of hydrogen peroxide and hydroxyl radicals induced by X-rays in aqueous solutions and preventing the formation of 8-oxoguanine in DNA solutions. These compounds neutralize the long-lived protein radicals in vitro induced by radiation. In vivo they exhibit pronounced radiotherapeutic properties, increasing the survival rate of mice up to 50% by intraperitoneal injection (45 mg/kg) after the exposure to a lethal dose of 7 Gy. The tested compounds stimulate hemopoiesis, increasing the number of white blood cells and platelets in the peripheral blood of animals in postradiation period, as well as radiation recovery of DNA damage when administered both before and after irradiation. These purine compounds can be considered as potentially promising preventive and therapeutic agents to reduce the risk of the pathological effects of ionizing radiation on the body of mammals.

Mizoribine versus mycophenolate mofetil or intravenous cyclophosphamide for induction treatment of active lupus nephritis

BACKGROUND

Lupus nephritis (LN) is one of the most serious manifestations of systemic lupus erythematosus. Although there have been substantial improvements in LN treatment over the last decade, the outcome remains unoptimistic in a considerable percentage of patients. The aim of this study was to evaluate the efficacy and safety of mizoribine (MZR), a novel selective inhibitor of inosine monophosphate dehydrogenase, as induction treatment for active LN in comparison with mycophenolate mofetil (MMF) and intravenous cyclophosphamide (CYC).

METHODS

Ninety patients with active LN were observed. Thirty patients were given MZR orally at the dose of 300 mg every other day. Thirty patients took MMF at 2 g per day in two divided doses. Thirty patients received CYC intravenously 0.5 g every 2 weeks. Therapeutic effects and adverse events (AEs) were evaluated at the end of 24-week treatment. One-way analysis of variance (ANOVA) followed by Dunn's test was applied to compare the difference among the groups. For comparing categorical data between two groups, χ(2) test was employed.

RESULTS

Early responses at week 12 were achieved by 73.3%, 90.0%, and 96.7% in MZR, MMF, and CYC groups, respectively. There was no significant difference in the complete remission rates (22.7%, 24.0%, and 25.0%, respectively) or overall response rates (68.2%, 72.0%, and 75.0%, respectively) among the three groups at week 24. The most prominent drop-down of Systemic Lupus Erythematosus Disease Activity Index scores was observed in MMF or CYC group, and the decline of health assessment questionnaire scores in MZR or MMF group was more prominent than that in the CYC group at week 12. Serum complement 3 (C3) or C4 levels were elevated in all groups after the treatments. CYC was more effective in inhibiting anti-double-stranded DNA antibody, while MZR was more effective in inhibiting antinuclear antibody. The incidences of AEs in patients treated with CYC were significantly higher than those in patients treated with MZR or MMF (24.2% for CYC vs. 3.3% for MZR, and 2.6% for MMF, P = 0.01).

CONCLUSIONS

MZR is well tolerated and has an effect similar to MMF in the induction therapy of active LN. MZR may serve as an alternative approach for LN patients.

A case of microscopic polyangiitis with skin manifestations in a seven-year-old girl

A case of a 7-year-old girl with microscopic polyangiitis (MPA) with a skin eruption characterized by maculopapular, erythematous and purpuric lesions on the face, elbows, and knees is presented. Anti-neutrophil cytoplasmic autoantibodies (ANCA) with myeloperoxidase specificity (MPO-ANCA) were identified. Chest X-ray and computed tomography scan revealed diffuse infiltrates in both lung fields, suggesting alveolar hemorrhage. Microscopic hematuria was detected but a renal biopsy showed no abnormalities. Histological examination of a skin biopsy from a purpuric papule showed leukocytoclastic vasculitis of the small vessels in the entire dermis. The patient was treated with prednisolone and mizoribine, resulting in an improvement in the skin lesions except for those on the knee.

Loss of the anorexic response to systemic 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside administration despite reducing hypothalamic AMP-activated protein kinase phosphorylation in insulin-deficient rats

This study tested whether chronic systemic administration of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) could attenuate hyperphagia, reduce lean and fat mass losses, and improve whole-body energy homeostasis in insulin-deficient rats. Male Wistar rats were first rendered diabetic through streptozotocin (STZ) administration and then intraperitoneally injected with AICAR for 7 consecutive days. Food and water intake, ambulatory activity, and energy expenditure were assessed at the end of the AICAR-treatment period. Blood was collected for circulating leptin measurement and the hypothalami were extracted for the determination of suppressor of cytokine signaling 3 (SOCS3) content, as well as the content and phosphorylation of AMP-kinase (AMPK), acetyl-CoA carboxylase (ACC), and the signal transducer and activator of transcription 3 (STAT3). Rats were thoroughly dissected for adiposity and lean body mass (LBM) determinations. In non-diabetic rats, despite reducing adiposity, AICAR increased (∼1.7-fold) circulating leptin and reduced hypothalamic SOCS3 content and food intake by 67% and 25%, respectively. The anorexic effect of AICAR was lost in diabetic rats, even though hypothalamic AMPK and ACC phosphorylation markedly decreased in these animals. Importantly, hypothalamic SOCS3 and STAT3 levels remained elevated and reduced, respectively, after treatment of insulin-deficient rats with AICAR. Diabetic rats were lethargic and displayed marked losses of fat and LBM. AICAR treatment increased ambulatory activity and whole-body energy expenditure while also attenuating diabetes-induced fat and LBM losses. In conclusion, AICAR did not reverse hyperphagia, but it promoted anti-catabolic effects on skeletal muscle and fat, enhanced spontaneous physical activity, and improved the ability of rats to cope with the diabetes-induced dysfunctional alterations in glucose metabolism and whole-body energy homeostasis.

The immunosuppressive agent mizoribine monophosphate is an inhibitor of the human RNA capping enzyme

Mizoribine monophosphate (MZP) is a specific inhibitor of the cellular inosine-5′-monophosphate dehydrogenase (IMPDH), the enzyme catalyzing the rate-limiting step of de novo guanine nucleotide biosynthesis. MZP is a highly potent antagonistic inhibitor of IMPDH that blocks the proliferation of T and B lymphocytes that use the de novo pathway of guanine nucleotide synthesis almost exclusively. In the present study, we investigated the ability of MZP to directly inhibit the human RNA capping enzyme (HCE), a protein harboring both RNA 5′-triphosphatase and RNA guanylyltransferase activities. HCE is involved in the synthesis of the cap structure found at the 5′ end of eukaryotic mRNAs, which is critical for the splicing of the cap-proximal intron, the transport of mRNAs from the nucleus to the cytoplasm, and for both the stability and translation of mRNAs. Our biochemical studies provide the first insight that MZP can inhibit the formation of the RNA cap structure catalyzed by HCE. In the presence of MZP, the RNA 5′-triphosphatase activity appears to be relatively unaffected while the RNA guanylyltransferase activity is inhibited, indicating that the RNA guanylyltransferase activity is the main target of MZP inhibition. Kinetic studies reveal that MZP is a non-competitive inhibitor that likely targets an allosteric site on HCE. Mizoribine also impairs mRNA capping in living cells, which could account for the global mechanism of action of this therapeutic agent. Together, our study clearly demonstrates that mizoribine monophosphate inhibits the human RNA guanylyltransferase in vitro and impair mRNA capping in cellulo.

Successful treatment of class IV+V lupus nephritis with combination therapy of high-dose corticosteroids, tacrolimus and intravenous cyclophosphamide

A substantial number of patients with lupus nephritis (LN) are refractory to conventional glucocorticoid (GC) treatment. Although many of these patients respond to immunosuppressive drugs such as intravenous cyclophosphamide (IVCY), azathioprine (AZA), mizoribine, tacrolimus, cyclosporine A (CSA) and mycofenolate mofetil (MMF), some remain refractory to such therapies. Recent studies of multi-target therapies have reported effective outcomes for immunosuppression following renal transplantation and refractory LN when therapy consists of two or more immunosuppressive drugs with different mechanisms of action. We herein report a case of LN unresponsive to IVCY that was successfully treated with the addition of tacrolimus and discuss the usefulness of multi-target therapy for LN.

The beneficial effect of high-dose mizoribine combined with cyclosporine, basiliximab, and corticosteroids on CMV infection in renal transplant recipients

BACKGROUND

Mizoribine (MZR) has been developed as an immunosuppressive agent, but has a less potent immunosuppressive effect up to 3 mg/kg/day MZR. Therefore, we investigated whether high-dose MZR, at 6 mg/kg/day, would be effective and safe for kidney transplant patients in conjunction with cyclosporine (CsA), basiliximab, and corticosteroids.

METHODS

A total of 40 living related patients were administered MZR (6 mg/kg/day), CsA (7 mg/kg/day), prednisolone (maintenance dose 10 mg/day), and basiliximab (20 mg/body). A control group (n = 38) treated with CsA, mycophenolate mofetil (MMF, 25 mg/kg/day), basiliximab, and corticosteroids was also employed in this study.

RESULTS

The 2-year graft survival rates for the MZR and MMF groups were 100 and 94.7 %, respectively. The rejection rate in the MZR group (25 %) was not significantly higher than that in the MMF group (16 %). Serum creatinine level was not significant between the two groups. The number of patients who developed cytomegalovirus (CMV) disease was 0 (0 %) in the MZR group and 7 (18.4 %) in the MMF group (P < 0.05). The number of patients treated with ganciclovir was 3 (7.5 %) and 11 (28.9 %) (P < 0.05), respectively.

CONCLUSIONS

The combination of high-dose MZR with CsA, basiliximab, and corticosteroids can establish not only satisfactory immunosuppression but also a low rate of CMV infection in vivo.

Effect of single-dose oral mizoribine pulse therapy twice per week for frequently relapsing steroid-dependent nephrotic syndrome

AIM

To evaluate the efficacy of single-dose oral mizoribine (MZB) pulse therapy given twice weekly for frequently relapsing steroid-dependent nephrotic syndrome (FR-SDNS).

METHODS

The subjects were 8 patients with FR-SDNS with a median age of 6.9 years old (range 3.1 - 18.0 y). The study was performed as a Phase II trial. The MZB dose was adjusted to achieve a peak blood level of 3 - 5 μg/ml (3.9 - 15.9 mg/kg/d, maximum dose: 750 mg) using a single dose given twice weekly before a meal. The therapeutic benefits of MZB pulse therapy were assessed based on a comparison of the incidence of relapse and the required daily dosage of prednisolone (PSL) in the 12 months prior to and following therapy.

RESULTS

The incidence of relapse after therapy was significantly lower than that before therapy (2.5 ± 1.4 vs. 4.3 ± 0.5, p < 0.01) and the required daily dosage of prednisolone (PSL) after therapy was lower than that before therapy (0.48 ± 0.23 vs. 0.52 ± 0.32 mg/kg/d, not significant). However, this therapy was not effective for 3 out of 4 patients treated with cyclosporine. During follow-up, discontinuation of PSL was possible in 4 of 5 patients who showed a decreased rate of relapse after therapy. The peak blood concentration of MZB in these patients was significantly higher than that in 3 patients who did not show a decreased rate of relapse (3.95 ± 0.11 vs. 3.05 ± 0.21 μg/ml, p < 0.01). No adverse effects were observed in any patients.

CONCLUSION

Our results show that single-dose oral MZB pulse therapy is effective in decreasing the frequency of relapse in some pediatric patients with FR-SDNS. A peak concentration of MZB of ~3.8 - 4.0 μg/ ml may be required for FR-SDNS therapy.

AKT inhibition by triciribine alone or as combination therapy for growth control of gastroenteropancreatic neuroendocrine tumors

Up-regulation of phosphatidylinositol-3-kinase (PI3K)-AKT signaling facilitates tumor cell growth and inhibits cell demise. The AKT-pathway also plays an important role in cytostatic therapy resistance and response to hypoxia and angiogenesis. Using real-time cell proliferation assay we examined the potency of triciribine in three distinct neuroendocrine gastrointestinal tumor cell lines. Also we investigated triciribine's induction of apoptosis and effects on a broad range of cancer-associated gene products. Furthermore, we characterized the role of PTEN as a possible predictor of sensitivity to triciribine in GEP-NETs. We also looked for additive anti-neoplastic effects of triciribine when combined with conventional cytostatic drugs or other targeted drugs, affecting different molecules of the PI3K-AKT-pathway and we assessed the potency of triciribine to inhibit tumor growth in vivo, by using the chick chorioallantoic membrane assay. Treatment of insulinoma (CM) or gut neuroendocrine tumor cells (STC-1) with triciribine significantly reduced tumor cell growth by 59% and 65%, respectively. By contrast, the highly expressing PTEN carcinoid cell line BON did not respond, even at higher doses. Combinations of triciribine with classic cytostatic drugs as well as drugs targeting other molecules of the PI3K-AKT-pathway led to synergistic anti-proliferative effects. Additional in vivo-evaluations confirmed the anti-neoplastic potency of triciribine. Thus, our data show that inhibition the AKT-pathway potently reduces the growth of GEP-NET cells alone or in combination therapies. AKT inhibition may provide a rationale for future evaluations.

[Two cases of rapidly progressive nephritic syndrome complicated with alcoholic liver cirrhosis]

It has been reported that glomerulosclerosis with IgA deposition is likely to be complicated with alcoholic liver cirrhosis. On the other hand, it is said that complications of nephrotic syndrome or rapidly progressive glomerulonephritis (RPGN) are relatively rare. We experienced two patients with alcoholic liver cirrhosis complicated with RPGN syndrome who had obtained favorable outcomes through the use of steroids and immune system suppressors. Case 1 was a 55-year-old male. He was being treated for alcoholic liver cirrhosis, but as bloody urine was noticed macroscopically, his renal function rapidly decreased. Specimens from a renal biopsy showed endocapillary proliferative lesions accompanying necrotic lesions. Granular deposition of IgA (IgA1) and C3 was seen along the capillary walls and in the mesangial areas. After the combined treatments of bilateral palatotonsillectomy, three courses of steroid semi-pulse therapy and post-therapy with steroids and mizoribin (MZR)were started, his hematuria and proteinuria disappeared and renal function improved markedly. Case 2 was a 37-year-old male with alcoholic liver cirrhosis complicated with hepatic encephalopathy. Although he was being treated at another hospital, nephritic syndrome occurred with rapidly worsening renal function and massive ascites. After continuous drainage of the ascites, we performed a renal biopsy. Mild proliferative lesions and notable wrinkling, thickening and doubling of the basal membrane were seen. Crescent formations were found in about half of the glomeruli. The fluorescent antibody technique showed positive pictures of IgA (IgA1) and C3. When three courses of steroid semi-pulse therapy and post therapy with steroids and MZR were combined, his proteinuria and serum Cre level decreased and stagnated ascites markedly decreased. The two cases were diagnosed as having secondary IgA nephropathy induced by the deposition of the IgA1 derived mainly from the intestinal tract, which had increased in the blood due to alcoholic liver cirrhosis. Active use of immune system suppressor therapy was effective.

Efficacy and safety of mizoribine by one single dose administration for patients with rheumatoid arthritis

OBJECTIVE

Mizoribine (MZR) is an immunosuppressant that inhibits nucleic acid metabolism and is a relatively safe disease-modifying anti-rheumatic drug (DMARD). We evaluated the efficacy and safety of one single dose per day for patients with rheumatoid arthritis (RA).

PATIENTS AND METHODS

In this study 32 patients with RA received MZR therapy. We evaluated the average dose of MZR and prednisolone, response to treatment and peak plasma level of MZR.

RESULTS

The average dose of MZR was 146.1±31.2 (range: 50-200) mg/day. The average dose of prednisolone was 4.63±3.59 (range: 0-14) mg/day. The average plasma level of MZR, measured after 3 hours, was 2.20±0.49 µg/mL in the responder group and 1.59±0.82 µg/mL in the non-responder group (p=0.020). The treatment with MZR for 24 weeks was completed by 71.9% of patients and the proportion of patients who achieved a good and moderate response rate according to the European League Against Rheumatism (EULAR) criteria was 56.3% at 24 weeks. The plasma level of MZR which was greater than or equal to 2.12 µg/mL was significantly correlated with the clinical response (p<0.01). Only one of thirty-two cases discontinued the treatment, because of skin eruption.

CONCLUSION

This study included patients that could not be treated with other DMARDs and/or biologic agents because of age, interstitial pneumonia and other complications. We show that MZR may be a useful and relatively safe therapy for patients in this group.

A case of Mikulicz's disease, IgG4-related plasmacytic syndrome, successfully treated by corticosteroid and mizoribine, followed by mizoribine alone

We report a case of Mikulicz's disease, IgG4-related plasmacytic syndrome, successfully treated with corticosteroid and mizoribine, followed by mizoribine alone. A 56-year-old woman experienced persistent bilateral swelling in the eyelids and submandibular region accompanied by lymphadenopathy without pain. The patient was diagnosed as having Mikulicz's disease since her bilateral lacrimal glands showed persistent swelling and biopsy specimens of the submandibular glands and lymph node showed diffuse infiltration of lymphocytes and plasma cells. Symptoms and laboratory data were improved with corticosteroids (30 mg). However, after tapering prednisolone to 5 mg, submandibular swelling developed. Adding mizoribine resulted in clinical improvement. Prednisolone was tapered and finally discontinued. Since the levels of IgG4 in peripheral blood were increased even after corticosteroid therapy and IgG4 was positive in a submandibular gland specimen obtained before the start of corticoid therapy. Thus, this case may be associated with IgG4. The present case is the first case in which mizoribine was effective for Mikulicz's disease and IgG4-related plasmacytic syndrome.

Intra-arterial AICA-riboside administration induces NO-dependent vasodilation in vivo in human skeletal muscle

In animal models, administration of the adenosine analog AICA-riboside has shown beneficial effects on ischemia-reperfusion injury and glucose homeostasis. The vascular and/or metabolic effects of AICA-riboside administration in humans remain to be established. AICA-riboside was infused intra-arterially in four different dosages up to 8 mg x min(-1) x dl(-1) in 24 healthy subjects. Forearm blood flow (FBF) and glucose uptake and plasma glucose, free fatty acid, and AICA-riboside concentrations were assessed. We also combined AICA-riboside infusion (2 mg x min(-1) x dl(-1)) with the intra-arterial administration of the adenosine receptor antagonist caffeine (90 microg x min(-1) x dl(-1); n = 6) and with the endothelial NO synthase inhibitor l-NMMA (0.4 mg x min(-1) x dl(-1); n = 6). Additional in vitro experiments were performed to explain our in vivo effects of AICA-riboside in humans. AICA-riboside increased FBF dose dependently from 2.0 +/- 0.2 to 13.2 +/- 1.9 ml x min(-1) x dl(-1) maximally (P < 0.05 for all dosages). The latter was not reduced by caffeine administration but was significantly attenuated by l-NMMA infusion. Despite high plasma AICA-riboside concentrations, forearm glucose uptake did not change. In vitro experiments showed rapid uptake of AICA-riboside by the equilibrative nucleoside transporter in erythrocytes and subsequent phosphorylation to AICA-ribotide. We conclude that AICA-riboside induces a potent vasodilator response in humans that is mediated by NO. Despite high local plasma concentrations, AICA-riboside does not increase skeletal muscle glucose uptake.

d‐penicillamine‐induced pemphigus successfully treated with combination therapy of mizoribine and prednisolone

A 63-year-old woman had D-penicillamine-induced pemphigus with a high index value of circulating autoantibodies against desmoglein 1. Because of the lack of response to prednisolone monotherapy, the patient was treated with a combination therapy of mizoribine and low-dose prednisolone. The skin eruption was improved by this combination with a declined value of circulating anti-desmoglein 1 antibody. Currently, a remission of 2 months has been achieved, and prednisolone could be tapered.

Mizoribine may suppress bone erosion in patients with rheumatoid arthritis by inhibiting osteoclastogenesis

Mizoribine is a disease-modifying anti-rheumatic drug (DMARD) that is used in the treatment of rheumatoid arthritis. However, clinical use of the drug is restricted to a few Asian countries due to a lack of comprehensive evidence on its effectiveness. The inhibitory effect of the drug on human osteoclastogenesis was investigated in the hopes of providing some clear evidence. Mizoribine was found to inhibit in vitro osteoclastogenesis in a dose-dependent manner. In addition, the size of the pit area was closely related to the number of osteoclasts in a bone resorption assay. However, mizoribine did not affect the phosphorylation of MAP kinase (p38, JNK, ERK), the degradation of IkappaBalpha, or receptor activator of NF-kappaB ligand (RANKL) expression in fibroblast-like synoviocytes stimulated with IL-1beta. These results suggested that mizoribine may partially suppress osteoclastogenesis, leading to progressive bone erosion by inhibiting the growth or the signaling pathway of precursor cells to form osteoclasts rather than fibroblast-like synoviocytes.

Activation of AMP-activated protein kinase by 5-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside prevents leucine-stimulated protein synthesis in rat skeletal muscle

Several stress conditions are characterized by activation of 5'-AMP-activated protein kinase (AMPK) and the development of leucine resistance in skeletal muscle. In the present study, we determined whether direct activation of the AMPK by 5-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR) prevents the characteristic leucine-induced increase in protein synthesis by altering mammalian target of rapamycin (mTOR) signal transduction. Rats were injected with AICAR or saline (Sal) and 1 h thereafter received an oral gavage of leucine (or Sal). Efficacy of AICAR was verified by increased AMPK phosphorylation. AICAR decreased basal in vivo muscle (gastrocnemius) protein synthesis and completely prevented the leucine-induced increase, independent of a change in muscle adenine nucleotide concentration. AICAR also prevented the hyperphosphorylation of eukaryotic initiation factor (eIF) 4E binding protein (4E-BP1), ribosomal protein S6 kinase (S6K1), S6, and eIF4G in response to leucine, suggesting a decrease in mTOR activity. Moreover, AICAR prevented the leucine-induced redistribution of eIF4E from the inactive eIF4E.4E-BP1 to the active eIF4E.eIF4G complex. This ability of AICAR to produce muscle leucine resistance could not be attributed to a change in phosphorylation of tuberous sclerosis complex (TSC)2, the formation of a TSC1.TSC2 complex, the binding of raptor with mTOR, or the phosphorylation of eukaryotic elongation factor-2. However, the inhibitory actions of AICAR were associated with reduced phosphorylation of proline-rich Akt substrate-40 and increased phosphorylation of raptor, which represent potential mechanisms by which AICAR might be expected to inhibit leucine-induced increases in mTOR activity and protein synthesis under in vivo conditions.

Effect of ketoconazole on the pharmacokinetics of maribavir in healthy adults

Maribavir, an oral antiviral drug with activity against cytomegalovirus, is currently undergoing studies to assess its efficacy and safety as cytomegalovirus prophylaxis following stem cell or solid organ transplantation. The main objective of this study was to assess the effects of oral ketoconazole, a potent inhibitor of the cytochrome P450 3A4 (CYP3A4) isoenzyme, on the pharmacokinetics of maribavir. This was an open-label crossover study with 20 healthy adults. Subjects were administered a single dose of maribavir at 400 mg. After a washout period, subjects received a single dose of ketoconazole at 400 mg followed by a single dose of maribavir. Blood samples were collected for each drug sequence, and pharmacokinetic parameters for maribavir and its principal metabolite, VP 44469, were determined. Safety was evaluated by physical examination, clinical laboratory testing, 12-lead electrocardiogram, and monitoring for adverse events. Ketoconazole moderately reduced the clearance of both maribavir and VP 44469; oral clearance values were 35% and 13% lower, respectively, for maribavir-plus-ketoconazole treatment than for maribavir alone. Based on the assumption of complete inhibition of CYP3A4 activity, CYP3A4 is responsible for 35% of the overall clearance of maribavir. Treatment was generally well tolerated. The most-common adverse event was dysgeusia (taste disturbance), reported by nine (47%) and seven (35%) subjects in the maribavir alone and maribavir-plus-ketoconazole groups, respectively. The pharmacokinetic findings, in combination with the acceptable tolerability within the maribavir and maribavir-plus-ketoconazole treatment groups, suggest that no dose adjustment of maribavir is necessary when coadministered with CYP3A4 inhibitors or substrates.

Preclinical testing of clinically applicable strategies for overcoming trastuzumab resistance caused by PTEN deficiency

PURPOSE

We have previously shown that PTEN loss confers trastuzumab resistance in ErbB2-overexpressing breast cancer using cell culture, xenograft models, and patient samples. This is a critical clinical problem because trastuzumab is used in a variety of therapeutic regimens, and at the current time, there are no established clinical strategies to overcome trastuzumab resistance. Here, we did preclinical studies on the efficacy of clinically applicable inhibitors of the Akt/mammalian target of rapamycin (mTOR) pathway to restore trastuzumab sensitivity to PTEN-deficient cells.

EXPERIMENTAL DESIGN

Cell culture and xenograft models were used to test a panel of clinically applicable, small-molecule inhibitors of the Akt/mTOR signal transduction pathway, a critical pathway downstream of ErbB2, and identify compounds with the ability to restore trastuzumab sensitivity to PTEN-deficient cells.

RESULTS

When trastuzumab was combined with the Akt inhibitor triciribine, breast cancer cell growth was inhibited and apoptosis was induced. In a xenograft model, combination therapy with trastuzumab and triciribine dramatically inhibited tumor growth. The combination of trastuzumab and the mTOR inhibitor RAD001 also slowed breast cancer cell growth in vitro and in vivo.

CONCLUSIONS

Combining trastuzumab with inhibitors of the Akt/mTOR pathway is a clinically applicable strategy and combinations of trastuzumab with triciribine or RAD001 are promising regimens for rescue of trastuzumab resistance caused by PTEN loss.

Long-term intermittent pulse therapy with mizoribine attenuates histologic progression in young patients with severe lupus nephritis: report of two patients

Mizoribine (MZR), a novel selective inhibitor of inosine monophosphate dehydrogenase in the de novo pathway, whose mode of action is very similar to that of mycophenolate mofetil, has been successfully applied without serious adverse effects for the treatment of renal diseases. We have previously reported the efficacy and safety of a new MZR treatment regimen, namely, oral MZR intermittent pulse therapy, which we examined based on the observation that it might show superior efficacy to the conventional daily low-dose MZR regimen on account of the higher peak serum MZR levels, in selected patients with lupus nephritis. Two Japanese patients with severe lupus nephritis (WHO class IV-G) who were administered long-term intermittent MZR pulse therapy, and in whom pre- and post-treatment renal biopsies were reported. Post-treatment renal biopsy confirmed the marked attenuation of histologic progression by the treatment. These clinical observations may lend further support, from the histologic standpoint, to the efficacy of long-term MZR intermittent pulse therapy for selected patients with active lupus nephritis.

5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside acutely stimulates skeletal muscle 2-deoxyglucose uptake in healthy men

Activation of AMP-activated protein kinase (AMPK) in rodent muscle by exercise, metformin, 5-aminoimidazole-4-carboxamide 1-beta-d-ribofuranoside (AICAR), and adiponectin increases glucose uptake. The aim of this study was to determine whether AICAR stimulates muscle glucose uptake in humans. We studied 29 healthy men (aged 26 +/- 8 years, BMI 25 +/- 4 kg/m(2) [mean +/- SD]). Rates of muscle 2-deoxyglucose (2DG) uptake were determined by measuring accumulation of total muscle 2DG (2DG and 2DG-6-phosphate) during a primed, continuous 2DG infusion. The effects of AICAR and exercise on muscle AMPK activity/phosphorylation and 2DG uptake were determined. Whole-body glucose disposal was compared before and during AICAR with the euglycemic-hyperinsulinemic clamp. Muscle 2DG uptake was linear over 9 h (R(2) = 0.88 +/- 0.09). After 3 h, 2DG uptake increased 2.1 +/- 0.8- and 4.7 +/- 1.7-fold in response to AICAR or bicycle exercise, respectively. AMPK alpha(1) and alpha(2) activity or AMPK phosphorylation was unchanged after 20 min or 3 h of AICAR, but AMPK phosphorylation significantly increased immediately and 3 h after bicycle exercise. AICAR significantly increased phosphorylation of extracellular signal-regulated kinase 1/2, but phosphorylation of beta-acetyl-CoA carboxylase, glycogen synthase, and protein kinase B or insulin receptor substrate-1 level was unchanged. Mean whole-body glucose disposal increased by 7% with AICAR from 9.3 +/- 0.6 to 10 +/- 0.6 mg x kg(-1) x min(-1) (P < 0.05). In healthy people, AICAR acutely stimulates muscle 2DG uptake with a minor effect on whole-body glucose disposal.

Efficacy of steroid pulse, plasmapheresis, and mizoribine in a patient with focal segmental glomerulosclerosis

There have been few reports on successful treatment for focal segmental glomerulosclerosis (FSGS) complicated by leukoencephalopathy. We report the efficacy of the steroid pulse and mizoribine (MZB) combined with plasmapheresis (PP) for a case of FSGS with leukoencephalopathy induced by cyclosporine (CyA). The patient was a 4-year-old boy with FSGS who presented with steroid-resistant nephrotic syndrome (NS) and was treated with CyA. On the 7th day after starting CyA, he complained of one visual disorder, and hypertension and tonic convulsions were observed. Electroencephalography (EEG) revealed generalized slow waves, and magnetic resonance imaging (MRI) disclosed high signal intensity in the white matter. A diagnosis of leukoencephalopathy induced by CyA was made on the basis of these findings with the improvement in clinical manifestations upon discontinuation of CyA. We treated the patient with steroid pulse therapy and MZB combined with PP, and the proteinuria gradually decreased and only microscopic hematuria remained. We report that steroid pulse and MZB combined with PP may be an effective treatment in a patient with FSGS complicated by CyA-induced leukoencephalopathy.

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.

The synergistic apoptotic effects of thiophenfurin, an inosine monophosphate dehydrogenase inhibitor, in combination with retinoids in HL60 cells

New effective cytotoxic agents and combinations are urgently needed in cancer treatment. The enzyme inosine monophosphate dehydrogenase is a potentially useful target for drug development, since its activity has been shown to be amplified in malignant cells. Thiophenfurin, an inhibitor of the enzyme synthesized by us, is endowed with a significant apoptotic activity in promyelocytic leukaemia HL60 cells. Since retinoids were successfully employed in the treatment of patients with leukaemia, demonstrating significant differentiation-inducing and apoptotic effects, we carried out this study to evaluate the effects of the combination of thiophenfurin and several retinoid molecules, acting in different phases of the cell cycle in vitro. The results show that thiophenfurin is capable of eliciting significant S phase-specific antiproliferative effects in different sensitive and resistant cell lines with the IC50s ranging from 6.7 to 26 microM. When HL60 cells were treated with thiophenfurin in combination with retinoids, the effects on cell growth were additive or synergistic, depending on the kind of retinoid used and the sequence of treatment. In particular, we observed additive effects when the cells were exposed to thiophenfurin and all-transretinoic acid either simultaneously or sequentially. Instead, when the new heterocyclic retinoid isoxazole benzoic acid was used, synergism was obtained in the cells treated sequentially. The combination of thiophenfurin and isoxazole benzoic acid determined synergistic apoptotic effects through a mitochondrion-dependent mechanism, suggesting the possible usefulness of this combination in the treatment of leukaemia.

Efficacy of single dose of oral mizoribine pulse therapy two times per week for frequently relapsing nephrotic syndrome

We assessed the efficacy of a single dose of oral mizoribine (MZB) pulse therapy two times per week for children with frequently relapsing nephrotic syndrome (FRNS). Eleven children with FRNS in remission were treated with oral MZB pulse therapy (daily dose 6 mg/kg; maximum total dose 300 mg). We compared their clinical manifestations before and after oral MZB pulse therapy and examined the changes in serum MZB concentration in each patient on the days when MZB was administered. Eight patients had no subsequent relapses (responders), and prednisolone could be discontinued. Although 2 of the other 3 patients (nonresponders) had one relapse and the remaining patient had two relapses, both the dosages of prednisolone and frequency of relapse after oral MZB pulse therapy were significantly lower than before oral MZB pulse therapy. The peak blood concentration and AUC0-4 of MZB in the responders were higher than in the nonresponders. None of patients had severe adverse effects, such as uricacidemia, leukopenia, liver dysfunction or alopecia. Oral mizoribine pulse therapy consisting of a single dose two days a week may be effective and safe in some FRNS patients.

Safety, tolerability and pharmacokinetics of higher-dose mizoribine in healthy male volunteers

AIMS

Mizoribine is an oral immunosuppressive agent approved in several countries for prevention of rejection in renal transplantation. Its therapeutic window is based on trough concentrations staying at > or =0.5 but <3 microg ml(-1). It has been postulated that as renal function returns to normal, higher doses may be needed to maintain efficacy than the current clinical dosage of 2-5 mg kg(-1) day(-1). The safety, tolerability and pharmacokinetics from two clinical trials of higher-dose mizoribine treatments in healthy male volunteers are presented.

METHODS

Forty-eight healthy White male nonsmokers participated in two randomized, double-blind, placebo-controlled trials: 32 in a single-dose study (3, 6, 9 and 12 mg kg(-1)) and 16 in a multiple-dose study [6 mg kg(-1) day(-1) once daily for 5 days or twice daily (12 mg kg(-1) day(-1)) for 7 days]. Standard assessments of safety, tolerability and pharmacokinetics were performed.

RESULTS

The safety profiles of both studies were generally unremarkable, except for elevated serum uric acid concentrations at the highest dose (12 mg kg(-1) day(-1)) in the multiple-dose study. Orally administered mizoribine reached peak concentrations within 2-3 h and was eliminated mostly via the kidney (65-100% of dose) with a 3-h half-life. Only the 12 mg kg(-1) day(-1) group achieved trough concentrations that were within the therapeutic window. Conclusions Based on the favourable safety profile and current pharmacokinetic information, a new starting dose in the 6-12 mg kg(-1) day(-1) range is recommended in the up to 3 months acute phase following transplantation, with dose reduction recommended only if the function of the transplanted kidney is impaired.

Acceptability and usefulness of mizoribine in the management of rheumatoid arthritis in methotrexate-refractory patients and elderly patients, based on analysis of data from a large-scale observational cohort study

This report documents the results of a study performed to examine clinical use of mizoribine (MZR), using data from a large-scale prospective cohort study, IORRA (Institute of Rheumatology Rheumatoid Arthritis). The number of patients with RA entered in this study from October 2000 through October 2003 was 6238. Three hundred and six patients (4.9%) received MZR therapy. Mizoribine users who were taking methotrexate (MTX) (MTX-MZR group, n = 94) and over 70 years of age (elderly group, n = 45) were collected. Cumulative retention rates of MZR were calculated by Kaplan-Meier analysis. Median drug survival of MZR was 28 months for the poor responders to MTX and 43 months for the poor responders to MZR, with no significant difference between these groups. Cumulative retention rate of MZR in the elderly group did not show a significant difference compared to that in patients aged under 70 years. Ten patients (10.6%) in the MTX-MZR group and 10 patients (22.2%) in the elderly group experienced adverse effects of MZR. None of these adverse effects was serious. This study indicated that, although MZR has not been frequently prescribed for RA patients, it may be useful and relatively safe for patients who are poor responders to MTX as an additional regimen to MTX therapy as well as for elderly patients.

Revival of effective and safe high-dose mizoribine for the kidney transplantation

We investigated whether high-dose Mizoribine (MIZ: a water-soluble anti-metabolite), 4-6 mg/kg/d was as effective and safe as mycophenolate mofetil (MMF) for patients after kidney transplantation. Between January 2001 and December 2005, 36 recipients at a stable phase more than one month passed after transplantation underwent conversion from MMF to MIZ, two from Azathioprine to MIZ, and two cases on MIZ from the beginning. There were 24-male and 16-female patients whose average age was 43.3 yr old and average weight was 54.0 kg. The types of transplantations were living donor renal transplantation 25, cadaveric renal transplantation 11, and simultaneous pancreas-kidney transplantation four examples. Of these, 33 patients were on Tacrolimus-based triple regimen and seven patients on Cyclosporine A base. The drugs used together with MIZ were basically the same as those before conversion. The reasons for conversion to MIZ were infection in 18 cases (45.0%), bone marrow suppression in nine cases (22.5%) and diarrhea in eight cases (20.0%), and post-transplant lymphoproliferative disorder in one case (2.5%). We initiated 4-6 mg/kg/d of MIZ divided twice a day depending on the serum creatinine (sCr) value of each patient. There was no big difference in the sCr value before and after MIZ administration in each individual patient, 1.79 +/- 1.37 and 1.65 +/- 1.30 mg/dL, respectively. A 12 h pharmaco-kinetic study of MIZ revealed that a peak value reached 2.87 microg/mL on average at three h (C3) followed by a slow decrease afterward. Acute rejection occurred in two cases and adverse effects were seen in five cases. The results of analysis of 349 points divided into three groups by renal function were as follows; poor renal function Group A revealed a trough level of 2.21 +/- 0.99 microg/mL and dosage 2.20 +/- 1.06 mg/kg, good renal function Group B had a trough level of 1.06 +/- 0.82 microg/mL and dosage 4.40 +/- 1.72 mg/kg, and excellent function Group C had a trough level of 0.92 +/- 0.55 microg/mL and dosage of 4.36 +/- 1.08 mg/kg. High-dose MIZ 4-6 mg/kg/d is an anti-metabolite having an equivalent immunosuppressive effect, fewer serious adverse events and good cost-effectiveness as MMF even for patients with prolonged hemodialysis period and declined digestive function in Japan.

Activation of AMP-activated protein kinase within the ventromedial hypothalamus amplifies counterregulatory hormone responses in rats with defective counterregulation

Defective counterregulatory responses (CRRs) to hypoglycemia are associated with a marked increase in the risk of severe hypoglycemia. The mechanisms leading to the development of defective CRRs remain largely unknown, although they are associated with antecedent hypoglycemia. Activation of AMP-activated protein kinase (AMPK) in the ventromedial hypothalamus (VMH) amplifies the counterregulatory increase in glucose production during acute hypoglycemia. To examine whether activation of AMPK in the VMH restores defective CRR, controlled hypoglycemia ( approximately 2.8 mmol/l) was induced in a group of 24 Sprague-Dawley rats, all of which had undergone a 3-day model of recurrent hypoglycemia before the clamp study. Before the acute study, rats were microinjected to the VMH with either 5-aminoimidazole-4-carboxamide (AICAR; n=12), to activate AMPK, or saline (n=12). In a subset of rats, an infusion of H(3)-glucose was additionally started to calculate glucose turnover. Stimulation of AMPK within the VMH was found to amplify hormonal CRR and increase endogenous glucose production. In addition, analysis of tissue from both whole hypothalamus and VMH showed that recurrent hypoglycemia induces an increase in the gene expression of AMPK alpha(1) and alpha(2). These findings suggest that the development of novel drugs designed to selectively activate AMPK in the VMH offer a future therapeutic potential for individuals with type 1 diabetes who have defective CRRs to hypoglycemia.

High-dose mizoribine treatment for adolescents with systemic lupus erythematosus

BACKGROUND

In treating pediatric patients with systemic lupus erythematosus (SLE), it is necessary to quickly attain remission to avoid sequelae in various organs and to maintain it over a long period. However, to maintain remission, the prolonged use of immunosuppressants which have various adverse effects, is often necessary in addition to steroids, and complications due to such immunosuppressants pose very important problems. A regimen of mizoribin (MZR) at 150 mg/day divided into two or three doses has been recommended, but while this regimen has been safe, its efficacy has not been satisfactory. However, MZR produces effects dose-dependently, and the dose recommended to date may have been insufficient for the treatment of children with SLE.

METHODS

The authors administered oral MZR at 300 mg/day in two divided doses, which is twice the conventional dose for adults, to five adolescents with SLE. Three of these five were markedly steroid-dependent patients and two had previously been treated with steroids only. Thereafter, the authors evaluated the safety and efficacy of the regimen by following the patients for at least 7 months after the beginning of treatment.

RESULTS

Patients 1 and 2 had been treated with prednisolone (PSL) and cyclosporine (CyA), but as the duration of CyA administration became long, it was replaced with 300 mg MZR. This transition could be accomplished smoothly. Patient 3 showed repeated recurrence during the treatment with PSL and CyA or CPM, but the symptoms could be controlled by the addition of 300 mg MZR. In patients 4 and 5, the control of symptoms with PSL alone was judged to be difficult, and concomitant administration of MZR at 300 mg was started. This resulted in a decrease in the dose of PSL. The Cmax (C2) of MZR was 1.33 microg/mL or higher in all five patients, and the efficacy of the treatment was satisfactory. Concerning side-effects, hyperuricemia was noted in two patients, but it was resolved in one of them by reducing the dose of MZR and in the other spontaneously while the treatment was continued. Temporary exacerbation of hair loss was observed in two patients, but it disappeared in both of them after a few months.

CONCLUSION

MZR could be administered at a high dose effectively and safely. However, monitoring of the serum uric acid level was necessary. High-dose MZR therapy showed an efficacy and safety that would warrant its application to steroid-dependent pediatric patients with SLE.

[Beneficial and adverse effects of high-dosage MZR therapy in the management of children with frequently relapsing nephrotic syndrome]

BACKGROUND

Long-term therapy of mizoribine (MZR 2-5 mg/kg/day) has been reported in the management of children with frequently relapsing nephrotic syndrome(FRNS). It had minimum adverse effects, however, MZR therapy does not sufficiently suppress the relapse of FRNS. Previous reports suggested that modification of MZR therapy with a total dosage and administration schedule may improve the therapeutic effect. To elucidate the issue, we retrospectively evaluated the efficacy and safety of high-dose MZR therapy for children with FRNS.

METHODS

The subjects comprised 13 affected children with FRNS (9 boys and 4 girls: median age of 11.7 years, ranging from 7.8 to 20.1 years). They were divided into a high dose group (MZR 7-10 mg/kg/ day; Max 400 mg) and a low dose group (MZR 4-6 mg/kg/day). We compared the therapeutic benefits between both groups, including the incidence of relapse(times/year) and daily dosages of prednisolone (PSL, mg/kg/day). The Wilcoxon test was used for statistical analysis. We also evaluated the relationship between the therapeutic effects and serum concentration of MZR two hours after the administration.

RESULTS

The low dose and high-dose groups were well matched in terms of baseline characteristics. After the initiation of MZR, beneficial therapeutic effects ensued in the high-dose group (incidence of relapse: 3.61 vs. 1.59 times/year before and after the therapy, p < 0.05), daily dosages of PSL (0.65 vs. 0.29 mg/kg/day before and after therapy, p<0.001), but did not occur in the low-dose group(3.97 vs. 2.84 times/year; 0.84 vs. 0.53 mg/kg/day, n. s.). All patients with a serum MZR concentration of over 3 microg/ml had relapses less than three times a year. One patient in the high-dose group and the other in the low-dose group showed hyperuricemia, and responded well to medical treatment. No other adverse effect was observed.

CONCLUSIONS

High-dose MZR therapy in the management for FRNS may provide more beneficial effects without significant adverse effects.

Targeting the phosphatidylinositol-3 kinase/Akt pathway for the treatment of cancer

Phosphatidylinositol-3 kinase (PI3K)/Akt is overactivated in a wide range of tumor types, and this triggers a cascade of responses, from cell growth and proliferation to survival, motility, epithelial-mesenchymal transition and angiogenesis. Therefore, this pathway presents an exciting target for molecular therapeutics. In addition, ectopic expression of PI3K or Akt, especially constitutively activated PI3K (p110alpha) or Akt, is sufficient to induce the oncogenic transformation of cells and tumor formation in transgenic mice, as well as the development of chemoresistance. Inhibition of PI3K/Akt signaling induces apoptosis and inhibits the growth of tumor cells that have elevated Akt levels. The dependence of certain tumors on PI3K/Akt signaling for survival and growth has wide implications for cancer therapy, offering the potential for preferential tumor cell killing. In the past few years, a number of inhibitors of the Akt pathway have been identified by combinatorial chemistry, high-throughput and virtual screening, or traditional medicinal chemistry. This review focuses on ongoing translational efforts to therapeutically target the PI3K/Akt pathway.