A Randomized 2x2 Factorial Clinical Trial of Renal Transplantation: Steroid-Free Maintenance Immunosuppression with Calcineurin Inhibitor Withdrawal after Six Months Associates with Improved Renal Function and Reduced Chronic Histopathology.

INTRODUCTION: The two most significant impediments to renal allograft survival are rejection and the direct nephrotoxicity of the immunosuppressant drugs required to prevent it. Calcineurin inhibitors (CNI), a mainstay of most immunosuppression regimens, are particularly nephrotoxic. Until less toxic antirejection agents become available, the only option is to optimize our use of those at hand. AIM: To determine whether intensive rabbit anti-thymocyte globulin (rATG) induction followed by CNI withdrawal would individually or combined improve graft function and reduce graft chronic histopathology-surrogates for graft and, therefore, patient survival. As previously reported, a single large rATG dose over 24 hours was well-tolerated and associated with better renal function, fewer infections, and improved patient survival. Here we report testing whether complete CNI discontinuation would improve renal function and decrease graft pathology. METHODS: Between April 20, 2004 and 4-14-2009 we conducted a prospective, randomized, non-blinded renal transplantation trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment = 180). Subsequent maintenance immunosuppression consisted of tacrolimus, a CNI, and sirolimus, a mammalian target of rapamycin inhibitor. We report here the outcome of converting patients after six months either to minimized tacrolimus/sirolimus or mycophenolate mofetil/sirolimus. Primary endpoints were graft function and chronic histopathology from protocol kidney biopsies at 12 and 24 months. RESULTS: CNI withdrawal (on-treatment analysis) associated with better graft function (p <0.001) and lower chronic histopathology composite scores in protocol biopsies at 12 (p = 0.003) and 24 (p = 0.013) months, without affecting patient (p = 0.81) or graft (p = 0.93) survival, or rejection rate (p = 0.17). CONCLUSION: CNI (tacrolimus) withdrawal at six months may provide a strategy for decreased nephrotoxicity and improved long-term function in steroid-free low immunological risk renal transplant patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT00556933.

A randomized 2×2 factorial trial, part 1: single-dose rabbit antithymocyte globulin induction may improve renal transplantation outcomes.

BACKGROUND: We conducted a randomized and unblinded 2 × 2 sequential-factorial trial, composed of an induction arm (part 1) comparing single-dose (SD) versus divided-dose rabbit antithymocyte globulin (rATG), and a maintenance arm (part 2) comparing tacrolimus minimization versus withdrawal. We report the long-term safety and efficacy of SD-rATG induction in the context of early steroid withdrawal and tacrolimus minimization or withdrawal. METHODS: Patients (n=180) received 6 mg/kg rATG, SD or four alternate-day doses (1.5 mg/kg/dose), with early steroid withdrawal and tacrolimus or sirolimus maintenance. After 6 months targeted maintenance levels were tacrolimus, 2 to 4 ng/mL and sirolimus, 4 to 6 ng/mL or, if calcineurin inhibitor-withdrawn, sirolimus 8 to 12 ng/mL with mycophenolate mofetil 2 g two times per day. Primary endpoints were renal function (abbreviated modification of diet in renal disease) and chronic graft histopathology (Banff). Secondary endpoints included patient survival, graft survival, biopsy-proven rejection, and infectious or noninfectious complications. RESULTS: Follow-up averaged longer than 4 years. Tacrolimus or sirolimus and mycophenolate mofetil exposure was identical between groups. The SD-rATG associated with improved renal function (2-36 months; P<0.001) in deceased donor recipients. The SD-rATG associated with quicker lymphocyte, CD4 T cell, and CD4-CD8 recovery and fewer infections. Cox multivariate hazard modeling showed divided-dose-rATG (P=0.019), deceased donor (P=0.003), serious infection (P=0.0.018), and lower lymphocyte count (P=0.001) associated with increased mortality. Patients with all four covariates showed a 27-fold increased likelihood of death (P=0.00002). Chronic graft histopathology, rejection rates, and death-censored graft survival were not significantly different between groups. CONCLUSION: The SD-rATG induction improves the 3-year renal function in recipients of deceased donor kidneys. This benefit, along with possibly improved patient survival and fewer infections suggest that how rATG is administered may impact its efficacy and safety.

Single-dose rATG induction at renal transplantation: superior renal function and glucoregulation with less hypomagnesemia.

BACKGROUND: Rabbit anti-thymocyte globulin (rATG) induction reduces reperfusion injury and improves renal function in kidney recipients by means of properties unrelated to T-cell lysis. Here, we analyze intensive rATG induction (single dose, rATG(S) , vs. divided dose, rATG(D) ) for improved renal function and protection against hyperglycemia. METHODS: Patients without diabetes (n = 98 of 180) in a prospective randomized trial of intensive rATG induction were followed for six months for the major secondary composite end point of impaired glucose regulation (hyperglycemia and new-onset diabetes after transplantation, NODAT). Prospectively collected data included fasting blood glucose and HbA(1c). Serum Mg(++) was routinely collected and retrospectively analyzed. RESULTS: Induction with rATG(S) produced less impaired glucose regulation (p = 0.05), delayed NODAT development (p = 0.02), less hyperglycemia (p = 0.02), better renal function (p = 0.04), and less hypomagnesemia (p = 0.02), a factor associated with a lower incidence of NODAT. Generalized linear modeling confirmed that rATG(S) protects against a synergistic interaction between tacrolimus and sirolimus that otherwise increased hypomagnesemia (p = 0.008) and hyperglycemia (p = 0.03). CONCLUSIONS: rATG(S) initiated before renal reperfusion improved early renal function and reduced impaired glucose regulation, an injury by diabetogenic maintenance agents (tacrolimus and sirolimus).

Albuminuria after renal transplantation: maintenance with sirolimus/low-dose tacrolimus vs. mycophenolate mofetil/high-dose tacrolimus.

Maintenance immunosuppression with sirolimus (SRL) in renal transplantation has been associated with proteinuria. We report long-term outcomes of kidney transplant recipients maintained on steroid-free regimens, either SRL with low-dose tacrolimus (SRL/L-Tac) or mycophenolate mofetil (MMF) with high-dose tacrolimus (MMF/H-Tac). We conducted a case-matched study of 50 patients receiving MMF/H-Tac, matched 1:2 with 100 patients maintained on SRL/L-Tac. All patients were induced with rabbit antithymocyte globulin followed by early steroid withdrawal. Comparisons were made of patient and graft survival, graft function, acute rejection, and albuminuria. There were no significant differences between the SRL/L-Tac and MMF/H-Tac groups for patient survival, graft survival, occurrence of acute rejection, or graft function. There was no difference in the proportion of patients with albumin/creatinine ratio (ACR) ≥300 µg/mg (19% vs. 20%), but more patients in the SRL group were receiving renin-angiotensin system blocking agents (72% vs. 53%, p = 0.04). Only flushing the donor kidney with histidine-tryptophan-ketoglutarate solution (vs. UW solution) was predictive of albuminuria. Long-term outcomes are similar at our center for kidney transplant patients receiving either SRL/L-Tac or MMF/H-Tac. Although the occurrence of albuminuria was not different, significantly more SRL-treated patients were receiving antiproteinuric medications.

Randomized trial of single-dose versus divided-dose rabbit anti-thymocyte globulin induction in renal transplantation: an interim report.

BACKGROUND: The optimal dosing protocol for rabbit anti-thymocyte globulin (rATG) induction in renal transplantation has not been determined, but evidence exists that rATG infusion before renal allograft reperfusion improves early graft function. Infusing a large rATG dose over a short interval has not previously been evaluated for its effect on renal function and allograft nephropathy in a prospective, randomized comparison against conventional rATG induction. METHODS: Between April 20, 2004 and December 26, 2007 we enrolled renal transplant patients into a prospective, randomized, nonblinded trial of two rATG dosing protocols (single dose, 6 mg/kg vs. divided doses, 1.5 mg/kg every other day x 4; target enrollment=160) followed after 6 months by calcineurin-inhibitor withdrawal. Primary endpoints are renal function by calculated glomerular filtration rate (GFR) and chronic allograft nephropathy at protocol biopsy. We now present the early GFR data of all 160 patients and safety and efficacy data of the first 142 patients with 6 months follow up and before calcineurin inhibitor withdrawal (average follow up=23.3+/-11.6 months). RESULTS: There were no differences between groups in rATG-related adverse events, patient and graft survival, acute rejection, or chronic allograft nephropathy rate at 6 months. Calculated DeltaGFR (POD 1-4) was significantly better in the single-dose group (P=0.02), with a trend toward improved renal function from months 2 to 6 in recipients of deceased donor kidneys (P=0.08). CONCLUSIONS: This study demonstrates that administering 6 mg/kg of rATG over 24 hr is safe and is associated with improved early renal function compared with administering rATG in alternate-day doses.