Tacrolimus-based triple-drug immunosuppression minimizes serum lipid elevations in pediatric cardiac transplant recipients

Dyslipidemia after pediatric renal transplantation-The impact of immunosuppressive regimens

Dyslipidemia contributes to cardiovascular morbidity and mortality in pediatric transplant recipients. Data on prevalence and risk factors in pediatric cohorts are, however, scarce. We therefore determined the prevalence of dyslipidemia in 386 pediatric renal transplant recipients enrolled in the CERTAIN registry. Data were obtained before and during the first year after RTx to analyze possible non-modifiable and modifiable risk factors. The prevalence of dyslipidemia was 95% before engraftment and 88% at 1 year post-transplant. Low estimated glomerular filtration rate at 1 year post-transplant was associated with elevated serum triglyceride levels. The use of TAC and of MPA was associated with significantly lower concentrations of all lipid parameters compared to regimens containing CsA and mTORi. Immunosuppressive regimens consisting of CsA, MPA, and steroids as well as of CsA, mTORi, and steroids were associated with a three- and 25-fold (P<.001) increased risk of having more than one pathologic lipid parameter as compared to the use of TAC, MPA, and steroids. Thus, amelioration of the cardiovascular risk profile after pediatric RTx may be attained by adaption of the immunosuppressive regimen according to the individual risk profile.

Nutrition management after pediatric solid organ transplantation

Survival rates for pediatric transplant recipients and organ grafts have increased due to improvements in surgical techniques and with immunosuppressant treatment therapies. Interdisciplinary management after pediatric organ transplantation is essential to assist not only with the complex medical issues and complications that can result from immunosuppressant therapy but also with the achievement of normal growth and development. Impaired growth is a complication frequently experienced by pediatric transplant patients. The presence or absence of impaired growth is affected by the length of illness prior to transplant, graft function, the use of corticosteroids, and the development of infectious complications after surgery. A review of posttransplant nutrition assessment, nutrition requirements, and nutrition goals is provided. In addition, a case series of experiences with nutrition management of pediatric solid organ transplant recipients is described.

Adverse effects of immunosuppression in pediatric solid organ transplantation

Solid organ transplantation is a life-saving treatment for end-stage organ failure in children. Immunosuppressant medications are used to prevent rejection of the organ transplant. However, these medications are associated with significant adverse effects that impact growth and development, quality of life (QOL), and sometimes long-term survival after transplantation. Adverse effects can differ between the immunosuppressants, but many result from the overall state of immunosuppression. Strategies to manage immunosuppressant adverse effects often involve minimizing exposure to the drugs while balancing the risk for rejection. Early recognition of immunosuppressant adverse effects may help to reduce morbidities associated with solid organ transplantation, improve QOL, and possibly increase overall patient survival.

Advances in pediatric heart transplantation

PURPOSE OF REVIEW

Heart transplantation has become a reasonable treatment option for pediatric patients with end-stage heart failure or complex congenital cardiac defects not amenable to conventional surgical intervention. This review will summarize the current state of pediatric cardiac transplantation and review recent advances leading to new therapies.

RECENT FINDINGS

Improvements in early mortality after cardiac transplantation have occurred consistently over time since the 1980s, short-term survival rates are high, and most patients enjoy an excellent quality of life with minimal restrictions. The reduction of late mortality is still a major challenge, however, largely as a result of transplant-related coronary artery disease causing chronic graft failure and arrhythmogenic sudden death. Additional causes of morbidity and mortality occurring late after transplantation include renal dysfunction related to chronic immunosuppressive therapy with calcineurin inhibitors (tacrolimus or cyclosporine) and posttransplant lymphoproliferative disorders related to chronic immunosuppression. Newer agents (sirolimus, everolimus) have shown promise in immunosuppressive regimens that may alter the development or progression of long-term complications.

SUMMARY

New immunosuppressive agents allow alterations in drug regimens to minimize renal complications, and may influence the incidence and progression of transplant vasculopathy. Recent studies on posttransplant lymphoproliferative disorders should result in earlier diagnosis and therapy.

Current issues in pediatric transplantation

Pediatric solid organ transplantation is so successful that >80% of children will survive to become teenagers and adults. Therefore, it is essential that these children maintain a good quality life, free of significant long-term side effects. While intensive immunosuppressive regimens (containing CsA, tacrolimus, MMF, and steroids) effectively reduce acute or chronic rejection, they can produce long-term side effects including viral infection, renal dysfunction, hypertension, and stunting. The development of effective methods of diagnosis, prevention, and treatment of CMV means that this is no longer a significant cause of mortality, but morbidity remains high. In contrast, infection rates of EBV remain high in EBV-negative pre-transplant patients. However, pre-emptive reduction of immunosuppression or treatment with rituximab or adoptive T-cell therapy is effective in preventing/treating post-transplant lymphoproliferative disease. Recent protocols have concentrated on reducing CsA immunosuppression, to prevent unacceptable cosmetic effects, and to reduce the hypertension, hyperlipidemia, and nephrotoxicity. Both CsA and tacrolimus cause a 30% reduction in renal function, with 4-5% of patients developing severe chronic renal failure. The use of IL-2 inhibitors for induction therapy with low-dose calcineurin inhibitors, in combination with renal-sparing drugs such as MMF or sirolimus for maintenance immunosuppression, should prevent significant renal dysfunction in the future. The concept of steroid-free immunosuppression with IL-2 inhibitors, tacrolimus, and MMF is an attractive option, which may reduce stunting and renal dysfunction. However, these regimens may be associated with the increased development of de-novo autoimmune hepatitis in 2-3% of children. The most important challenge to long-term survival in transplanted children is the management of non-adherence and other adolescent issues, particularly when transferring to adult units, as this is the time when many successful transplant survivors lose their grafts.

Three-Year Observational Follow-up of a Multicenter, Randomized Trial on Tacrolimus-Based Therapy with Withdrawal of Steroids or Mycophenolate Mofetil after Renal Transplant

BACKGROUND

The challenge in renal transplantation is to improve long-term patient and graft survival without increasing early acute rejection by minimizing immunosuppression.

METHODS

This multicenter, observational study investigated the effects of withdrawal of steroids or mycophenolate mofetil (MMF) from a tacrolimus-based triple regimen (tac/MMF/steroids) 3 months posttransplant at 3 years; no additional interventions or assessments were undertaken. Adult patients, included in the intent-to-treat population of the THOMAS study, participated. Patient and graft survival, adverse events, rejection episodes, and immunosuppressive and concomitant medications were assessed.

RESULTS

Data at Year 3 was available for 718 patients (triple therapy, n=237; steroid stop, n=235; MMF stop, n=246). The original randomized regimen was maintained in 45.6% of patients in the triple, 62.6% in the steroid stop, and 53.9% in the MMF stop groups. Graft survival rates were 88.1% (triple), 86.4% (steroid stop), and 85.8% (MMF stop); patient survival was 96.1%, 95.9%, and 95.7%, respectively. The incidence of biopsy-proven acute rejection was similar in all groups between Month 7 and Year 3: 1.2% (triple), 2.0% (steroid stop) and 2.0% (MMF stop). Patients in the steroid stop group had less hypertension and significantly lower mean total cholesterol and LDL-cholesterol at Year 3 compared with Month 3 (P=0.02). Median serum creatinine levels remained stable throughout the follow-up and were comparable between groups.

CONCLUSION

Immunosuppression minimization initiated at Month 3 was maintained at Year 3 in over half of the patients. Steroid withdrawal was advantageous in reducing the cardiovascular risk factors hyperlipidemia, hypertension and diabetes mellitus. Renal function was stable in all groups.

Cardiac allograft vasculopathy in pediatric heart transplant recipients

Metabolic parameters for coronary allograft vasculopathy (CAV) have not been well defined in children. CAV (by angiography or autopsy) was studied in 337 heart recipients on a cyclosporine-based steroid-sparing regimen. Freedom from CAV for all was 79% at 10 years. Fifty-nine patients (18%) developed CAV at a mean of 6.5 +/- 3 years post-transplant. First year rejections were significantly higher in CAV, mean 2.3 vs. 1.4, P = 0.003, odds ratio (OR) 1.8. Rejection with hemodynamic compromise beyond 1 year post-transplant was associated with CAV, P < 0.001, OR 8.4. There was no significant correlation among human leukocyte antigen DR (HLA DR) mismatch, pacemaker use or homocysteine levels and the development of CAV. Maximum cholesterol and low density lipoprotein (LDL) levels were not significantly different. Neither diabetes nor hypertension was significant predictors of CAV on multivariate logistic regression analysis. In conclusion, frequent and severe rejection episodes may predict pediatric CAV. Neither glucose intolerance nor lipid abnormalities appeared to alter risk for CAV in this population.

Lipid profiles in pediatric thoracic transplant recipients are determined by their immunosuppressive regimens

BACKGROUND

Controversy exists over the pattern of lipidemic effects from calcineurin inhibitors and prednisone. We report an extensive longitudinal study of lipid profiles in pediatric thoracic transplant recipients.

METHODS

Serial fasting lipids of subjects from a single pediatric center, along with their immunosuppressive regimens, were examined. Groups were analyzed according to cyclosporine- or tacrolimus-based immunosuppression in addition to whether prednisone was used as adjunctive therapy.

RESULTS

Of a total of 119 subjects, 85 were and remained on tacrolimus (TAC), 13 remained on cyclosporine (CSA), 4 switched from TAC to CSA, and 17 switched from CSA to TAC. The median age at transplant was 100 months, and the latest follow-up was 48 months. The CSA Group had higher lipid levels than the TAC Group, and levels changed minimally over time. At 1 year, TAC vs CSA total cholesterol was 153 vs 186 mg/dl (p = 0.002), low-density lipoprotein (LDL) cholesterol was 92 vs 117 (p = 0.09), and high-density lipoprotein (HDL) cholesterol was 42 vs 48 (p = NS), respectively. At the latest follow-up, the TAC vs CSA cholesterol was 143 vs 180 mg/dl (p = 0.001), LDL was 84 vs 115 (p = 0.001), and HDL was 42 vs 41 (p = NS). Profiles of subjects that switched agents reflected the agent used (e.g., higher total cholesterol, LDL, and HDL while on cyclosporine). Sub-group analysis showed prednisone augmented the hyperlipidemic effects.

CONCLUSION

Hyperlipidemia is common in pediatric thoracic transplant patients and persists over time. It is more pronounced in cyclosporine subjects and is further elevated with prednisone. These findings indicate the need for close monitoring, and consideration for intervention, especially in high-risk sub-groups.

Predictors of graft longevity in pediatric heart transplantation

Given the volume of pediatric orthotopic heart transplants (OHTs) at several centers, it is now possible to generate pediatric-specific, single-center OHT survival data. The transplant experience for 152 pediatric OHT patients at our institution was reviewed. The following were noted for each patient: graft survival; immunosuppressant therapy; initial diagnosis; cause of graft failure; clinical status at time of transplant; donor and recipient blood type, sex, weight, and age; ischemic time; previous cardiac surgery; race; and immune status. A series of Kaplan-Meier survival curves were constructed. Univariate comparisons of survival curves were performed with the Breslow test to determine equality of each pair of curves. Only immunosuppression with tacrolimus and an initial diagnosis of noncongenital heart disease positively influenced survival in pediatric OHT patients (p < or = 0.021 and p < or = 0.03, respectively). The more recently transplanted patients, managed with tacrolimus, had less mortality early after OHT (acute rejection) and less mortality during the period 2 or 3 years after OHT. No other factors, including prior cardiothoracic surgery, sex matching, and race matching, significantly influenced survival. Recently transplanted patients managed with tacrolimus-based immunosuppression and patients with noncongenital cardiomyopathy have significantly superior graft survival.

Clinical pharmacokinetics and pharmacodynamics of tacrolimus in solid organ transplantation

The aim of this review is to analyse critically the recent literature on the clinical pharmacokinetics and pharmacodynamics of tacrolimus in solid organ transplant recipients. Dosage and target concentration recommendations for tacrolimus vary from centre to centre, and large pharmacokinetic variability makes it difficult to predict what concentration will be achieved with a particular dose or dosage change. Therapeutic ranges have not been based on statistical approaches. The majority of pharmacokinetic studies have involved intense blood sampling in small homogeneous groups in the immediate post-transplant period. Most have used nonspecific immunoassays and provide little information on pharmacokinetic variability. Demographic investigations seeking correlations between pharmacokinetic parameters and patient factors have generally looked at one covariate at a time and have involved small patient numbers. Factors reported to influence the pharmacokinetics of tacrolimus include the patient group studied, hepatic dysfunction, hepatitis C status, time after transplantation, patient age, donor liver characteristics, recipient race, haematocrit and albumin concentrations, diurnal rhythm, food administration, corticosteroid dosage, diarrhoea and cytochrome P450 (CYP) isoenzyme and P-glycoprotein expression. Population analyses are adding to our understanding of the pharmacokinetics of tacrolimus, but such investigations are still in their infancy. A significant proportion of model variability remains unexplained. Population modelling and Bayesian forecasting may be improved if CYP isoenzymes and/or P-glycoprotein expression could be considered as covariates. Reports have been conflicting as to whether low tacrolimus trough concentrations are related to rejection. Several studies have demonstrated a correlation between high trough concentrations and toxicity, particularly nephrotoxicity. The best predictor of pharmacological effect may be drug concentrations in the transplanted organ itself. Researchers have started to question current reliance on trough measurement during therapeutic drug monitoring, with instances of toxicity and rejection occurring when trough concentrations are within 'acceptable' ranges. The correlation between blood concentration and drug exposure can be improved by use of non-trough timepoints. However, controversy exists as to whether this will provide any great benefit, given the added complexity in monitoring. Investigators are now attempting to quantify the pharmacological effects of tacrolimus on immune cells through assays that measure in vivo calcineurin inhibition and markers of immunosuppression such as cytokine concentration. To date, no studies have correlated pharmacodynamic marker assay results with immunosuppressive efficacy, as determined by allograft outcome, or investigated the relationship between calcineurin inhibition and drug adverse effects. Little is known about the magnitude of the pharmacodynamic variability of tacrolimus.

Immunosuppression and transplant vascular disease: benefits and adverse effects

Cardiac allograft vasculopathy (CAV) occurs within 5 years of transplantation surgery and represents the main cause of death in long-term heart transplant survivors. The detailed pathogenesis of CAV is unknown, but there are strong indications that immunologic mechanisms, which are regulated by nonimmunologic factors, are the major cause of this phenomenon. Cyclosporine A (CsA) is a frequently used immunosuppressive agent in transplant medicine to prevent rejection. The mechanism of action of CsA involves initial binding to cyclophilin to form a complex that then inhibits calcineurin (CN), leading to reduced interleukin (IL)-2 production as part of the signal transduction pathway for the activation of B-lymphocytes and T-lymphocytes. Based on this proposed mechanism, it was expected that CsA should be an effective strategy in attenuating the host immune response against transplanted allograft tissue; however, CsA has not changed the outcome of CAV. Several mechanisms have been suggested for the ineffectiveness of CsA in long-term prevention of CAV. For example, routine therapeutic doses of CsA may block CN incompletely (50%), whereas complete blockade requires doses that are not clinically tolerable. Another explanation is the possible activation of T-cell receptors directly (CN independent) by the immune response, which induces protein kinase C theta (PKCtheta) and leads to IL-2 production and immune rejection. Moreover, there may be a role for nonimmunologic mechanisms, such as complement, which cannot be controlled by CsA, or CsA may cause hypercholesterolemia or induce overexpression of transforming growth factor-beta (TGF-beta). This review also compares the effect of CsA with other immunosuppressants in allograft artery preservation and their clinical efficacy.

Current status of heart transplantation in children: update 2003

Heart transplant is an effective therapy for children with end-stage heart disease. Success of this treatment depends on coordination and careful communication among the family, primary care physician, and transplant team. Primary care physicians play an essential role in the monitoring and management of the medical, nutritional, developmental, and psychosocial issues of pediatric heart transplant patients and their families (Box 3). Ongoing assessment of the child and parent's progress in adapting to transplant is crucial in order for appropriate referrals to occur. Relationships with the primary care team can improve medical outcomes for this complex group of patients and provide a framework for improved adherence to care.

The current state of, and future prospects for, cardiac transplantation in children

During the last two decades, several advances have resulted in marked improvement in medium-term survival, with excellent quality of life, in children undergoing cardiac transplantation. Improved outcomes reflect better selection of donors and recipients, increased surgical experience in transplantation for complex congenital heart disease, development of effective surveillance for rejection, and wider choice of immunosuppressive medications. Despite all of these advances, recipients continue to suffer from the adverse effects of non-specific immunosupression, including infections, induction of lymphoproliferative disorders and other malignancies, renal dysfunction, and other important end-organ toxicities. Furthermore, newer immunosuppressive regimes, thus far, appear to have had relatively little impact on the incidence of chronic rejection. Progress in our understanding of the immunologic mechanisms of rejection and graft acceptance should lead to more targeted immunosuppressive therapy and avoidance of non-specific immunosupression. The ultimate goal is to induce a state of tolerance, wherein the recipient will accept the allograft indefinitely, without the need for long-term immunusupression, and yet remain immuno-competent to all non-donor antigens. This quest is currently being realized in many animal models of solid organ transplantation, and offers great hope for the future.

Optimal immunosuppression in teenagers

Adolescence is a difficult time for transplant recipients, who need to cope with the challenges of becoming independent from their parents, as well as taking responsibility for their own behavior and medication. They need to balance their developing sexuality with a body image which may be affected by the side-effects of immunosuppression. It is now anticipated that more than 80% of children will survive their transplant to become teenagers and adults, and it is therefore important to ensure that immunosuppressive medication is acceptable, convenient for drug level monitoring and free of significant long-term side-effects.

Pediatric heart transplantation

Heart transplantation is now a treatment option with good outcome for infants and children with end-stage heart failure or complex, inoperable congenital cardiac defects. One-year and 5-year actuarial survival rates are high, approximately 75% and 65%, respectively, with overall patient survival half-life greater than 10 years. To date, survival has been improving as a result of reducing early mortality. Further reductions in late mortality, in part because of graft coronary artery disease and rejection, will allow achievement of the goal of decades-long survival. Quality of life in surviving children, as judged by activity, is usually "normal." Somatic growth is usually at the low normal range but linear growth can be reduced. Of infant recipients, 85% evaluated at 6 years of age or older were in an age-appropriate grade level. Long-term management of childhood heart recipients requires the collaboration of transplant physicians, given the increasing number of immunosuppressive agents and the balance between rejection and infection. Currently, recipients are maintained on immunosuppressive medications that target calcineurin (eg, cyclosporine, tacrolimus), lymphocyte proliferation (eg, azathioprine, mycophenolate mofetil [MMF], sirolimus) and, in some instances antiinflammatory corticosteroids. Emerging evidence now suggests a favorable immunologic opportunity for transplantation in childhood and, conversely, a higher mortality rate in children who have had prior cardiac surgery. Further studies are needed to define age-dependent factors that are likely to play a role in graft survival and possible graft-specific tolerance (eg, optimal conditions for tolerance induction and how immunosuppressive regimens should be changed with maturation of the immune system). As late outcomes continue to improve, the need for donor organs likely will increase, as transplantation affords a better quality and duration of life for children with complex congenital heart disease, otherwise facing a future of multiple palliative operations and chronic heart failure.

Dyslipidemia in pediatric renal disease: epidemiology, pathophysiology, and management

Dyslipidemia increases the risk of cardiovascular events among individuals with renal disease, and there is a growing body of evidence that it hastens the progression of renal disease itself. Children with nephrotic syndrome or renal transplants have easily recognized hyperlipidemia. Among those with chronic renal insufficiency or end-stage renal disease, detection of dyslipidemia requires more careful analysis and knowledge of normal pediatric ranges. Disordered lipoprotein metabolism results from complex interactions among many factors, including the primary disease process, use of medications such as corticosteroids, the presence of malnutrition or obesity, and diet. The systematic treatment of dyslipidemia in children with chronic renal disease is controversial because conclusive data regarding the risks and benefits are lacking. Hepatic 3-methylglutaryl coenzyme A reductase inhibitors (statins), fibrates, plant stanols, bile acid-binding resins, and dietary manipulation are options for individualized treatment. Prospective investigations are required to guide clinical management.

Safety and efficacy of pravastatin therapy for the prevention of hyperlipidemia in pediatric and adolescent cardiac transplant recipients

BACKGROUND

Hyperlipidemia is common after cardiac transplantation and it is a risk factor for post-transplantation coronary artery disease. Immunosuppression with corticosteroids and cyclosporine has been associated with hyperlipidemia. Pravastatin, a HMG-CoA reductase inhibitor, has been shown to be effective and safe for cholesterol reduction in adult heart transplant recipients. To our knowledge the safety and efficacy of pravastatin therapy in pediatric and adolescent heart transplant populations have not been previously analyzed. Therefore, we evaluated lipid profiles, liver transaminases, rejection data, and possible side effects in pediatric and adolescent cardiac transplant recipients treated with pravastatin.

METHODS

The study group consisted of 40 cardiac transplant recipients 10 to 21 years old (mean age 16.9 years). Twenty-two patients received pravastatin in addition to an immunosuppressive regimen of either cyclosporine or tacrolimus, azathioprine or mycophenolate mofetil, and prednisone. Serial determinations of total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein, and triglycerides were available for all pravastatin-treated patients. Pre-treatment lipid values and hepatic transaminases were compared with those measured after therapy with pravastatin. Comparison of pravastatin-induced lipid reduction between groups treated with cyclosporine vs tacrolimus was also made.

RESULTS

Patients receiving pravastatin experienced a mean 32 mg/dl decrease in TC (p < 0.005) and a mean 31 mg/dl decrease in LDL (p < 0.005), regardless of their immunosuppressive regimen. No statistical differences occurred in the magnitude of mean lipid reduction induced by pravastatin between the groups treated with cyclosporine vs tacrolimus. No significant changes in hepatic transaminase levels were noted, and no clinical evidence of pravastatin-induced myositis occurred in any subjects.

CONCLUSION

Pravastatin therapy is effective and safe when used in pediatric and adolescent cardiac transplant recipients. Although the pravastatin-induced reduction in TC and LDL was more pronounced in patients receiving cyclosporine, the reduction was not statistically different from that in the tacrolimus group. No evidence of hepatic dysfunction or rhabdomyolysis in patients treated with pravastatin was noted. Long-term studies are required to evaluate the effect of pravastatin therapy on the incidence of accelerated coronary atherosclerosis in this population.

Lipoprotein abnormalities are highly prevalent in pediatric heart transplant recipients

The role of hyperlipidemia in graft coronary artery disease (GCAD) is controversial although hyper-triglyceridemia is an independent risk factor. Recent studies show that 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) inhibitors decrease the incidence of GCAD in adults. The incidence of GCAD in pediatric patients is lower than in adults; it is not clear whether age-related differences in lipid metabolism account for some of this protection. This study was performed to: characterize the lipoprotein profile in children after heart transplantation; demonstrate that total cholesterol (TC) is a poor marker for underlying lipoprotein abnormalities; and to compare lipid abnormalities in patients who had been converted from cyclosporin A (CsA) to tacrolimus. Seventy-one determinations of fasting lipoprotein profiles were performed in a cohort of 28 children. Each child had at least two determinations on separate occasions. TC, low-density lipoprotein (LDL), and serum triglyceride (TG) levels were categorized as abnormal if greater than the 75th percentile for age and gender. A high-density lipoprotein (HDL) level less than the 25th percentile was considered abnormal. Immunosuppression included CsA or tacrolimus, azathioprine, and prednisone. We found that 90% of the patients studied had abnormalities of either TG or HDL. In contrast, LDL tended to be normal when adjusted for age and gender. TC was a poor indicator of any underlying abnormality in TG, LDL, or HDL. In patients converted to tacrolimus, no significant differences were found in the levels of TG, LDL or HDL compared with each patient's respective values while receiving CsA. Hence, lipoprotein abnormalities among pediatric heart transplant recipients are highly prevalent. TC is a poor screening tool in the evaluation for lipid abnormalities. Lipoprotein profiles remain statistically unchanged after conversion from CsA to tacrolimus.

Tacrolimus: a further update of its pharmacology and therapeutic use in the management of organ transplantation

Tacrolimus (FK-506) is an immunosuppressant agent that acts by a variety of different mechanisms which include inhibition of calcineurin. It is used as a therapeutic alternative to cyclosporin, and therefore represents a cornerstone of immunosuppressive therapy in organ transplant recipients. Tacrolimus is now well established for primary immunosuppression in liver and kidney transplantation, and experience with its use in other types of solid organ transplantation, including heart, lung, pancreas and intestinal, as well as its use for the prevention of graft-versus-host disease in allogeneic bone marrow transplantation (BMT), is rapidly accumulating. Large randomised nonblind multicentre studies conducted in the US and Europe in both liver and kidney transplantation showed similar patient and graft survival rates between treatment groups (although rates were numerically higher with tacrolimus- versus cyclosporin-based immunosuppression in adults with liver transplants), and a consistent statistically significant advantage for tacrolimus with respect to acute rejection rate. Chronic rejection rates were also significantly lower with tacrolimus in a large randomised liver transplantation trial, and a trend towards a lower rate of chronic rejection was noted with tacrolimus in a large multicentre renal transplantation study. In general, a similar trend in overall efficacy has been demonstrated in a number of additional clinical trials comparing tacrolimus- with cyclosporin-based immunosuppression in various types of transplantation. One notable exception is in BMT, where a large randomised trial showed significantly better 2-year patient survival with cyclosporin over tacrolimus, which was primarily attributed to patients with advanced haematological malignancies at the time of (matched sibling donor) BMT. These survival results in BMT require further elucidation. Tacrolimus has also demonstrated efficacy in various types of transplantation as rescue therapy in patients who experience persistent acute rejection (or significant adverse effect's) with cyclosporin-based therapy, whereas cyclosporin has not demonstrated a similar capacity to reverse refractory acute rejection. A corticosteroid-sparing effect has been demonstrated in several studies with tacrolimus, which may be a particularly useful consideration in children receiving transplants. The differences in the tolerability profiles of tacrolimus and cyclosporin may well be an influential factor in selecting the optimal treatment for patients undergoing organ transplantation. Although both drugs have a similar degree of nephrotoxicity, cyclosporin has a higher incidence of significant hypertension, hypercholesterolaemia, hirsutism and gingival hyperplasia, while tacrolimus has a higher incidence of diabetes mellitus, some types of neurotoxicity (e.g. tremor, paraesthesia), diarrhoea and alopecia.

CONCLUSION

Tacrolimus is an important therapeutic option for the optimal individualisation of immunosuppressive therapy in transplant recipients.