Tacrolimus rescue therapy for renal allograft rejection--five-year experience

Sensorineural Deafness Following Tacrolimus Use

Early trials of tacrolimus in renal transplant recipients have not revealed hearing loss as an adverse effect. Here, we present a case report and a review of the literature of deafness after tacrolimus use. The review of the literature and our experience suggested that the possible reason for hearing loss could be due to an initiation of a sudden spike in the tacrolimus serum level, which was later worsened by its cumulative toxic effect.

Anti-thymocyte globulins in kidney transplantation: focus on current indications and long-term immunological side effects

Antithymocyte globulins (ATGs) are part of the immunosuppression arsenal currently used by clinicians to prevent or treat acute rejection in solid organ transplantation. ATG is a mixture of non-specific anti-lymphocyte immunoglobulins targeting not only T cell subsets but also several other immune and non-immune cells, rendering its precise immunoglobulin composition difficult to appreciate or to compare from one preparation to another. Furthermore, several mechanisms of action have been described. Taken together, this probably explains the efficacy and the side effects associated with this drug. Recent data suggest a long-term negative impact on allograft and patient outcomes, pointing out the need to better characterize the potential toxicity and the benefit-risk balance associated to this immunosuppressive therapy within large clinical trials.

Two Decades of Tacrolimus in Renal Transplant: Basic Science and Clinical Evidences

Tacrolimus, a calcineurin inhibitor, has been the cornerstone of immunosuppressive regimens in renal transplant over 2 decades. This has significantly improved the outcomes of renal transplant, including reduction of acute rejection episodes, improvement of renal function and graft survival, and reduction of some of the adverse effects associated with cyclosporine. However, use of tacrolimus is associated with a number of undesirable effects, such as nephrotoxicity, posttransplant diabetes mellitus, neurotoxicity, and cosmetic and electrolyte disturbances. To alleviate these effects, several strategies have been adopted to minimize or eliminate tacrolimus from maintenance regimens of immunosuppression, with some success. This review focuses on advancements in the understanding of the basic science related to tacrolimus and the clinical evidences that have examined the efficacy and safety of tacrolimus in renal transplant over the past 2 decades and highlights the future directions.

Efficacy and Safety of Elective Conversion From Sotrastaurin (STN) to Tacrolimus (TAC) or Mycophenolate (MPS) in Stable Kidney Transplant Recipients

BACKGROUND

This study aimed to evaluate the efficacy and safety outcomes of conversion strategies in stable kidney transplant recipients after premature termination of the sotrastaurin (STN) development program.

METHODS

This is an exploratory and prospective study, including 38 stable renal transplant recipients. Tacrolimus (TAC) group [STN → mycophenolate sodium (MPS)] consisted of 9 patients receiving TAC, STN, and prednisone that were converted from STN to MPS. Everolimus (EVR) group (STN → TAC) consisted of 29 patients receiving EVR, STN, and prednisone that were converted from STN to TAC.

RESULTS

In TAC (STN → MPS) group, dose-adjusted TAC concentrations decreased from baseline to first week (2.3 ± 1.1 versus 1.5 ± 1.0 ng·mL·mg, P < 0.05). Two patients experienced a first acute rejection episode. Conversion to MPS was associated with a higher incidence of adverse events. In EVR (STN → TAC) group, dose-adjusted EVR concentrations decreased from baseline to first week (3.6 ± 2.3 ng·mL·mg versus 1.9 ± 0.8 ng·mL·mg, P < 0.01). The proportion of patients with donor-specific antibodies was lower in TAC (STN → MPS) (11%) compared to EVR (STN → TAC) (31%) before conversion. Conversion from STN to TAC was associated with a reduction in estimated glomerular filtration rate (69.6 ± 16.9 versus 61.0 ± 18.8 mL·min·1.73 m, P < 0.01) and a decreased proportion of patients with donor-specific antibodies (31% versus 14%) at 12 months.

CONCLUSIONS

Conversion from TAC/STN to TAC/MPS or from EVR/STN to TAC/EVR was associated with significant pharmacokinetic changes in both TAC and EVR whole-blood trough concentrations due to known drug-to-drug interaction, which were associated with changes in efficacy and safety.

Advances in pharmacotherapy to treat kidney transplant rejection

INTRODUCTION

Current immunosuppressive combination therapy provides excellent prevention of T-cell-mediated rejection following renal transplantation; however, antibody-mediated rejection remains of high concern and accounts for a large number of long-term allograft losses. The recent development of protocol biopsies resulted in the definition of subclinical rejection (SCR), showing histologic evidence for rejection but unremarkable clinical course.

AREAS COVERED

This review describes the current knowledge and evidence of pharmacotherapy to treat kidney allograft rejections and covers SCR treatment options. Each substance is analyzed with regard to its classical indication and further discussed for the treatment of other forms of rejection.

EXPERT OPINION

Despite a lack of randomized trials, early acute T-cell-mediated rejection can be treated effectively in most cases without graft loss. The necessity to treat SCR is currently unclear. Due to a lack of effective therapies, new treatment approaches for antibody-mediated rejection are an urgent medical need to improve long-term outcomes. Future research should aim to better define pathophysiology and histology, stratify risk, and develop rational treatment strategies from randomized controlled trials, in order to establish the value of novel therapies in the arsenal of rejection pharmacotherapy. However, the effective prevention of rejection with minimal side effects still remains the goal in immunosuppression.

Tacrolimus in transplant rejection

INTRODUCTION

Renal transplantation is the best therapy for patients with end-stage renal disease. To avoid graft rejection, adequate immunosuppressive therapy is crucial. Tacrolimus is approved for prophylaxis of transplant rejection in liver, kidney or heart allograft recipients and for the treatment of allograft rejection resistant to treatment with other immunosuppressive medicinal products.

AREAS COVERED

The objective of this review is to summarize the clinical efficacy of tacrolimus in renal transplantation with special emphasis on acute rejection, refractory rejection and nephrotoxicity and post-transplant diabetes mellitus as typical adverse effects of the drug.

EXPERT OPINION

Since its approval in 1994, tacrolimus has proven its efficacy as a cornerstone of modern immunosuppressive therapy not only in numerous randomized clinical trials but also in standard clinical care. Compared with cyclosporine, the use of tacrolimus in renal transplant recipients is associated with a reduced risk for acute rejection, a reduction in the occurrence of steroid-resistant rejection and a better graft function. The avoidance of nephrotoxicity and especially post-transplant diabetes mellitus are of major interest in long-term care of renal transplant recipients.

Belatacept utilization recommendations: an expert position

INTRODUCTION

There is a continuing need for an immunosuppressive therapy that offers a high benefit-risk profile for renal transplant recipients, supporting long-term patient and graft survival while minimizing cumulative nephrotoxicity and other side effects. Belatacept , the first biological agent developed for primary maintenance immunosuppression, was recently approved for use in Europe. Belatacept combined with corticosteroids and a mycophenolic acid is indicated for prophylaxis of graft rejection in adults receiving renal transplant. Its use is contraindicated in Epstein-Barr virus seronegative or serostatus unknown patients due to increased risk of developing posttransplant lymphoproliferative disorder.

AREAS COVERED

This review provides practical recommendations for the use of belatacept, based on safety and efficacy data from Phase II and Phase III clinical trials in de novo kidney transplant recipients.

EXPERT OPINION

Treatment with belatacept is associated with improved long-term graft function, making belatacept an important option for prevention of kidney allograft rejection. Furthermore, efficacy and safety data over several years of therapy suggest that belatacept is particularly suitable for long-term immunosuppression, and the selective targeting offered by belatacept may help avoid some of the non-specific chronic safety risks associated with calcineurin inhibitors and steroids. Future studies will clarify the optimal regimen for belatacept usage.

New treatments for acute humoral rejection of kidney allografts

Acute antibody-mediated rejection (acute humoral rejection; AHR) of organ allografts usually presents as severe dysfunction with a high risk of allograft loss. Peritubular capillary complement C4d deposition with renal dysfunction, associated with circulating donor-specific anti-human leukocyte antigen alloantibodies, is diagnostic of AHR in kidney allografts. Removal of alloantibodies with suppression of antibody production and rejection reversal is now possible. Therapeutic strategies that include combinations of plasmapheresis (or immunoadsorption), tacrolimus, mycophenolate mofetil and/or intravenous immunoglobulins, as well as rituximab or splenectomy, have been recently used to successfully treat AHR. However, the optimal protocol to treat AHR still remains to be defined. Anti-CD20+ monoclonal antibody therapy (rituximab) aiming at depleting B cells and suppressing antibody production has been used as rescue therapy in some episodes of steroid- and antilymphocyte-resistant humoral rejection. Plasmapheresis and/or intravenous polyclonal immunoglobulin, as well as rituximab, have also been used to successfully desensitize selected high-immunological risk patients in anticipation of a previously cross-match positive (or ABO incompatible) kidney transplantation. In the near future, the possible role of new specific anti-B-cell approaches or, possibly, of new anti-T-cell activation approaches using selective agents such as belatacept should be assessed to further refine the present treatment of humoral rejection.

OKT3 Therapy in Addition to Tacrolimus Is Associated with Improved Long-Term Function in Patients with Steroid Refractory Renal Allograft Rejection

BACKGROUND/AIMS

The aim of this study was to evaluate long-term allograft salvage rates of patients with steroid refractory allograft rejection after kidney transplantation and to identify factors indicating a successful outcome.

PATIENTS AND METHODS

Fifty patients with continuing rejection after high-dose steroids were included in the study. Baseline immunosuppression was switched from cyclosporine to tacrolimus in all patients. Twenty patients additionally received OKT3 as antirejection therapy. Patients having received a cadaveric renal transplant in 1995, excluding patients with steroid resistant rejection, were chosen as a control cohort.

RESULTS

Patient survival rates were 96% (n = 48) and 90% (n = 45) and allograft survival rates were 66% (n = 33) and 62% (n = 31) after 5 and 7 years following steroid refractory renal allograft rejection. Graft survival within the control cohort was 73% after 5 years and 69% after 7 years. Creatinine clearance increased from 20 +/- 15 ml/min/1.73 m2 at the start of tacrolimus therapy to 37 +/- 29 ml/min/1.73 m2 and to 32 +/- 26 ml/min/1.73 m2 after 5 and 7 years. OKT3 treatment predicted successful rescue therapy (p = 0.005 and p = 0.04 after 5 and 7 years).

CONCLUSION

Our data indicate a reasonable graft survival in steroid refractory renal allograft rejection using tacrolimus. OKT3 treatment in addition to tacrolimus therapy may be beneficial for long-term allograft survival.

Influence of CYP3A5 gene polymorphisms of donor rather than recipient to tacrolimus individual dose requirement in liver transplantation

BACKGROUND

Tacrolimus is a widely used immunosuppressant in organ transplantation, but it is characterized by a narrow therapeutic index and high interindividual variations of its pharmacokinetics. Tacrolimus is a substrate for CYP3A. It has been conjectured that CYP3A5 polymorphism is associated with tacrolimus pharmacokinetic variations. The objective of this study was to evaluate the contribution of polymorphisms of the donor and recipient CYP3A5 gene on tacrolimus disposition in liver transplantation.

METHODS

Fifty-three liver transplant recipients treated with tacrolimus were enrolled in this study. Tacrolimus dosage and blood trough concentration were investigated at 1 week, 2 weeks, and 1 month after transplantation. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was applied to determine the genotype of CYP3A5 gene.

RESULTS

The concentration/dose (C/D) ratios in patients with *1/*1(*1/*3) genotype donor were significantly lower than in patients with *3/*3 genotype donor at 2 weeks (P = 0.036) and 1 month (P = 0.021), but not at 1 week posttransplantation. Combination analysis showed that such significance still existed between CYP3A5 expressor group and nonexpressor group for both donor and recipient genotype. Also differences of C/D ratio between CYP3A5 expressor and nonexpressor donors in nonexpressor recipients were larger than those between recipients in nonexpressor donors.

CONCLUSION

The large interindividual variation of tacrolimus dose requirement is influenced by the metabolic activity of CYP3A5. Polymorphisms of the donor CYP3A5 gene seem to contribute more to such variation than the recipient. A larger population and further studies are needed to explore the exact mechanisms for tacrolimus pharmacokinetics.

Effects of and predictors for tacrolimus rescue therapy among renal transplant patients under cyclosporine-based immunosuppression

BACKGROUND

Though cyclosporine has dramatically decreased rejection rates and improved graft survival rates of renal allografts, there is still a remarkable rate of acute rejection and progressive deterioration of renal function after transplantation. Rescue therapy with tacrolimus has been used for allografts failing under cyclosporine-based treatment in order to get some renal functional recovery or stabilization. The aim was to evaluate tacrolimus rescue therapy for failing allografts under cyclosporine-based immunosuppression for possible prediction factors for success.

PATIENTS AND METHODS

Thirty-five renal allograft recipients with failing transplants under cyclosporine-based immunosuppression were enrolled into this study. Renal function was evaluated by reciprocal serum creatinine level (1/Cr) and calculated CCr. The slope of changes in 1/Cr and CCr were calculated before and after tacrolimus therapy. The possible risk factors that affect the outcome of tacrolimus rescue therapy were analyzed.

RESULTS

Nineteen patients showed improved renal function (group 1) and 16 patients, persistent deterioration (group 2) after rescue therapy. Group 1 showed positive slopes of changes of 1/Cr and CCr after rescue therapy. Group 2 patients showed persistent negative slopes although less negative than before rescue therapy. Only the posttransplant time was the significant predictive factor for successful tacrolimus therapy (P = .018).

CONCLUSION

Tacrolimus rescue therapy improved or stabilized renal function in some patients with failing grafts under cyclosporine-based immunosuppression. To assure a successful rescue effect, it should be given early after transplantation, if there is a tendency toward deterioration of renal function.

Biodegradable microsphere-loaded tacrolimus enhanced the effect on mice islet allograft and reduced the adverse effect on insulin secretion

The adverse effects of tacrolimus have limited the use of this potent immunosuppressive drug in clinical transplantation. To improve the therapeutic effects, we developed a new type of tacrolimus with biodegradable microsphere technology and examined the immunosuppressive effects on allogeneic islet transplantation and the side-effects on insulin secretion in vivo. With a single subcutaneous injection, mouse blood concentrations of tacrolimus (M-FK) carried in biodegradable microspheres remained flat for 2 weeks (only 10 h for conventional tacrolimus). A single subcutaneous administration of 20 mg/kg of M-FK significantly prolonged the survival of islet allografts (MST = 28 days) compared with the control group (MST = 10 days). Series administration of 10 mg/kg of M-FK at 7-day intervals markedly prolonged the survival of islet grafts, and resulted in 60% allograft acceptance. In mice with syngeneic islet transplantations, a single administration of 30 mg/kg of tacrolimus inhibited insulin secretion, whereas a single administration of an equal dosage of M-FK did not. The results suggested that M-FK enhanced the immunosuppressive effects on islet allograft rejection more effectively with reduced side-effects on insulin secretion.

Use of cyclosporine in renal transplantation

The first cyclosporine trials in renal transplantation began in Cambridge in 1978. Between 1982 and 1985 several large multicenter trials and the reports from large series of patients evidenced that cyclosporine was a major advance in the prevention of acute rejection episodes and in improving short-term and long-term graft survival. Cyclosporine also showed the capacity to mitigate immunologic risk factors, HLA mismatching, and lack of pretransplant transfusions. However, cyclosporine has the serious defect of being nephrotoxic. Induction therapy with OKT3, polyclonal antibodies, and more recently with anti IL-2R monoclonal antibodies allowed the delay of introduction cyclosporine in patients showing posttransplant graft dysfunction. Other relatively unsuccessful attempts for overcoming cyclosporine nephrotoxicity were made before the association of new xenobiotics such as mycophenolate mofetil or sirolimus permitted cyclosporine doses to be reduced. These combinations reduce acute rejection incidence to below 20%, with its consequent positive impact on long-term graft outcome and also allow a safer steroid sparing and withdrawal early posttransplantation. Also, the association of cyclosporine with other new compounds such as the lymphocyte homing FTY20 or the peripheral lymphocyte-depleting Campath-1-IgG is currently under clinical investigation. Cyclosporine's future place is yet to be established in the new era of immunosuppression.

Tacrolimus conversion in kidney transplant recipients: analysis of 107 patients

Early results of an alteration in immunosuppressive protocol of tacrolimus conversion at a mean follow-up of 16 (range 1 to 36) months are presented with a mean time after transplantation of 34 +/- 1.4 months (range 1 to 158 months). Chronic allograft nephropathy in 16 (17%) patients, nephrotoxicity related to cyclosporine in 27(23%) patients and steroids resistant acute rejection in 64 (58%) represented the indications for tacrolimus conversion. Before starting tacrolimus there were 1 acute rejection episode in 37 patients, 2 in 17 patients, and 3 in 10 patients. After the drug conversion, 1 acute rejection occurred in 18 and 2 acute rejection in 4 patients. Graft loss was seen in 16 (16%) patients after drug conversion. Tacrolimus was withdrawn due to diabetes mellitus (n = 9), epilepsy (n = 4), and severe Nocardia sepsis, lymphoma and Kaposi sarcoma (each in one patient). Decreases in serum creatinine and increases in blood glucose levels were significantly associated with the tacrolimus doses (P = 0.0004 and P = 0.0400, respectively). The increase in creatinine clearance values were closely related to higher tacrolimus levels. The target range with maximum efficacy and minimum toxicity seemed to be 10 to 15 ng/mL. Tacrolimus conversion can be successful in cases of rejection and nephrotoxicity, but dose-dependent blood glucose elevations require close observation in these patients.

Sensitivity of Whole-Blood T Lymphocytes in Individual Patients to Tacrolimus (FK 506): Impact of Interleukin-2 mRNA Expression as Surrogate Measure of Immunosuppressive Effect

Background: To optimize immunosuppressive treatment in individual transplant patients, functional measurements of the effects of tacrolimus (FK 506) are of clinical importance. Previous investigations have demonstrated the occurrence of tacrolimus-resistant production of interleukin-2 (IL-2) in vitro, which may explain in part why rejection episodes are still a frequent problem despite attainment of therapeutic blood concentrations and HLA matching. However, an adequate surrogate marker to define the tacrolimus response in individual patients has not been established.

Methods: We investigated the immunosuppressive effects of tacrolimus on anti-CD3/anti-CD28 T-cell costimulation in a human whole-blood assay, analyzing T-cell proliferation, activation marker expression (CD25, CD69), IL-2 protein expression, and cytokine mRNA expression in vitro (n = 11 healthy individuals). We also quantified IL-2 mRNA expression in patients undergoing tacrolimus (n = 4) or cyclosporin A (CsA; n = 4) monotherapy before ex vivo living-donor kidney transplantation.

Results: T-cell proliferation; CD25, CD69, and IL-2 concentrations; and IL-4 mRNA were significantly decreased in vitro. In contrast, cytokine mRNA profiles revealed variable tacrolimus sensitivity. Whole-blood samples from 3 of 11 healthy individuals demonstrated marked suppression of IL-2 mRNA expression (&gt;50%) when tacrolimus was administered in vitro. When CsA was added to whole-blood cultures, the influence on IL-2 mRNA expression was comparable to that of tacrolimus in 9 of 11 individuals. Two individuals responded conversely, indicating that differences in the in vitro response to tacrolimus and CsA among individuals may be attributable to potential heterogeneity in the involvement of the CD28 pathway. Kinetic profiles of IL-2 mRNA expression also revealed individually distinct degrees of calcineurin inhibitor sensitivity in patients undergoing tacrolimus or CsA monotherapy before living-donor kidney transplantation.

Conclusions: Our results suggest an individual degree of calcineurin inhibitor sensitivity of activated whole-blood lymphocytes based on IL-2 mRNA expression. Our approach is potentially valuable for identifying transplant patients in whom IL-2 mRNA expression is unaffected or even enhanced after initiation of immunosuppressive therapy. Such individuals may be less sensitive to the immunosuppressive agent and therefore at increased risk of transplant rejection. Prospective studies are necessary to determine the correlation of IL-2 mRNA expression with the clinical risk of transplant rejection.

Inhibitors of Calcineurin

Before the early 1980s, patient and allograft survival for solid organ transplant recipients was dismal. By 1983, the first calcineurin blocker, cyclosporine (Sandimmun), had been introduced, and outcomes were dramatically improved. However, cyclosporine macroemulsion had suboptimal pharmacokinetics, significant drug interactions, and several adverse effects, including nephrotoxicity, neurotoxicity, hyperlipidemia, and hypertension. Recent advances with cyclosporine include the introduction of modified dosage formulations: Neoral, a microemulsion, and several generic microemulsion products. The potent second-generation calcineurin blocker tacrolimus (Prograf) was introduced in 1994 and has become the drug of choice for several types of transplant recipients. Although tacrolimus has improved pharmacokinetics and therapeutic drugmonitoring parameters, it has adverse effects such as nephrotoxicity, neurotoxicity, and diabetes. Thus, current immunosuppressive regimens implementing calcineurin blockers often involve additional immunosuppressive agents to “spare” the use of these agents, minimizing their adverse effects. This article reviews the mechanisms of action, pharmacokinetics, clinical use, therapeutic drug monitoring, drug interactions, adverse effects, and dosing of cyclosporine and tacrolimus in solid organ transplant recipients.

Tacrolimus dosing in pediatric heart transplant patients is related to CYP3A5 and MDR1 gene polymorphisms

Tacrolimus is a substrate for P-glycoprotein (P-gp) and cytochrome (CYP) P4503A. P-gp is encoded by the multiple drug resistance gene MDR1 and CYP3A is the major enzyme responsible for tacrolimus metabolism. Both MDR1 and CYP3A5 genes have multiple single nucleotide polymorphisms. The objective of this study was to evaluate whether the MDR1 exon21 and exon26 polymorphisms and the CYP3A5 polymorphism are associated with tacrolimus disposition in pediatric heart transplant patients. At 3, 6 and 12 months post transplantation, a significant difference in tacrolimus blood level per dose/kg/day was found between the CYP3A5 *1/*3 (CYP3A5 expressor) vs. *3/*3 (nonexpressor) genotypes with the *1/*3 patients requiring a larger tacrolimus dose to maintain the same blood concentration. There were no significant differences in tacrolimus blood level per dose/kg/day between MDR1 exon21 G2677T and exon 26 C3435T at 3 months, but both were found to have a significant association with tacrolimus blood level per dose/kg/day at 6 and 12 months. We conclude that specific genotypes of MDR1 and CYP3A5 in pediatric heart transplant patients require larger tacrolimus doses to maintain their tacrolimus blood concentration, and that this information could be used prospectively to manage patient's immunosuppressive therapy.

Comparative evaluation of 'TaqMan' RT-PCR and RT-PCR ELISA for immunological monitoring of renal transplant recipients

By sequentially monitoring cytokine gene expression (using RT-PCR ELISA technology) in peripheral blood cells of renal transplant recipients in the early post-operatively period we have shown that expression patterns correlate with clinical events, namely acute allograft rejection. This strategy may have the potential of predicting acute rejection prior to clinical detection. Unfortunately, the technique used was time consuming and only semi-quantitative and, therefore, not suitable for clinical application. In this study, we have sought to confirm the results of the early work using a real time quantitative RT-PCR technique ('TaqMan'), which may be applicable in the clinical laboratory. 'TaqMan' primers and probes were designed for Interleukin (IL)-4 and IL-10 using Primer Express software. Cytokine gene expression for both cytokines was re-measured in stored cDNA samples from 27 non-rejectors and 14 patients experiencing an episode of biopsy proven acute rejection. Compared to pre-transplant levels, IL-4 gene expression fell significantly on post-operative days 2 and 7 before returning to baseline values by day 14 in the non-rejectors. In the rejectors, the initial significant fall was again seen, but with an earlier return to pre-transplant levels at the time of rejection diagnosis. This was followed by a further significant fall in levels 48 h after the initiation of anti-rejection therapy. These different patterns for rejectors and non-rejectors were seen using both techniques. For IL-10, gene expression increased significantly following transplantation throughout the study period when compared to baseline values. This pattern was seen using both techniques. In the rejectors, there were different patterns seen depending on the technique used. When using RT-PCR ELISA, the initial rise was again seen followed by a return to baseline values at the time of rejection diagnosis followed by a further significant rise in gene expression after the start of anti-rejection treatment. The pattern resembled those of the non-rejectors when expression was measured using 'TaqMan'. This study has confirmed that sequential monitoring of cytokine gene expression, measured in peripheral blood mononuclear cells, detects significant changes that correlate with clinical events in renal transplant recipients, including acute rejection, although not all changes detected with RT-PCR ELISA were confirmed. Therefore, real time quantitative RT-PCR technology may be useful in monitoring the immunological status of these patients in the early post-operative period.

Tacrolimus and cyclosporine differ in their capacity to overcome ongoing allograft rejection as a result of their differential abilities to inhibit interleukin-10 production

BACKGROUND

Accumulated evidence from clinical transplantation has suggested that tacrolimus-based treatment can reverse ongoing allograft rejection in patients treated with cyclosporine (CsA)-based immunosuppression, even when a high dose of antirejection rescue therapy has failed. This evidence prompted us to investigate whether these two compounds, which share an in vitro mechanism, would differ in their abilities to regulate in situ cellular and molecular events during ongoing allograft rejection.

METHODS

The equivalent effective doses of tacrolimus (3.2 mg/kg/day) and CsA (10 mg/kg/day), when administered orally to Lewis rats for 10 days (day 0-9), were predetermined and defined as the ability of the drug to induce a similar survival of Brown Norway rat heart allografts with an equal suppression of intragraft interleukin (IL)-2 mRNA expression. To investigate the ability of each drug to rescue ongoing allograft rejection, Lewis recipients of Brown Norway rat heart grafts were left untreated for the first 5 days after transplantation. Tacrolimus or CsA was then administered at the equivalent effective dose for 10 days (days 5-14). Heart grafts and blood samples, harvested on days 3, 5, 7, and 10, were analyzed by reverse transcriptase-polymerase chain reaction, real-time quantitative polymerase chain reaction, ELISA, and immunohistology.

RESULTS

Ongoing allograft rejection was found to be rescued by tacrolimus but not by CsA at the equivalent dose (median survival time: untreated, 6 days; tacrolimus, 18 days; and CsA, 7 days). A significant suppression of local intragraft IL-10 mRNA expression and serum protein production along with a dramatic down-regulation of functional CD8+ T and NKR-P1a+ natural killer cell local infiltration by means of decreased of cytotoxic factor release, including granzyme B and perforin 1, was found to be associated with tacrolimus but not CsA treatment. However, both drugs inhibited other immune cells (CD4+ T cell, ED2+ macrophage) and cytokines (IL-1beta, IL-2, IL-4, IL-6, IL-12, interferon-gamma, transforming growth factor-beta, and tumor necrosis factor-alpha) at almost the same levels. The inability of CsA to overcome ongoing allograft rejection could be rescued by cotreating recipients with neutralizing anti-IL-10 antibody on day 5 and day 6 after transplantation: anti-IL-10 antibody alone did not show such an effect.

CONCLUSIONS

Inhibition of IL-10 production is a critical factor in the ability of tacrolimus to reverse ongoing allograft rejection.

Contemporary immunosuppression in renal transplantation

Over the past 3 decades, renal allograft survival has improved significantly as a result of the development of powerful immunosuppressive agents. Nevertheless, the overall half-life of renal allografts has increased marginally during that time period, owing to drug-related nephrotoxicity and chronic rejection. New immunosuppressive agents are being evaluated because of the need for a reduction in the dose of nephrotoxic calcineurin inhibitors and corticosteroids. Additional agents have demonstrated the ability to retard the onset of chronic rejection in preclinical transplant models. In concert with these efforts, approaches are in development to alleviate the ever increasing shortage of donor organs, including the as yet unrealized goals of successful and practical xenotransplantation and the bioartificial kidney. Further identification and development of novel agents that target the specific components of the allograft response will provide the key to the achievement of donor-specific tolerance, the "Holy Grail" of solid organ transplantation.

Reversal of steroid- and anti-lymphocyte antibody-resistant rejection using intravenous immunoglobulin (IVIG) in renal transplant recipients

BACKGROUND

Despite the recent advances in immunosuppression, steroid-resistant rejection remains a difficult problem in renal transplant recipients.

METHODS

We reviewed our experience with i.v. immunoglobulin (IVIG) in the treatment of steroid- and antilymphocyte antibody-resistant rejection in renal transplant patients. Between September 1996 and March 1999, 17 patients were treated with IVIG to reverse steroid- or antilymphocyte antibody-resistant rejection. A total of 2 g/kg of IVIG was administered to patients during each treatment course.

RESULTS

With a mean follow-up of 21.5+/-9.5 months from the time of IVIG administration, patient and graft survival rates were 94% (16/17) and 71% (12/17), respectively. The baseline mean serum creatinine level prior to rejection was 2.2+/-0.7 mg/dl and peaked at 3.3+/-1.1 mg/dl at the time of the diagnosis of refractory rejection. IVIG therapy was associated with a fall in the mean creatinine to 2.8+/-1.1 mg/dl. The most recent serum creatinine in patients with functioning grafts was 2.8+/-1.6 mg/dl. In 82% of allograft biopsies after IVIG, reversal or reduction in the severity of rejection was demonstrated. In addition, IVIG therapy rescued three of four patients with antilymphocyte antibody-resistant rejection.

CONCLUSIONS

IVIG rescue therapy for steroid- or antilymphocyte antibody-resistant rejection is associated with resolution or improvement of rejection severity, stable renal function, and reasonable graft survival.

Immunologic Aspects of Transplant Management: Pharmacotherapy and Rejection

The intensivist caring for the critically ill transplant patient must be knowledgeable in the management of immunosuppression or have expert help. Critical illness often has a major impact on the absorption and metabolism of immunosuppressive drugs, increasing or decreasing net immunosuppression. Too little immunosuppression brings the risk of graft loss, while too much increases the morbidity and mortality of serious infection. Optimum management often requires the skillful manipulation of dosage and/or routes of drug delivery. In many cases of life-threatening infection, immunosuppression must be discontinued altogether and restarted prior to significant graft injury. The cost of miscalculation is very high. Loss of a renal, pancreas, or small bowel transplant is tragic, while loss of a heart, lung, or liver is usually fatal. Unfortunately the management of immunosuppression is becoming more complex. As the field of transplantation matures, new immunosuppressants are being introduced. Also, more experience and growing numbers of clinical trials are making the required knowledge base ever larger. Each type of transplant has its own set of evolving immunosuppression strategies. This review presents the basic mechanisms of the most widely used drugs and the dangers of immunosuppression. The drugs are then discussed in the context of liver, small bowel, kidney, pancreas, heart, and lung transplantation. Finally, a brief section on the practical pharmacokinetics of the drugs is presented.

The use of mycophenolate mofetil in transplant recipients

With the development of new immunosuppressive agents, the focus of anti-rejection therapy has shifted from prevention of acute allograft rejection to an emphasis on sufficient immunosuppression with minimal toxicity. Mycophenolate mofetil (MMF) is a recently developed immunosuppressive drug, which acts to inhibit T and B cell proliferation by blocking the production of guanosine nucleotides required for DNA synthesis. It also prevents the glycosylation of adhesion molecules that are involved in attachment of lymphocytes to endothelium and potentially in leukocyte infiltration of an allograft during an immune response. High-quality randomized clinical trials have demonstrated that MMF, when used with cyclosporine (CsA) and steroids, reduces the frequency and severity of acute rejection episodes in kidney and heart transplants, improves patient and graft survival in heart allograft recipients and increases renal allograft survival at 3 years. It has also been effective in reversing acute and resistant rejection episodes in heart, kidney and liver recipients. The ability of MMF to facilitate sparing of other immunosuppressive agents, particularly in CsA-related nephrotoxicity, is also promising. By permitting reduction in CsA doses, MMF may stabilize or improve renal graft function in patients with CsA-related nephrotoxicity or chronic allograft nephropathy. Early results of phase I and II trials evaluating MMF therapy in liver and combined pancreas/kidney transplant recipients are encouraging. The main adverse effects associated with oral or intravenous MMF are gastrointestinal and hematologic in nature. Although the direct costs of using MMF vs. azathioprine (AZA) are higher, the decreased incidence and treatment of acute rejection in patients treated with MMF supports its use as a cost-effective option during the first year following transplantation.Thus, MMF has become an important therapeutic tool in the transplant clinician's armamentarium. Ongoing issues to be resolved in clinical trials include the role of MMF in the absence of other potent agents, e.g., as monotherapy or with a steroid but without calcineurin inhibitor; whether MMF will have an impact on chronic allograft dysfunction; and the cost-effectiveness of treatment following the first year of transplantation.

Conversion from tacrolimus to cyclosporine in stable renal transplant patients: safety, metabolic changes, and pharmacokinetic comparison

BACKGROUND

Although conversion between tacrolimus and cyclosporine has been performed when indicated for rejection or adverse effects, the safety and metabolic outcome of elective conversion from tacrolimus to cyclosporine has not previously been examined.

METHODS

Conversion from tacrolimus to cyclosporine was performed in 19 recipients of cadaver renal transplants at 3-6 months after transplantation. Pharmacokinetic profiles and biochemical studies were performed three times, in steady state, before, and after conversion.

RESULTS

Patient and graft survival was 100% at 3 months after conversion, with no rejection episodes. Three patients have been subsequently converted back to tacrolimus, two for rejection and one for hirsutism. There were no significant changes in creatinine, urate, or blood sugar levels after conversion, but the mean plasma magnesium rose from 0.73 (0.63-0.97) to 0.82 (0.65-1) mmol/L (P=0.037), and the mean plasma cholesterol rose from 5.2 (3.4-6.8) to 5.5 (3.8-7.6) mmol/L (P=0.033). Pharmacokinetic profiles were measured before and after conversion, and showed that cyclosporine (Neoral) exhibited significantly less interpatient and intrapatient variability than tacrolimus, for area under the curve (AUC), maximum concentration after dose (Cmax), minimum concentration after dose (Cmin), and time to maximum concentration (Tmax).

CONCLUSION

This is the first study that has examined the outcome of conversion from tacrolimus- to cyclosporine-based immunosuppression in stable patients after renal transplantation. This conversion was performed without early immunological hazard, but there was a small rise in blood cholesterol levels after conversion. Pharmacokinetic studies showed that cyclosporine in the form of Neoral exhibited less inter- and intrapatient variability than tacrolimus, although this is of uncertain clinical significance.

Safety and efficacy of tacrolimus in combination with mycophenolate mofetil (MMF) in cadaveric renal transplant recipients. FK506/MMF Dose-Ranging Kidney Transplant Study Group

BACKGROUND

Tacrolimus (FK506) is a safe and effective treatment for the prevention of rejection of renal allografts. Mycophenolate mofetil (MMF) has been used as adjunct immunosuppressive therapy with cyclosporine and corticosteroids for the same purpose. The objective of this study was to investigate the safety and efficacy of FK506 and MMF in renal transplant recipients.

METHODS

After cadaveric renal transplant, patients were randomized to receive tacrolimus in combination with either azathioprine (AZA, n=59), MMF 1 g/day (n=59), or MMF 2 g/day group (n=58). Patients were followed for 1 yr posttransplant for the incidence of biopsy-confirmed acute rejection, patient and graft survival, and adverse events.

RESULTS

Tacrolimus doses and trough concentrations were similar between treatment groups at all time points; 80% of patients were maintained within a range of 5.0-13.9 ng/ml at 12 months posttransplant. The mean dose of MMF decreased in the 2 g/day group to 1.5 g/day by 6 months posttransplant, primarily due to gastrointestinal GI-related disorders. The incidence of biopsy-confirmed acute rejection at 1 year was 32.2%, 32.2%, and 8.6% in the AZA, MMF 1 g/day, and MMF 2 g/day groups, respectively (P<0.01). The use of antilymphocyte antibodies for the treatment of rejection was comparable across treatment groups. The incidence of most adverse events was similar across treatment groups and comparable with previous reports. The overall incidence of posttransplant diabetes mellitus was 11.9%, with the lowest rate observed in the MMF 2 g/day group (4.7%), and was reversible in 40% of patients. The incidence of malignancies and opportunistic infections was low and not different across treatment groups.

CONCLUSION

Tacrolimus in combination with an initial dose of MMF 2 g/day is a very effective and safe regimen in cadaveric kidney transplant recipients.

Results of pancreas transplantation after steroid withdrawal under tacrolimus immunosuppression

PURPOSE

The results of steroid withdrawal in pancreas transplant recipients under tacrolimus immunosuppression were analyzed.

METHODS

From July 4, 1994 until April 30, 1998, 147 pancreas transplantations were performed in 141 patients, including 126 simultaneous pancreas-kidney transplantations, 13 pancreas after kidney transplantation, and 8 pancreas transplantations alone. Baseline immunosuppression consisted of tacrolimus and steroids without antilymphocyte induction. Twenty-three patients were excluded from analysis because of early graft loss in 17 cases, retransplantation in 5 cases, and simultaneous pancreas-kidney transplantation after heart transplantation in 1 patient.

RESULTS

With a mean follow-up of 2.8+/-1.1 years (range 1.0 to 4.8 years), complete steroid withdrawal was achieved in 58 (47%) patients with a mean time to steroid withdrawal of 15.2+/-8 months (range 4 to 40 months after transplantation). Of the entire cohort of 141 patients, overall 1-, 2-, and 4-year patient survival rates were 98%, 95.5%, and 86%, respectively. Overall 1-, 2-, and 4-year graft survival rates were 83%, 80%, and 71% (pancreas) and 95%, 91%, and 84% (kidney), respectively. Of the 124 patients analyzed for steroid withdrawal, 1-, 2-, and 4-year patient survival rates were 98%, 97%, and 92%, respectively. Overall 1-, 2-, and 4-year graft survival rates were 98%, 91.5%, 83% (pancreas) and 97%, 95%, and 91% (kidney). Patient, pancreas, and kidney survival rates at 1 year were 100%, 100%, and 98% (off steroids) versus 97%, 91%, and 96% (on steroids, all NS) and at 4 years were 100%, 94%, and 95% (off steroids) versus 78%, 68%, and 85% (on steroids, P = 0.01, 0.002, and NS, respectively). The cumulative risk of rejection at the time of follow-up was 76% for patients on steroids versus 74% for patients off steroids (P = NS). Seven patients originally tapered off steroids were treated for subsequent rejection episodes, which were all steroid sensitive, and two of these seven patients are currently off steroids. Thirteen patients received antilymphocyte therapy for steroid-resistant rejection, five of whom are now off steroids. Tacrolimus trough levels were 9.3+/-2.4 ng/ml (off steroids) and 9.7+/-4.3 (on steroids, P = NS). Mean fasting glucose levels were 98+/-34 mg/dl (off steroids) and 110+/-41 mg/dl (on steroids, P = NS). Mean glycosylated hemoglobin levels were 5.2+/-0.9% (off steroids) and 6.2+/-2.1% (on steroids, P = 0.02), and mean serum creatinine levels were 1.4+/-0.8 mg/dl (off steroids) and 1.7+/-1.0 mg/dl (on steroids, P = 0.02).

CONCLUSION

These data show for the first time that steroid withdrawal can be safely accomplished in pancreas transplant recipients maintained on tacrolimus-based immunosuppression. Steroid withdrawal is associated with excellent patient and graft survival with no increase in the cumulative risk of rejection.

Differences in Type 1 and Type 2 intracytoplasmic cytokines, detected by flow cytometry, according to immunosuppression (cyclosporine A vs. tacrolimus) in stable renal allograft recipients

Recent multicenter, randomized clinical trials have shown that in renal transplant patients tacrolimus (FK506) was more efficient than cyclosporine A (CsA) at preventing acute rejection. In order to try and evaluate whether this difference was related to a different in vivo T-cell suppression we assessed, in a prospective study, the frequencies of interleukin (IL)-2-, IL-4-, IL-5-, IL-6-, IL-10-, interferon-gamma (IFN-gamma)- and double-positive IL-2/IFN-gamma-producing whole T cells, CD4 + and CD8 + T-cell subsets by means of cytokine flow cytometry. This was performed after in vitro stimulation of peripheral blood mononuclear cells (PBMCs) with phorbol myristate acetate (PMA) and ionomycin, in the presence of monensin, in 14 healthy volunteers (controls) and in 14 renal transplant patients. The immunosuppression of the latter was based either on CsA (n = 7) or on FK506 (n = 7). Cytokine-expressing T-cell frequencies were assessed immediately pretransplantation (DO), and subsequently 3 months (M3) and 6 months (M6) afterwards in fasting patients prior to the morning intake of the immunosuppressive drug. We found that at DO the frequencies of IL-2-(22 +/- 2% vs. 22.2 +/- 2%), IFN-gamma-(26 +/- 3% vs. 29 + 3.4%) and IL-4-(0.8 +/- 0.2% vs. 1.4 +/- 0.2%)-expressing T lymphocytes were not significantly different between the controls and the patients, respectively. Conversely, the frequency of IL-2/IFN-gamma double positive cells was higher in the latter (9.3 +/- 1.6%) than in the controls (5.6 +/- 0.8); p = 0.06. Finally, on D0 the frequencies of IL-5-, IL-6-, and IL-10-producing T lymphocytes were lower than 1%, in both groups, as well as after grafting, i.e. on M3 and M6. As compared to baseline (DO): (a) chronic immunosuppression significantly decreased the frequencies of IL-2-, IL-4- and IL-2/IFN-gamma-expressing T cells, whereas those of IFN-gamma, IL-5, IL-6, and IL-10 were not significantly affected; (b) the frequencies of cytokine-expressing T cells were not statistically different between M3 and M6; (c) the decrease in the frequencies of IL-2- and IL-2/IFN-gamma-expressing T cells affected CD4 + and CD8 + cells equally; (d) there was a marginal decrease in the frequency of IFN-gamma-expressing cells only in the CD4 + subset but not in the CD8 population; and (e) for CsA, but not for FK506, the frequency of the IL-2-expressing T cells was negatively correlated with the whole blood trough levels. When we compared the frequencies of cytokine-expressing cells in FK506- and CsA-treated patients, we found that the frequency of IL-2-expressing T cells was significantly lower with FK506 (10.9+/-1.61%) than with CsA (16.3 +/- 1.8%; p = 0.03), whereas the frequencies of the other cytokine-expressing cells were not statistically different between the two groups. In conclusion, our study clearly demonstrated that studied ex vivo, FK506 and CsA decrease the frequencies of cells expressing IL-2, IL-4 and IL-2/IFN-gamma in vivo but do not affect those expressing IFN-gamma. Meanwhile, the frequency of IL-2-producing T cells was more affected with FK506 than with CsA and was negatively correlated with the CsA trough level. Finally, our results regarding IL-2 might explain to some extent the higher efficiency of FK506 in vivo than CsA.