Tacrolimus predose concentrations do not predict the risk of acute rejection after renal transplantation: a pooled analysis from three randomized-controlled clinical trials(†).

Therapeutic drug monitoring (TDM) for tacrolimus (Tac) is universally applied. However, the concentration-effect relationship for Tac is poorly defined. This study investigated whether Tac concentrations are associated with acute rejection in kidney transplant recipients. Data from three large trials were pooled. We used univariate and multivariate analysis to investigate the relationship between biopsy-proven acute rejection (BPAR) and Tac predose concentration at five time points (day 3, 10 and 14, and month 1 and 6 after transplantation). A total of 136/1304 patients experienced BPAR, giving an overall incidence of 10.4%. We did not find any significant correlations between Tac predose concentrations and the incidence of BPAR at the different time points. In the multivariate analysis, only delayed graft function (DGF) and the use of induction therapy were independently correlated with BPAR, with an odds ratio of 2.7 [95% CI: 1.8-4.0; p < 0.001] for DGF and 0.66 [95% CI: 0.44-0.99; p = 0.049] for induction therapy. The other variables, including the Tac predose concentrations, were not statistically significantly associated with BPAR. We did not find an association between the Tac predose concentrations measured at five time points after kidney transplantation and the incidence of acute rejection occurring thereafter. Based on this study it is not possible to define the optimal target concentrations for Tac.

Prevention of acute and chronic allograft rejection by combinations of tolerogenic dendritic cells.

It is well known that adoptive transfer of donor-derived tolerogenic dendritic cells (DC) helps to reduce acute allograft rejection. However, this method cannot effectively prevent grafts from infiltration of inflammatory cells and fibrosis, and thus has minimal effect on chronic allograft rejection. In this study, we used mitomycin C (MMC) to generate tolerogenic DC and demonstrated that donor (Balb/c)-derived MMC-DC could induce hyporesponsiveness of recipient (C57BL/6) T cells in vitro, potentially by inducing T-cell apoptosis, decreasing IL-2 and IL-12 secretion, and increasing regulatory T-cell numbers and IL-10 secretion. Furthermore, anti-CD154 monoclonal antibody (mAb) treatment combined with donor-derived MMC-DC prolonged the survival of the allografts in vivo. The mechanisms were similar to those in vitro. Impressively, both acute and chronic rejection were prevented when donor and F1 generation (Balb/c × C57BL/6) derived MMC-DC were injected together with anti-CD154 mAb into recipients before heart allotransplantation. In summary, we showed that donor and F1-derived tolerogenic DC have a synergistic effect on induction and maintenance of T-cell regulation and the secretion of immunosuppressive cytokines. Moreover, adoptive transfer of these two types of DC could inhibit both acute and chronic transplant rejection in mice.

Small islets are essential for successful intraportal transplantation in a diabetes mouse model.

Optimization of islet transplantation protocols is necessary for improved success of treatment for type 1 diabetes. Here, we investigated whether the size of islets transplanted into the portal vein (PV) of the liver can affect engraftment in the early post-transplantation in an experimental mouse model. Small (average diameter < 250 µm, group A) or large (average diameter > 250 µm, group B) islets (400 islet equivalents/recipient) purified from normal BALB/c mice were transplanted into syngenic recipients with diabetes induced by STZ. The percentage of mice returning to a non-diabetic status was higher in group A (100%) than that of group B (62.5%). Focal areas of liver necrosis associated with the islets emboli were observed in both groups, but the pathology in group B was significantly worse. Multiple proinflammatory cytokines were significantly higher in group B than that of A at 3 h post-transplantation. Our study determined that the size of islets plays a critical role in the success of intraportal islet transplantation (IPIT) and should be taken into account in future IPIT protocols for the treatment of diabetes.

Effect of triple costimulation blockade on islet allograft survival in sensitized mice.

BACKGROUND: Islet allograft rejection in sensitized recipients is difficult to control by costimulation blockade using anti-CD154 and cytotoxic T-lymphocyte antigen-4 immunoglobulin (CTLA4Ig). Because leukocyte function antigen (LFA) 1 is highly expressed on memory T cells, adding an LFA-1 blockade may inhibit memory T-cell activities. We examined the effects on islet allograft survival of triple costimulation blockade in presensitized recipient mice. METHODS: C57BL/6 mice were sensitized by transplantation under the kidney capsule or intraperitoneal injection of Balb/c islets. Four weeks after transplantation, sensitization was confirmed by flow-cytometric detection of alloreactive antibodies. Diabetes was induced by a single intravenous injection of streptozotocin. Recipients were transplanted with 200 Balb/c islets under the right kidney capsule. Graft function was assessed by daily blood glucose and body weight records. Transplanted animals were divided into 3 treatment groups: group 1, control antibody; group 2, anti-CD154 and CTLA-4 Ig double therapy; group 3, anti-CD154, CTLA4Ig, and anti-LFA-1 triple therapy. Injections were administered every second day from day -2 to day 8. RESULTS: Naïve mice rejected islet allografts between days 7 and 29 (mean 16 +/- 6 d; n = 5), sensitized mice in group 1 between days 0 and 14 (mean 7 +/- 5 d; n = 8), in group 2 between days 4 and 16 (mean 8 +/- 4 d; n = 7), and in group 3 between days 4 and 26 (mean 11 +/- 7 d; n = 10). CONCLUSION: Triple costimulation blockade with anti-CD154, CTLA4Ig, and anti-LFA-1 was not sufficient to improve islet allograft survival in sensitized recipients.

KDIGO clinical practice guideline for the care of kidney transplant recipients: a summary

The 2009 Kidney Disease: Improving Global Outcomes (KDIGO) clinical practice guideline on the monitoring, management, and treatment of kidney transplant recipients is intended to assist the practitioner caring for adults and children after kidney transplantation. The guideline development process followed an evidence-based approach, and management recommendations are based on systematic reviews of relevant treatment trials. Critical appraisal of the quality of the evidence and the strength of recommendations followed the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach. The guideline makes recommendations for immunosuppression and graft monitoring, as well as prevention and treatment of infection, cardiovascular disease, malignancy, and other complications that are common in kidney transplant recipients, including hematological and bone disorders. Limitations of the evidence, especially the lack of definitive clinical outcome trials, are discussed and suggestions are provided for future research. This summary includes a brief description of methodology and the complete guideline recommendations but does not include the rationale and references for each recommendation, which are published elsewhere.

Subgroup analyses in randomized controlled trials: the need for risk stratification in kidney transplantation.

Although randomized controlled trials (RCT) are the gold standard for establishing causation in clinical research, their aggregated results can be misleading when applied to individual patients. A treatment may be beneficial in some patients, but its harms may outweigh benefits in others. While conventional one-variable-at-a-time subgroup analyses have well-known limitations, multivariable risk-based analyses can help uncover clinically significant heterogeneity in treatment effects that may be otherwise obscured. Trials in kidney transplantation have yielded the finding that a reduction in acute rejection does not translate into a similar benefit in prolonging graft survival and improving graft function. This paradox might be explained by the variation in risk for acute rejection among included kidney transplant recipients varying the likelihood of benefit or harm from intense immunosuppressive regimens. Analyses that stratify patients by their immunological risk may resolve these otherwise puzzling results. Reliable risk models should be developed to investigate benefits and harms in rationally designed risk-based subgroups of patients in existing RCT data sets. These risk strata would need to be validated in future prospective clinical trials examining long-term effects on patient and graft survival. This approach may allow better individualized treatment choices for kidney transplant recipients.

Calcineurin inhibitor minimization in the Symphony study: observational results 3 years after transplantation.

The Symphony study showed that at 1 year posttransplant, a regimen based on daclizumab induction, 2 g mycophenolate mofetil (MMF), low-dose tacrolimus and steroids resulted in better renal function and lower acute rejection and graft loss rates compared with three other regimens: two with low-doses of cyclosporine or sirolimus instead of tacrolimus and one with no induction and standard cyclosporine dosage. This is an observational follow-up for 2 additional years with the same endpoints as the core study. Overall, 958 patients participated in the follow-up. During the study, many patients changed their immunosuppressive regimen (e.g. switched from sirolimus to tacrolimus), but the vast majority (95%) remained on MMF. During the follow-up, renal function remained stable (mean change: -0.6 ml/min), and rates of death, graft loss and acute rejection were low (all about 1% per year). The MMF and low-dose tacrolimus arm continued to have the highest GFR (68.6 +/- 23.8 ml/min vs. 65.9 +/- 26.2 ml/min in the standard-dose cyclosporine, 64.0 +/- 23.1 ml/min in the low-dose cyclosporine and 65.3 +/- 26.2 ml/min in the low-dose sirolimus arm), but the difference with the other arms was not significant (p = 0.17 in an overall test and 0.077, 0.039 and 0.11, respectively, in pair-wise tests). The MMF and low-dose tacrolimus arm also had the highest graft survival rate, but with reduced differences between groups over time, and the least acute rejection rate. In the Symphony study, the largest ever prospective study in de novo kidney transplantation, over 3 years, daclizumab induction, MMF, steroids and low-dose tacrolimus proved highly efficacious, without the negative effects on renal function commonly reported for standard CNI regimens.

Cyclosporine sparing with mycophenolate mofetil, daclizumab and corticosteroids in renal allograft recipients: the CAESAR Study.

Although the calcineurin inhibitors (CNI) cyclosporine (CsA) and tacrolimus are highly effective immunosuppressants, they are associated with serious side effects. There is great interest in immunosuppressive regimens that permit reduction or elimination of CNIs, while maintaining adequate immunosuppression and acceptable acute rejection rates. Patients (n = 536) receiving their first renal allograft were randomized to one of three immunosuppressant regimens: daclizumab, mycophenolate mofetil (MMF), corticosteroids (CS) and low-dose CsA (target trough levels of 50-100 ng/mL), weaned from month 4 and withdrawn by month 6; daclizumab, MMF, CS and low-dose CsA; or MMF, CS and standard-dose CsA. Mean GFR 12 months after transplantation (primary end point) was not statistically different in the CsA withdrawal and low-dose CsA groups (both 50.9 mL/min/1.73 m(2)) vs. the standard-dose CsA group (48.6 mL/min/1.73 m(2)). At 12 months, the incidence of biopsy-proven acute rejection was significantly higher in the CsA withdrawal group (38%) vs. the low- or standard-dose CsA groups (25.4% and 27.5%, respectively; p < 0.05). In summary, a regimen of continuous low-dose CsA with MMF, CS and daclizumab induction is a clinically safe and effective immunosuppressive regimen in renal transplant recipients.

Combined costimulation blockade prevents rejection of allogeneic islets in mice.

There is a need for immunosuppressive protocols in islet transplantation that are neither nephrotoxic nor diabetogenic. We have examined blockade of the CD28-B7, CD40-CD40L and ICAM-LFA-1 pathways in a model of allogeneic islet transplantation in mice to determine the efficacy of this blockade in prolongation of graft survival. Histological evidences of inflammation and function were evaluated in grafts that had been functioning for 100 days. Treatment with a combination of all three drugs, or with CTLA4Ig and anti-CD40L, administered four times during the first six postoperative days, resulted in an excellent graft survival. All animals had a graft survival of >100 days (i.e. indefinitely). Mice treated with CTLA4Ig and anti-CD40L all showed well-preserved islets without signs of degeneration or destruction. There were no signs of rejection, as evidenced by the absence of infiltrating lymphocytes. This group had the least amount of rejection/inflammation changes according to ranking of all grafts. In conclusion, a short induction treatment with anti-CD40L and CTLA4Ig totally prevents rejection and preserves the allogeneic islets transplanted to mice. The addition of anti-LFA-1 did not confer any benefit.

Differential expression of tissue factor (TF) in calcineurin inhibitor-induced nephrotoxicity and rejection--implications for development of a possible diagnostic marker.

Deposition of fibrin in the form of fibrinoid necrosis is a common feature of severe acute renal allograft rejection. The role of the coagulation system and its initiator tissue factor (TF) during this process is, however, still poorly understood. In this study, we analyzed the expression of TF in 88 renal transplants afflicted with different forms of rejection and calcineurin inhibitor-induced nephrotoxicity, to see whether there was differential expression of this protein. TF immunoreactivity was evaluated semiquantitatively in six different renal structures: the podocytes, Bowman epithelium, the endothelium of the glomeruli, the brush border of tubular cells, the thin ascending loop of Henle, and small arteries/arterioles. The TF expression of normal renal tissue (n=6) was restricted to the glomerular podocytes and Bowman epithelium, and to some extent the ascending loop of Henle. Renal allografts undergoing acute rejection (AR) of grades I-III, (n=13, n=17 and n=12, respectively) did not show any altered TF expression in the glomeruli or vascular endothelium. In the ascending loop of Henle, a reduced expression could be seen (ARI, p=0.015; and ARII, p=0.043). TF staining of the brush border of renal transplants undergoing acute cyclosporin A (CsA) nephrotoxicity (n=18) was significantly higher than in normal kidneys (p=0.0003), as well as in transplants undergoing various degrees of acute rejection (ARI, p=0.027; ARII, p=0.0012; and ARIII, p=0.0001). Tubular brush border-expressed TF was also evident in 10 of 15 allografts suffering from chronic CsA nephrotoxicity, compared to 4 out of 13 cases with chronic allograft vasculopathy (CAV), but the increase was not statistically significant relative to normal kidneys. The majority of the grafts afflicted with either of the two chronic conditions displayed a TF-positive arterial endothelium (CAV, p=0.0034; and chronic CsA nephrotoxicity, p=0.0026) relative to controls. In conclusion, these results indicate that vascular TF expression is not altered during acute rejection, but may be of importance in chronic allograft nephropathy. Furthermore, TF immunoreactivity in the tubular brush border may be specific to acute CsA nephrotoxicity and might be used as a biomarker for this condition. Further studies are required to evaluate the possible role of brush border-expressed TF in the pathogenesis of CsA nephrotoxicity.

Additive effects of leflunomide and tacrolimus in prevention of islet xenograft rejection.

Leflunomide is a low molecular weight immunosuppressive drug which inhibits the enzymes dehydroorotate dehydrogenase and protein tyrosine kinase, both of which are important components in the immune response. As the mechanisms of action of leflunomide and tacrolimus are different, we postulated an additive or synergistic effect of the two drugs and investigated the effects of leflunomide alone, or in combination with a suboptimal dose of tacrolimus, on xenogeneic islet transplantation in a rat-to-mouse model. A total of 1200-1500 rat islets were transplanted under the left kidney capsule of streptozotocin-induced diabetic BALB/c mice. The median survival time (MST) of the untreated group was 6 days. Leflunomide at 5, 10 and 20 mg/kg/d administrated for 10 days significantly prolonged MST to 10, 16 and 20 days. A dose of tacrolimus (2 mg/kg/d) was associated with a graft survival of 9 (range 6-12) days; most grafts rejected during ongoing therapy. When tacrolimus (2 mg/kg/d) was combined with leflunomide (10 mg/kg/d), the survival time of the islet xenografts was increased further to 22 days, significantly longer than with leflunomide or tacrolimus alone. In summary, our findings demonstrate that leflunomide prolonged xenogeneic islet graft survival, and that its immunosuppressive effect was improved when combined with tacrolimus.

Renal replacement therapy in Sweden.

OBJECTIVE: The Swedish Registry for Active Treatment of Uraemia (SRAU) was founded in 1991 with the objective of documenting demographic data on patients treated for end-stage renal disease (ESRD). The aim of this study was to describe the prevalence, incidence, comorbidity risk factors and survival of patients with ESRD who underwent dialysis treatment and/ or kidney transplantation in Sweden between 1991 and 2002. MATERIAL AND METHODS: All dialysis and transplant units (n = 65) presently report to the SRAU and almost all patients are reported and followed until death. RESULTS: The prevalence of patients on dialysis and transplantation, being approximately 750 per million population (PMP), has increased by 75% in 12 years. The recent annual rise is approximately 3% (200 patients). The incidence has been stable since 1997 at approximately 125 patients PMP. In 2002, there were 1113 new patients, the majority of whom were aged > or =65 years. Their original kidney disease was most often diabetic nephropathy (23.7%), with nephrosclerosis (19.0%) being the second most common disease. The total number of renal transplantations performed has decreased to some extent. The overall 5-year patient survival rate was 23.1% in patients on dialysis and 85.5% after kidney transplantation. The major cause of death was cardiovascular disease (48%) and an increasing frequency of malignancy after transplantation (26%) was noted. CONCLUSION: The prevalence of ESRD has nearly doubled since 1990 and the number of new patients being referred for dialysis has increased. These patients are becoming older, with a large proportion having non-renal complicating diseases. Survival after transplantation was excellent. The shortage of cadaveric donors in Sweden in recent years and increasing mortality from malignant disease after transplantation are issues of great concern.

Linomide and antibody-targeted superantigen therapy abolishes formation of liver metastases in mice.

Hematogenous spread of tumor cells and metastasis formation in the liver are insidious aspects of cancer progression and are not frequently amenable to curative treatment. We examined the effect of Linomide and antibody-targeted therapy against the formation of hepatic metastases in vivo. For this purpose, syngenic B16 melanoma cells transfected with GA733-2 (a human colon cancer cell surface antigen) were injected into a mesenteric vein of C57/Bl6 mice. To test bacterial superantigen (Sag) targeting for immunotherapy of liver metastases, we used genetically fused proteins consisting of SEA and a Fab moiety of a GA733-2 tumor-reactive antibody (C215Fab-SEA). Linomide dose-dependently reduced hepatic metastases, and at 300 mg/kg this reduction was more than 80%. Treatment with C215Fab-SEA decreased metastases formation by 49% and the combination of Linomide and C215Fab-SEA was found to completely abolish liver metastases (>99% reduction). Taken together, our novel data suggest that Linomide and antibody-targeted superantigen therapy individually markedly reduce and together abolish liver metastases. Considering that current therapy of hepatic metastases is mainly limited to surgical resection in a subgroup of patients, these findings indicate that Linomide alone or in combination with antibody-targeted superantigen may provide a novel approach against liver metastases.

Two doses of daclizumab in conjunction with low-dose cyclosporine, mycophenolate mofetil and steroids resulted in a low incidence of acute rejection after renal transplantation.

Five doses of daclizumab, given initially after kidney transplantation, reduce the rate of acute rejection (AR). Without cyclosporin A (CsA), a protocol, including daclizumab, mycophenolate mofetil (MMF) and corticosteroids (CSs), has recently shown efficacy in terms of graft function and survival. The rate of AR was relatively high, however. In this single-centre study, a CsA low-dose regimen was combined with two doses of daclizumab (1 mg/kg day 0 and 14), plus MMF (2 g) and CS. Forty-three cadaver donor renal recipients were included. Following the onset of graft function, target trough levels of CsA were 150-200 ng/ml for 90 days, then 100-150 ng/ml. One year AR rate was 23% (n = 10) and events occurred at a median of 2.9 months (range from 9 days to 9.6 months). Delayed graft function (DGF) (absent spontaneous reduction of serum creatinine day 1) was 51%. Graft survival was 95% and patient survival 98% after 1 year. With respect to our previous experience, we used CsA, azathioprine and CSs (n = 223) from 1988 to 1995, and the rate of AR was 57%. From 1996 to 1998, standard CsA doses, MMF and CS (n = 67) resulted in 31% AR. Median time to AR was 0.8 and 1.0 month, and the rate of DGF was 20 and 22%, respectively. This CsA low-dose protocol, including two doses of daclizumab, MMF and CS, resulted in a reduction and delay of AR episodes and excellent graft function, graft survival and patient survival, despite an increase in DGF.

Dose optimization of mycophenolate mofetil when administered with a low dose of tacrolimus in cadaveric renal transplant recipients.

BACKGROUND: Supplementation of immunosuppressive therapy with mycophenolate mofetil (MMF) has been found to reduce the rate of acute rejection in renal transplantation. We report a dose-finding study for MMF when administered in combination with low-dose tacrolimus and corticosteroid prophylaxis in cadaveric renal transplant recipients. METHODS: Two hundred thirty-two patients at 16 centers were enrolled in this randomized, parallel-group study. The three treatment groups were tacrolimus and corticosteroids (MMF-0 group, n=82); tacrolimus, corticosteroids, and 1 g of MMF daily (MMF-1 g group, n=79); and tacrolimus, corticosteroids, and 2 g of MMF daily (MMF-2 g group, n=71). Study duration was 6 months, and patients were followed up for patient and graft survival for 12 months. RESULTS: At 6 months posttransplantation, daily doses of 1 g and 2 g of MMF were associated with significantly lower rates of acute rejection compared with tacrolimus alone. The Kaplan-Meier rates were 48.5%, 24.9%, and 22.9%, respectively, for the three treatment groups when acute rejection was determined by clinical criteria (P=0.007). At month 12, patient survival rates were 100%, 97.5%, and 97.2% and graft survival rates were 90.2%, 92.4%, and 93.0% for the MMF-0 group, MMF-1 g group, and the MMF-2 g group, respectively. Gastrointestinal adverse events and leukopenia were higher in the MMF groups, especially in the MMF-2 g group (P<0.05). CONCLUSIONS: Low-dose tacrolimus combined with a MMF dose of 1 g daily and corticosteroids provided an optimized efficacy and safety profile. A higher dose of MMF (2 g) was associated with greater toxicity without a significant improvement in efficacy.

Multicenter trial exploring calcineurin inhibitors avoidance in renal transplantation.

BACKGROUND: The adoption of calcineurin inhibitors (CNI) as the mainstay of immunosuppression has resuited in a significant decrease of acute rejection and improvement of short-term graft survival. However, because of the irreversible nephrotoxicity associated with the chronic use of the CNI, the magnitude of the improvement of long-term graft survival has been more modest. Therefore, an effective immunosuppression regimen that does not rely on CNI may result in improvement of long-term outcome and simplification of the management of transplant recipients. METHODS: Ninety-eight patients of primary cadaver or living donor kidneys at low immunologic risk were enrolled in a CNI avoidance study. The immunosuppression regimen consisted of daclizumab, a humanized monoclonal antibody that binds to the alpha chain of the interleukin-2 receptor (IL-2Ralpha), administered for a total of five doses at biweekly intervals; 3 gm/day mycophenolate mofetil for the first 6 month and 2 gm thereafter; and conventional corticosteroid therapy. Patients who underwent rejection episodes could be started on CNI. The primary efficacy end-point was biopsy-proven rejection during the first 6 months posttransplant. RESULTS: Biopsy-proven rejection was diagnosed in 48% of patients during the first 6 months after transplantation. The majority of rejection episodes were Banff grade I and IIA and were fully reversed with corticosteroid therapy. The median time to the first biopsy-proven rejection among patients who experienced this event during the first 6 months was 39 days. In 22 patients with delayed graft function, the proportion of patients with biopsy-proven rejection was 50% at 6 months. However in the first 2 weeks posttransplant, only 1 of 22 patients with delayed graft function developed biopsy-proven rejection. At 1 year, patient survival was 97% and graft survival was 96%. Only two grafts were lost secondary to rejection. At 1-year posttransplant, 62% of patients had received CNI for more than 7 days. At 1-year posttransplant, the mean serum creatinine in the nonrejectors with no CNI use was 113 micromol/L (95%, confidence interval [CI], 100.7 to 125.3 micromol/L) and in the rejectors or patients with CNI use (more than 7 days) was 154 micromol/L (95% CI, 135.0 to 173.0 micromol/L). In selected patients with rejection, analysis of circulating and intragraft lymphocytes revealed complete IL-2Ralpha saturation. CONCLUSIONS: This CNI avoidance study in immunologic low-risk patients, while only partially successful in preventing acute rejection, provided benefits to a sizable minority of patients who have not required chronic CNI therapy. However, wide acceptance of a CNI-sparing immunosuppression regimen may require a lower rate of acute rejection, possibly through the addition of a non-nephrotoxic dose of CNI. However, because complete IL-2Ralpha blockade was present during rejection, it can be assumed that alternative pathways, such as IL-15, may be responsible for the rejection; thus, the incorporation of non-nephrotoxic immunosuppressive agents, such as sirolimus, may provide a more strategic approach.