Comparison of low versus high tacrolimus levels in kidney transplantation: assessment of efficacy by protocol biopsies

BACKGROUND: The use of calcineurin inhibitors is generally guided by drug blood levels. However, those levels are chosen based on clinical experience, lacking adequate titration studies. METHODS: In these analyses, we compared clinical and histologic endpoints in two groups of kidney transplant recipients: in the first (HiTAC, January 2000 to June 2002, n=245) tacrolimus levels were significantly higher than in the second (LoTAC, July 2002 to September 2004, n=330). This change in drug levels (15% reduction) was made in an attempt to reduce the incidence of polyoma virus nephropathy (PVAN). Other immunosuppressive medications were unchanged during these two time periods. RESULTS: The recipient and donor demographics were not statistically different between the two groups. Compared to HiTAC, at one year posttransplant LoTAC had: 1) lower incidence of PVAN (10.5% vs. 2.5%, P<0.0001); 2) lower fasting glucose levels; 3) higher iothalamate glomerular filtration rate (52+/-19 vs. 59+/-17 ml/min/m, P<0.0001); and 4) on protocol one-year biopsies, lower incidence and severity of interstitial fibrosis (67% vs. 45%, P=0.003) and tubular atrophy (82% vs., 66%, P=0.01). The incidence and severity of acute rejection episodes was similar between both groups (7.8% versus 7.6%). CONCLUSIONS: Modest reductions in tacrolimus exposure early posttransplant are associated with significant beneficial effects for the patient and the allograft without an increased immunologic risk.     

采用程序化肾活检评估肾移植后低水平和标准水平他克莫司的疗效

目的以程序化肾活检评估低水平与标准水平他克莫司(FK506)的免疫抑制方案的疗效及其安全性。方法采用前瞻性、开放、随机对照研究,将48例首次接受尸体肾移植受者按随机数字分为两组:低水平FK506组(低FK506组,24例)和标准水平FK506组(标准FK506组,24例)。两组患者均采用麦考酚吗乙酯(MMF)+FK506+肾上腺皮质激素(激素)的三联免疫抑制方案,两组的MMF与激素用法相同。标准FK506组的FK506血药谷浓度:在入组后前3个月维持在10～12 ng/ml,3个月后维持在8～10 ng/ml。低FK506组的FK506血药谷浓度:入组后头2个月为8～10 ng/ml,第3个月为3～7 ng/ml,3个月后为3～5 ng/ml。术后定期随访1年,内容包括测定FK506血药谷浓度,检测肾功能[血清肌酐(Scr)、内生肌酐清除率(endogenous creatinine clearancerate,Ccr)]、空腹血糖、糖化血红蛋白、血清白蛋白、血脂。同时于术后3个月和12个月予以程序化移植肾活组织检查(活检),了解急性排斥反应(AR)发生情况、病理损伤指标评分及慢性移植物损伤指数(chronic allograft damage index,CADI)变化。观察术后1年的人、肾存活率及不良事件发生情况。结果移植术后1年,与标准FK506组比较,低FK506组:(1)FK506血药谷浓度较低(P<0.01),且达到目标水平的患者所占比例较高;(2)Ccr水平较高,(83±14)ml/min比(62±16)ml/min,P<0.05;(3)血糖水平较低(P<0.05);(4)根据程序化肾活检的结果,间质纤维化、肾小管萎缩和肾小球硬化评分较低(均为P<0.05);(5)AR发生率及其严重程度相似,术后1年人、肾存活率相近,均为100%(均为P>0.05)(6)术后1年的肺部感染与新发糖尿病的发生率较低(分别为P<0.05和P<0.01)。结论采用程序化肾活检评估疗效结果可靠,并有助于发现移植肾的慢性化改变,移植术后早期适度降低FK506血药谷浓度对于移植肾和患者均有较大益处,且不增加发生排斥反应的风险。     

Randomized trial of tacrolimus versus cyclosporin microemulsion in renal transplantation

This study was undertaken to compare the efficacy and safety of tacrolimus (Tac) with the microemulsion formulation of cyclosporin (CyA) in children undergoing renal transplantation. A 6-month, randomized, prospective, open, parallel group study with an open extension phase was conducted in 18 centers from nine European countries. In total, 196 pediatric patients (<18 years) were randomly assigned (1:1) to receive either Tac (n=103) or CyA microemulsion (n=93) administered concomitantly with azathioprine and corticosteroids. The primary endpoint was incidence and time to first acute rejection. Baselinecharacteristics were comparable between treatment groups. Tac therapy resulted in a significantly lower incidence of acute re-jection (36.9%) compared with CyA therapy (59.1%) (P=0.003). The incidence of corticosteroid-resistant rejection was also significantly lower in the Tac group compared with the CyA group (7.8% vs. 25.8%, P=0.001). The differences were also significant for biopsy-confirmed acute rejection (16.5% vs. 39.8%, P<0.001). At 1 year, patient survival was similar (96.1% vs. 96.6%), while 10 grafts were lost in the Tac group compared with 17 graft losses in the CyA group (P=0.06). At 1 year, mean glomerular filtration rate (Schwartz estimate) was significantly higher in the Tac group (62±20 ml/min per 1.73 m², n=84) than in the CyA group (56±21 ml/min per 1.73 m², n=74, P=0.03). The most frequent adverse events during the first 6 months were hypertension (68.9% vs. 61.3%), hypomagnesemia (34.0% vs. 12.9%, P=0.001), and urinary tract infection (29.1% vs. 33.3%). Statistically significant differences (P<0.05) were observed for diarrhea (13.6% vs. 3.2%), hypertrichosis (0.0% vs. 7.5%), flu syndrome (0.0% vs. 5.4%), and gum hyperplasia (0.0% vs. 5.4%). In previously non-diabetic children, the incidence of long-term (>30 days) insulin use was 3.0% (Tac) and 2.2% (CyA). Post-transplant lymphoproliferative disease was observed in 1 patient in the Tac group and 2 patients in the CyA group. In conclusion, Tac was significantly more effective than CyA microemulsion in preventing acute rejection after renal transplantation in a pediatric population. The overall safety profiles of the two regimens were comparable. Received: 1 October 2001 / Revised: 25 October 2001 / Accepted: 15 November 2001     

Differences between cyclosporin A and tacrolimus in organ transplantation.

In addition to their effect on the TCR-mediated signal transduction, both CyA and tacrolimus affect a wide variety of other biological processes, including induction of cell exocytosis and side effects. Although calcineurin has been implicated directly or indirectly in many of these processes, it seems plausible that the mechanisms by which these two drugs exert their full immunosuppressive activity are not necessarily the same. The cellular and molecular networks under differential immunosuppression by these two drugs remain to be explored. However, considering that investigations in this area are still ongoing, the answers will undoubtedly be available in the not too distant future.     

Use of tacrolimus in renal transplantation

Tacrolimus is a very potent drug for preventing all types of acute rejection after renal transplantation. The decrease of vascular rejection may have important long-term implications. This is demonstrated in the 3-year data of the U.S. multicentre trial, where a significant decrease of graft loss was observed in the tacrolimus patients compared to cyclosporine patients. Safety profiles of both drugs are the same, but there are some major differences in side effects. Hyperglycemia is more common during tacrolimus, but generally the induction of hyperglycemia is a dose-dependent reversible process, which leads generally to diabetes mellitus during high systemic exposure, in certain races and prediabetics. Gum hyperplasia and hirsutism are not seen during tacrolimus therapy and there is a more favorable cardiovascular risk profile during tacrolimus as compared to cyclosporine based immunosuppression.     

Steroid avoidance in renal transplantation using basiliximab induction, cyclosporine-based immunosuppression and protocol biopsies

BACKGROUND: Reducing chronic steroid exposure is important to minimize steroid-related morbidity, particularly for susceptible renal transplant recipients. Steroid-free and steroid-sparing protocols have shown benefits, but safety has not been established for all populations. We investigated the safety of steroid avoidance (SA) in a population including African-Americans, using modern immunosuppression with protocol biopsy monitoring. METHODS: A randomized-controlled SA trial (early discontinuation, days 2-7) was conducted in a population (n = 77) including African-Americans and cadaveric kidney recipients. Patients received basiliximab, cyclosporine (CsA), and mycophenolate mofetil (MMF). In controls, steroids were tapered to 5 mg prednisone/d by day 30. Protocol biopsies were performed (1, 6, 12 and 24 months) to evaluate subclinical acute rejection (SCAR) and chronic allograft nephropathy (CAN). RESULTS: The SA did not result in significantly higher incidences of graft loss, AR, SCAR, CAN, or renal fibrosis. SA patients experienced similar renal function, comparable serum lipid levels, and a trend toward fewer cases of new-onset diabetes. Clinical outcomes of African-American and non-African-American patients did not significantly differ. CONCLUSIONS: The SA is safe in the context of basiliximab induction and CsA-based immunosuppression. This protocol could minimize steroid-related side effects in susceptible groups, including African-Americans, without increasing the risk of AR or graft failure.     

Hypertrichosis and gingival hypertrophy regression in renal transplants following the substitution of cyclosporin by tacrolimus

Gingival Hyperplasia (GH) and hypertrichosis (HT) are two sides effects associated with the usage of cyclosporine (CyA) but not with tacrolimus (FK 506). The aim of this study is to evaluate the efficacy and security of the conversion from CsA to FK 506 to treat those two complications. From August 1996 to May 1997, 15 patients (9 males, 6 females) aged from 23 to 63 years old (38 +/- 14, mean +/- SD) were switched from CsA to FK 506, 12 for GH, 2 for HT and one for combined presentation. FK 506 was first initiated at a dose of 0.15 mg/kg/day and then adjusted to a level target of 8 ng/ml. The conversion was done on an out patient basis at average 35 (5-83) months after transplantation. Patients were followed prospectively for 12 months. There was a significant reduction in GH in all patients within 3 months. Five out 13 patients had a complete resolution of GH within three months of conversion, 9/12 within 6 months and all by 12 months. HT resolved completely within 6 months. No rejection episode occurred and the serum creatinin remain stable over one year post conversion. Conversion from CsA to FK 506 is thus a safe and valid option to treat CsA induced GH and HT.     

Low-dose tacrolimus (FK506)-based immunosuppressive protocol in living donor renal transplantation

Abstract In order to avoid the side effects of tacrolimus (FK506), a low-dose FK506-based regimen was started from 1 June 1991. The dose was adjusted to maintain the FK506 whole blood trough level at 15–20 ng/ml for 7 days postoperatively, at 10–15 ng/ml for 2 months, and under 10 ng/ml thereafter. The graft survival rates at 3 years and 5 years were 87.8 and 82.3 % (FK506) vs 86.8 and 86.8% [cy-closporine (CyA)]. The incidence of acute rejection within the first 90 days was 31.6% in the FK506 group which was lower than the 57.1% of the CyA group ( P - 0.0585). Grades of acute rejection episodes over IIA in the FK506 group were 20 %, which was lower than the 37 % in the CyA group. The mean oral dosages of FK506 were 0.061 and 0.04 mg/kg per day at 3 and 5 years, respectively. The incidence of new onset diabetes was 27.8% in the FK506 group and 17.1 % in the CyA group. However, insulin therapy was withdrawn in all patients of the FK506 group within 5 months. The percentage of patients who required an antihypertensive agent was 28.6 % and 40 % in the FK506 group and 73.2% and 88 % in the CyA group at 1 and 3 years, respectively ( P < 0.05). Nephrotoxicity was seen in 20% of the FK506 group and 14.3 % of the CyA group. Hypercholesterolemia was less frequent in the FK506 group than the CyA group. The FK506-based regimen described here is a protocol with the potential to reduce its adverse effects. The whole blood concentration of FK506 should be monitored and blood levels maintained in the range of 5–10 ng/ml after 90 postoperative days for optimal efficacy and minimal toxicity.     

Interstitial fibrosis and tubular atrophy on protocol biopsies at 1 year after renal transplantation

Background

Advancements in immunosuppressive therapy have enabled control of early acute rejection and improved long-term kidney transplantation (KT) survival. Chronic histopathologic changes influence graft survival rate. We examined tubulointerstitial changes at 1 year after KT, focusing on the progression of interstitial fibrosis and/or tubular atrophy (IF/TA).

Methods

Using the Banff' 07 classification, we assessed the histological findings obtained at 1 year after transplantation of 38 patients who underwent the procedure between January 2008, and March 2010. In 24 cases, we obtained scores for interstitial fibrosis (ci) >1 and/or tubular atrophy (ct) > 1. We classified the patients into two groups, namely, less than borderline changes (BCs) (t0, i0, or i1; group A) versus BCs and above (t > 1, i2, or i3; group B). We compared their baseline data, renal function, and pathological scores.

Results

The mean serum creatinine levels were 1.06 mg/dL for group A and 1.32 mg/dL for group B. The “ct” grading according to the Banff' 07 classification was 0.83 for group A and 1.50 for group B (both P < .05). No significant difference was observed with respect to the percentage of patients with IF/TA (Banff category 5).

Conclusion

Patients more within 1 year after KT with BCs who show irreversible tubular atrophy by biopsy experience impaired renal function. The presence of BC at the first year may not be associated with IF/TA.     

The use of tacrolimus in renal transplantation

Summary Tacrolimus (FK 506) is a novel immunosuppressive agent that has been in clinical use for solid organ transplantation since 1989. Early clinical trials of tacrolimus in liver, heart, kidney, lung, and intestinal transplantation at the University of Pittsburgh have demonstrated it to be a safe and effective agent with several potential advantages over existing immunosuppressive drugs. More recently, phase I and II multicenter trials of tacrolimus for renal transplantation have been performed; however, data are not yet available from these trials. Our experience with this drug has demonstrated excellent 1- and 2-year actuarial graft survival rates of 89% and 83%, respectively, in adult renal transplantation and 1- and 3-year graft survival rates of 98% and 85%, respectively in pediatric renal transplantation. A major advantage of tacrolimus noted in these trials was the ability to discontinue steroid therapy in approximately 50% of the patients. Tacrolimus has also shown efficacy as a rescue agent for renal allograft rejection failing conventional therapy in 74% of cases. This paper expands on these observations and focuses on the experience we have gained with the use of tacrolimus at our institution over the last 6 years.     

Efficacy and safety of tacrolimus compared with cyclosporin A microemulsion in renal transplantation: 2 year follow-up results.

BACKGROUND: Comparison studies of calcineurin inhibitors as cornerstone immunosuppressants in renal transplantation have demonstrated that tacrolimus consistently reduces acute rejection rates and, in some studies, also improves long-term renal outcome in comparison to cyclosporin A (CsA). The aim of the present 2 year follow-up of the European Tacrolimus vs Cyclosporin A Microemulsion Renal Transplantation Study was to investigate long-term clinical outcome in terms of rate of acute rejection, graft and patient survival and graft function. METHODS: The European Tacrolimus vs Cyclosporin A Microemulsion Renal Transplantation Study was a randomized, comparative 6 month trial of the calcineurin inhibitors tacrolimus and CsA in combination with both azathioprine and steroids. The intent-to-treat population (ITT) consisted of 286 patients in the tacrolimus arm and 271 in the CsA microemulsion (CsA-ME) arm. Whereas whole blood level targets were 10-20 and 5-15 ng/ml for tacrolimus and 100-400 and 100-200 ng/ml for CsA during months 0-3 and 4-6, respectively, during the investigator-driven follow-up after termination of the main study (months 7-24) no specific calcineurin inhibitor target levels were required. Follow-up data were collected at 2 years post-transplantation from 237 (82.9% of the ITT population) patients who received tacrolimus and 222 (81.9% of the ITT population) patients who received CsA-ME. RESULTS: Calculated on ITT populations, mortality (2.0% vs 3.3%; P<0.05 in Kaplan-Meier analysis) was lower, but rate of graft loss (9.3% vs 11.2%; P = 0.12 in Kaplan-Meier analysis) was not significantly different after 2 years with tacrolimus- vs CsA-ME-based immunosuppression. Biopsy-proven acute rejection was significantly lower (19.6%) with tacrolimus than with CsA-ME (37.3%) during months 0-6 (P<0.0001), but was not significantly different during months 7-12 and 13-24 of follow-up (1.7% and 0.8% with tacrolimus and 4.7% and 0.9% with CsA-ME, respectively). A composite endpoint consisting of graft loss, patient death and biopsy-proven acute rejection occurred significantly more frequently in CsA-ME patients than in tacrolimus patients (42.8% vs 25.9%; P<0.001) during 24 months follow-up. Renal function 2 years post-transplant, measured by serum creatinine concentrations, was significantly better in tacrolimus-based compared with CsA-ME-based immunosuppression (136.9 vs 161.6 micromol/l; P<0.01). Cornerstone immunosuppression remained unchanged in 82.5% and 66.2% of patients treated with tacrolimus and CsA-ME, respectively. At 2 years, more patients in the tacrolimus arm were off steroids and received calcineurin inhibitor monotherapy, and fewer tacrolimus patients remained on a triple immunosuppressive regimen. The cardiovascular risk profile was affected favourably in the tacrolimus arm, with lower cholesterol and triglyceride concentrations (despite less use of cholesterol-lowering drugs); no significant difference in requirement for antidiabetic medication was noted. CONCLUSIONS: The 2 year study results confirm that tacrolimus is a highly efficacious cornerstone immunosuppressant in kidney transplantation. Tacrolimus-based immunosuppression may induce long-term benefits with regard to graft function and graft survival. The overall side-effect profile is considered to be favourable.     

Histological evaluation of renal allograft protocol biopsies in the early period and 1 year after transplantation

Abstract:  We histologically evaluated protocol biopsy specimens of renal allografts obtained in the early period and 1 year after transplantation. The patients were divided into those with at least one history of acute rejection (AR group) and no history of rejection (NAR group), and the histopathological features in the two groups were compared. A total of 45 early protocol biopsy specimens were obtained from 40 patients, and 31 1-year biopsy specimens were obtained from 30 patients. Acute rejection (AR) or borderline change was observed in the early protocol biopsy specimens from 19 (45.2%) cases. AR or borderline change was observed in 12 of 19 (63.2%) in the AR group, and in 7/26 cases (26.9%) in the NAR group. The incidence of AR or borderline change in the AR group was higher than in the NAR group. Toxic tubulopathy was found in the early protocol biopsy in 16 cases (35.6%). The 1-year biopsies tended to reveal more complicated findings. Chronic rejection (CR) was seen in 8/16 cases (50.0%) in the AR group, and it was more frequent than NAR group (two cases, 13.3%). In conclusion, the incidences of both AR and CR were higher in the cases with a previous episode of AR. The early protocol biopsy was useful in screening for subclinical AR and toxic tubulopathy. The 1-year biopsy was useful for evaluating various types of chronic graft damage. We expect that adequate treatment based on protocol biopsy findings in each patient will lead to better graft survival.     

The role of the protocol biopsies in renal allograft recipients

Subclinical rejection and long-term cyclosporine nephrotoxicity are well-known risk factors of chronic allograft nephropathy. In a prospective study 32 low-risk patients were randomized to either a reduced CsA dose (5 mg/kg/d) and daclizumab (group A, n = 16) for 7 months posttransplant with subsequent CsA tapering/withdrawal, or to a normal CsA dose (10 mg/kg/day) without daclizumab (group B, n = 16). Both groups received MMF and prednisone. Protocol biopsies were obtained at engraftment and 3 and 12 months after Tx. The number of rejection episodes was the primary endpoint. The secondary endpoints were: renal function, histological parameters related to CsA, and serum levels of TGF-beta and PDGF-BB. A low incidence of clinically suspected rejection episodes was observed (19% in group A and 12.4% in group B; P = NS). Although protocol biopsies showed 12 subclinical rejection episodes (six in group A, six in group B), serum creatinine levels were not different between the examined groups at 3 months. However, at 12 months, there was a statistically improved mean creatinine level in group A patients (1.2 mg/dL +/- 0.5 in group A vs 1.54 mg/dL in group B; P <.05). Chronic histopathologic changes were significant for biopsies at 3 and 12 months in both groups compared to the baseline findings for protocol biopsies (with no differences between groups, or between 3 and 12 months in both groups). Serum TGF-beta and PDGF-BB did not differ between the groups. Protocol biopsies may be useful to monitor safety and efficiency of new immunosuppressive protocols. Immunosuppressive regimens with low CsA doses followed by the drug's complete withdrawal seem to be efficient and safe in low-risk kidney allograft recipients.     

Interest of screening biopsies in renal transplantation

Renal biopsy is an invaluable tool used for the monitoring of grafts and the management of their survival. Since 1993, thanks to research on biopsy tissues that enabled to distinguish the different types of rejection and to find markers of reversible or irreversible rejection, a classification of renal lesions has been established to achieve the regularly updated Banff classification. The last in date (2005) has defined the antibody-mediated chronic rejection, forsaken the term "chronic allograft nephropathy" and described a new class with interstitial fibrosis and tubular atrophy (IF/TA). Systematic or screening biopsies allow revealing infraclinical rejection lesions before any renal function degradation, better understanding of allograft nephropathy pathophysiology, confirming the diagnostic, but also displaying other more specific lesions that could benefit from a treatment. However, the interest of biopsies is limited by interpretation problems and risks for the patient.