[Pharmacological profiles of mycophenolate mofetil (CellCept), a new immunosuppressive agent]

Anti-inflammatory Therapy for Sarcoidosis

Over 50% of patients with sarcoidosis will require anti-inflammatory therapy at some point in their disease course. Indications for therapy are to improve health-related quality of life, prevent or arrest organ dysfunction (or organ failure) or avoid death. Recently published treatment guidelines recommended a stepwise approach to therapy however there are some patients for whom up front combination or more intense therapy maybe reasonable. The last decade has seen an explosion of studies and trials evaluating novel therapeutic agents and treatment strategies. Currently available anti-inflammatory therapies and several novel therapies are discussed here.

Targeting NAD-dependent dehydrogenases in drug discovery against infectious diseases and cancer

Dehydrogenases are oxidoreductase enzymes that play a variety of fundamental functions in the living organisms and have primary roles in pathogen survival and infection processes as well as in cancer development. We review here a sub-set of NAD-dependent dehydrogenases involved in human diseases and the recent advancements in drug development targeting pathogen-associated NAD-dependent dehydrogenases. We focus also on the molecular aspects of the inhibition process listing the structures of the most relevant molecules targeting this enzyme family. Our aim is to review the most impacting findings regarding the discovery of novel inhibitory compounds targeting the selected NAD-dependent dehydrogenases involved in cancer and infectious diseases.

Pharmacokinetic Variability of Mycophenolic Acid in Pediatric and Adult Patients With Hematopoietic Stem Cell Transplantation

The aim of this study was to evaluate the pharmacokinetic variations of mycophenolic acid (MPA), the active metabolite of mycophenolate mofetil (MMF), in both pediatric and adult patients following hematopoietic stem cell transplantation (HSCT). Twenty pediatric patients with a median age of 3 years (range 0.2-12 years) and 13 adult patients with a median age of 54 years (range 18-63 years) were enrolled. Blood samples were collected on days 0, 7, 14, 21, and 30 after allogeneic HSCT. Total and free (unbound) MPA as well as MPA 7-O-glucuronide (MPAG) were quantified using a validated LC-MS/MS assay. The plasma protein binding of MPA and MPAG did not change significantly in pediatric patients over the 1-month sampling period post-HSCT. However, it increased in adult patients from day 7 to day 30 post-HSCT, from 97.3 ± 0.8% to 98.3 ± 0.6% for MPA (P < .05), and 74.6 ± 9.4% to 82.9 ± 8.1% for MPAG (P < .05). The plasma protein binding of MPA was significantly higher in males compared to females in both pediatric (98.3 ± 1.1% vs 97.4 ± 1.1%) and adult (98.1 ± 0.7% vs 97.4 ± 1.2%) patients (P < .05). The MPAG/MPA ratios on a milligram-per-kilogram dose basis in adult patients were significantly higher than those in pediatric patients (4.3 ± 3.4 vs 2.4 ± 2.6; P < .05). Time-dependent plasma protein binding and age-related differences in MPA metabolism at least in part impact the reported large intra- and interindividual variability in MPA pharmacokinetics. These patient and pharmacologic factors, if incorporated into MMF regimen design and modification, may contribute to the rational dose selection of MMF in HSCT patients.

Current methods of the analysis of immunosuppressive agents in clinical materials: A review

More than 100000 solid organ transplantations are performed every year worldwide. Calcineurin (cyclosporine A, tacrolimus), serine/threonine kinase (sirolimus, everolimus) and inosine monophosphate dehydrogenase inhibitor (mycophenolate mofetil), are the most common drugs used as immunosuppressive agents after solid organ transplantation. Immunosuppressive therapy, although necessary after transplantation, is associated with many adverse consequences, including the formation of secondary metabolites of drugs and the induction of their side effects. Calcineurin inhibitors are associated with nephrotoxicity, cardiotoxicity and neurotoxicity; moreover, they increase the risk of many diseases after transplantation. The review presents a study of the movement of drugs in the body, including the processes of absorption, distribution, localisation in tissues, biotransformation and excretion, and also their accompanying side effects. Therefore, there is a necessity to monitor immunosuppressants, especially because these drugs are characterised by narrow therapeutic ranges. Their incorrect concentrations in a patient's blood could result in transplant rejection or in the accumulation of toxic effects. Immunosuppressive pharmaceuticals are macrolide lactones, peptides, and high molecular weight molecules that can be metabolised to several metabolites. Therefore the two main analytical methods used for their determination are high performance liquid chromatography with various detection methods and immunoassay methods. Despite the rapid development of new analytical methods of analysing immunosuppressive agents, the application of the latest generation of detectors and increasing sensitivity of such methods, there is still a great demand for the development of highly selective, sensitive, specific, rapid and relatively simple methods of immunosuppressive drugs analysis.

Drugs and drug intermediates from fungi: Striving for greener processes

There is an ever-increasing demand of newer and improved drugs from biological sources to cater to the bio-pharmaceutical sector. Among various other resources, fungal species have an immense contribution owing to their potential to carry out the bio-transformations and drug synthesis in diverse conditions and in an eco-friendly manner. Advancement in the biotechnological processes has accelerated the process. Genome sequence information of various fungal species has opened newer avenues for improved and faster drug targeting and designing. The review highlights the production of pharmaceutical drugs and drug intermediates like antibiotics, anti-cancer, anti-cholesterol, anti-diabetic, immunosuppressant, anti-anxiety, anti-virals and many other drugs from fungus. Many of these have been commercialized and there are many more which are either in research or in clinical trial phase. There is a need to exploit and explore the vast biota of fungi in the hope of discovering untapped therapeutic uses of the earth's countless species of fungus.

Potential immunological advantage of intravenous mycophenolate mofetil with tacrolimus and steroids in primary deceased donor liver transplantation and live donor liver transplantation without antibody induction

With the current immunosuppressive regimens, graft loss secondary to immunological reasons after successful liver transplantation is a rarity; acute rejections, however, do occur, with the majority of them being steroid-responsive. The aim of the present study is to examine the rate of acute rejection with tacrolimus, intravenous (IV) mycophenolate mofetil (MMF), and steroids in primary deceased donor liver transplant (DDLT) and live donor liver transplant (LDLT) recipients. During the year 2005, 130 patients (mean age: 54.9 +/- 10.8, males: 84, females: 46, 112 DDLT and 18 LDLT) received primary liver transplantation. They were followed up for the incidence of acute rejection in the first 12 months. Liver biopsies were performed as clinically indicated; protocol liver biopsies were never performed. A total of 127 liver biopsies were performed. Thirty-two had a rejection activity index (RAI) score of > or =3, of which 24 biopsies in 20 patients were not treated with a steroid bolus. Eight (6.1%) patients (mean RAI score: 5.1 +/- 1.4) received 750 to 1500 mg of methylprednisolone over 3 days. Out of these, 2 were noncompliant, 4 were off MMF, and 1 was on cyclosporine. All patients responded to steroid therapy. None of the patients required any antibody preparation. In conclusion, IV MMF with tacrolimus and steroids is useful and required antirejection therapy in 6.1% of liver transplant recipients.

Synergy between imatinib and mycophenolic acid in inducing apoptosis in cell lines expressing Bcr-Abl

Bcr-Abl tyrosine kinase activity initiates a number of intracellular signaling cascades that result in leukemogenesis. Imatinib mesylate, a specific Bcr-Abl tyrosine kinase inhibitor, has been highly successful in the treatment of chronic myelogenous leukemia (CML). However, the emergence of imatinib resistance and the incomplete molecular response of a significant number of patients receiving this therapy have led to a search for combinations of drugs that will enhance the efficacy of imatinib. We have demonstrated that mycophenolic acid (MPA), a specific inosine monophosphate dehydrogenase (IMPDH) inhibitor that results in depletion of intracellular guanine nucleotides, is synergistic with imatinib in inducing apoptosis in Bcr-Abl-expressing cell lines. Studies of signaling pathways downstream of Bcr-Abl demonstrated that the addition of MPA to imatinib reduced the phosphorylation of both Stat5 and Lyn, a Src kinase family member. The phosphorylation of S6 ribosomal protein was also greatly reduced. These results demonstrate that inhibitors of guanine nucleotide biosynthesis may synergize with imatinib in reducing the levels of minimal residual disease in CML and lay the foundation for clinical trials in which IMPDH inhibitors are added to imatinib in patients who have suboptimal molecular responses to single agent therapy or who have progressive disease.

Mycophenolate mofetil treatment following renal transplantation decreases GTP concentrations in mononuclear leucocytes

MMF (mycophenolate mofetil) has been proven to provide an effective immunosuppression by non-competitive selective reversible inhibition of IMPDH (inosine monophosphate dehydrogenase), the enzyme playing a crucial role in GTP biosynthesis. However, the exact metabolic changes induced by inhibition of IMPDH in target cells of the immune system have been the subject of recent debate. The aim of the present study was to evaluate whether MMF treatment produced sustained changes in the guanosine nucleotide pool of MNLs (mononuclear leucocytes) in vivo. Sixty-two renal failure patients were divided into three groups: chronic renal failure patients undergoing haemodialysis (CRF-HD; n=20) and two groups of patients after renal transplantation, the first on AZA (azathioprine; TN-AZA; n=23) and the second treated with MMF (TN-MMF; n=19). In addition, MNLs from 25 healthy subjects were analysed as controls. Anion-exchange HPLC was used to quantify purine and pyrimidine nucleotides in MNLs. We report a significant decrease in GTP and the total MNL guanine nucleotide pool in the TN-MMF group (P<0.05) compared with control, CRF-HD and TN-AZA groups, although no significant differences were found between any of the other groups. Adenine nucleotide concentrations in MNLs were decreased in the TN-AZA group, but not in the TN-MMF group compared with the CRF-HD group and controls. There were no differences in CTP concentrations, but UTP concentrations were decreased in the CRF-HD, TN-AZA and TN-MMF groups compared with controls. MMF caused a significant and sustained decrease in the guanine nucleotide pool in MNLs from renal transplant recipients. This decrease contrasts with the elevation in GTP reported in erythrocytes of MMF-treated patients.

Mycophenolate mofetil in the treatment of autoimmune HCV-associated haematological disorders showing steroid resistance or dependence

We report two cases of hepatitis C virus (HCV) associated autoimmune haematological disorders successfully treated with an unusual protocol (mycophenolate mofetil: MMF). The first case was a male patient with chronic HCV infection who developed, during interferon (IFN)/ribavirin therapy, severe autoimmune thrombocytopenia unresponsive to steroids. MMF was then administered and, simultaneously, the steroid dose was gradually reduced until withdrawal. Following this strategy, a progressive increase in platelet count and complete negativity of anti-PLT antibodies were achieved without changes in HCV-RNA quantitative determination. The second case was a woman with HCV liver cirrhosis with severe anaemia and Coombs test positivity partially responsive to continuous administration of steroid high doses. However, this treatment unmasked a severely painful vertebral osteoporosis. For this reason we introduced MMF and simultaneously steroid therapy was progressively reduced until withdrawal. Haemoglobin reached a normal value and the Coombs test became negative within 60 days. These case reports suggest that MMF may represent an interesting therapeutic approach for autoimmune HCV associated haematological disorders.

Induction of apoptosis in IL-3-dependent hematopoietic cell lines by guanine nucleotide depletion

Inosine 5'-monophosphate dehydrogenase (IMPDH) is a rate-limiting enzyme that catalyzes the conversion of IMP to xanthosine monophosphate (XMP) at the branch point of purine nucleotide biosynthesis, leading to the generation of guanine nucleotides. Inhibition of IMPDH results in the depletion of guanine nucleotides, prevents cell growth by G1 arrest, and induces cell differentiation in a cell-type-specific manner. The molecular and sensing mechanisms underlying these effects are not clear. We have examined the induction of apoptosis by mycophenolic acid (MPA), a specific IMPDH inhibitor, in interleukin-3 (IL-3)-dependent murine hematopoietic cell lines. MPA treatment, at clinically relevant doses, caused apoptosis in 32D myeloid cells and in FL5.12 and BaF3 pre-B cells in the ongoing presence of IL-3. Apoptosis was completely prevented by the addition of guanosine at time points up to 12 hours, after which caspase 3 activity increased and apoptosis was not reversible. MPA treatment caused marked down-regulation of the MAP kinase kinase/extracellular regulatory kinase (MEK/Erk) pathway at 3 hours while simultaneously increasing the phosphorylation of c-Jun kinase. In addition, MPA strongly down-regulated the mammalian target of rapamcyin (mTOR) pathway, as indicated by the decreased phosphorylation of p70 S6 kinase and of 4EBP1. Inhibition of either the mitogen-activated protein kinase (MAPK) or the mTOR pathway alone by standard pharmacologic inhibitors did not induce apoptosis in IL-3-dependent cells, whereas inhibition of both pathways simulated the effects of MPA treatment. These results indicate that IMPDH inhibitors may be effective in modulating signal transduction pathways in hematopoietic cells, suggesting their usefulness in chemotherapeutic regimens for hematologic malignancies.