Immunosuppression: evolution in practice and trends, 1994-2004

Primary care of the renal transplant patient

There has been a remarkable rise in the number of kidney transplant recipients (KTR) in the US over the last decade. Increasing use of potent immunosuppressants, which are also potentially diabetogenic and atherogenic, can result in worsening of pre-existing medical conditions as well as development of post-transplant disease. This, coupled with improving long-term survival, is putting tremendous pressure on transplant centers that were not designed to deliver primary care to KTR. Thus, increasing numbers of KTR will present to their primary care physicians (PCP) post-transplant for routine medical care. Similar to native chronic kidney disease patients, KTRs are vulnerable to cardiovascular disease as well as a host of other problems including bone disease, infections and malignancies. Deaths related to complications of cardiovascular disease and malignancies account for 60-65% of long-term mortality among KTRs. Guidelines from the National Kidney Foundation and the European Best Practice Guidelines Expert Group on the management of hypertension, dyslipidemia, smoking, diabetes and bone disease should be incorporated into the long-term care plan of the KTR to improve outcomes. A number of transplant centers do not supply PCPs with protocols and guidelines, making the task of the PCP more difficult. Despite this, PCPs are expected to continue to provide general preventive medicine, vaccinations and management of chronic medical problems. In this narrative review, we examine the common medical problems seen in KTR from the PCP's perspective. Medical management issues related to immunosuppressive medications are also briefly discussed.

Randomized crossover study to assess the inter- and intrasubject variability of morning mycophenolic acid concentrations from enteric-coated mycophenolate sodium and mycophenolate mofetil in stable renal transplant recipients

The delayed release of mycophenolic acid (MPA) from enteric-coated mycophenolate sodium (EC-MPS, myfortic®) may have an impact on the variability of MPA trough (C0 h) levels. A randomized, two-period crossover study was performed in 24 maintenance renal transplants to evaluate the inter- and intrasubject variability of MPA predose levels from EC-MPS and mycophenolate mofetil (MMF, CellCept®), both in combination with cyclosporine. Patients received EC-MPS (720 mg b.i.d.) and MMF (1000 mg b.i.d.) for a period of 21 d each. MPA plasma levels were measured over the final seven consecutive days at -1, 0, 1, 2, and 3 h after the morning MPA dose. Intersubject coefficients of variation (%CV) for MPA troughs were 47.5% (95% CI, 34.1-80.3) and 54.4% (40.0-86.8) for EC-MPS and MMF, respectively; intrasubject %CVs were 62.7% (55.1-72.9) and 42.8% (37.9-49.2). High MPA C0 h levels>10 μg/mL were rarely observed with both EC-MPS (1.8%) and MMF (0.6%). Mean MPA area under the curve (AUC)0-3 h was comparable between treatments, while MPA C0 h was on average 46% higher with EC-MPS. In conclusion, predose MPA trough level monitoring appears of limited value during EC-MPS and MMF therapy given the large intrasubject variability in MPA C0 h levels with both treatments.

Dosing tacrolimus based on CYP3A5 genotype: will it improve clinical outcome?

Tacrolimus, widely used to prevent acute rejection following solid-organ transplantation, has become the cornerstone of immunosuppressive therapy after kidney transplantation. More than 70% of all renal transplant recipients receive this remarkably effective agent.(1) But tacrolimus is also highly toxic, and there is great between-patient variability in its pharmacokinetics. This, combined with a low therapeutic index, mandates routine therapeutic drug monitoring in clinical practice.(2) Typically, predose concentrations are monitored and the dose is adjusted to aim for target values that depend on immunological risk, comedication, and time since transplantation.(2).

Heterogeneity of induction therapy in Spain: changing patterns according to year, centre, indications and results

Background. The use of induction drugs has increased markedly over the last 15 years in the USA, but there are few data about their use in other countries. Moreover, there are not enough data about when they are indicated and their long-term effects. The aim of our study was to know the rates of use and the drugs used as induction therapy, in which patients they were prescribed and the long-term graft survival effect in Spain.

Methods. We conducted a retrospective cohort study with adult patients (4861) receiving a kidney allograft in Spain over four different years (1990, 1994, 1998 and 2002) with a functioning graft at the end of the first post-transplant year. Induction therapy was defined as when the patient received polyclonal antibodies, OKT3 monoclonal antibodies or anti-CD25 monoclonal antibodies.

Results. From 1990 to 2002, the use of induction therapy in Spain changed, with a progressive reduction in the use of OKT3 and an increasing use of anti-CD25 antibodies. There were great differences in the rate of induction use from one centre to another, although with a common trend to greater use at each centre. Induction therapy was mainly prescribed in patients with a higher rejection risk (higher panel reactive antibody (PRA) titres and mismatches and re-transplants) and in older and diabetic recipients. Lastly, patients who were treated with induction therapy had significant higher allograft survival than those who did not (P value = 0.035).

Conclusions. The use of induction therapy in Spain has changed, with an increasing use of monoclonal antibodies in recent years. Induction therapy has a protective role in long-term graft survival.

Treatment of polyomavirus infection in kidney transplant recipients: a systematic review

BACKGROUND.: Polyomavirus-associated nephropathy (PVAN) is an important cause of kidney graft loss but there is no consensus on its management. This study aimed to systematically document all published treatments for PVAN to determine the most effective therapy. METHODS.: A computerized search in MEDLINE, EMBASE, and Cochrane databases (1950-2008) was performed. References from review articles and published abstracts from the American Transplant Congress (2005-2008) were also included. Study selection criteria included (a) population: adult (>18 years) kidney-only, primary or repeat renal transplant recipients; (b) setting: polyoma viruria, viremia or biopsy-proven PVAN or both; and (c) treatment: immunosuppression reduction alone or with adjuvant agents. The primary outcome was graft failure rate, and secondary outcomes included acute rejection rate, elimination of viruria and viremia, graft function, patient survival, and adverse events. RESULTS.: Of 555 identified citations, 40 studies examining the effect of immunosuppression reduction alone or in combination with cidofovir, leflunomide, intravenous immunoglobulin, or ciprofloxacin were included for appraisal. Pooled results found a death-censored graft loss rate of 8/100 patient-years for immunosuppression reduction alone and 8 and 13/100 patient-years for the addition of cidofovir or leflunomide, respectively. CONCLUSIONS.: There does not seem to be a graft survival benefit of adding cidofovir or leflunomide to immunosuppression reduction for the management of PVAN. However, the evidence base is poor and highlights the urgent need for adequately powered randomized trials to define the optimal treatment of this important condition.

A receptor-independent, cell-based JAK activation assay for screening for JAK3-specific inhibitors

New immunosuppressive compounds with less systemic toxicity that could replace calcineurin inhibitors are urgently needed. For identification of specific inhibitors of JAK3, a potential new drug target, from large chemical libraries we developed a cell-based screening system. TEL-JAK fusion proteins composed of an oligomerization domain of TEL and kinase and/or pseudokinase domains of JAKs provided constitutive activation of JAKs without receiving a signal from the cytokine receptors. These fusion proteins also induced STAT5b phosphorylation in the absence of cytokine receptors. Both the kinase and pseudokinase domains of JAKs were required for full activation of the JAKs, and four copies of STAT5 response elements provided the greatest luciferase activity. The sensitivity and specificity of the system was evaluated using specific JAK3, JAK2, or MEK inhibitors. Thus, we generated a receptor-independent, cell-based selective screening system for specific JAK3 inhibitors, which is easily convertible to a high-throughput screening platform.

Sirolimus-based calcineurin inhibitor withdrawal immunosuppressive regimen in kidney transplantation: a single center experience

BACKGROUND/AIM

This observational study was conducted to evaluate the safety and efficacy of the conversion from calcineurin inhibitors (CNIs) to sirolimus (SRL)-based immunosuppressive therapy in kidney transplantation.

MATERIALS AND METHODS

Sixty-four kidney recipients of mean age 38.3 +/- 14.6 years were converted to SRL. The main reasons for conversion were elective in 45 (70.3%) and biopsy-proven chronic allograft nephropathy in 11 (17.2%). The primary CNI used was cyclosporine A in 51 patients. Mean time to conversion was 50.5 months. After conversion, 61 patients received mycophenolate mofetil. We evaluated the impact of conversion on renal function for 5 years post-conversion. The overall mean follow-up time was 72.8 months.

RESULTS

The analysis showed significant improvement in renal function at month 3 post-conversion (P < 0.05) with stabilization thereafter. Lipid parameters and blood sugar levels were similar pre- and post-conversion. Abnormal liver function test was transient in 12.8%. Reasons for SRL discontinuation were nephrotic range proteinuria in two patients and mouth ulceration in one. We compared patients with serum creatinine <140 micromol/l and those with serum creatinine > or = 140 micromol/l, and found that serum creatinine was an independent risk factor for chronic allograft dysfunction (P = 0.02). Graft loss occurred in three patients because of cardiovascular death in two and an acute rejection episode in one.

CONCLUSIONS

We concluded that conversion from CNIs to SRL is an option and of benefit without significant acute rejection episodes or chronic allograft dysfunction especially in well-selected kidney transplant recipients with good graft function.

Pharmacogenetic influences on mycophenolate therapy

Mycophenolic acid (MPA) is a cornerstone immunosuppressant therapy in solid organ transplantation. MPA is metabolized by uridine diphosphate glucuronosyltransferase to inactive 7-O-MPA-glucuronide (MPAG). At least three minor metabolites are also formed, including a pharmacologically active acyl-glucuronide. MPA and MPAG are subject to enterohepatic recirculation. Biliary excretion of MPA/MPAG involves several transporters, including organic anion transporting polypeptides and multidrug resistant protein-2 (MRP-2). MPA metabolites are also excreted via the kidney, at least in part by MRP-2. MPA exerts its immunosuppressive effect through the inhibition of inosine-5-monophosphate dehydrogenase. Several SNPs have been identified in the genes encoding for uridine diphosphate glucuronosyltransferase, organic anion transporting polypeptides, MRP-2 and inosine-5-monophosphate dehydrogenase. This article provides an extensive overview of the known effects of these SNPs on the pharmacokinetics and pharmacodynamics of MPA.

The influence of induction therapy on graft and patient survival in patients with and without hepatitis C after liver transplantation

We used the United Network for Organ Sharing Database to determine the influence of antibody-based induction therapy on patient and graft survival in orthotopic liver transplant (OLT) recipients with and without hepatitis C (HCV). We identified all initial OLT patients with HCV serology. Patients were divided into four groups: HCV positive without induction (17 362), HCV positive with induction (3479), HCV negative without induction (20 417) and HCV negative with induction (4357). Both HCV positive and negative patients who received induction did better than those who did not. For HCV positive patients, 5-year patient survival was 70.8% versus 68.7% (p = 0.004) and graft survival was 65.2% versus 62.1% (p < 0.001). For HCV negative patients, 5-year patient survival was 78.8% versus 76.7% (p < 0.001) and graft survival was 74.0% versus 70.8% (p < 0.001). On multivariate analysis, induction was associated with improved patient (HR = 0.91: p = 0.024) and graft (HR = 0.88: p < 0.001) survival in HCV positive patients and improved patient (HR = 0.87: p = 0.003) and graft survival (HR = 0.87: p < 0.001) in HCV negative patients. The benefit of induction occurred early and largely dissipated when patients with death within a year were censored. The benefit of induction therapy appeared most pronounced in patients with renal insufficiency or on organ-perfusion support at transplant.

RGS4 controls renal blood flow and inhibits cyclosporine-mediated nephrotoxicity

Calcineurin inhibitors (CNI) are powerful immunomodulatory agents that produce marked renal dysfunction due in part to endothelin-1-mediated reductions in renal blood flow. Ligand-stimulated Gq protein signaling promotes the contraction of smooth muscle cells via phospholipase Cbeta-mediated stimulation of cytosolic calcium release. RGS4 is a GTPase activating protein that promotes the deactivation of Gq and Gi family members. To investigate the role of G protein-mediated signaling in the pathogenesis of CNI-mediated renal injury, we used mice deficient for RGS4 (rgs4(-/-)). Compared to congenic wild type control animals, rgs4(-/-) mice were intolerant of the CNI, cyclosporine (CyA), rapidly developing fatal renal failure. Rgs4(-/-) mice exhibited markedly reduced renal blood flow after CyA treatment when compared to congenic wild type control mice as measured by magnetic resonance imaging (MRI). Hypoperfusion was reversed by coadministration of CyA with the endothelin antagonist, bosentan. The MAPK/ERK pathway was activated by cyclosporine administration and was inhibited by cotreatment with bosentan. These results show that endothelin-1-mediated Gq protein signaling plays a key role in the pathogenesis of vasoconstrictive renal injury and that RGS4 antagonizes the deleterious effects of excess endothelin receptor activation in the kidney.

New insights into the pharmacokinetics and pharmacodynamics of the calcineurin inhibitors and mycophenolic acid: possible consequences for therapeutic drug monitoring in solid organ transplantation

Although therapeutic drug monitoring (TDM) of immunosuppressive drugs has been an integral part of routine clinical practice in solid organ transplantation for many years, ongoing research in the field of immunosuppressive drug metabolism, pharmacokinetics, pharmacogenetics, pharmacodynamics, and clinical TDM keeps yielding new insights that might have future clinical implications. In this review, the authors will highlight some of these new insights for the calcineurin inhibitors (CNIs) cyclosporine and tacrolimus and the antimetabolite mycophenolic acid (MPA) and will discuss the possible consequences. For CNIs, important relevant lessons for TDM can be learned from the results of 2 recently published large CNI minimization trials. Furthermore, because acute rejection and drug-related adverse events do occur despite routine application of CNI TDM, alternative approaches to better predict the dose-concentration-response relationship in the individual patient are being explored. Monitoring of CNI concentrations in lymphocytes and other tissues, determination of CNI metabolites, and CNI pharmacogenetics and pharmacodynamics are in their infancy but have the potential to become useful additions to conventional CNI TDM. Although MPA is usually administered at a fixed dose, there is a rationale for MPA TDM, and this is substantiated by the increasing knowledge of the many nongenetic and genetic factors contributing to the interindividual and intraindividual variability in MPA pharmacokinetics. However, recent, large, randomized clinical trials investigating the clinical utility of MPA TDM have reported conflicting data. Therefore, alternative pharmacokinetic (ie, MPA free fraction and metabolites) and pharmacodynamic approaches to better predict drug efficacy and toxicity are being explored. Finally, for MPA and tacrolimus, novel formulations have become available. For MPA, the differences in pharmacokinetic behavior between the old and the novel formulation will have implications for TDM, whereas for tacrolimus, this probably will not to be the case.

Histological findings of early graft biopsies in old donor renal transplant patients receiving induction therapy

Since recipients of transplants from elderly donors are exposed to an increased risk of delayed graft function (DGF) and acute rejection episodes, administration of induction treatment represents an alternative to preserve renal mass and improve graft survival. We compared the evolution and histological findings of early graft biopsies among 38 recipients treated with Thymoglobulim (33.6%) versus 75 (66.4%) with basiliximab. No differences were observes in the rate of DGF (P = .39). Forty kidneys were biopsed during the first 2 weeks after transplantation: 9 in the Thymoglobulin group (23.68%) and 31 in the basiliximab group (41.3%). Histological evaluation showed: acute tabular necrosis in 7 (78%) Thymoglobulin patients versus 14 (45%) basiliximab patients, with calcineurin nephrotoxicity in 2 (22%) and 1 (3.2%), respectively. An acute rejection episode was not diagnosed in the Thymoglobulin group, but 13 patients (17.3%) in the basiliximab group experienced this complication (P = .006). Banff classification showed: 6 grade IA (19.4%), 1 grade IB (3.2%), 3 grade IIA (9.7%), 1 grade IIB (3.2%), and 2 grade III (6.5%). Six of these patients required rescue treatment with Thymoglobulin. Serum creatinine and proteinuria levels between the 2 groups were not different (P > .05). There were no differences in cytomegalovirus (CMV) disease (P = .152), admission due to infection (P = .120), or neoplasia (P = .29). Graft and patient survivals at 3 years did not show a difference. The histological findings revealed that low doses of Thymoglobulin were much more effective to prevent renal inflammation and acute rejection episodes than basiliximab among renal transplant recipients, albiet without differences in survival at a mean of 3 years follow-up.

Long-term management of the liver transplant patient: recommendations for the primary care doctor

No official document has been published for primary care physicians regarding the management of liver transplant patients. With no official source of reference, primary care physicians often question their care of these patients. The following guidelines have been approved by the American Society of Transplantation and represent the position of the association. The data presented are based on formal review and analysis of published literature in the field and the clinical experience of the authors. These guidelines address drug interactions and side effects of immunosuppressive agents, allograft dysfunction, renal dysfunction, metabolic disorders, preventive medicine, malignancies, disability and productivity in the workforce, issues specific to pregnancy and sexual function, and pediatric patient concerns. These guidelines are intended to provide a bridge between transplant centers and primary care physicians in the long-term management of the liver transplant patient.

Tacrolimus/sirolimus versus tacrolimus/mycophenolate in kidney transplantation: improved 3-year graft and patient survival in recent era

BACKGROUND

Registry analyses suggest that tacrolimus (TAC)/mycophenolate (MPA) immunosuppression is associated with superior kidney graft survival versus TAC/sirolimus (SRL). Large single-center experience can assist in clarifying these findings, by examining outcomes related to specific utilization practice.

METHODS

We retrospectively examined the outcomes of 518 consecutive first renal transplants at a single center treated with TAC/SRL (n=307) or TAC/MPA (n=211) with prednisone. Graft and patient survival, acute rejection, and 1-year glomerular filtration rate (GFR) were analyzed by era of transplant (2000-2002 vs. 2003-2006). Changes in TAC/SRL utilization between eras included elimination of the SRL loading dose and a reduction in TAC target trough concentrations.

RESULTS

Three-year graft survival with TAC/SRL was lower when first used (2000-2002) because of a higher incidence of patient death, primarily due to cardiovascular causes. Survival improved from 85.3% to 95.9% between 2000 to 2002 and 2003 to 2006 (P=0.001), with comparable graft and patient survival between TAC/SRL and TAC/MPA cohorts, confirmed following multivariable analysis controlling for donor and recipient factors. Rates of BK virus and acute rejection were comparable, but a higher incidence of hyperlipidemia, anemia, posttransplant diabetes, and a lower 1-year GFR (57.6 vs. 63.1 mL/min, P=0.008) was noted in the TAC/SRL cohort.

CONCLUSIONS

These data, as the largest long-term single-center report comparing TAC/SRL with TAC/MPA in kidney transplantation, demonstrate worse patient survival initially with TAC/SRL, with improved outcomes in a later era that were temporally associated with reduced TAC exposure. Differences in cardiovascular risk factors and 1-year GFR highlight the need for further investigation of the optimal utilization of SRL in kidney transplantation.

Alefacept promotes co-stimulation blockade based allograft survival in nonhuman primates

Memory T cells promote allograft rejection particularly in co-stimulation blockade-based immunosuppressive regimens. Here we show that the CD2-specific fusion protein alefacept (lymphocyte function-associated antigen-3-Ig; LFA -3-Ig) selectively eliminates memory T cells and, when combined with a co-stimulation blockade-based regimen using cytotoxic T lymphocyte antigen-4 (CTLA-4)-Ig, a CD80- and CD86-specific fusion protein, prevents renal allograft rejection and alloantibody formation in nonhuman primates. These results support the immediate translation of a regimen for the prevention of allograft rejection without the use of calcineurin inhibitors, steroids or pan-T cell depletion.

A matched cohort pharmacoepidemiological analysis of steroid free immunosuppression in renal transplantation

BACKGROUND

This longitudinal, sequential, matched closed-cohort design pharmacoepidemiological analysis examined the influence of maintenance steroid therapy in 380 first graft recipients after renal transplantation under conditions of normal clinical practice.

METHODS

Nonexposed (steroid avoidance, n=190) and exposed (steroid treated, n=190) cohorts were matched 1:1 for key demographic factors, including donor source (living or deceased), diabetic status, panel reactive antibody level, recipient age (by decade), and sex.

RESULTS

Cohorts were comparable for all variables except median human leukocyte antigen mismatch (4 vs. 3, P=0.03), use of tacrolimus (90.0% vs. 59.5%, P<or=0.0001), and of basiliximab (94.7% vs. 57.4%, P<or=0.0001), which were higher in the nonexposed cohort. Estimated glomerular filtration rate (mL/min/1.73 m) was comparable at 1 year (median: 58.1 vs. 58.3, P=0.92) and 2 years (median: 55.5 vs. 58.0, P=0.97) in nonexposed and in exposed cohorts (P=0.97). There was no difference in Kaplan-Meier estimates of biopsy-proven acute rejection (14.8% vs. 17.0%; hazard ratio: 0.88, P=0.60) or of 2-year death censored graft failure (4.7% vs. 3.2%; P=0.44) between nonexposed or exposed cohorts. Median total cholesterol (4.6 vs. 5.0 mmol/L, P=0.0002), low-density lipoprotein (2.6 vs. 2.8 mmol/L, P=0.005), high-density lipoprotein levels (1.1 vs. 1.3, P=0.0001), and median weight change from baseline (-1.7 vs. +1.0 kg, P=0.001) were significantly lower in the nonexposed cohort. Forty-five patients (29%) in the nonexposed cohort commenced steroid therapy, principally for graft dysfunction or acute rejection.

CONCLUSION

In summary, steroid avoidance did not negatively impact 2-year graft function, biopsy-proven acute rejection rate, or short-term graft survival and offers clinical benefits, which weigh in the decision regarding maintenance therapy.

Mycophenolic acid formulations in adult renal transplantation - update on efficacy and tolerability

The description more than 30 years ago of the role of de novo purine synthesis in T and B lymphocytes clonal proliferation opened the possibility for selective immunosuppression by targeting specific enzymatic pathways. Mycophenolic acid (MPA) blocks the key enzyme inosine monophosphate dehydrogenase and the production of guanosine nucleotides required for DNA synthesis. Two MPA formulations are currently used in clinical transplantation as part of the maintenance immunosuppressive regimen. Mycophenolate mofetil (MMF) was the first MPA agent to be approved for the prevention of acute rejection following renal transplantation, in combination with cyclosporine and steroids. Enteric-coated mycophenolate sodium (EC-MPS) is an alternative MPA formulation available in clinical transplantation. In this review, we will discuss the clinical trials that have evaluated the efficacy and safety of MPA in adult kidney transplantation for the prevention of acute rejection and their use in new combination regimens aiming at minimizing calcineurin inhibitor toxicity and chronic allograft nephropathy. We will also discuss MPA pharmacokinetics and the rationale for therapeutic drug monitoring in optimizing the balance between efficacy and safety in individual patients.

Twelve-month pancreas graft function significantly influences survival following simultaneous pancreas-kidney transplantation

BACKGROUND AND OBJECTIVES

Simultaneous pancreas-kidney transplantation (SPK) is regarded as the treatment of choice for type 1 diabetes (T1DM) and kidney dysfunction, despite the morbidity associated with pancreas transplantation. These morbidities often influence selection of SPK versus living-donor kidney alone (LD KA) transplant. This study quantifies the impact of pancreas graft function on outcomes following SPK.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Using the SRTR database, SPK wait-listed patients transplanted from 1997 to 2005 were evaluated and segregated as: (1) SPK recipients with functioning pancreas graft 12 mo posttransplant (SPK, P+); (2) SPK recipients with loss of pancreas graft function within 12 mo posttransplant (SPK, P-); (3) recipients of deceased donor (DD) KA; (4) recipients of LD KA. The study compared patient and kidney graft survival to 84 mo posttransplant.

RESULTS

Patient survival for SPK, P+ was significantly better than the LD KA; SPK, P-; and DD KA cohorts (88.6% versus 80.0%, 73.9% and 64.8%, respectively [P < 0.001]), a finding confirmed by multivariate analysis and not influenced by pancreas-after-kidney transplantation (PAK) rates and outcomes. Unadjusted graft survival was also highest in the SPK, P+ cohort (72.0% versus 63.6%, 59.8%, 49.7%, P = 0.015 versus LD KA).

CONCLUSIONS

SPK recipients with functioning pancreas grafts have superior survival compared with LD KA and DD KA, including in the setting of PAK. Early pancreas graft failure results in kidney and patient survival rates similar to KA. These data help further clarify the decision-making of SPK versus KA transplant options for patients and providers.

Pharmacodynamics of mycophenolic acid in CD4+ cells: a single-dose study of IMPDH and purine nucleotide responses in healthy individuals

Mycophenolate mofetil is used in rejection prophylaxis after allograft transplantation. The highly variable pharmacokinetics and pharmacodynamics (PD) of the active moiety mycophenolic acid (MPA) render this drug attractive for therapeutic monitoring. The aim of this study was to characterize the exposure-response relationship for MPA to guide future strategies for individualized therapy based on PD monitoring. A single-dose (100, 250, 500, and 1000 mg mycophenolate mofetil) crossover exposure-response study of MPA PD in CD4 cells was performed in 5 healthy individuals. The activity of inosine 5'-monophosphate dehydrogenase (IMPDH) at time 0 ranged from 1.2 to 7.2 pmol per 10 cells/min. IMPDH was strongly inhibited by MPA; MPA EC50 (concentration required for 50% inhibition) of 2.3 mg/L was determined by a pooled data analysis. Decreased IMPDH gene expression was associated with the exposure to MPA. There were no immediate reductions of guanine nucleotides. On the contrary, a trend toward increased guanosine triphosphate was observed. IMPDH activity AUC0-12h approached maximum reduction at MPA AUC0-12h 22 mg x h/L (corresponding to the 500 mg dose), whereas plasma concentrations exceeding approximately 6 mg/L did not further increase the IMPDH inhibition. The results suggest that guanine nucleotides in circulating lymphocytes may not serve as immediate response biomarkers to MPA. Strategies for preventing over- or underexposure to MPA may be developed by means of IMPDH activity combined with MPA concentration measurement.

Benefits of conversion from mycophenolate mofetil to enteric-coated mycophenolate sodium in pediatric renal transplant patients with stable graft function

Conversion from MMF to EC-MPS may reduce GI complications and permit increased MPA dosing with a concomitant reduction in CNI dose. In a prospective trial, paediatric renal transplant patients with stable graft function were converted from MMF to EC-MPS and followed-up for 12 months. Data from 28 patients (mean age 13.9 +/- 3.1 yr) were available for analysis. Mean EC-MPS dose increased significantly from conversion to month 12 (668 +/- 81 mg/m(2)/day vs. 747 +/- 98 mg/m(2)/day, p < 0.001). CsA-ME dose (n = 23) decreased from 5.3 +/- 1.7 mg/kg/day at conversion to 4.6 +/- 1.4 mg/kg/day at month 12 (p = 0.010). cGFR increased from 69.5 +/- 23.3 mL/min/1.73 m(2) at the time of conversion to 80.7 +/- 30.7 mL/min/1.73 m(2) at month 12 (p = 0.007). The number of patients reporting at least one GI event during six months prior to conversion was 15/28 (53.6%), declining to 8/28 (28.6%) at month 6 post-conversion and 5/28 (17.8%) at month 12. This single-arm study suggests that conversion of paediatric renal transplant patients from MMF to EC-MPS does not compromise efficacy and leads to improved GI tolerability. MPA dose increased and CsA-ME dose decreased significantly, with an associated improvement in calculated GFR. A large-scale controlled trial is required to confirm these promising findings.

Efficacy of induction therapy on acute rejection and graft outcomes in African American kidney transplantation

BACKGROUND

African Americans (AA) have higher rejection rates and poorer graft outcomes compared to non-AAs. Induction therapy is yet unproven in this high risk population.

METHODS

This retrospective study compared the efficacy of induction therapy [IL-2 receptor antibodies (IL2RA) or thymoglobulin] vs. no induction.

RESULTS

One hundred and seventy-five AA patients were included in this analysis. Patients were well matched for demographic and immunologic characteristics in the non-induction and IL2RA induction groups; the Thymoglobulin induction group had significantly higher risk patients. Significantly fewer episodes of acute rejection occurred at one yr in patients treated with thymoglobulin and IL2RA vs. no induction (18% vs. 47%, p = 0.003, 26% vs. 47%, p = 0.02). Three yr graft survival was significantly improved in the IL2RA group compared to the non-induction group (85% vs. 68%, p = 0.032). Despite the thymoglobulin group being at high risk, they had similar graft survival rates compared to both the IL2RA group (76% vs. 85%, p = 0.18) and the non-induction group (76% vs. 68%, p = 0.48). Multivariate analysis demonstrated that induction therapy (combining IL2RA and thymoglobulin) independently reduced the risk of both acute rejection and graft loss.

CONCLUSION

The use and type of induction therapy in AA patients significantly reduces acute rejection rates and may improve long-term graft outcomes in AA patients.

Should heart, lung, and liver transplant recipients receive immunosuppression induction for kidney transplantation?

As the outcomes of heart, liver, and lung transplantation continue to improve, more patients will present for subsequent renal transplantation. It remains unclear whether these patients benefit from induction immunosuppression. We retrospectively reviewed induction on solid organ graft recipients who underwent renal transplant at our center from January 1, 1995 to March 30, 2007. Induction and the non-induction groups were compared by univariate and Kaplan-Meier analyses. There were 21 patients in each group, with mean follow-up of 4.5-6.0 years. Forty-seven percent of patients receiving induction had a severe post-operative infection, compared with 28.6% in the non-induction group (p = NS). The one yr rejection rate in the induction group was 9.5% compared with 14.3% for non-induction (p = NS). One-yr graft survival was 81.0% and 95.2% in the induction and non-induction group (p = NS). In summary, there is a trend toward lower patient and graft survival among patients undergoing induction. These trends could relate to selection bias in the decision to prescribe induction immunosuppression, but further study is needed to better define the risks and benefits of antibody-induction regimens in this population.

Living donor kidney versus simultaneous pancreas-kidney transplant in type I diabetics: an analysis of the OPTN/UNOS database

BACKGROUND AND OBJECTIVES

Transplant options for type I diabetics with end-stage renal disease include simultaneous pancreas-kidney (SPKT), living donor kidney (LDKT), and deceased donor kidney transplant (DDKT). It is unclear whether SPKT offers a survival benefit over LDKT in the current era of transplantation. The authors compared outcomes of kidney transplant recipients with type I diabetes using data from the Organ Procurement and Transplant Network/United Network for Organ Sharing.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Adult (age 20 to 59) type I diabetics who received a solitary first-time kidney transplant between 2000 and 2007 were studied. Outcomes included overall kidney graft and patient survival. Multivariate analysis was performed using a stepwise Cox proportional hazards model.

RESULTS

Kidney graft survival was better for recipients of LDKT compared with SPKT (P = 0.008), although patient survival was similar (P = 0.346). On multivariate analysis, LDKT was associated with lower adjusted risks over 72 mo follow-up of kidney graft failure (HR 0.71; 95% CI 0.61 to 0.83) and patient death (HR 0.78; 95% CI 0.65 to 0.94) versus SPKT. Compared with DDKT, SPKT had superior unadjusted kidney graft and patient survival, partly due to favorable SPKT donor and recipient factors.

CONCLUSIONS

Despite more transplants from older donors and among older recipients, LDKT was associated with superior outcomes compared with SPKT and was coupled with the least wait time and dialysis exposure. LDKT utilization should be considered in all type I diabetics with an available living donor, particularly given the challenges of ongoing organ shortage.

Orthotopic liver transplantation and what to do during follow-up: recommendations for the practitioner

Improvements in surgical technique and the introduction of several new immunosuppressive medications mean that outcome after orthotopic liver transplantation (OLT) has improved continuously over the past 15 years. Given the increasing longevity of patients after OLT, the recognition and prevention of long-term complications after transplantation have become ever more important. With respect to graft function, physicians responsible for the everyday care of patients following transplantation should be particularly aware of the risk of late and chronic rejection episodes and of recurrence of the underlying liver disease. The major challenge of post-transplant care is, however, how best to prevent and manage the long-term adverse effects caused by the immunosuppressive medications prescribed. Screening investigations for early diagnosis of malignancy, strict control of cardiovascular risk factors, preservation of renal function, and prevention of infections are, therefore, fundamental. This Review suggests guidelines for the management of OLT recipients to improve long-term survival, overall outcome and health-related quality of life.

Calcineurin inhibitor sparing in paediatric solid organ transplantation : managing the efficacy/toxicity conundrum

Despite their efficacy, the calcineurin inhibitors (CNIs) ciclosporin and tacrolimus carry a risk of debilitating adverse effects, especially nephrotoxicity, that affect the long-term outcome and survival of children who are given organ transplants. Simple reduction in dosage of CNI has little or no long-term benefit on their adverse effects, and complete withdrawal without threatening graft outcome may only be possible after liver transplantation. Until the last decade, the only option was to increase corticosteroid and/or azathioprine doses, which imposed additional long-term hazards. Considered here are the emerging generation of new agents offering an opportunity for improving long-term graft survival, minimizing CNI-related adverse events and ensuring patient well-being.A holistic, multifaceted strategy may need to be considered - initial selection and optimized use and monitoring of immunosuppressant regimens, early recognition of indicators of patient and graft dysfunction, and, where applicable, early introduction of CNI-sparing regimens facilitating CNI withdrawal. The evidence reviewed here supports these approaches but remains far from definitive in paediatric solid organ transplantation. Because de novo immunosuppression uses CNI in more than 93% of patients, reduction of CNI-related adverse effects has focused on CNI sparing or withdrawal.A recurring theme where sirolimus and mycophenolate mofetil have been used for this purpose is the importance of their early introduction to limit CNI damage and provide long-term benefit: for example, long-term renal function critically reflects that at 1 year post-transplant. While mycophenolic acid shows advantages over sirolimus in preserving renal function because the latter is associated with proteinuria, sirolimus appears the more potent immunosuppressant but also impairs early wound healing. The use of CNI-free immunosuppressant regimens with depleting or non-depleting antibodies plus sirolimus and mycophenolic acid needs much wider investigation to achieve acceptable rejection rates and conserve renal function. The adverse effects of the alternative immunosuppressants, particularly the dyslipidaemia associated with sirolimus, needs to be minimized to avoid replacing one set of adverse effects (from CNIs) with another. While we can only conjecture that judicious combinations with the second generation of novel immunosuppressants currently in development will provide these solutions, a rationale of low-dose therapy with multiple immunosuppressants acting by complementary mechanisms seems to hold the promise for efficacy with minimal toxicity until the vision of tolerance achieves reality.

Calcineurin inhibitor sparing in renal transplantation

Although calcineurin inhibitors (CNIs) are effective at preventing acute rejection, their long-term use is associated with nephrotoxicity that may compromise long-term renal allograft survival. Consequently, there is considerable interest in identifying immunosuppressive regimens that permit reduced exposure to CNIs while maintaining adequate immunosuppression. Introducing such strategies early after transplantation may mean that the development of CNI-associated nephrotoxicity could be minimized or prevented. Several CNI-sparing regimens have shown at least comparable efficacy with standard-dose CNI regimens. In particular, a regimen of mycophenolate mofetil (MMF), corticosteroids, interleukin-2 receptor antagonist induction, and low-dose tacrolimus from the time of transplantation provided superior renal function and a lower acute rejection rate than the same regimen but with low-dose cyclosporine or low-dose sirolimus, or standard-dose cyclosporine, MMF, and corticosteroids. The use of low-dose cyclosporine does not seem to eliminate nephrotoxicity in de novo renal transplant recipients. The early withdrawal of CNIs from MMF-based regimens generally improves renal function but has been associated with an increased risk of acute rejection, in particular when the levels of mycophenolic acid were not adjusted to maintain the same total level of immunosuppression. Research aiming to achieve the "best" balance of efficacy and toxicity of available immunosuppressive regimens continues.