Kazuya Isogai

Comparative study of the cellular pharmacodynamics of tacrolimus in renal transplant recipients treated with and without basiliximab.

Basiliximab is a recently developed immunosuppressive agent for the prevention of acute allograft rejection in renal transplant recipients. The combination use of basiliximab and a calcineurin inhibitor was suggested to be more effective in comparison to immunosuppressive therapy using calcineurin inhibitor without basiliximab. Cyclosporine has been generally administered with basiliximab for renal transplant recipients. However, in cases of tacrolimus-based immunosuppressive regimen, the clinical efficacy and safety of combined use of tacrolimus and basiliximab remains to be elucidated. This study evaluated the tacrolimus pharmacological efficacy using a lymphocyte immunosuppressant sensitivity test (LIST) with MTT assay procedures in 16 cases of renal transplant recipients treated by tacrolimus without basiliximab and in 13 cases treated by tacrolimus in combination with basiliximab. The rate of acute rejection episodes in the recipients treated with tacrolimus plus basiliximab was 1/13 (7.7%), whereas the rate in the recipients treated with tacrolimus without basiliximab was 6/16 (37.5%). The recipients were divided into two groups according to their peripheral blood mononuclear cell (PBMC) sensitivity to tacrolimus [i.e., including a tacrolimus high sensitivity group (IC50 <1.0 ng/ml) and a low sensitivity group (IC50 >1.0 ng/ml). In the recipients treated with tacrolimus without basiliximab, the rate of acute rejection episodes in the tacrolimus high sensitivity group was 1/10 (10.0%), which was significantly lower than the rate in the low sensitivity group of 5/6 (83.3%; p = 0.008). The incidence of cytomegalovirus infection was not significantly different between the tacrolimus high and the low sensitivity groups of the recipients treated with tacrolimus with and without basiliximab. Therefore, in the case of selected tacrolimus-based immunosuppressive therapy for renal transplant recipients, the tacrolimus pharmacological efficacy should be evaluated using LIST at a time just before the transplant procedure in order to accurately predict allograft rejection. The data also suggested that low tacrolimus sensitivity recipients should be treated with tacrolimus-based immunosuppressive therapy in combination with basiliximab.

Correlation between the pharmacological efficacy of cyclosporine and tacrolimus as evaluated by the lymphocyte immunosuppressant sensitivity test (LIST) and the MTT assay procedure in patients before and after renal transplantation.

OBJECTIVES Cyclosporine and tacrolimus are calcineurin inhibitors that are used to prevent acute rejection in renal transplant recipients. The lymphocyte immunosuppressant sensitivity test (LIST) can predict the pharmacological efficacy of these immunosuppressive agents for renal transplant recipients. There is a correlation between cyclosporine and tacrolimus pharmacological efficacy as evaluated by LIST by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay procedure prior to renal transplantation. However, the LIST can also evaluate patients before and after the transplantation. MATERIALS AND METHODS The present study examined the relationship between cyclosporine and tacrolimus pharmacological efficacy by LIST using the MTT assay in 16 renal transplant recipients at 1, 3 and 12 months after transplantation, as well as before the operation. RESULTS The relationship of cyclosporine and tacrolimus pharmacological efficacy gave a significant Kendall and Spearmans coefficient correlation in these transplant recipients by the LIST using the MTT assay procedure immediately prior to renal transplantation (rk = 0.711, rs = 0.877, p < 0.01). Furthermore, correlations between the cyclosporine and tacrolimus IC50 values were also observed with a significant Kendall and Spearmans coefficient correlation at 1 and 12 months after transplantation (rk1month = 0.65, rs1month = 0.829, p < 0.01, and k12month = 0.433, rs12month = 0.603, p < 0.01, respectively). However, no statistically significant relationship was observed between the pharmacological efficacies of the calcineurin inhibitors at 3 months after transplantation (rk3month = 0.117, rs3month = 0.1, p > 0.05). CONCLUSIONS Both cyclosporine and tacrolimus exhibit pharmacological efficacy by the inhibition of calcineurin. However, the correlation between cyclosporine and tacrolimus pharmacological efficacies may be altered, due to immunosuppressive therapy or clinical events at 3 months after renal transplantation.

Cyclosporine pharmacological efficacy estimated by lymphocyte immunosuppressant sensitivity test before and after renal transplantation

Objective:  Lymphocyte immunosuppressant sensitivity test (LIST) is useful for predicting the pharmacological efficacy of immunosuppressive agents. In this study, the pharmacological efficacy of cyclosporine was estimated by LIST before and after renal transplantation.

Clinical Significance of the Pharmacological Efficacy of Tacrolimus Estimated by the Lymphocyte Immunosuppressant Sensitivity Test (LIST) before and after Renal Transplantation

The lymphocyte immunosuppressant sensitivity test (LIST) with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay procedure can predict the pharmacological efficacy of immunosuppressive agents. A previous study reported the pharmacological efficacy of tacrolimus evaluated by LIST just before renal transplantation significantly correlated with the incidence of acute rejection episodes. However, the pharmacological efficacy of tacrolimus has not been estimated after renal transplantation. Therefore, the present study evaluated the pharmacological efficacy of tacrolimus by LIST using the MTT assay procedure before and 1, 3, and 12 months after transplantation in 17 renal transplant recipients that received tacrolimus-based immunosuppressive therapy. The tacrolimus pharmacological efficacies before and after the procedure were also compared with incidence of acute rejection and cytomegalovirus (CMV) infection episodes. The individual values of tacrolimus 50% inhibition of lymphocyte proliferation (IC50) varied widely before transplantation, and the mean value of the IC50 was 126.4 ± 337.7 ng/ml. The patients were divided into two groups according to the tacrolimus IC50 values evaluated before transplantation. The rate of acute rejection episodes in the tacrolimus high-sensitivity group was significantly lower than that in the tacrolimus low-sensitivity group (p = 0.005). The tacrolimus IC50 deviation between patients expanded further at one and three months after surgery. However, the sensitivity deviation almost converged at 1 year after surgery. Moreover, the pharmacological efficacy of tacrolimus evaluated at 1, 3, and 12 months after transplantation did not significantly correlate with the incidence of acute rejection episodes. The pharmacological efficacies of tacrolimus evaluated at both before and after surgery were not significantly correlated with the episodes of CMV infection. These findings suggest that the pharmacological efficacy of tacrolimus evaluated with LIST before surgery is a useful biomarker for predicting the occurrence of acute allograft rejection in renal transplantation.

The pharmacological efficacy of mycophenolic acid before and after renal transplantation as estimated by the lymphocyte immunosuppressant sensitivity test (LIST)

The lymphocyte immunosuppressant sensitivity test (LIST) can predict the pharmacological efficacy of immunosuppressive agents. We herein estimated the mycophenolic acid efficacy using LIST before and 1, 3, and 12 months after the operation in 15 renal transplant recipients. The pharmacological efficacy of mycophenolic acid as assessed before transplantation showed small individual variations, whereas the variability greatly increased at 1 and 3 months after transplantation. Furthermore, the individual IC50 variation among these subjects at 1-year after operation was closely similar to that observed before surgery. No significant implications of these individual differences in the mycophenolic acid sensitivity were noted in regard to the clinical courses of these recipients.

Relationship between the Peripheral Lymphocyte Response to Mycophenolic Acid in vitro and the Level of ATP in Peripheral CD4+ Lymphocytes before and after Renal Transplantation

OBJECTIVE The lymphocyte immunosuppressant sensitivity test has been used to predict the pharmacodynamics of immunosuppressive drugs for the purpose of preventing acute rejection and infection after renal transplantation. On the other hand, measuring the ATP levels in peripheral CD4+ lymphocytes is also able to monitor the risks of rejection and infection in transplant recipients. In the present study, we examined the relationship between the mycophenolic acid pharmacodynamics and the ATP levels in peripheral lymphocytes before and after renal transplantation. METHODS We examined both the pharmacological efficacy of mycophenolic acid and the lymphocyte ATP levels before and 2, 4 and 6 weeks after the operation in 20 renal transplant recipients. The drugs pharmacological efficacy was evaluated by the 50% inhibitory concentration of the drug against the in vitro proliferation of peripheral blood lymphocytes activated by T cell mitogen. The ATP levels in peripheral CD4+ lymphocytes were measured by the Immuknow assay kit. The relationships between the mycophenolic acid pharmacodynamics and ATP levels in peripheral lymphocytes were examined in these recipients. RESULTS The immunosuppressive effects of mycophenolic acid against mitogen-activated lymphocyte proliferation were significantly and positively correlated with the lymphocyte ATP levels, but only at 6 weeks after transplantation. The relationship was not significant before or at 2 or 4 weeks after the operation. CONCLUSION Our present data raised the possibility that evaluating the pharmacological efficacy of mycophenolic acid pre-transplantation and monitoring the ATP level 6 weeks after transplantation can predict the risk of rejection and/or infection in renal transplant recipients.

Peripheral Lymphocyte Response to Mycophenolic Acid In Vitro and Incidence of Cytomegalovirus Infection in Renal Transplantation.

The lymphocyte immunosuppressant sensitivity test (LIST) with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay procedure has been used to predict the pharmacological efficacy of immunosuppressive agents to prevent acute rejection episodes for renal transplant recipients. In this study, mycophenolic acid (MPA) pharmacological efficacies were evaluated by LIST at both prior to and just after renal transplantation. We compared the efficacies to the clinical outcome of these recipients. MPAs pharmacological efficacy was evaluated by LIST not only before the operation but also at 2, 4, and 6 weeks after transplantation in 16 renal transplant recipients. These recipients were divided into high- and low-sensitivity groups according to peripheral blood mononuclear cell (PBMC) sensitivity to MPA in vitro. The MPA sensitivities were compared to cytomegalovirus (CMV) infection and acute rejection episodes in these recipients under MPA immunosuppressive therapy. The rate of CMV infection episodes in the low-MPA pharmacological efficacy group categorized at 2 weeks after renal transplantation was 5/6 (83.3%), which was significantly higher than the rate of 1/10 (10.0%) (p < 0.01) in the high-MPA sensitivity group. However, the MPA pharmacological efficacy evaluated both before and after transplantation had no relationship with the incidence of rejection episodes. These findings suggest that the MPA pharmacological efficacy evaluated by LIST at 2 weeks after operation is a useful biomarker for predicting the following occurrence of CMV infection episodes in renal transplant recipients.