EC-MPS permits lower gastrointestinal symptom burden despite higher MPA exposure in patients with severe MMF-related gastrointestinal side-effects

Conventional and Novel Approaches to Immunosuppression in Lung Transplantation

Most therapeutic advances in immunosuppression have occurred over the past few decades. Although modern strategies have been effective in reducing acute cellular rejection, excess immunosuppression comes at the price of toxicity, opportunistic infection, and malignancy. As our understanding of the immune system and allograft rejection becomes more nuanced, there is an opportunity to evolve immunosuppression protocols to optimize longer term outcomes while mitigating the deleterious effects of traditional protocols.

Antibody-Mediated Rejection in Adult Liver Transplant Recipients: A Case Series and Literature Review

Antibody-mediated rejection is a rare complication following liver transplantation and there is a lack of a comprehensive treatment strategy to provide detailed information about the dose and duration of antibody-mediated rejection treatment. This study describes eight adult liver transplantation recipients who developed antibody-mediated rejection between 2002 and 2021 in our center, as well as a review of the literature on the reported cases of antibody-mediated rejection in liver transplantation recipients. Our center's medical records were reviewed retrospectively to extract the necessary data on patients' characteristics, management, and outcomes. Then, a comprehensive search using Embase, PubMed, Web of Science, Cochrane library, and Google Scholar databases was conducted without time limitation until June, 2021. Finally, a stepwise protocol was developed for managing acute, chronic, and recurrent antibody-mediated rejection in liver transplantation patients, based on our own experience, reported cases in the literature, and data from kidney transplantation. By review of the literature, 24 case studies containing 64 patients were identified and their management strategies and outcomes were evaluated. Although, various combinations of corticosteroids, plasma exchange, intravenous immunoglobulin, and biological agents are used in the treatment of acute antibody-mediated rejection in liver transplantation, treatment strategies should be classified according to the type, severity, and the timing of its onset. Given the importance of early treatment, rituximab and/or bortezomib should be started as soon as possible if no improvement in liver enzymes/bilirubin is observed during the initial treatment strategy using corticosteroids, plasma exchange and intravenous immunoglobulin. This article is protected by copyright. All rights reserved.

Association of ABCC2 Haplotypes to Mycophenolic Acid Pharmacokinetics in Stable Kidney Transplant Recipients

Mycophenolic acid exhibits significant interpatient pharmacokinetic variability attributed to factors including race, sex, concurrent medications, and enterohepatic circulation of the mycophenolic acid glucuronide metabolite to mycophenolic acid. This conversion by enterohepatic circulation is mediated by the multidrug resistance-associated protein 2, encoded by ABCC2. This study investigated ABCC2 haplotype associations with mycophenolic acid pharmacokinetics in 147 stable kidney transplant recipients receiving mycophenolic acid in combination with calcineurin inhibitors. The role of the ABCC2 genotypes -24C>T (rs717620), 1249C>T (rs2273697), and 3972C>T (rs3740066) were evaluated in prospective, cross-sectional pharmacokinetic studies of stable recipients receiving mycophenolic acid and either tacrolimus or cyclosporine. Haplotype phenotypic associations with mycophenolic acid pharmacokinetic parameters were computed using THESIAS (v. 3.1). Four ABCC2 haplotypes with estimated frequencies greater than 10% were identified (H1:CGC [wild type], H9:CGT, H2:CAC, H12:TGT). There were no differences in haplotype frequencies by either race or sex. There were significant associations of pharmacokinetic parameters with ABCC2 haplotypes for mycophenolic acid clearance (L/h), mycophenolic acid AUC_0-12h (mg·h/L), and the ratio of mycophenolic acid glucuronide to mycophenolic acid AUC_0-12h . The wild-type haplotype ABCC2 CGC had greater mycophenolic acid AUC_0-12h (P = .017), slower clearance (P = .013), and lower mycophenolic acid glucuronide to mycophenolic acid AUC_0-12h ratio (P = .047) compared with the reduced function ABCC2 haplotype CGT. These differences were most pronounced among patients receiving tacrolimus cotreatment. No phenotypic associations were found with the cyclosporine-mycophenolic acid regimen. Variation in ABCC2 haplotypes contributes to subtherapeutic mycophenolic acid exposure and influences interpatient variability in pharmacokinetic phenotypes based on concurrent calcineurin inhibitor treatment.

Mycophenolic Acid Concentration on Vietnamese Renal Transplant Recipients

Background: Kidney recipients often use a calcineurin inhibitor and a proliferation inhibitor after transplantation. The therapeutic drug monitoring for calcineurin inhibitor is more simple and feasible in clinical than proliferation inhibitor. In Vietnam, mycophenolic acid is a popular proliferation inhibitor used for transplantation patients. Although therapeutic mycophenolic acid monitoring is so important in treating kidney transplantation, the monitoring is still difficult to execute in Vietnam. Objectives: This study aimed to determine the MPA concentration on Vietnamese renal transplant recipients. Methods: This observational study was conducted on 35 adult kidney recipients to evaluate the MPA concentration at five sampling time points (predose, 1, 2, 3, and 6 hours) on day 3, day 10, and month 6 after transplantation. Results: Plasma MPA trough levels (C0) were 2.32 ± 1.47;1.58 ± 1.39; 2.29 ± 1.4 mg/L and the MPA-AUC0-12 h values were 50.1 ± 20.4; 41.9 ± 14.5; 60.3 ± 25.9 mg.h/L on day 3, day 10, and month 6. The number of patients who reached MPA-AUC0-12 h values of 30 - 60 mg.h/L was 18 (51.4%), 23 (65.7%) and 17 (51.5%) on day 3, day 10, and month 6, respectively. The number of patients who achieved the MPA C0 values of 1.5 - 2.5 mg/L was 15 (42.9 %), 14 (40%), and 10 (30.3%) on day 3, day 10, and month 6, respectively; and the linear correlation coefficients between AUC0-12 h and C0 were 0.652, 0.415, and 0.752, respectively. Conclusions: In renal transplant patients, the MPA-AUC0-12 h was lower on day 3 and day 10 post-transplantation than month 6 for the half dose of MMF or MPS. Therefore, MPA therapeutic drug level should be monitored usually in transplantation patients who use MPA.

Clinical characteristics and prognostic risk factors of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAV)

OBJECTIVE

The complement alternative pathway is involved in the development of AVV. Several studies showed that AVV patients with low serum complement C3 (sC3) levels tend to have a poor prognosis. The aim of this study was to determine whether low sC3 measured at AAV onset is a risk factor for survival prognosis in patients with AVV, and further identified other potential risk factors for predicting patient survival prognosis.

METHODS

A retrospective analysis of 52 newly onset AAV patients was performed. The clinical parameters of the AAV patients were collected. The laboratory parameters before immunosuppressive treatment were evaluated. According to the level of sC3, the patients were divided into low sC3 group (n = 19) and normal sC3 group (n = 33). Disease outcome measures included end-stage renal disease (ESRD) or death. The clinical parameters and survival rate between the two groups were compared. Spearson correlation analysis was used to analyze the correlation between sC3 and other laboratory parameters.

RESULTS

Significant differences were found regarding Birmingham Vasculitis Activity Score (BVAS), sC3, sC4, lactate dehydrogenase, blood urea nitrogen, procalcitonin (PCT), and estimated glomerular filtration rate (eGFR) between the two groups (p = 0.006, 0.000, 0.001, 0.049, 0.019, 0.000 and 0.045, respectively). The survival rate of the low sC3 group was significantly lower than that of the normal sC3 group (Log Rank Chi-square = 4.416, P = 0.036). Low sC3 was significantly associated with lower sC4 (r = 0.570, P = 0.000), lower serum albumin (r = 0.311, P = 0.025), lower eGFR (r = 0.289, P = 0.037), higher PCT (r = -0.566, P = 0.000), and higher lactate dehydrogenase (r = -0.323, P = 0.019).

CONCLUSION

This retrospective study demonstrates that AAV patients with low sC3 level at diagnosis tend to have lower baseline eGFR and poorer survival prognosis than those of the normal sC3 level. Furthermore, the high procalcitonin (PCT), low serum albumin and high lactate dehydrogenase in AVV patients may be predictors of poor prognosis.

A novel bispecific antibody alleviates bleomycin-induced systemic sclerosis injury

Systemic sclerosis (SSc) is induced by variety of factors and eventually causes multiple organ damage. In recent years, biological agents targeting cytokines and cell surface molecules have gradually come to market. Here, the anti-inflammatory and antifibrotic effects of a novel bispecific antibody (FL-BsAb1/17) targeting interleukin-17A (IL-17A) and interleukin-1β (IL-1β) were detected. Bleomycin (BLM) was subcutaneously injected for 21 consecutive days to establish the SSc mouse model, and mice were subsequently treated with etanercept or different doses (1, 5, 10 mg/kg) of FL-BsAb1/17. The results showed that FL-BsAb1/17 treatment (10 mg/kg, 5 mg/kg) significantly attenuated BLM-induced SSc-like inflammation by inhibiting the expression of inflammatory factors (IL-17A, IL-1β, IL-8, IL-22, IL-23, IL-6) and fibrosis, with specific outcomes of dermis thickening and lung fibrosis, by inhibiting the expression of fibrotic factors (TGF-β, α-sma, Col-1, Col-3) in the serum, skin and lungs. In addition, FL-BsAb1/17 (10 mg/kg, 5 mg/kg) downregulated protein levels of TGF-β and phosphorylated Smad2/3 in the skin and lungs and reduced collagen 1 protein levels. This indicated that FL-BsAb1/17 can inhibit the development of fibrosis by inhibiting the TGF-β/Smad2/3 signaling pathway. FL-BsAb1/17 (10 mg/kg, 5 mg/kg) could also effectively reduce the content of MDA, increase the activity of SOD and CAT, and improve the total antioxidant capacity (T-AOC). In conclusion, FL-BsAb1/17 alleviated BLM-induced SSc by downregulating inflammatory cascades, relieving oxidative stress and inhibiting TGF-β/Smad2/3 signaling. These data suggest that FL-BsAb1/17 has potential as a novel therapeutic candidate for SSc.

Is Conversion from Mycophenolate Mofetil to Enteric-Coated Mycophenolate Sodium Justifiable for Gastrointestinal Quality of Life?

BACKGROUND

Globally, enteric-coated mycophenolate sodium (EC-MPS) is replacing mycophenolate mofetil (MMF) in maintenance immunosuppressant regimens. The predominant reason for conversion is the purported improvement in gastrointestinal (GI) quality of life. This paper considers the level of bias associated with studies comparing EC-MPS and MMF for GI-related improvement and provides insight into whether conversion is supported by evidence.

METHODS

Using a pre-determined protocol, a literature search was conducted. Full-text review, data extraction and risk of bias analysis was conducted by two independent authors using the Cochrane domain-based evaluation of risk of bias. The review was reported according to the preferred reporting items for systematic reviews and meta-analyses.

RESULTS

Twenty-nine studies were included in risk of bias analysis. Of these, only three were deemed a low risk of bias. Across these three studies, there were no statistically significant differences in the proportion of GI-related adverse events nor was there a significant difference in the GI-related quality of life between EC-MPS- and MMF-treated patients in these data.

CONCLUSION

There was a high risk of bias across the 29 studies investigating conversion from MMF to EC-MPS for potential improvement in GI-related quality of life. The consolidated results of the three studies with low risk of bias suggest no evidence to convert patients stabilised on MMF. If a patient experiences GI-related adverse events whilst taking MMF, other methods should be explored before conversion to EC-MPS.

Replacement of mycophenolate mofetil with a JAK inhibitor, AS2553627, in combination with low-dose tacrolimus, for renal allograft rejection in non-human primates

In renal transplant patients, using mycophenolate mofetil (MMF) with calcineurin inhibitors (CNIs; cyclosporine and tacrolimus [TAC]) has led to a significant improvement in graft survival. However, reducing or withholding MMF due to its gastrointestinal adverse events increases rejection risk. CNI-sparing strategies are important to avoid CNI-related nephrotoxicity in clinical settings. Here, we investigated AS2553627, a JAK inhibitor replacing MMF in combination with a sub-therapeutic dose of TAC to treat allograft rejection in a monkey model. AS2553627 inhibited proliferation of IL-2 stimulated T cells with little species difference between monkeys and humans. In MMF monotherapy, oral administration of 20 or 40 mg/kg/day prolonged graft survival with median survival times (MSTs) of 16.5 days and 33 days, respectively, whereas untreated animals showed MST of 6 days. In MMF/TAC (1 mg/kg/day, p.o.) combination therapy, pharmacokinetic analysis indicated that MMF 20 mg/kg/day achieved the clinical target AUC_0-24h and prolonged renal allograft survival, with MST of 24 days. Oral administration of AS2553627 0.24 mg/kg/day in combination with TAC significantly prolonged renal allograft survival to MST of >90 days with low plasma creatinine levels. Histopathological analysis revealed that acute T cell-mediated rejection events such as vasculitis and interstitial mononuclear cell infiltration were significantly inhibited in AS2553627/TAC-treated allografts compared with MMF/TAC-treated allografts. All AS2553627/TAC-treated monkeys surviving >90 days exhibited less interstitial fibrosis/tubular atrophy than monkeys in the MMF/TAC group. These results suggest that AS2553627 replacing MMF is an attractive CNI-sparing strategy to prevent renal allograft rejection.

Intestinal infection at onset of mycophenolic acid-associated chronic diarrhea in kidney transplant recipients

BACKGROUND

Chronic diarrhea after kidney transplantation is often attributed to mycophenolic acid (MPA) toxicity. We hypothesize that intestinal infections contribute to the pathogenesis of chronic MPA-associated diarrhea.

METHODS

In this retrospective study, all patients (n = 726) receiving a kidney transplant between 2000 and 2010 at the University Hospital Zurich were followed until July 2014 for occurrence of chronic diarrhea (≥4 weeks). Infectious triggers at diarrhea onset were assessed by reviewing medical history, stool microbiology, and histology of colon biopsies.

RESULTS

In 46 patients (6.3% of the cohort), a total of 51 episodes of chronic diarrhea during MPA treatment were documented. The diarrhea episodes were often severe, as confirmed by significant weight loss. The cumulative incidence of chronic diarrhea was uniformly distributed throughout the post-transplant period, with 2.0%, 5.1%, and 9.6% at 1, 5, and 10 years, respectively. Evidence was found for intestinal infection at diarrhea onset in 38 episodes (74.5%). Occurrence of diarrhea onset showed a seasonal distribution with peaks in April and October/November. Specific antimicrobial treatment alone was associated with a 19% resolution rate only, whereas combination with dose reduction of MPA or switch from mycophenolate mofetil to enteric-coated mycophenolate sodium resulted in a 22.7% and 76.5% resolution rate, respectively. Change to an MPA-free regimen was associated with a 100% resolution rate.

CONCLUSION

These results provide first evidence for a contribution of intestinal infections in chronic post-transplant diarrhea associated with MPA treatment.

Mycophenolate revisited

The patent of mycophenolate mofetil (MMF) has expired, and for enteric-coated mycophenolate sodium (EC-MPS), this will happen in 2017. In the twenty years these drugs have been used, they have become extremely popular. In this review, the reasons for the popularity of mycophenolate are discussed, including the benefits compared to azathioprine. MMF and EC-MPS are therapeutically equivalent. Although neither is considered to be a narrow therapeutic index drug, this should not lead to careless switching between the innovator drug and generic formulations, or between one generic formulation and another. The pipeline of new immunosuppressive drugs is dry, and it is very likely that we will be using mycophenolate for many more years to come as a first-line immunosuppressive drug in our transplant population. Whether or not the development of donor-specific anti-HLA antibodies is related to drug exposure (mycophenolic acid concentrations) remains to be investigated.

Enteric-coated mycophenolate sodium containing GvHD prophylaxis reduces GvHD rate after allogeneic HSCT

OBJECTIVES

The aim of this study was to evaluate whether cyclosporine A (CsA)-based Graft vs. Host Disease (GvHD) prophylaxis with enteric-coated mycophenolate sodium (EC-MPS) instead of mycophenolate mofetil (MMF) or methotrexate (MTX) reduces the GvHD incidence and lowers gastrointestinal (GI-) toxicities.

METHODS

In a retrospective analysis of 102 allogeneic hematopoietic stem cell transplant (HSCT) patients, incidences of overall and severe aGvHD (>II°), cGvHD as well as overall and severe (CTC >II°) GI-toxicities were compared between GvHD prophylaxis containing EC-MPS vs. MMF or MTX (control group).

RESULTS

The overall aGvHD rate was significantly lower in the EC-MPS group compared to the control (47% vs. 72%, P = 0.022) with lower rates of severe aGvHD (10% vs. 25%, P = 0.088) and cGvHD (20% vs. 39%, P = 0.065). Prophylaxis with EC-MPS remained significantly associated with a lower aGvHD rate in a multiple logistic regression model. GI-toxicities did not differ between both groups except for severe abdominal pain for which the incidence was increased in the EC-MPS group (17% vs. 3%, P = 0.022).

CONCLUSIONS

This data support the hypothesis that replacement of MMF or MTX by EC-MPS reduces GvHD rates after HSCT. This appears not to be due to a reduced GI-toxicity of EC-MPS.

Enteric-coated mycophenolate sodium given in combination with tacrolimus has a lower incidence of serious infections in Asian renal-transplant recipients compared with mycophenolate mofetil

AIMS

To compare the characteristics of the enteric-coated formulation of mycophenolate sodium (EC-MPS, myfortic) and mycophenolate mofetil (MMF, CellCept) given in combination with tacrolimus in Asian renal-transplant recipients.

METHODS

In a 24-month, single-centre, randomized, open-label, prospective study, 101 live-donor kidney transplant recipients were randomized to the EC-MPS (n = 50) or MMF (n = 51) group. The incidence of infection, therapeutic effect and adverse events were monitored.

RESULTS

The incidences of infection were 40% and 49% for the EC-MPS and MMF groups, respectively (p = 0.362). However, serious infection was only observed in the MMF group (11.8%; p = 0.027). The incidences of gastro-intestinal adverse events (GI AEs) were 24% and 41.2% for EC-MPS and MMF, respectively (p = 0.066). However, serious diarrhoea only occurred in the MMF group (9.8%; p = 0.056). The trough level of FK 506 at the time of diarrhoea (13.22 ± 3.66 ng/ml) was significantly higher than the level within 1 month before (9.18 ± 1.12 ng/ml; p < 0.05) and 1 month after diarrhoea (9.13 ± 0.85 ng/ml; p < 0.05). The infection rate of patients with diarrhoea was significantly higher than those without diarrhoea (68%, 39%, p = 0.024). The serum creatinine level was 698 ± 60 μmol/l for EC-MPS and 673 ± 68 μmol/l for MMF from baseline (p > 0.05), and it decreased to 66 ± 6 μmol/l for EC-MPS and 69 ± 8 μmol/l for MMF at 24 months (p > 0.05). The incidences of biopsy proven acute rejection (BPAR) were 20% and 25.5% for EC-MPS and MMF, respectively (p = 0.511).

CONCLUSIONS

Enteric-coated formulation of mycophenolate sodium, given in combination with tacrolimus, has a lower incidence of serious infection in Asian renal-transplant recipients compared with MMF, and the therapeutic effect of EC-MPS is similar to MMF. The clinical trial registration number is ChiCTR-IPR-14005509. The registry name is 'Effect of Enteric-coated mycophenolate sodium on posttransplant infection rate after renal transplantation compared with Mycophenolate mofetil'.

Update on the Teratogenicity of Maternal Mycophenolate Mofetil

Mycophenolic acid (MPA) products, namely mycophenolate mofetil and mycophenolate sodium, are immunosuppressive medications used to prevent rejection in solid organ transplant recipients and to treat various autoimmune disorders. Mycophenolate therapy is considered to be teratogenic based on observational studies of pregnancies exposed to MPA, which demonstrated an increased incidence of miscarriages in pregnancies exposed to MPA during their first trimester and a pattern of birth defects in the offspring of some pregnancies exposed to MPA. Herein, we have detailed case and series reports in a comprehensive literature review summarizing what is known to date regarding fetal exposure to MPA. Based on evidence from the literature, results of postmarketing surveillance, and information from registries such as the National Transplantation Pregnancy Registry in the United States, it is advised that pregnancy be avoided by women taking MPA. Preconception planning offers the opportunity to explore the alternatives to protect the mother, her transplanted organ, and minimize fetal risk. How to proceed in cases of unplanned pregnancies exposed to MPA in transplant recipients is a complex issue. Research involving large epidemiological studies is expected to be sparse as women heed the warnings about becoming pregnant on MPA. Published recommendations for managing MPA in women of childbearing potential include discontinuing the medication prior to conception, switching the MPA to another medication, or discontinuing the MPA when the pregnancy is discovered.

Improvement in gastrointestinal and health-related quality of life outcomes after conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in liver transplant recipients

OBJECTIVE

To evaluate improvement in gastrointestinal (GI) symptoms and health-related quality of life (HRQoL) in liver transplant recipients switched from mycophenolate mofetil (MMF) to enteric-coated mycophenolate sodium (EC-MPS).

METHODS

A multicenter, open-label, single-arm study was undertaken in maintenance liver transplant recipients who reported GI complications with MMF therapy. The patients were switched to equimolar doses of EC-MPS at baseline. The primary end point was the change in the Gastrointestinal Symptom Rating Scale (GSRS) total score after 6 to 8 weeks of treatment with EC-MPS. Other key assessments for GI symptoms and HRQoL included the GSRS subscores, the Gastrointestinal Quality of Life Index (GIQLI), the Psychological General Well-Being Index, and the Overall Treatment Effect (OTE). Paired t-test was used to assess the difference in the mean score changes over time.

RESULTS

A total of 34 patients were enrolled and switched to equimolar doses of EC-MPS. After 6 to 8 weeks of EC-MPS treatment, mean GSRS total score improved significantly from 2.88 ± 0.66 to 2.10 ± 0.78. Mean improvement in GSRS total score (-0.77 score points; P = .001) exceeded the minimal clinically important difference. Significant improvements were observed in all GSRS subscales (P < .05), GIQLI total scores (P = .001), and GIQLI subscales "GI symptoms" (P < .001) and "physical function" (0.013). Patients who continued EC-MPS reported sustained benefits compared with patients who switched back to MMF after 6 to 8 weeks of treatment with EC-MPS. On the OTE scale, improvement in symptoms was reported in 76.5% and 61.8% of the patients as perceived by the physicians and the patients. Improvement in HRQoL was reported by 41.2% of the patients. No deaths, biopsy proven acute rejections, or graft losses were reported during the study.

CONCLUSION

Conversion from MMF to EC-MPS was associated with a significant improvement in GI symptoms and HRQoL in liver transplant recipients.

Pharmacology and toxicology of mycophenolate in organ transplant recipients: an update

This review aims to provide an update of the literature on the pharmacology and toxicology of mycophenolate in solid organ transplant recipients. Mycophenolate is now the antimetabolite of choice in immunosuppressant regimens in transplant recipients. The active drug moiety mycophenolic acid (MPA) is available as an ester pro-drug and an enteric-coated sodium salt. MPA is a competitive, selective and reversible inhibitor of inosine-5'-monophosphate dehydrogenase (IMPDH), an important rate-limiting enzyme in purine synthesis. MPA suppresses T and B lymphocyte proliferation; it also decreases expression of glycoproteins and adhesion molecules responsible for recruiting monocytes and lymphocytes to sites of inflammation and graft rejection; and may destroy activated lymphocytes by induction of a necrotic signal. Improved long-term allograft survival has been demonstrated for MPA and may be due to inhibition of monocyte chemoattractant protein 1 or fibroblast proliferation. Recent research also suggested a differential effect of mycophenolate on the regulatory T cell/helper T cell balance which could potentially encourage immune tolerance. Lower exposure to calcineurin inhibitors (renal sparing) appears to be possible with concomitant use of MPA in renal transplant recipients without undue risk of rejection. MPA displays large between- and within-subject pharmacokinetic variability. At least three studies have now reported that MPA exhibits nonlinear pharmacokinetics, with bioavailability decreasing significantly with increasing doses, perhaps due to saturable absorption processes or saturable enterohepatic recirculation. The role of therapeutic drug monitoring (TDM) is still controversial and the ability of routine MPA TDM to improve long-term graft survival and patient outcomes is largely unknown. MPA monitoring may be more important in high-immunological recipients, those on calcineurin-inhibitor-sparing regimens and in whom unexpected rejection or infections have occurred. The majority of pharmacodynamic data on MPA has been obtained in patients receiving MMF therapy in the first year after kidney transplantation. Low MPA area under the concentration time from 0 to 12 h post-dose (AUC0-12) is associated with increased incidence of biopsy-proven acute rejection although AUC0-12 optimal cut-off values vary across study populations. IMPDH monitoring to identify individuals at increased risk of rejection shows some promise but is still in the experimental stage. A relationship between MPA exposure and adverse events was identified in some but not all studies. Genetic variants within genes involved in MPA metabolism (UGT1A9, UGT1A8, UGT2B7), cellular transportation (SLCOB1, SLCO1B3, ABCC2) and targets (IMPDH) have been reported to effect MPA pharmacokinetics and/or response in some studies; however, larger studies across different ethnic groups that take into account genetic linkage and drug interactions that can alter a patient's phenotype are needed before any clinical recommendations based on patient genotype can be formulated. There is little data on the pharmacology and toxicology of MPA in older and paediatric transplant recipients.

Evaluation of mycophenolic acid exposure using a limited sampling strategy in renal transplant recipients

BACKGROUND/AIMS

While there are drug exposure equation models based on limited sampling times for mycophenolate mofetil (MMF), there are few for enteric-coated mycophenolate sodium (EC-MPS), and none that studied Chinese individuals. Our objective is to generate the optimal model equations for estimation of the mycophenolic acid (MPA) area under the plasma concentration-time curve from 0 to 12 h (MPA-AUC(0-12h)) with a limited sampling strategy (LSS) for renal transplant recipients receiving EC-MPS.

METHODS

The pharmacokinetics in 31 Chinese renal allograft recipients treated with EC-MPS in combination with tacrolimus and steroids were determined. The model equations were generated by multiple stepwise regression analysis for estimation of the MPA-AUC.

RESULTS

A total of 31 patients with an average age and weight of 37.58 ± 10.9 years and 60.9 ± 10.7 kg, respectively, were included. Mean serum creatinine and glomerular filtration rate were 112.2 ± 17.7 μmol/l and 65.6 ± 14.6 ml/min, respectively. The mean values of AUC(0-12h), pre-dose MPA trough concentration (C0), maximum concentrations (C(max)), and time to reach C(max) (T(max)) were 61.17 ± 26.39 mg·h/l (range 22.9-123.0 mg·h/l), 4.98 ± 4.65 mg/l (range 0.13-20.04 mg/l), 17.54 ± 10.67 mg/l (range 4.08-42.36 mg/l), and 5.0 ± 2.6 h (range 1.0-10.5 h), respectively. The best predictive equation for estimation of MPA-AUC(0-12h) was -3.63 + 8.35 × C4 + 17.04 × C7 + 13.74 × C12 (r(2) = 0.7491), prediction bias (PE%) was 20.9 ± 20.37, and prediction precision (APE%) was 3.66 ± 29.20.

CONCLUSIONS

This model provides an effective approach for estimation of full MPA-AUC(0-12h) in Chinese adult renal allograft recipients treated with EC-MPS and tacrolimus.

Mycophenolic Acid pharmacokinetics early after kidney transplant

OBJECTIVES

To determine the mycophenolic acid pharmacokinetic profile early after transplant in Iranian kidney graft recipients.

MATERIALS AND METHODS

A cross-sectional study was performed during 6 months in 31 patients who recently had kidney transplant and received fixed doses of mycophenolate mofetil (2 g/d). The plasma levels of mycophenolic acid were determined by high performance liquid chromatography.

RESULTS

The mean first mycophenolic acid peak level was 10 ± 5 mg/L. The mean mycophenolic acid area under the curve was 26 ± 19 mgh/L and apparent clearance was 57 ± 55 L/h. The mycophenolic acid area under the curve values of only 8 patients (26%) were within the therapeutic range (30-60 mgh/L). The first, second, and third mycophenolic acid peak levels correlated significantly with mycophenolic acid area under the curve (P < .05). Mycophenolic acid concentration at 10 hours had the highest correlation with mycophenolic acid area under the curve (r=0.962; P < .05). No statistically significant differences were evident in the mean mycophenolic acid area under the curve between men and women.

CONCLUSIONS

There was a high degree of variation between different patients in mycophenolic acid pharmacokinetics early after kidney transplant.

Does reduction in mycophenolic acid dose compromise efficacy regardless of tacrolimus exposure level? An analysis of prospective data from the Mycophenolic Renal Transplant (MORE) Registry

Prospective data are lacking concerning the effect of reduced mycophenolic acid (MPA) dosing on efficacy and the influence of concomitant tacrolimus exposure. The Mycophenolic Renal Transplant (MORE) Registry is a prospective, observational study of de novo kidney transplant patients receiving MPA therapy under routine management. The effect of MPA dose reduction, interruption, or discontinuation (dose changes) was assessed in 870 tacrolimus-treated patients: 375 (43.1%) reduced tacrolimus (≤7 ng/mL at baseline) and 495 (56.9%) standard tacrolimus (>7 ng/mL); enteric-coated mycophenolate sodium 589 (67.7%) and mycophenolate mofetil 281 (32.3%). During baseline to month 1, months 1–3, months 3–6, and months 6–12, 9.3% (78/838), 16.6% (132/794), 20.7% (145/701), and 13.1% (70/535) patients, respectively, required MPA dose changes. These patients experienced an increased risk of biopsy-proven acute rejection at one yr with tacrolimus exposure either included in the model (hazard ratio [HR] 2.60, 95% CI 1.28–5.29, p = 0.008) or excluded (HR 2.58, 95% CI 1.28–5.23, p = 0.008). MPA dose changes were significantly associated with one yr graft failure when tacrolimus exposure was included (HR 2.23; 95% CI 1.01–4.89, p = 0.047) but not when tacrolimus exposure was excluded (HR 2.16; 95% CI 0.99–4.79; p = 0.054). These results suggest that reducing or discontinuing MPA can adversely affect graft outcomes regardless of tacrolimus trough levels.

Tolerance of enteric-coated mycophenolate sodium in combination with calcineurin inhibitor in kidney transplant recipients: Polish experience

INTRODUCTION

Enteric-coated mycophenolate sodium (EC-MPS) was developed to reduce the incidence of gastrointestinal adverse effects. This multicenter observational study was designed to evaluate the safety profile and drug tolerance in kidney transplant recipients.

METHODS

Three hundred adult kidney recipients (median age 48 years) were enrolled over 3 years to receive EC-MPS de novo (n=175), as a switch from azathioprine (n=62) or mycophenolate mofetil MMF (n=63); in combination with calcineurin inhibitor. Drug doses, serum creatinine, estimated glomerular filtration rate (eGFR), as well as drug tolerance, patient and physician evaluation of therapy (on a 4-point scale) were recorded at enrollment and followed over 28 weeks. We modeled the probability of the highest level (ie, best result) of the categorical outcome variable.

RESULTS

Two hundred seventy-three patients completed the study (91%). In the pooled study group (1) best drug tolerance was expected more frequently with tacrolimus versus cyclosporine (odds ratio [OR] 2.12, P<.05); (2) best physician evaluation, with earlier EC-MPS introduction (OR for 4-week delay: 0.99, P<.03) and higher eGFR (OR for 5 mL/min increase: 1.21, P<.01). Among the EC-MPS de novo administrations group: (1) best drug tolerance was expected more frequently with coadministered tacrolimus versus cyclosporine (OR 3.14, P<.02); (2) best patient evaluation, with higher eGFR (OR for 1 mL/min increase: 1.04, P<.04); and (3) best physician evaluation, with higher eGFR (OR for 1 mL/min increase: 1.04, P<.001) and earlier EC-MPS introduction (OR for 4-week delay: 0.99, P<.03). In the conversion from MMF to EC-MPS group: (1) best drug tolerance was expected less frequently with coadministered cyclosporine versus tacrolimus (OR 0.05, P<.04) and more frequently with younger recipients (OR .001, P<.04); (2) best physician evaluation was expected more frequently with lower EC-MPS dose (OR for 360-mg dose increase: 0.4, P<.01) and with higher eGFR (OR for 5 mL/min increase: 1.42, P<.002). Adverse events were reported among 49/300 patients (16 serious adverse events).

CONCLUSIONS

EC-MPS was tolerated better by younger kidney recipients, when combined with tacrolimus versus cyclosporine, and when introduced earlier after transplantation. EC-MPS tolerance decreased gradually with renal function deterioration.

Gastrointestinal quality of life improvement of renal transplant recipients converted from mycophenolate mofetil to enteric-coated mycophenolate sodium drugs or agents: mycophenolate mofetil and enteric-coated mycophenolate sodium

BACKGROUND

In renal transplant (RT) recipients, treatment with enteric-coated mycophenolate sodium (EC-MPS) improves gastrointestinal (GI) tolerability compared with mycophenolate mofetil (MMF). The impact of conversion from MMF to EC-MPS on patient's health-related quality of life (HRQoL) using GI-specific instruments has been scarcely evaluated in randomized trials.

METHODS

The present randomized, multicenter, open-labeled, 12-week study included RT recipients experiencing GI adverse events due to MMF treatment. Patients were randomized to continue with MMF (n=54) or change to EC-MPS (n=59). Patients were converted at equimolar doses, and dose was optimized between weeks 2 and 6 to achieve maximum tolerated dose.

RESULTS

Incidence of GI complications (particularly diarrhea) was significantly lower in the EC-MPS group (67.8% vs. 87.0%, P=0.015). The baseline-adjusted mean global scores at 12 weeks in GI quality of life index were significantly higher in the EC-MPS group versus MMF (P=0.014). Results at 12 weeks for all secondary scales indicated better HRQoL in the EC-MPS group compared with the MMF group (Gastrointestinal Symptom Rating Scale, Psychological General Well-Being Index, and overall treatment effect). In the EC-MPS group, a higher percentage of patients were receiving intermediate doses of mycophenolic acid (720 mg/day) at 12 weeks compared with MMF (55.4% vs. 27.4%, P=0.003), whereas no differences were observed for high doses (>720 mg/day).

CONCLUSIONS

In RT patients with GI undesirable effects due to MMF, switching from MMF to EC-MPS may enable an increase in the maximum tolerated dose of mycophenolic acid and reduce GI complications, thus enhancing patients' GI HRQoL.

Evalutation of mycophenolic acid systemic exposure by limited sampling strategy in kidney transplant recipients receiving enteric-coated mycophenolate sodium (EC-MPS) and cyclosporine

BACKGROUND

Enteric-coated mycophenolate sodium (EC-MPS) and mycophenolate mofetil (MMF) are prodrugs of mycophenolic acid (MPA). Although many patients still receive MMF as an inosine monophosphate dehydrogenase inhibitor, EC-MPS could be considered a reliable alternative to MMF in the immunosuppressive protocols of kidney transplant recipients. MPA shows high pharmacokinetic variability and consequently a 12-h area under the curve (AUC(0-12)) should be used to guide the therapeutic dosage. However, patient compliance and economic costs make MPA AUC(0-12) an unpractical approach. Limited sampling strategies or predictive systemic drug exposure equation models based on limited sampling times are available only for MMF but lack for EC-MPS.

METHODS

The present study enrolled 26 kidney transplant recipients receiving EC-MPS as part of their immunosuppressive therapy. Twenty-six full MPA AUC(0-12) were performed. By using multiple stepwise regression analysis, we obtained several predictive equations of MPA systemic exposure in this group of patients. The value of the selected equations was tested in a subsequently enrolled group of 26 kidney transplant recipients.

RESULTS

The best equations obtained in the first group of patients were the following: 22.906 + 3.880·C(0) + 1.117·C(1) + 7.527·C(8) (r = 0.901) and 35.064 +3.784·C(0) + 1.002·C(1) + 1.192·C(2) (r = 0.846). These equation models showed an optimal agreement between the full AUCs and estimated AUCs by using the validation group of patients.

CONCLUSIONS

Limited sampling strategies are useful for MPA AUC(0-12) estimation in patients receiving EC-MPS and cyclosporine. The choice of one or the other equation model depends on the pharmacokinetic characteristics of the patients, in particular the potential presence of enterohepatic recirculation.

Pharmacokinetic evaluation of mycophenolate mofetil for pemphigus

INTRODUCTION

Pemphigus is an autoimmune blistering disease of the skin and mucous membranes characterized by the development of autoantibodies against the desmosomal proteins, desmoglein-1 and -3. Before the advent of corticosteroids, therapy was almost fatal. The introduction of high-dose corticosteroid therapy has reduced mortality rates to ∼ 10%, but long-term use of steroids can lead to side effects, many of which are severe and associated with significant morbidity. Thus, the major goal of pemphigus therapy has been to reduce the patient's cumulative exposure to systemic corticosteroids. Over the last 2 decades, a range of corticosteroid-sparing immunosuppressive agents have been described, but these therapies are not without potentially serious complications. Despite the range of treatment options, a proportion of patients do not achieve remission, while others show an initial treatment response but remain poorly controlled. The recent availability of mycophenolate mofetil (MMF), originally developed for preventing allograft rejection, appears to be effective in autoimmune blistering diseases in combination with systemic corticosteroid or as a monotherapy.

AREAS COVERED

This review aims to provide an extensive overview of the literature on the clinical pharmacokinetics of MMF in pemphigus treatment and a brief summary of current pharmacodynamic information. After completing this learning activity, readers should be able to summarize the pharmacology of MMF as an immunosuppressant; recognize its potential role in the treatment of pemphigus, including general dosing guidelines and laboratory monitoring schedules, use in patient populations and potential adverse effects; and identify future considerations and developing areas of research regarding the use of mycophenolic acid in the treatment of autoimmune blistering diseases.

EXPERT OPINION

Current morbidity of pemphigus is largely iatrogenic, caused by side effects of the long-term, high-dose corticosteroid therapy that is necessary to sustain disease control. MMF demonstrates complex pharmacokinetics and displays large between-subject pharmacokinetic variability. Experience with MMF has demonstrated long-term safety and tolerability in the treatment of pemphigus.