Conversion to sirolimus in a population of kidney and kidney-pancreas transplant recipients

INTRODUCTION: Calcineurin inhibitors (CI) are associated with nephrotoxicity that might reduce long-term graft survival. We report our experience with sirolimus (SRL) conversion among a population of kidney and kidney pancreas transplant recipients. METHODS: Thirty transplant recipients (6 women, 24 men; age 41 +/- 10.5 years old) were converted to SRL therapy at 25.97 +/- 32.5 months after transplantation. Indications for conversion were: intolerance to mycophenolate mofetil (n = 13), diabetes mellitus (n = 3), CI nephrotoxicity (n = 11), CI nephrotoxicity with chronic allograft rejection (n = 2), and side effects of azathioprine (n = 1). Follow-up after conversion is 3 to 45 months. RESULTS: No significant changes were observed in the 3 months postconversion in renal function, hematological profile, and mean arterial blood pressure. In contrast there was a significant increase in cholesterol values (pre: 198.7 +/- 49.4, versus post 221.2 +/- 60.8, P = .018). At a follow-up of 15.2 +/- 9.9 months after conversion two patients (6.7%) died with functioning allograft (one because of infection and one to myocardial infarct) three kidney allografts (10.7%) have been lost: two chronic rejection; one infection. In two patients SRL therapy was discontinued (one infection, one refractory edema). Neither significant change in renal function nor episodes of acute rejection were observed. CONCLUSIONS: Conversion to SRL was safe. There was no deterioration in renal function nor episodes of acute rejection. There was a significant increase in cholesterol values after conversion. The size of the sample and the time of follow-up may have determined our results.     

Proteinuria following a switch from calcineurin inhibitors to sirolimus

BACKGROUND: Sirolimus is an alternative option for kidney transplant patients treated with calcineurin inhibitors (CNI) when renal function is deteriorating. However, the incidence of proteinuria following a switch from CNI to sirolimus has caused concern, and was therefore investigated here. METHODS: In a retrospective study, 68 renal transplant recipients were switched from CNI to sirolimus. Proteinuria was measured using 24-hour urine collection before the switch and collections 3, 6, 12, and 24 months thereafter. In addition, proteinuria was measured in patients who had to be switched back to CNI due to side effects. Survival analyses were performed. RESULTS: Baseline proteinuria was 0.39+/-0.69 g/day in all 68 patients. It increased to a mean 1.44+/-1.90 g/day at 3 months (P<0.001) and remained elevated at 6, 12 and 24 months. When sirolimus was withdrawn after the CNI-sirolimus switch for 19 patients, proteinuria decreased from 1.95+/-2.06 g/day to 0.9+/-1.4 g/day (P<0.05). Proteinuria above 0.3 g/day before the CNI-sirolimus switch correlated significantly with the decrease of renal function thereafter. CONCLUSION: CNI-treated kidney transplant recipients may develop reversible proteinuria when switched to sirolimus.     

Clinical Predictors of Proteinuria after Conversion to Sirolimus in Kidney Transplant Recipients

Proteinuria is an increasingly recognized effect of sirolimus (SRL) therapy in kidney transplant recipients. Predictors of proteinuria after conversion to SRL are not well described, and in particular the risk in African‐American (AA) kidney recipients is unknown. We sought to analyze risk factors for proteinuria with SRL therapy in a cohort of 39 patients (44% AA) converted from tacrolimus to SRL at a mean time of 4 months posttransplantation. Patients were maintained on therapy with mycophenolate mofetil while most patients underwent early steroid withdrawal. Urinary protein to creatinine ratio (Up/cr) at a mean of 14 months postconversion increased to ≥500 mg/g in 65% of AAs versus 14% of non‐AAs (p = 0.001). Mean arterial blood pressure at the time of conversion and pretransplant proteinuric kidney disease were also predictors of proteinuria after SRL conversion. In conclusion, AAs appear to be at high risk for proteinuria and should be monitored closely after conversion to SRL in calcineurin inhibitor sparing protocols.     

Long‐term results after conversion from calcineurin inhibitors to sirolimus in renal transplant patients

Martinez‐Mier G, Avila‐Pardo SF, Mendez‐Lopez MT, Budar‐Fernandez LF. Long‐term results after conversion from calcineurin inhibitors to sirolimus in renal transplant patients.
Clin Transplant 2010: 24: 467–473.
© 2009 John Wiley & Sons A/S. Abstract: Background: Calcineurin inhibitors (CNI) toxicity is one of the contributing factors for the development and progression of chronic allograft dysfunction (CAD). Conversion to sirolimus (SRL) from CNI improves renal function kidney in transplant recipients. Methods: A retrospective review from patients abruptly converted from CNI to SRL over a three yr period is reported. Results: Thirty‐nine patients were converted 55.2 ± 58 months after renal transplantation. 24 month patient and graft survival was 100% and 92%. Acute rejection incidence was 7.6%. Overall, serum creatinine (SCr) and Cockcroft–Gault creatinine clearance (CGCrCl) improved. In responders, SCr improved from 2.48 ± 0.8 to 1.94 ± 0.8 mg/dL (p < 0.05) CGCrCl improved from 37.8 ± 17.4 to 51.9 ± 23.8 mL/min at two years. An increase in proteinuria was observed from conversion to month 12 in responders (189.4 ± 512.8 to 488.3 ± 890.6 mg/day, p < 0.05) and from conversion to month six in non‐responders (1179.4 ± 2001.1 to 2357 ± 4172.9 mg/day, p < 0.05). Low proteinuria had positive predictive value for renal response after conversion. Conclusion: Conversion from CNI to SRL with CAD is associated with improved renal function with an increase in proteinuria. Low proteinuria is a possible positive predictive factor for successful conversion.     

Conversion from cyclosporine to sirolimus in stable renal transplant recipients

BACKGROUND: Conversion from cyclosporine (CsA) to sirolimus (SRL) has mainly been done in clinical conditions warranting calcineurin inhibitor discontinuation. Little is known about the clinical outcome of conversion in renal transplant recipients without transplant dysfunction. METHODS: This prospective, open-label, multicentric pilot study evaluates the safety and efficacy of converting patients with stable renal function from CsA to SRL. RESULTS: Forty stable patients on CsA, mycophenolate mofetil (MMF) (1.5 g/day), and steroids (ST) were converted at 7.6+/-1.4 months after renal transplantation. At 1 year, graft and patient survival was 100% and the incidence of acute rejection 5%. Calculated glomerular filtration rate (GFR) increased from 54+/-18 to 66+/-16 ml/min (P<0.0001). Blood pressure remained unchanged. A gradual increase in the incidence and severity of proteinuria was observed from month 6 onwards with de novo proteinuria in 30% of the patients at 1 year. Protein excretion was below 1 g/day in 12.5%, between 1 and 3 g/day in 17.5% and above 3 g/day in 7.5% of the proteinuric cohort (P=0.0043, compared to baseline). No predictors could be identified for the development of proteinuria. All patients had a reduction in protein excretion following renin-angiotensin blockade and were continued on SRL. CONCLUSION: Conversion of stable renal transplant recipients from a CsA-MMF-ST to a SRL-MMF-ST regimen is safe and results in improved renal function but is associated with the development of proteinuria in 30% of the patients requiring renin-angiotensin blockade.     

mToR inhibitors-induced proteinuria: mechanisms, significance, and management

Massive urinary protein excretion has been observed after conversion from calcineurin inhibitors to mammalian target of rapamycin (mToR) inhibitors, especially sirolimus, in renal transplant recipients with chronic allograft nephropathy. Because proteinuria is a major predictive factor of poor transplantation outcome, many studies focused on this adverse event during the past years. Whether proteinuria was due to sirolimus or only a consequence of calcineurin inhibitors withdrawal remained unsolved until high range proteinuria has been observed during sirolimus therapy in islet transplantation and in patients who received sirolimus de novo. Podocyte injury and focal segmental glomerulosclerosis have been related to mToR inhibition in some patients, but the pathways underlying these lesions remain hypothetic. We discuss herein the possible mechanisms and the significance of mToR blockade-induced proteinuria.     

Rapid conversion to sirolimus for chronic progressive deterioration of the renal function in kidney allograft recipients

The aim of this study was to evaluate the safety of conversion to sirolimus (SRL) immunosuppression among 19 renal transplant recipients (KTX) with progressive chronic renal allograft dysfunction (CRAD). Conversion to SRL was performed with concomitant sharp withdrawal of the calcineurin inhibitor (CI). SRL was added at a starting dose of 3 mg, then adjusted to obtain SRL target trough blood levels of 8 to 10 ng/mL. CI were stopped the evening before starting SRL. All patients enrolled in the study have now completed 6 months of follow-up: all are alive without acute rejection or major infection following rapid conversion to SRL. No significant change in the 6 months postconversion hematologic and hepatic profile was observed compared with the preconversion values, while significant dyslipidemia was induced. After conversion to SRL, significant amelioration of the renal function was found in 36% of patients, stabilization in 21%, and continuous deterioration in 43%. Patients whose renal function improved were found to have been converted at a significantly lower creatinine: (pre 2.6 +/- 0.9 vs post 1.9 +/- 0.2; P =.038) with respect to those patients who had continuous renal deterioration. In KTX with CRAD, sharp withdrawal of CI with concomitant conversion to SRL is safe, avoiding major infections, acute rejections, and significant side effects. Short-term amelioration of the renal function is best obtained when early conversion is performed. Long-term follow-up will be necessary to confirm these preliminary data.     

Long-term results in renal transplant patients with allograft dysfunction after switching from calcineurin inhibitors to sirolimus.

BACKGROUND: Switching from calcineurin inhibitors (CNIs) to sirolimus might improve renal function in chronic renal transplant patients. METHODS: In a prospective study, we assessed long-term efficacy and safety parameters in 43 renal transplant recipients who were switched from a CNI (cyclosporin A, 65%; and tacrolimus, 35%) to sirolimus for either chronic allograft dysfunction (n = 38) or recurrent cutaneous cancers (n = 5). A kidney biopsy was done in 79% of patients prior to conversion, and showed either chronic allograft nephropathy (n = 26) or CNI nephrotoxicity (n = 7). Conversion was either abrupt or progressive, with CNI withdrawal over 3 weeks. All patients also received steroids with or without mycophenolate mofetil or azathioprin. Patient data were recorded at baseline (D0), at 1 (D30) and 6 months (D180), and at 1, 1.5 and 2 years post-conversion. RESULTS: After a mean post-conversion follow-up of 27+/-1.5 months, 58% of the patients were still on sirolimus. The survival of intent to treat patients and grafts was 95.3 and 93%, respectively. Overall, there was significant improvement in renal function, creatinine clearance increasing from 49.4+/-14.9 to 53+/-16.3 ml/min at D30 (P = 0.01), and to 54.7+/-20 ml/min at D180 (P = 0.01). Thereafter, creatinine clearance was not different from baseline, i.e. 54.7+/-21.7, 52.8+/-20 and 51.7+/-20.3 ml/min at years 1, 1.5 and 2, respectively. We divided the patients into two groups: responders (n = 29), those with an increase in creatinine clearance at 6 months post-conversion compared with D0, and non-responders (n = 14), those with a decrease in creatinine clearance at 6 months post-conversion compared with D0. In univariate analysis, factors predictive of response included proteinuria at D0 and the magnitudes of the differences between D30 and D0 for serum creatinine and lactate dehydrogenase. The conversion was associated with (i) significant decreases in serum calcium, phosphorus and uric acid, and in haemoglobin levels; (ii) significant increases in serum alkaline phosphatase, total cholesterol, parathyroid hormone, and the number of patients on statin and recombinant erythropoietin therapies; and (iii) the appearance of de novo proteinuria of >1 g/day in 28% of patients (P < 0.0009), which was >2 g/day in 12% of the entire cohort. Kidney biopsies in 17 patients 2 years after conversion showed the same Banff scores as observed at baseline. We identified three independent predictive factors for a renal response to the switch: absence of proteinuria, presence of antihypertensive therapy at D0 and serum lactate dehydrogenase level at D30. CONCLUSION: Conversion from CNIs to sirolimus in renal transplant patients with chronic allograft nephropathy was associated with improved renal function; however, 33% of the patients developed overt proteinuria.     

Is sirolimus responsible for proteinuria?

Sirolimus (SRL) is suspected to induce proteinuria. We retrospectively studied proteinuria in a population of liver (n = 29) and kidney transplant (n = 30) recipients switched to SRL with progressive diminution or withdrawal of calcineurin inhibitors (CNI). We also observed estimated glomerular filtration rate (GFR), modification of treatment with antiproteinuric drugs, and changes in concentration of SRL. Collection of data started 3 months before SRL introduction at a mean follow-up of 21 months. Following SRL introduction, proteinuria was not detected in the 28 liver transplant patients, and was stable in the two others. In the kidney transplant group, proteinuria did not occur in 12 patients, remained stable in three, and was slightly increased in 14 (0.57 +/- 0.93 g/d vs 1.83 +/- 1.26 g/d). For all patients, eGFR remained stable; there was no difference in management of antiproteinuric drugs. As suspected, cyclosporin (CsA) and tacrolimus (FK) serum concentrations were decreased. We observed a significant correlation between the variation of proteinuria and the variation of serum concentration of CsA or FK (respectively, P = .001 and P = .007). On the other hand, we did not find any correlation between variation in proteinuria and concentration of SRL. This retrospective study suggests that in our cohort of liver transplant patients without previous renal damage, SRL did not provoke proteinuria. On the other hand, the slight aggravation of proteinuria in a subgroup of kidney transplant patients seems to be linked to the hemodynamic renal effects due to CNI withdrawal.     

Conversion from a calcineurin inhibitor-based immunosuppressive regimen to everolimus in renal transplant recipients: effect on renal function and proteinuria

New immunosuppressive agents are being actively researched to avoid complications of chronic allograft nephropathy (CAN), calcineurin inhibitor (CNI) nephrotoxicity, and posttransplantation cancer. The family of mTOR inhibitors offers a unique immunosuppressive opportunity to avoid CNI toxicity and reduce the incidence of malignancy. Nevertheless, increasing data have demonstrated that sirolimus (SRL), the first mTOR introduced in the treatment of solid organ transplant recipients, induces proteinuria, an adverse event that could produce deterioration of long-term renal function. In this short-term study of patients followed for 1 to 16 months, we examined changes in renal function and proteinuria among renal transplant recipients converted from a CNI-based regimen to an everolimus (EVL)-based one, a recently introduced mTOR inhibitor. Our data showed that renal function can be optimized after conversion to EVL by up to 42% in recipients showing CAN grade 1 or 2, or CNI nephrotoxicity. Importantly, patients who improved their creatinine clearance did not show increased proteinuria measured in a voided specimen as the ratio of urinary protein and creatinine concentration (P/C). These results, if confirmed with long-term follow-up and a larger number of patients, would allow us to consider EVL as a promising agent for maintenance immunosuppressive regimens in kidney transplantation.     

Sirolimus-based immunosuppressive therapy in liver transplant recipient with tacrolimus-related chronic renal insufficiency

BACKGROUND: While providing potent immunosuppression for liver transplant recipients, calcineurin inhibitors (CNI) exhibit nephrotoxicity as a major side effect. The purpose of this study was to evaluate the safety and efficacy of conversion from CNI to sirolimus (SRL) among liver transplant recipients with CNI-induced chronic nephrotoxicity. METHODS: Between January 2004 and June 2005, we performed conversion in 16 recipients after a median period of 8.5 months after liver transplantation. The indication for conversion was CNI-related nephrotoxicity with a serum creatinine (sCr) value >132.6 umol/L. Renal function was measured before and after conversion to SRL. Clinical and laboratory data related to the clinical course of the patients were recorded to investigate the safety and efficacy of conversion. RESULTS: Sixteen patients were converted to SRL after developing nephrotoxicity. Their renal function improved gradually after conversion. The levels of sCr decreased significantly within the first 30 days (164.1 +/- 12.48 micromol/L to 130.1 +/- 5.573 micromol/L), and over the next 60 days after conversion (97.86 +/- 11.69 micromol/L to 90.7 +/- 8.95 micromol/L) (P < .01). Similarly, the mean glomerular filtration rate (GFR) increased significantly during the same period. Four recipients experienced hypercholesterolemia, 1 with ankle edema, and 1 with acute rejection. The median follow-up was 2.4 years. No patient discontinued SRL due to side effects. No patient needed dialysis or kidney transplantation during the study period. CONCLUSIONS: SRL is a safe, effective replacement agent as primary immunosuppressive therapy following withdrawal of CNIs in liver transplant recipients with CNI-induced chronic nephrotoxicity.     

Conversion to sirolimus from cyclosporine may induce nephrotic proteinuria and progressive deterioration of renal function in chronic allograft nephropathy patients

Antiproliferative and non-nephrotoxic properties of sirolimus have been exploited for treatment of patients with chronic graft dysfunction. In this paper we point to the possible association of nephrotic syndrome and renal impairment with rapid conversion from cyclosporine (CsA) to sirolimus in patients with chronic nephropathy. Five male patients, ages 34 to 56 years, with chronic renal failure in the course of glomerulonephritis, were transplanted between 1997 and 1999. For the first 49 to 65 months, the immunosuppressive regimen consisted of CsA, azathioprine (AZA), and prednisone. Thereafter, due to chronic nephropathy evidenced by biopsy, conversion to sirolimus was performed with sharp withdrawal of CsA. The serum creatinine level prior to conversion was 1.9 +/- 0.3 mg/dL. Trace to 86 mg/dL proteinuria was found in 3 patients, while 2 patients had about 200 mg/dL. After 2 to 4 months of sirolimus treatment the proteinuria progressed (558 +/- 183 mg/dL); edema, hypoproteinemia, hypoalbuminemia, and hyperlipidemia developed; and the serum creatinine increased to 3.5 +/- 0.8 mg/dL. Biopsies performed in three patients revealed new pathologic changes. After 4 to 5 months, we performed reconversion to calcineurin inhibitor. Proteinuria decreased to 0 to 150 mg/dL; nevertheless the serum creatinine was continuously rising. Six to 15 months after the conversion, 3 patients returned to dialysis. The fourth patient, who was earlier reconverted, has a serum creatinine level of 2.0 mg/dL after 15 months. In conclusion, conversion from CsA to sirolimus may induce nephrotic syndrome with progressive deterioration of renal function. Converted patients require careful monitoring of proteinuria and renal function. Early reconversion to calcineurin inhibitor may prevent progressive deterioration of graft function.     

A pilot study of immunosuppression minimization after pancreas-kidney transplantation utilizing thymoglobulin induction and sirolimus maintenance therapy

AIMS: To determine outcomes utilizing thymoglobulin and sirolimus immunosuppression, with early steroid withdrawal in low-immune responder pancreas-kidney (SPK) recipients, and conversion from cyclosporine (CsA) to mycophenolic acid (MPA) in all recipients at 6 months posttransplantation. METHODS: SPK recipients received thymoglobulin, sirolimus, and reduced-dose CsA immunosuppression. Low immune responders (non-African-Americans with a pretransplant PRA < 30%) were withdrawn from prednisone on posttransplant day 5 and high immune responders were continued on prednisone. All recipients were converted from CsA to MPA at 6 months posttransplantation. During conversion, recipient immune response was monitored by flow PRA and a T-cell stimulation assay (Cylex). RESULTS: With a mean follow-up of 9 +/- 4 months, one pancreas was lost to pancreatitis, with no patient or kidney losses and no acute rejection episodes. All eight low immune responder patients were steroid-free at 9 +/- 5 months posttransplantation. Seven patients (five low and two high immune responders) with at least 6-month follow-up were converted from CsA to MPA. One high immune responder with a pretransplant PRA of 43% remained with a PRA of 53% +/- 2% postconversion. The second high immune responder had a pretransplant PRA of 34% and a postconversion PRA of 0%. The five low immune responders had a mean pretransplant PRA of 16% +/- 15% and a postconversion PRA of 0% (P < .01). The Cylex assay resulted in 67% low responsiveness for both high and low immune responders. CONCLUSION: Thymoglobulin induction with sirolimus maintenance therapy permitted immunosuppression minimization in selected pancreas transplant recipients. Posttransplant evaluation revealed a diminished (regulated) immune response in six of seven patients.     

在移植肾功能稳定的受者中主动撤除环孢素A的临床研究

目的 研究在移植肾功能稳定的受者中主动撤除环孢素A(CSA)对急性排斥反应发生率及肾功能的影响.方法 选择35例肾功能稳定的肾移植受者,其中尸体肾移植23例,亲属活体肾移植12例.除2例为再次肾移植外,其余均为初次肾移植.分别在肾移植术后6个月～6年时停用CsA,平均为术后(13.3±9.1)个月.撤除CsA后免疫抑制方案为:霉酚酸酯(MMF)+西罗莫司(SRL)+泼尼松(Pred).撤除CsA前有9例做了移植肾穿刺活检,8例测定了抗HLA抗体.结果 对35例受者随访6个月～4.5年,平均14.8个月.撤除CsA前、后血肌酐平均值分别为(88.1±15.5)μmol/L和(92.3±23.7)/μmol/L(P0.05).撤除CsA后,有2例经活检证实发生急性排斥反应,治疗后均逆转;CsA所致的毒副作用,如牙龈增生、糖耐量异常和多毛症等明显改善.9例移植肾活检中,有3例肾功能正常的受者已出现轻度慢性移植肾肾病表现.抗HLA抗体检测中,7例阴性者在撤除CsA前、后肾功能无明显变化.1例抗HLA抗体呈强阳性者在撤除CsA后进展为慢性移植肾肾病,恢复血液透析.结论 对移植肾功能稳定的受者在移植6个月后撤除CsA,转换为"霉酚酸酯+西罗莫司+泼尼松"的免疫抑制方案是安全的,不增加急性排斥反应风险;撤除CsA有利于消除一些与其相关的毒副作用;对抗HLA抗体呈强阳性者.撤除CsA后很难改变肾功能的进展.     

Glucose metabolism in renal transplant recipients: effect of calcineurin inhibitor withdrawal and conversion to sirolimus

Cyclosporine A (CsA) and tacrolimus have been associated with an increased risk for diabetes after transplantation, whereas sirolimus is deemed to be devoid of any effect on glucose metabolism. This study was performed to investigate the effect of the withdrawal of calcineurin inhibitors and the switch to sirolimus on peripheral insulin resistance and pancreatic beta cell response. Twenty-six patients who received a kidney transplant and discontinued CsA and were converted to sirolimus and 15 recipients of suboptimal kidneys who were treated with tacrolimus plus sirolimus for the first 3 mo after grafting and thereafter with sirolimus alone were enrolled. All patients underwent an oral glucose tolerance test and intravenous insulin tolerance test before and 6 mo after the conversion to sirolimus-alone therapy. The withdrawal of CsA or tacrolimus was associated with a significant fall of insulin sensitivity (both P = 0.01) and with a defect in the compensatory beta cell response, as measured by the disposition index (P = 0.004 and P = 0.02, respectively). The increase of insulin resistance and the decrease of disposition index significantly correlated with the change of serum triglyceride concentration after the conversion to sirolimus-based therapy (R(2) = 0.30, P = 0.0002; and R(2) = 0.19, P = 0.004, respectively). Clinically, the switch to sirolimus was associated with a 30% increase of incidence of impaired glucose tolerance and with four patients' developing new-onset diabetes. In conclusion, the discontinuation of calcineurin inhibitors and their replacement by sirolimus fail to ameliorate the glycometabolic profile of kidney transplant recipients. Rather, it is associated with a worsening of insulin resistance and an inappropriately low insulin response.     

Interstitial Fibrosis Quantification in Renal Transplant Recipients Randomized to Continue Cyclosporine or Convert to Sirolimus

Conversion from cyclosporine (CsA) to sirolimus at week 12 after kidney transplantation is associated with a significant improvement in renal function. The aim of this analysis was to investigate the effect of this conversion on interstitial fibrosis (IF), a hallmark of chronic allograft injury, in patients taking part in the CONCEPT trial. This multicenter, prospective, trial included 193 renal recipients randomized at week 12 to switch from CsA to sirolimus or to continue CsA, with mycophenolate mofetil. Routine biopsy with automated, quantified assessment of IF by a program of color segmentation was performed at 1 year in 121 patients. At 1 year, renal function was significantly improved in the conversion group as assessed by estimated GFR (MDRD) and measured GFR. Biopsy results, however, showed no between-group difference in percentage of IF. Calculated GFR at 1 year was significantly associated with the percentage of IF (p = 0.004, R²= 0.07). By multivariate analysis diabetic patients had more fibrosis than non-diabetic patients. In conclusion, although kidney transplant patients converted from CsA to sirolimus showed significant improvement in renal function, we found no difference of IF on 1-year biopsies.     

Mammalian target of rapamycin inhibition halts the progression of proteinuria in a rat model of reduced renal mass

Many kidney transplant patients experience an increase in proteinuria when converted from a calcineurin inhibitor-based regimen to one based on a mammalian target of rapamycin (mTOR) inhibitor, and preexisting proteinuria and poor renal function have been identified as risk factors for this increase. Our aim was to evaluate the effect of sirolimus, an mTOR inhibitor, on renal function and histology in a proteinuric model of reduced renal mass. Sirolimus-treated animals had approximately half as much proteinuria as vehicle-treated animals (P < 0.05), and had less glomerulosclerosis, tubular atrophy, interstitial fibrosis, and inflammation. Immunohistochemistry showed that sirolimus attenuated the increased expression of renal vascular endothelial growth factor (VEGF), as well as the expression of VEGF receptors 1 and 2. In conclusion, sirolimus halted the progression of proteinuria and structural damage in a rat model of reduced renal mass, possibly through a reduction in renal VEGF activity.     

Cyclosporin withdrawal with concomitant conversion from azathioprine to mycophenolate mofetil in renal transplant recipients with chronic allograft nephropathy: a 2-year follow-up

Because recent large studies have demonstrated that mycophenolate mofetil (MMF) is superior to azathioprine (AZA) as a post-transplant immunosuppressant, it has been speculated that MMF could have a cyclosporin (CsA)-sparing effect in renal transplant recipients with chronic allograft dysfunction. Between April 1996 and October 1998, 31 patients with chronic allograft dysfunction were assigned to have conversion from AZA to MMF with concomitant CsA withdrawal. Patient and graft outcomes were analysed. Mean follow-up time after MMF conversion was 27+/-11 months. Serum creatinine concentration (sCt) significantly decreased after conversion and remained stable at the end of follow-up (227+/-31 micro mol/l vs. 185+/-50 micro mol/l; P<0.0005). Mean variation in sCt was -24% after conversion, whereas it was +20% in the year before conversion ( P<0.001). There was a significant inverse relationship between proteinuria at baseline and improvement in renal function (r=-0.35; P=0.01). Proteinuria increased during follow-up (0.79+/-0.6 vs. 1.79+/-1.08 g/day; P=0.04). Isolated CsA nephropathy was associated with the best outcome. Renal function significantly improved in patients with grade 1 chronic rejection and remained stable in patients with grade 2 chronic rejection. Two patients (6.5%) experienced late acute rejection, respectively 13 and 24 months after CsA withdrawal. Eight patients (29%) experienced systemic infections requiring hospitalization. Blood pressure control and lipid profile improved after conversion. CsA withdrawal with a concomitant switch from AZA to MMF allows a substantial and durable improvement in renal function. Both allograft histology and proteinuria at baseline are predictive of the evolution of renal function after conversion. Physicians should consider the risk of over-immunosuppression possibly associated with this therapeutic strategy.     

A Randomized Controlled Trial of Late Conversion from CNI-Based to Sirolimus-Based Immunosuppression Following Renal Transplantation

Maintenance immunosuppression with calcineurin inhibitors (CNIs) following renal transplantation is associated with nephrotoxicity and accelerated graft loss. We aimed to assess whether conversion to sirolimus-based immunosuppression would affect the progression of renal impairment. In this single center, randomized controlled trial, 40 renal transplant recipients between 6 months and 8 years post-transplant were randomly assigned to remain on their CNI (cyclosporin or tacrolimus) or to switch to sirolimus. The primary outcome measure was change in glomerular filtration rate (GFR) measurement at 12 months. Analysis was by intention-to-treat. Of the 40 patients randomized, 2 patients never took the study drugs and were excluded, leaving 19 patients per group. There was a significant change in GFR at 12 months following conversion to sirolimus (12.9 mL/min, 95% CI 6.1-19.7; p < 0.001). Following conversion, the principal adverse events were the development of rashes (68%), particularly acne, and mouth ulcers (32%). No patient in either group experienced an acute rejection episode. In renal transplant recipients, a change in maintenance therapy from CNIs to sirolimus is associated with significant improvement in GFR at 12 months.     

Post-rapamycin proteinuria: incidence, evolution, and therapeutic handling at a single center

We performed a retrospective study to evaluate the safety, incidence, and management of proteinuria in 31 renal transplant recipients converted to Rapamycin (RAPA). All patients received RAPA immediately after the cessation of the calcineurin inhibitor or the antiproliferative drug. No acute rejection episodes were seen after this regimen. Chronic allograft nephropathy (58.1%) and calcineurin inhibitor toxicity (51.6%), both biopsy-proven, were the major reasons to introduce RAPA. Post-RAPA proteinuria was defined as the appearance of urine protein excretion >300 mg/d or any further increase in protein among those who showed previously elevated levels. We observed an elevated incidence of proteinuria of 48.4%. It started at 5.3 +/- 2.5 months after the conversion and 60% occurred within 6 months. The proteinuria increased from a median of 200 mg/d to 1466 mg/d (P < .001). Age, gender, race, HLA mismatches, time to onset of RAPA, level of previous proteinuria, glomerular filtration rate, use of renin-angiotensin blockers, and etiology of chronic kidney disease were similar between the groups with or without proteinuria. Once it appeared, we suspended the drug in only 4 patients (26.7%), initiated or augmented the dosage of renin-angiotensin blockers in 26.7%, adjusted the RAPA dose in 20.1%, and did not perform a specific measure in 40% (6 of 15). At 15.6 +/- 12.7 months, 91% showed no further increase or reduction in proteinuria. We observed a high prevalence of proteinuria among renal transplant recipients converted to RAPA (48.4%). In addition, RAPA was suspended in only 4 patients and the proteinuria showed a tendency to stabilize or reduce over time.