Review of Major Clinical Trials with Mycophenolate Mofetil in Cardiac Transplantation

Sixteen Years of Heart Transplant in an Open Cohort in Brazil: Analysis of Graft Survival of Patients using Immunosuppressants

BACKGROUND

Heart transplant is the main therapeutic alternative for advanced heart failure patients. Several risk factors affect these patients' survival; however, few studies about the topic are available in Brazil.

OBJECTIVES

To review the survival rates of heart transplant patients in the Brazilian Public Health System (Sistema Único de Saúde - SUS) between 2000 and 2015.

METHODS

This is a non-concurrent, open cohort study, involving cardiac transplant patients in Brazil. The cumulative survival probability was estimated by the Kaplan-Meier curve, and the curve comparison was done using the Log-Rank test. The Cox model was used to calculate the Hazard-Ratio (HR). Analyses were conducted at the 95% confidence level.

RESULTS

The heart transplant survival rate median in Brazil, during the period, was 8.3 years. Each additional year in the recipient's age, the occurrence of infections, and the performance of the surgical procedure in the South Region were associated with a higher risk of graft loss. A higher use ratio of immunosuppressants mycophenolate and azathioprine acted as a protection factor.

CONCLUSIONS

The analyses conducted provide the first information about the median survival time in heart transplant patients in Brazil. The difference noticed among the geographical regions may be related to the different treatment protocols adopted in the country, especially in the early 2000s. The rate of mycophenolate and azathioprine use as a protection factor suggests that, despite the absence of differences among therapeutic strategies, use of these drugs may favor survival of certain patients. The study provides robust epidemiological data, which are relevant for public health.

Vancomycin relieves mycophenolate mofetil-induced gastrointestinal toxicity by eliminating gut bacterial β-glucuronidase activity

Mycophenolate mofetil (MMF) is commonly prescribed and has proven advantages over other immunosuppressive drugs. However, frequent gastrointestinal side effects through an unknown mechanism limit its use. We have found that consumption of MMF alters the composition of the gut microbiota, selecting for bacteria expressing the enzyme β-glucuronidase (GUS) and leading to an up-regulation of GUS activity in the gut of mice and symptomatic humans. In the mouse, vancomycin eliminated GUS-expressing bacteria and prevented MMF-induced weight loss and colonic inflammation. Our work provides a mechanism for the toxicity associated with MMF and a future direction for the development of therapeutics.

Pharmacokinetic Drug-Drug Interactions Between Immunosuppressant and Anti-Infective Agents: Antimetabolites and Corticosteroids

Infections account for 15–20% of deaths in transplant recipients, requiring rapid and appropriate therapeutic interventions. Many anti-infective agents interact with immunosuppressive regimens used in transplantation, placing patients at increased risk for adverse drug reactions and prolonged hospitalizations. There is established data regarding the level of evidence and magnitude of interactions between calcineurin inhibitors and mammalian target of rapamycin inhibitors with anti-infective agents. Less is known about the interactions with anti-proliferative agents and corticosteroids, with gaps in knowledge on the appropriate management of these interactions. The objective of this review was to highlight the pharmacokinetic drug–drug interactions between antimetabolites and corticosteroids with commonly used anti-infective agents.

Genes and beans: pharmacogenomics of renal transplant

Advances in the management of patients after solid organ transplantation have led to dramatic decreases in rates of acute rejection, but long-term graft and patient survival have remained unchanged. Individualized therapy after transplant will ideally provide adequate immunosuppression while limiting the adverse effects of drug therapy that significantly impact graft survival. Therapeutic drug monitoring represents the best approximation of individualized drug therapy in transplant at this time; however, obtaining pharmacogenomic data in transplant patients has the potential to enhance our current practice. Polymorphisms of target genes that impact pharmacokinetics have been identified for most immunosuppressants, including tacrolimus, cyclosporine, mycophenolate, azathioprine and sirolimus. In the future, pre-emptive assessment of a patient's genetic profile may inform drug selection and provide information on specific doses that will improve efficacy and limit toxicity.

Improved survival in heart transplant recipients in the United States: racial differences in era effect

BACKGROUND

Posttransplant survival in heart transplant recipients has progressively improved during the past 2 decades. It is unknown, however, whether the major racial groups in the United States have benefited equally.

METHODS AND RESULTS

We analyzed all primary heart transplant recipients aged ≥18 years in the United States from 1987 to 2008. We compared posttransplant survival in white, black, and Hispanic recipients in 5 successive eras (1987 to 1992, 1993 to 1996, 1997 to 2000, 2001 to 2004, 2005 to 2008). Early survival was defined as freedom from death or retransplantation during the first 6 months posttransplant. Longer-term, conditional survival was assessed in patients who survived the first 6 months. There were 29 986 (81.6%) white, 4745 (12.9%) black, and 2017 (5.5%) Hispanic patients in the study cohort. Black patients were at increased risk of early death or retransplant (hazard ratio [HR], 1.15; 95% CI, 1.05 to 1.26) in adjusted analysis. Early posttransplant survival improved (HR, 0.83; 95% CI, 0.80 to 0.87 for successive eras) equally in all 3 groups (black-era interaction, P=0.94; Hispanic-era interaction, P=0.40). Longer-term survival improved in white (HR, 0.95; 95% CI, 0.92 to 0.97 for successive eras) but not in black (HR, 1.04; 95% CI, 0.99 to 1.09) or Hispanic (HR, 1.02; 95% CI, 0.95 to 1.09) recipients, resulting in increased disparities in longer-term survival with time.

CONCLUSIONS

Early posttransplant survival has improved equally in white, black, and Hispanic heart transplant recipients. Longer-term survival has improved in white but not in black or Hispanic recipients, resulting in a more marked disparity in outcomes in the current era. These disparities warrant further investigation and targeted interventions.

Improved survival in pediatric heart transplant recipients: have white, black and Hispanic children benefited equally?

We assessed whether the improvement in posttransplant survival in pediatric heart transplant (HT) recipients during the last two decades has benefited the major racial groups in the United States equally. We analyzed all children <18 years of age who underwent their first HT in the US during 1987-2008. We compared trends in graft loss (death or retransplant) in white, black and Hispanic children in five successive cohorts (1987-1992, 1993-1996, 1997-2000, 2001-2004, 2005-2008). The primary endpoint was early graft loss within 6 months posttransplant. Longer-term survival was assessed in recipients who survived the first 6 months. The improvement in early posttransplant survival was similar (hazard ratio [HR] for successive eras 0.80, 95% confidence interval [CI] 0.7, 0.9, p = 0.24 for black-era interaction, p = 0.22 for Hispanic-era interaction) in adjusted analysis. Longer-term survival was worse in black children (HR 2.2, CI 1.9, 2.5) and did not improve in any group with time (HR 1.0 for successive eras, CI 0.9, 1.1, p = 0.57; p = 0.19 for black-era interaction, p = 0.21 for Hispanic-era interaction). Thus, the improvement in early post-HT survival during the last two decades has benefited white, black and Hispanic children equally. Disparities in longer-term survival have not narrowed with time; the survival remains worse in black recipients.

Strategies to prevent cellular rejection in pediatric heart transplant recipients

Despite more than 40 years' experience in pediatric heart transplantation, cellular rejection remains a significant cause of morbidity and mortality. In this review, strategies and agents to prevent acute cellular rejection are discussed. Strategies to prevent rejection are divided into two phases - induction and maintenance therapies. Currently, the most commonly used induction agents are polyclonal antibodies (rabbit or equine antithymocyte globulin) and interleukin-2 receptor antibodies (daclizumab or basiliximab). Induction therapies have reduced early rejection, are renal sparing, and can reduce corticosteroid exposure, but have not yet been shown to have a longer term survival benefit. Multiple maintenance immunosuppressants are available. Nearly all regimens include a calcineurin inhibitor (either ciclosporin [cyclosporine] or tacrolimus). Most combinations in pediatric heart transplantation include an antiproliferative agent (azathioprine, mycophenolate mofetil or, less commonly, sirolimus). Everolimus has seen increasing use in adult heart transplant patients in Europe but, to date, its use is rare in pediatric heart transplantation. The use of corticosteroids as a third agent is still common, but strategies to avoid or minimize their use are increasing. The 'best' combination of therapies varies between studies. By gaining a better understanding of individuals' genetic and environmental risk factors, we may in the future be able to better predict the course of cardiac allografts and enhance our ability to tailor immunosuppression to individual patient variables with the ultimate goal of inducing a state of immune tolerance.

Immunosuppression armamentarium in 2010: mechanistic and clinical considerations

Effective immunosuppression is the key to successful organ transplantation, with success being defined as minimal rejection risk with concomitant minimal drug toxicities. Despite the general recognition of this fact, a paucity of appropriate clinical trials in children has contributed to lack of standardization of clinical management regimens, resulting in an extensive diversity of favored approaches. Nonetheless, although consensus has not been reached on the ideal approach to immunosuppression in pediatric transplantation, new drug therapies have contributed to a continuing improvement in graft and patient survival. Future clinical research must focus on diminishing the extensive burden of toxicities of these therapeutic agents in children.

Genetic polymorphisms influence mycophenolate mofetil-related adverse events in pediatric heart transplant patients

BACKGROUND

Mycophenolate mofetil (MMF) is an effective and commonly used immunosuppressant but has frequent adverse events. Genetic polymorphisms may contribute to variability in MMF efficacy and related complications. In this study we explore the distribution frequencies of common single nucleotide polymorphisms (SNPs) of IMPDH1, IMPDH2 and ABCC2 and investigate whether these SNPs influence MMF adverse events in 59 pediatric heart recipients.

METHODS

Genotypes were assessed by TaqMan analysis of: ABCC2 rs717620; IMPDH2 rs11706052; and IMPDH1 rs2288553, rs2288549, rs2278293, rs2278294 and rs2228075. Gastrointestinal (GI) intolerance was defined as diarrhea, vomiting, nausea or abdominal pain requiring dose-holding for >48 hours or MMF discontinuation. Bone marrow toxicity was evaluated using Common Terminology Criteria for Adverse Events Version 3 (CTCAE).

RESULTS

GI intolerance occurred in 21 patients, and 21 had bone marrow toxicity. The ABCC2 rs717620 A variant was significantly associated with GI intolerance leading to drug discontinuation (p < 0.001); the IMPDH1 rs2278294 A variant and rs2228075 A variant were also associated with greater GI intolerance (p = 0.029 and p = 0.002, respectively). The IMPDH2 rs11706052 G variant was associated with more frequent neutropenia requiring dose-holding (p = 0.046).

CONCLUSIONS

In this small sample of pediatric heart transplant patients receiving MMF, ABCC2, IMPDH1 and IMPDH2 SNPs were associated with MMF GI intolerance and bone marrow toxicity. Thus, genetic polymorphisms may directly influence MMF adverse events.

Proton pump inhibitors reduce mycophenolate exposure in heart transplant recipients-a prospective case-controlled study

This prospective study investigates the impact of proton pump inhibitors (PPI) on mycophenolic acid (MPA) pharmacokinetics in heart transplant recipients receiving mycophenolate mofetil (MMF) and tacrolimus. MPA plasma concentrations at baseline (C(0 h)), 30 min (C(0.5 h)), 1(C(1 h)) and 2 h (C(2 h)) were obtained by high-performance liquid chromatography (HPLC) in 22 patients treated with pantoprazole 40 mg and MMF 2000 mg. Measurements were repeated 1 month after pantoprazole withdrawal. A four-point limited-sampling strategy was applied to calculate the MPA area under the curve (MPA-AUC). Predose MPA concentrations with PPI were 2.6 +/- 1.6 mg/L versus 3.4 +/- 2.7 mg/L without PPI (p = ns). Postdose MPA concentrations were lower with PPI at C(0.5 h) (8.3 +/- 5.7 mg/L vs. 18.3 +/- 11.3 mg/L, p = 0.001) and C(1 h) (10.0 +/- 5.6 mg/L vs. 15.8 +/- 8.4 mg/L, p = 0.004), without significant differences at C(2 h) (8.3 +/- 6.5 mg/L vs. 7.6 +/- 3.9 mg/L). The MPA-AUC was significantly lower with PPI medication (51.2 +/- 26.6 mg x h/L vs. 68.7 +/- 30.3 mg x h/L; p = 0.003). The maximum concentration of MPA (MPA-C(max)) was lower (12.2 +/- 7.5 mg/L vs. 20.6 +/- 9.3 mg/L; p = 0.001) and the time to reach MPA-C(max) (t(max)) was longer with PPI (60.0 +/- 27.8 min vs. 46.4 +/- 22.2 min; p = 0.05). This is the first study to document an important drug interaction between a widely used immunosuppressive agent and a class of drugs frequently used in transplant patients. This interaction results in a decreased MMF drug exposure which may lead to patients having a higher risk for acute rejection and transplant vasculopathy.

A limited sampling strategy for estimating mycophenolic acid area under the curve in adult heart transplant patients treated with concomitant cyclosporine

OBJECTIVE

Heart transplantation studies have shown a relationship between the mycophenolic acid area under the curve (AUC) 0-12 h (MPA AUC(0-12h)) values and risk of acute rejection episodes and fewer side-effects in patient receiving cyclosporine during the first year post-transplant. However, measurement of full AUC is costly and time consuming and in this case it is an impractical approach to drug monitoring. Therefore, the authors describe a limited sampling strategy to estimate the MPA AUC(0-12h) value in adult heart transplant recipients.

METHODS

Ninety MPA pharmacokinetic (PK) profiles were studied. The samples were collected immediately before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 9, 12 h after the morning dose of mycophenolate mofetil (MMF) following an overnight fast. PK profiles were determined at 6-8 weeks, 6, 12 months and more than 1 year after transplantation. Using stepwise multiple linear regression analysis a sampling strategy from 60 of PK profiles was obtained and next the bias and precision of the model were evaluated in another 30 PK profiles.

RESULTS

The three-point model using C(0.5h), C(1h), C(2h) was found to be superior to all other models tested (r(2) = 0.841). The regression equation for AUC estimation which gave the best fit to this model is: 9.69 + 0.63C(0.5) + 0.61C(1) + 2.20C(2). Using that model 63 of the 90 (70%) full AUC values were estimated within 15% of their actual value. For the best-fit model, the mean prediction error was 3.2%, with 95% confidence intervals for prediction error to range from -42.2% to 40.3%. All other models which use one, two or three time-points over the first 2 h are poorer predictors of the full AUC than the model above.

CONCLUSION

The proposed three time-point equation to estimate AUC will be helpful in optimizing immunosuppressive therapy in heart transplantation.

Effect of mycophenolate mofetil on pulmonary function in scleroderma-associated interstitial lung disease

OBJECTIVE

We sought to determine the effectiveness of mycophenolate mofetil (MMF) in scleroderma- associated interstitial lung disease (SSc-ILD).

METHODS

We retrospectively identified patients who met criteria for systemic sclerosis, had evidence of SSc-ILD on chest CT, received > 1 g/d of MMF for >or= 6 months, and had pulmonary function data available. Vital capacity (VC) and diffusion capacity of the lung for carbon monoxide (Dlco) at treatment onset were compared with VC and Dlco values 12 months before and 12 months after treatment onset. Twelve-month values were imputed from regression lines generated using all VC and Dlco measurements made in the 24-month period either prior to or following treatment onset.

RESULTS

Among 13 patients who met inclusion criteria, MMF was associated with a significant improvement in VC (mean, + 159 mL; confidence interval [CI], + 30 to + 289 mL; and + 4% of the predicted normal value; CI, + 2 to + 7%) after 12 months of treatment. In contrast, patients had a significant decrease in VC (mean, - 239 mL; CI, - 477 to - 0.5 mL; and - 5% of the predicted normal value; CI, - 11 to - 0.3%) in the 12 months prior to MMF treatment. Dlco did not change significantly during MMF treatment (mean, + 1% of the predicted normal value; CI, - 2 to + 5%) but decreased significantly in the 12 months prior to treatment (mean, - 5% of the predicted normal value; CI, - 10 to - 1%).

CONCLUSION

These retrospective data suggest MMF improves VC in patients with SSc-ILD.

Conversion to sirolimus as primary immunosuppression attenuates the progression of allograft vasculopathy after cardiac transplantation

BACKGROUND

We investigated the potential of conversion to sirolimus (SRL) as a primary immunosuppressant in attenuating cardiac allograft vasculopathy progression.

METHODS AND RESULTS

Twenty-nine cardiac transplant recipients were converted to SRL 3.8+/-3.4 years after transplantation with complete calcineurin inhibitor (CNI) withdrawal. Secondary immunosuppressants (azathioprine or mycophenolate) and steroids remained unchanged. Forty patients (controls) 4.8+/-4.0 years from transplantation were maintained on CNIs. Three-dimensional intravascular ultrasound studies were performed at baseline and 12.1+/-2.6 months later. Mean plaque (media and intima) volume (PV) and plaque index (PI) (PV/vessel volume percent) increased significantly in the CNI group (1.28+/-2.86 mm(3)/mm, P=0.004; and 6+/-8%, P=0.0001) but not in the SRL group (0.1+/-1.13 mm(3)/mm, P=0.63; and 0.1+/-8%, P=0.94). In patients enrolled within 2 years after transplantation, the increases in PV (0.06+/-1.06 versus 1.77+/-1.65 mm(3)/mm; P=0.0081) and PI (0+/-9% versus 10+/-8%; P=0.0145) were smaller in the SRL group (n=11) than in the CNI (n=12) group. In patients enrolled >/=2 years after transplantation, the increase in PI was less in the SRL group compared with the CNI group (0.1+/-6.5% versus 5+/-8%; P=0.033), but changes in PV did not differ significantly. Treatment with azathioprine or mycophenolate did not affect PV or PI in either the SRL group (PV: 0.22+/-0.66 versus 0.05+/-1.45 mm(3)/mm, P=0.46; PI: 1.5+/-6% versus -1.6+/-8.5%, P=0.29) or the CNI group (PV: 1.42+/-1.39 versus 1.06+/-2.28 mm(3)/mm, P=0.49; PI: 7.8+/-8.7% versus 4.8+/-7.3%, P=0.23).

CONCLUSIONS

Substituting CNI with SRL as primary immunosuppression attenuates cardiac allograft vasculopathy progression.

Lack of an Effect of Oral Iron Administration on Mycophenolic Acid Pharmacokinetics in Stable Renal Transplant Recipients

STUDY OBJECTIVES

To determine if coadministration of polysaccharide iron complex and slow-release ferrous sulfate alter the absorption of mycophenolic acid (MPA), and to examine the potential influence of dosing relative to mycophenolate mofetil (MMF) administration and the effect of immediate- versus sustained-release iron products on the steady-state pharmacokinetics of MPA.

DESIGN

Prospective, open-label, three-phase, crossover, steady-state pharmacokinetic study.

SETTING

National Institutes of Health-sponsored General Clinical Research Center at a university medical center.

PATIENTS

Twelve adult (mean age 50 yrs) renal transplant recipients who were receiving concomitant iron and MMF maintenance therapy.

INTERVENTION

Oral iron therapy was coadministered with MMF on days -6-0, MMF was administered alone on days 1-8 (control phase), then oral iron therapy was administered 2 hours after MMF administration on days 9-16.

MEASUREMENTS AND MAIN RESULTS

Baseline demographics, concurrent drug regimens, and clinical laboratory values were assessed. Blood samples were obtained at baseline and at 1, 2, 3, 4, 6, 8, and 12 hours after MMF administration on days 0, 8, and 16. The MPA levels were measured by high-performance liquid chromatography. We found no significant differences in the dose-standardized area under the concentration-time curve from 0-12 hours (AUC(0-12)) for MPA between the control phase (39.66 +/- 8.70 mg mg x hr/L) and the concomitant ferrous sulfate or dose-separated ferrous sulfate (37.56 +/- 9.95 or 32.84 +/- 8.43 mg x hr/L, respectively, p>0.05) phases. Dose-standardized AUC(0-12) values for MPA did not significantly differ after the concomitant administration of polysaccharide iron complex from that of the control phase (48.46 +/- 9.68 and 43.80 +/- 9.46 mg x hr/L, respectively, p=0.065). However, the AUC(0-12) for MPA significantly increased when polysaccharide iron complex was administered 2 hours after MMF (53.41 +/- 11.75 mg x hr/L, p=0.012). Maximum concentrations and times to reach maximum concentrations remained consistent across all study phases in each arm of the trial (p>0.05).

CONCLUSION

Multiple doses of iron therapy-slow-release ferrous sulfate, or polysaccharide iron complex-did not significantly reduce systemic exposure to MMF, as measured by using AUC(0-12) values.

Drug-induced immunomodulation to affect the development and progression of atherosclerosis: a new opportunity?

Inflammation and cytokine pathways are crucial for the development and progression of atherosclerotic lesions. In this review, the hypothesis that immunomodulatory drugs provide a possible therapeutic modality for cardiovascular disease is evaluated. Therefore, after a short overview of the specific inflammatory pathways involved in atherosclerosis, literature on the effect of several immunomodulatory drugs, such as nonsteroidal anti-inflammatory drugs, specific cyclooxygenase inhibitors and immunosuppressive drugs, used currently in the prevention of rejection after organ transplant, on the development and progression of atherosclerosis is reviewed. In addition, the pleiotropic immunomodulatory effect of two established cardiovascular drugs (angiotensin-converting enzyme inhibitors and statins) is discussed.

Pharmacokinetics and variability of mycophenolic acid from enteric-coated mycophenolate sodium compared with mycophenolate mofetil in de novo heart transplant recipients

Sequential pharmacokinetic assessments were performed at five centers within the context of a multicenter, single-blind, randomized clinical trial comparing the efficacy and safety of enteric-coated mycophenolate sodium (EC-MPS, myfortic) and mycophenolate mofetil (MMF, CellCept) in de novo heart transplant recipients. Patients were randomized to either EC-MPS 1080 mg bid or MMF 1500 mg bid, as part of a triple immunosuppressive therapy including cyclosporine microemulsion. Steady-state pharmacokinetic profiles of mycophenolic acid (MPA) and its inactive phenolic glucuronide (MPAG) were assessed at weeks 2, 12, and 52. Pharmacokinetic parameters were evaluated in 32 patients (17 on EC-MPS and 15 on MMF). Dose-normalized peak (C(max,ss)) and area under the curve (AUC(tau,ss)) of MPA and MPAG increased between week 2 and week 12 assessments for both treatments. Comparisons between EC-MPS and MMF showed no statistically significant differences in MPA and MPAG AUC(tau,ss), C(max,ss), and trough (C(min,ss)) values (p-values ranged from 0.225 to 0.990). Consistent with the delayed release characteristics of EC-MPS, C(max,ss) occurred approximately one hour later compared with MMF. Inter-subject coefficients of variation (%CV) for MPA pharmacokinetic parameters of both EC-MPS and MMF were high (37-72% for AUC(tau,ss) at weeks 2 and 12). Also within patients, the pharmacokinetics of MPA varied considerably. Specifically, intra-subject %CVs for MPA AUC(tau,ss), C(max,ss), and C(min,ss) were 28%, 63%, and 34% with EC-MPS and 54%, 139%, and 41% with MMF respectively. These results indicate that a dose of EC-MPS 1080 mg bid in combination with cyclosporine provides adequate systemic MPA exposure in de novo heart transplant patients, comparable with MMF 1500 mg bid. Overall, there is a large inter- and intra-subject variability in MPA pharmacokinetic parameters with both treatments.

Mycophenolate mofetil in the treatment of non‐renal manifestations of systemic lupus erythematosus: a review

Mycophenolate mofetil (MMF) is efficacious in the management of transplantations and lupus nephritis. It is also useful in the treatment of autoimmune conditions as its mechanisms of action target the T‐ and B‐lymphocytes, leading to suppression of the cell‐mediated immune responses and antibody formation. It has been used successfully in immune‐mediated conditions like myasthenia gravis, autoimmune hepatitis and immune cytopenias. However, its optimal use in non‐renal manifestations (haematological, neuropsychiatric, myocardial, pulmonary, curaneous) in lupus patients are unclear and predominantly based on anecdotal reports. There are yet to be randomised controlled trials to guide the optimal doses and durations of MMF in such situations. MMF is relatively well tolerated and safe to use, though there are reports of serious adverse effects like urticaria, myopathy, Epstein‐Barr virus‐associated B‐cell lymphoma, cytomegalovirus infections and disseminated varicella zoster. Another area of concern for patients is the increased cost of using long‐term MMF. A practical approach for rheumatologists would be to use a dosing regimen guided by data from lupus nephritis trials and using MMF mainly in those lupus patients with non‐renal manifestations failing conventional therapy.

Therapeutic Drug Monitoring of Mycophenolic Acid in Solid Organ Transplant Patients Treated With Mycophenolate Mofetil: Review of the Literature

Mycophenolate mofetil (MMF) has conventionally been administered at a fixed dose without routinely monitoring blood levels of mycophenolic acid (MPA), the active metabolite. The contribution of therapeutic drug monitoring (TDM) during MMF therapy remains controversial. A literature review was performed to explore the usefulness of TDM for MPA in solid organ transplantation. In addition, emphasis was placed on the potential clinical benefits and limitations of TDM for MPA. Available studies have limitations and report conflicting results. Although early after transplantation MPA area under the curve might have predictive value for the risk of acute rejection, predose levels appear less reliable. With regard to MPA toxicity, most studies showed no correlation between MPA pharmacokinetics and adverse effects. TDM is hampered by several factors such as the considerable intra-subject variability of MPA pharmacokinetics and the increasing number of different drug combinations. Proposed target ranges are restricted to the early posttransplant period when MMF is used in combination with cyclosporine. The current review of the literature indicates no clear support for a substantial clinical benefit of TDM and more data from prospective randomized trials are needed.

Acute rejection after heart transplantation

Acute rejection (AR) seems to be less common with current immunosuppressive strategies; however, it remains a major cause of morbidity and mortality in the first year following heart transplantation. Despite great interest in noninvasive methods for detecting rejection, the endomyocardial biopsy remains the standard method for AR identification and, recently, the cardiac biopsy grading system has been reviewed. Moreover, the availability of several immunosuppressive drug combinations has generated confusion in the minds of clinicians. This review will focus on recently published studies that are related to the clinical impact of AR, combination regimens of chronic maintenance immunosuppression and specific therapeutic options for treating AR.