Comparison between a two-drug regimen with tacrolimus and steroids and a triple one with azathioprine in kidney transplantation: results of a European trial with 3-year follow up

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.

Safety of immunosuppressive drugs used as maintenance therapy in kidney transplantation: a systematic review and meta-analysis

To evaluate the safety of regimens containing calcineurin inhibitors (CNI), proliferation signal inhibitors (TOR-I) and antimetabolites, we conducted a meta-analysis of randomized clinical trials (RCTs) and observational studies. A total of 4,960 citations were identified in our electronic search and 14 additional articles were identified through hand searching. Forty-eight articles (11,432 participants) from 42 studies (38 RCTs and four cohorts) met the inclusion criteria. Meta-analysis results revealed the following: (i) tacrolimus was associated with an increased risk for diabetes and lower risk of dyslipidemia, compared to cyclosporine; (ii) mycophenolate mofetil (MMF) was associated with increased risk for total infections, abdominal pain, diarrhea and vomiting, compared with azathioprine; (iii) sirolimus was associated with higher risk of anemia, diabetes, dyslipidemia, lymphoceles and withdrawal compared to tacrolimus or cyclosporine, and cyclosporine was associated with an increased risk of CMV infection; (iv) the combination of CNI with antimetabolites was associated with more adverse events than CNI alone; (v) TOR-I was related to more adverse events than MMF. The data observed in this meta-analysis are similar to those describe by others authors; thus, the choice of treatment must be made by the clinical staff based on specific patient characteristics.

Long-term outcome of ATG vs. Basiliximab induction

BACKGROUND

An evaluation of the long-term efficacy and incidence of adverse events after induction therapy with antithymocyte globulin (ATG) vs. Basiliximab in renal transplant patients.

METHODS

Sixty recipients receiving ATG induction and a dual immunosuppression with Tacrolimus and steroids were compared retrospectively with 60 patients treated with Basiliximab. The following characteristics were evaluated: concomitant immunosuppression, recipient age, donor age, time on dialysis, cold ischemia time, year of transplantation and HLA mismatches.

RESULTS

The 6-year patient survival in the ATG group was 91·7% compared to 85% in the Basiliximab group (not significant, n.s.). Graft survival at 6 years was 89·7% and. 83·6% in the ATG and the Basiliximab group (n.s.), respectively. Incidence of biopsy proven acute rejection episodes (33·3% vs. 26·7%) and delayed graft function (30% vs. 33·3%) were similar in both groups. Kidney function was not significantly different at 1 and 6 years. CMV infections were more prevalent in the ATG arm (22% vs. 5%; P = 0·05), and a significantly higher rate of haematological complications was observed following ATG induction.

CONCLUSIONS

ATG induction was associated with an improved (but n.s.) trend in patient and graft survival. Patients induced with ATG had a higher rate of CMV infections and haematological complications.

Three-year follow-up of malignancies in tacrolimus-treated renal recipients--an analysis of European multicentre studies

Five prospective, multicentre adult renal studies of three yr duration conducted in Europe for which tacrolimus was used as the primary immunosuppressant in at least one treatment arm was identified. This was confirmed by literature review as the only source fulfilling these criteria. Our goal was to identify absolute (reported) incidences of malignancies in patients exposed to tacrolimus and relative rates as a proportion of the total malignancies recorded for three yr after transplant. The five studies provided 2435 patients in nine different treatment regimens. All regimens combined tacrolimus with azathioprine or mycophenolate mofetil and corticosteroids except for one regimen which also employed daclizumab without corticosteroids. There were 83 patients with malignancies or 3.4% of the total population. No patient experienced more than I malignancy type. Malignancy incidences relative to those patients experiencing a malignancy were: total skin 37.3%, lymphoma 15.7%, and non-skin-non-lymphoma 47.0%. Annual occurrence of all malignancies reflected a progressive increase with time. While the larger proportion of lymphoma and non-skin-non-lymphoma malignancies occurred during the first year after transplant, malignancies affecting the skin increased more linearly with time. These findings are consistent with reports in the literature, reflect the current established experience with tacrolimus to date, and should provide a robust basis for future comparisons with tacrolimus-based immunosuppression.

Spanish experience with cyclosporine

Our experience with cyclosporine (CsA) in de novo renal transplantation (RT) may be systematized in four consecutive periods. From February 1986 to December 1989, patient survival was higher among 128 consecutive CsA-prednisone-treated cadaver allograft recipients than in previous patients on azathioprine. One-year graft survival was significantly higher in CsA patients, a difference that was thereafter progressively reduced: at 10 years graft survivals were 50% versus 45%, and at 15 years 37% versus 35%, respectively. The most frequent cause of graft loss was death with a functioning graft. Acute rejection caused more graft losses among Aza-treated patients than CsA-treated ones. However, chronic allograft nephropathy produced more graft losses in CsA patients. After this initial experience with CsA-based immunosuppression we developed a second phase in which better results were obtained in 209 first cadaveric RT recipients. The use of lower initial CsA doses, more rapid steroid tapering, and a better approach to CsA nephrotoxicity or chronic nephropathy by substantial reductions in CsA exposure and delayed azathioprine addition, lead to these improvements. From March 1995 through 2000, we used the new microemulsion CsA formulation (Neoral) with steroids or azathioprine in 110 first de novo RT recipients. Mean donor and recipient ages were significantly higher in this phase than in previous ones; consequently, survival and function results were slightly worse. Blood CsA concentrations measured 2 hours after administration represent a more precise predictor of exposure than trough concentrations. The last step in optimizing Neoral use in RT on our service was application of reduced-dosage with C2 monitoring instead of classical C0 testing. Acute rejection and treatment failure rates were low and renal allograft function improved with respect to previous full-dose C0 experiences. CsA use has evolved in these two decades in four consecutive phases. Short-term results have improved or been maintained from phase to phase, even with expanded-criteria donors until excellent features during last years with C2 monitoring and combination with potent drugs such as MMF or everolimus. During the coming years, new drugs and protocols will allow even more optimized use.

Immunosuppression for Long-Term Maintenance of Renal Allograft Function

The incidence and severity of acute rejection episodes was markedly reduced by the introduction of new immunosuppressive drug regimens for renal transplantation, resulting in improved graft survival at 1 year. However, only modest improvement has been shown in long-term graft function rates. This overview evaluates the efficacy of currently used immunosuppressive drugs and drug combinations for long-term maintenance therapy. Prospective controlled trials rarely extend beyond 5 years; therefore, registry data and retrospective reports have also been employed. From currently available data it may be concluded that the initial beneficial effect of ciclosporin (cyclosporin) is lost 10 years after transplantation. Tacrolimus is an alternative to ciclosporin with a different profile of adverse effects and a higher efficacy in acute rejection treatment. For long-term maintenance, projected half-lives of kidney graft function are in favour of tacrolimus. Mycophenolate mofetil (MMF) has been shown to significantly reduce the incidence of early rejections. However, the improved long-term graft survival reported in retrospective studies has still to be confirmed in controlled trials. There is no convincing evidence for superiority of triple therapy including prednisone (or prednisolone), calcineurin inhibitors and azathioprine/MMF over dual therapy without azathioprine/MMF with respect to long-term outcome. Withdrawal of corticosteroids or calcineurin inhibitors clearly reduces adverse drug effects but carries the risk of acute rejection episodes. Avoidance of corticosteroids by using new immunosuppressive drug combinations may be an option to minimise toxic adverse effects in the future. At present, it seems unjustified to convert renal transplant recipients with stable graft function and tolerable adverse effects from one drug to another solely in expectation of future benefits. Acute early or late rejection episodes and intolerable adverse effects are good reasons for conversions between calcineurin inhibitors or cytotoxic agents. Chronic allograft nephropathy with slowly deteriorating graft function remains an unresolved problem.