Posterior Reversible Encephalopathy Syndrome Independently Associated With Tacrolimus and Sirolimus After Multivisceral Transplantation

Posterior reversible encephalopathy syndrome (PRES) is a small vessel microangiopathy of the cerebral vasculature that occurs in 0.5–5% of solid organ transplant recipients, most commonly associated with tacrolimus (Tac). Clinical manifestations include hypertension and neurologic symptoms. We report an adult multivisceral transplant recipient who experienced recurrent PRES initially associated with Tac and subsequently with sirolimus. A 49‐year‐old woman with short bowel syndrome underwent multivisceral transplantation due to total parenteral nutrition–related liver disease. She was initially maintained on Tac, mycophenalate mofetil (MMF) and prednisone. Three months after transplantation, she developed renal dysfunction, leading to a reduction in Tac and the addition of sirolimus. Eight months after transplantation, she developed PRES. Tac was discontinued and PRES resolved. Sirolimus was increased to maintain trough levels of 12–15 ng/mL. Fourteen months after transplant, she experienced recurrent PRES which resolved after discontinuing sirolimus. Currently 3 years posttransplant, she is maintained on cyclosporine, MMF and prednisone with no PRES recurrence. In addition to calcineurin inhibitors, sirolimus may also be associated with PRES after solid organ transplantation. Ours is the first report of sirolimus‐associated PRES in the setting of multivisceral transplantation. Identifying a safe alternative immunosuppression regimen was challenging but ultimately successful.     

Initial single-center experience with sirolimus after lung transplantation

BACKGROUND: Standard immunosuppression after lung transplantation includes calcineurin inhibitors, mycophenolate mofetil, and steroids. Long-term survivors of lung transplantation are often confronted with chronic kidney disease, by definition related to the intake of calcineurin inhibitors. Sirolimus has been increasingly proposed as an alternative immunosuppressive agent due to its absence of nephrotoxicity, which could be used in selected patients. METHODS: We prospectively administered sirolimus as an alternative to calcineurin inhibitors in 10 lung transplantation recipients with persistent drug nephrotoxicity. They were switched from tacrolimus to sirolimus. Four patients also had bronchiolitis obliterans syndrome. The conversion scheme consisted of an immediate stop of tacrolimus and an 6 to 8-mg loading dose of sirolimus, followed by 4 mg/d. After 5 days, the sirolimus dose was adjusted to maintain trough levels between 12 and 18 ng/mL or 6 and 12 ng/mL for combined sirolimus and tacrolimus. Patients were monitored for renal and graft function as well as clinical status. RESULTS: A significant decrease in creatinine was observed after 1 week of treatment (P = .011). Azotemia decreased after 1 month, remaining stable (P < .01). Pulmonary function tests did not show significant modification from before sirolimus, inception in patients with or without bronchiolitis obliterans syndrome. There were seven infections. One patient died of complications related to bronchiolitis obliterans. CONCLUSION: Sirolimus was a useful alternative immunosuppressant, allowing significant tacrolimus withdrawal in transplant recipients with renal impairment. Sirolimus administration allowed recovery of renal function with low morbidity; it was useful for rescue of chronic renal impairment after lung transplantation.     

Magnetic resonance-defined perinephric edema after clinical islet transplantation: a benign finding associated with mild renal impairment

Immunosuppression with sirolimus and low-dose tacrolimus has facilitated successful clinical islet transplantation (CIT). Because the long-term effects on the kidney are unknown and immunosuppressant drugs can be nephrotoxic, CIT is currently restricted to patients with preserved renal function or a functioning renal transplant. The impact of CIT on the native kidney of islet-alone recipients was assessed with magnetic resonance imaging (MRI). After successful CIT, MRI revealed perinephric edema (PNE) in 10 of 30 recipients. PNE was associated with a mild degree of renal impairment but was not associated with preexisting diabetic nephropathy, albuminuria, microscopic hematuria, graft function, or other clinical and metabolic parameters. The presence of PNE on MRI after CIT seems to be a common but benign finding, most likely an adverse effect of sirolimus. Although this novel observation does not seem to be of concern, further studies are required to examine the long-term impact of CIT and immunosuppression on renal function.     

Proteinuria following conversion from azathioprine to sirolimus in renal transplant recipients

Recent studies have reported a significant increase of proteinuria in kidney transplant recipients who were switched from a calcineurin inhibitor (CI) to sirolimus. This has (partly) been ascribed to the hemodynamic renal effects of CI withdrawal. We have evaluated the evolution of proteinuria in renal transplant recipients who underwent conversion from azathioprine to sirolimus. In a randomized, prospective, multicenter study called RESCUE (Recurrent cutanEous Squamous cell Carcinoma Under RapamunE) the efficacy and safety is investigated of conversion to sirolimus in stable renal transplant recipients with a cutaneus squamous cell carcinoma (SCC). In our center 25 patients have been included in this study of which 13 patients were randomized to continue their current immunosuppressive treatment and 12 to conversion to sirolimus. After a mean follow-up of 360 days mean proteinuria increased from 0.37+/-0.34 to 1.81+/-1.73 g/24 h after conversion to sirolimus (P<0.005). In the control group there was no change in proteinuria. A significant increase of proteinuria was observed in all seven patients with proteinuria before conversion, whereas proteinuria remained absent in all patients without previous proteinuria. Two of the patients with proteinuria were converted from cyclosporine and five were converted from azathioprine to sirolimus. Sirolimus was discontinued in five patients with proteinuria, and in all of them proteinuria declined to baseline values. Our study demonstrates that conversion from azathioprine to sirolimus after kidney transplantation may cause a reversible increase of proteinuria. Sirolimus-induced proteinuria therefore cannot be ascribed to the hemodynamic renal effects of withdrawal of CI.     

Randomized trial of tacrolimus in combination with sirolimus or mycophenolate mofetil in kidney transplantation: results at 6 months

BACKGROUND: This is the first report of a randomized, multicenter, clinical trial comparing the combination of sirolimus or mycophenolate mofetil (MMF) with tacrolimus-based immunosuppression in kidney transplantation. Results at 6 months of follow-up are presented. METHODS: Before transplantation, patients were randomized to receive tacrolimus plus corticosteroids with sirolimus (n=185) or MMF (n=176). The primary endpoint of the study was the incidence of biopsy-confirmed acute rejection. Patient and graft survival, renal function, and composite endpoints also were evaluated. Safety was assessed by monitoring laboratory parameters and adverse events. RESULTS: By 6 months of follow-up, the incidence of biopsy-confirmed acute rejection was similar in both treatment groups (13.0% tacrolimus+sirolimus vs. 11.4% tacrolimus+MMF; P=0.64 log-rank). Patient survival (97.3% tacrolimus+sirolimus vs. 97.7% tacrolimus+MMF) and graft survival (93.0% tacrolimus+sirolimus vs. 95.5% tacrolimus+MMF) were equivalent (P=0.53, overall survival log-rank). There was a significantly higher incidence of study drug discontinuation in patients receiving sirolimus (21.1% vs. 10.8%; P=0.008). Renal function was significantly better in the MMF-treatment group (serum creatinine 1.44+/-0.45 mg/dL vs. 1.77+/-1.42 mg/dL; P=0.018). Hyperlipidemia was significantly more prevalent in the sirolimus-treatment group. Diastolic blood pressure was significantly higher in sirolimus-treated patients. There were significantly more leukopenia and gastrointestinal adverse events in the MMF-treatment group. The incidence of posttransplant diabetes mellitus was 7.6% in the sirolimus group and 7.7% in the MMF group. CONCLUSION: Tacrolimus is equally effective in renal transplantation when combined with sirolimus or MMF. The tacrolimus-MMF combination may be superior in terms of improved renal function and improved cardiovascular risk factors including hyperlipidemia and hypertension.     

Sirolimus-associated diffuse alveolar hemorrhage in a renal transplant recipient on long-term anticoagulation

Sirolimus (rapamycin, rapamune) is an effective immunosuppressant that has been widely used in solid organ transplantation. Recently, two disconcerting side effects, namely pulmonary toxicity, usually in the form of interstitial pneumonitis, and the onset of nephrotic range proteinuria, have been recognized. We report the case of a renal transplant recipient who had been on chronic anticoagulation therapy for a mechanical aortic valve, and who developed pulmonary distress necessitating emergent intubation 18 days after starting sirolimus therapy. Open lung biopsy showed diffuse alveolar hemorrhage with fibrin deposits in the alveolar spaces and small bronchi. Urine protein/creatinine ratio at that time was 16.7. Upon discontinuation of sirolimus, alveolar hemorrhage and nephrotic range proteinuria resolved. We suggest that extra vigilance be paid in individuals who are on chronic anticoagulation and who are started on sirolimus.     

A prospective, randomized trial of tacrolimus in combination with sirolimus or mycophenolate mofetil in kidney transplantation: results at 1 year

BACKGROUND: This is the 1-year report of a randomized, multicenter, clinical trial comparing the combination of sirolimus or mycophenolate mofetil (MMF) with tacrolimus-based immunosuppression in kidney transplantation. METHODS: Prior to transplantation, recipients were randomized to receive tacrolimus plus corticosteroids with either sirolimus (n=185) or MMF (n=176). The incidence of biopsy-confirmed acute rejection at 6 months was the primary endpoint of the study. Patient and graft survival, renal function, study drug dosing and discontinuations were evaluated at 1 year. RESULTS: At 1 year, there was no difference in patient survival (95.7% sirolimus vs. 97.2% MMF; P=0.45) or graft survival (90.8% sirolimus vs. 94.3% MMF; P=0.22). Patients without delayed graft function (DGF) receiving MMF had significantly better graft survival (99% vs. 93%; P=0.01). Patients receiving a transplant from a live donor had a trend towards better graft survival with MMF as compared to sirolimus (98% vs. 91%; P=0.07). Patients receiving sirolimus had a significantly higher incidence of study drug discontinuation (26.5% vs. 14.8% MMF; P=0.006). Patients receiving MMF had significantly better renal function as shown by median serum creatinine levels (1.3 mg/dL vs. 1.5 mg/dL; P=0.03) and a trend towards higher calculated creatinine clearance (CrCl), (58.4 ml/min vs. 54.3 ml/min; P=0.06). More patients in the sirolimus group had a serum creatinine >2.0 mg/dL, (20.4% vs. 11.0%; P=0.02). CONCLUSIONS: Tacrolimus is safe and effective in live and deceased donor kidney transplantation when given in combination with sirolimus or MMF. Patient and graft survival were excellent in both arms. Renal function is superior for patients treated with tacrolimus + MMF combination.     

Long-term efficacy and safety of a calcineurin inhibitor-free regimen in live-donor renal transplant recipients

Calcineurin inhibitor (CNI) nephrotoxicity is a major concern after renal transplantation. To investigate the safety and efficacy of a CNI-free immunosuppressive regimen, 132 live-donor renal transplant recipients were included in a prospective, randomized controlled trial. All patients received induction therapy with basiliximab and steroids. The patients were randomized to a maintenance immunosuppression regimen that included steroids, sirolimus, and either low-dose tacrolimus or mycophenolate mofetil (MMF). Over a mean follow-up period of approximately 5 yr, patient and graft survival did not significantly differ between the two maintenance regimens. Patient survival was 93.8% and 98.5% in the tacrolimus/sirolimus and MMF/sirolimus groups, respectively, and graft survival was 83% and 88%, respectively. However, the MMF/sirolimus group had significantly better renal function, calculated by Cockcroft-Gault, from the second year post-transplant until the last follow-up. In addition, this group was less likely to require a change in their primary immunosuppression regimen than the tacrolimus/sirolimus group (20.8% versus 53.8%, P = 0.001). The safety profile was similar between groups. In summary, after long-term follow-up, a CNI-free maintenance regimen consisting of sirolimus, MMF, and steroids was both safe and efficacious among low to moderate immunologic risk renal transplant recipients.     

Sirolimus and mycophenolate mofetil as calcineurin inhibitor-free immunosuppression in a cardiac transplant patient with chronic renal failure.

Chronic renal failure triggered by calcineurin inhibitor (CNI)-based immunosuppression is a common complication after cardiac transplantation. Sirolimus and mycophenolate mofetil (MMF) are 2 newer immunosuppressive agents with no documented nephrotoxic side effects. This case report describes a patient with ongoing chronic renal failure 10 months after cardiac transplantation on cyclosporine-based immunosuppressive therapy. Conversion of the immunosuppressive regimen from cyclosporine to sirolimus and MMF resulted in freedom from acute rejection, excellent cardiac graft function and consistently improved renal function. This case illustrates the beneficial potential of sirolimus and MMF as CNI-free and safe long-term immunosuppression in a patient with chronic renal failure after heart transplantation.     

Multicenter Australian Trial of Islet Transplantation: Improving Accessibility and Outcomes

Whilst initial rates of insulin independence following islet transplantation are encouraging, long‐term function using the Edmonton Protocol remains a concern. The aim of this single‐arm, multicenter study was to evaluate an immunosuppressive protocol of initial antithymocyte globulin (ATG), tacrolimus and mycophenolate mofetil (MMF) followed by switching to sirolimus and MMF. Islets were cultured for 24 h prior to transplantation. The primary end‐point was an HbA1c of <7% and cessation of severe hypoglycemia. Seventeen recipients were followed for ≥12 months. Nine islet preparations were transported interstate for transplantation. Similar outcomes were achieved at all three centers. Fourteen of the 17 (82%) recipients achieved the primary end‐point. Nine (53%) recipients achieved insulin independence for a median of 26 months (range 7–39 months) and 6 (35%) remain insulin independent. All recipients were C‐peptide positive for at least 3 months. All subjects with unstimulated C‐peptide >0.2 nmol/L had cessation of severe hypoglycemia. Nine of the 17 recipients tolerated switching from tacrolimus to sirolimus with similar graft outcomes. There was a small but significant reduction in renal function in the first 12 months. The combination of islet culture, ATG, tacrolimus and MMF is a viable alternative for islet transplantation.     

Characteristics of sirolimus-associated interstitial pneumonitis in renal transplant patients

BACKGROUND: Sirolimus, a promising new immunosuppressive drug for organ transplantation, is currently associated with side effects, such as thrombocytopenia and hyperlipidemia. METHODS: Eight renal transplant recipients, who developed unexplained interstitial pneumonitis during sirolimus therapy, were extensively re-screened for all causes of pneumonitis. RESULTS: Interstitial pneumonitis was constantly characterized by bilateral interstitial infiltrates on chest x-rays and lung computed tomography scans, with marked general symptoms in all patients but one. Bronchoalveolar lavage (BAL) disclosed lymphocytic alveolitis (mainly of the CD4 type) in seven patients and alveolar hemorrhage in one. Transbronchial lung biopsies, performed in two patients, showed bronchiolitis obliterans with organizing pneumonia combined with lymphocytic interstitial pneumonitis. Pulmonary infections were ruled out by specific stainings and cultures of BAL, bronchial aspirates, and blood cultures. After the elimination of all possible causes, sirolimus-induced pneumonitis was considered probable. Discontinuation of sirolimus in seven cases and dose reduction in the remaining case dramatically improved clinical and radiological status within a few weeks and led to complete resolution within 3 months. CONCLUSIONS: Sirolimus is very probably responsible for interstitial pneumonitis on the following grounds: (a) occurrence of pneumonitis during sirolimus therapy; (b) absence of any other causes; and (c) resolution within 3 months of sirolimus discontinuation or dose reduction. Sirolimus should now be added to the list of possible causes of pulmonary complications after renal transplantation. Discontinuation or dose reduction of sirolimus led to complete and lasting resolution of symptoms.     

肝移植后并发他克莫司不良反应者的西罗莫司单药转换治疗14例

目的 总结出现钙调磷酸酶抑制剂(CNI)相关并发症的患者采用西罗莫司(SRL)单药转换治疗的体会.方法 肝移植患者14例,其中因CNI类药物致肾功能受损而行转换治疗者13例,因移植后血糖升高而行转换治疗者1例.转换治疗前,患者采用他克莫司(Tac)和糖皮质激素预防排斥反应,部分患者还加用霉酚酸酯.进行转换治疗后,初次给予SRL 4 mg/d;1周内给予SRL 1～2 mg/d,同时Tac的用量减至原来的一半;治疗1周后,根据血SRL浓度调整其剂量,维持血SRL浓度谷值为5～10μg/L,于转换治疗后1～2周完全撤除Tac.观察患者转换治疗后并发症的改善情况,肾功能、肝功能和急性排斥反应的发生情况及药物不良反应等.结果 转换治疗前,13例肾功能受损者的血肌酐为(158.3±41.6)μmol/L,随访结束时降低到(103.7±21.2)μmol/L;另1例血糖升高者在转换治疗后血糖得到有效控制,胰岛素用量由转换前的80 IU/L减少至24 IU/L.转换治疗后6个月内,14例中有2例(14.3%)发生急性排斥反应,治疗后均逆转.随访过程中,4例出现血脂升高,4例出现贫血或血小板减少,5例出现溃疡型口疮,但无患者因SRL不良反应而终止转换治疗.结论 肝移植术后出现CNI相关并发症的患者可以采用SRL单药转换治疗.     

Tacrolimus for the treatment of gout in renal transplantation: two case reports and review of the literature.

Episodes of gout are common in the setting of renal transplantation. Hyperuricemia and gout have been associated with the use of the calcineurin inhibitor, cyclosporine. We report two cases of severe polyarticular gout resistant to conventional therapy in renal transplant recipients that resolved after switching from cyclosporine to tacrolimus-based immunosuppression. There was no alteration in renal function, and trough concentrations of both cyclosporine and tacrolimus were within the recommended range. Resolution of gout occurred within a month of discontinuation of cyclosporine and commencement of tacrolimus. Use of tacrolimus may be beneficial in the renal transplant recipient with refractory gout.     

Comparative Effects of Sirolimus and Mycophenolate Mofetil on Erythropoiesis in Kidney Transplant Patients

Anemia and erythrocytosis (PTE) are common after kidney transplantation. We sought to determine the influence of sirolimus compared to mycophenolate mofetil (MMF) on post-transplant erythropoiesis. A total of 214 patients with recent kidney or kidney-pancreas transplants were treated with either sirolimus-based (n = 87) or MMF-based (n = 127) therapy. At 12 months, the prevalence of anemia was 31% with MMF and 57% with sirolimus (p < 0.001). Linear regression was used to examine the independent influence of sirolimus on hemoglobin at 12 months, controlling for multiple factors including gender and renal function. Sirolimus remained a significant correlate of lower hemoglobin in all patients (slope =-1.060, 95% CI: -1.76 to -0.362, p = 0.003), and in patients without PTE (slope =-0.671, 95% CI: -1.32 to -0.028, p = 0.041). PTE, defined as a persistent hematocrit above 51%, occurred in 19% with MMF and 7% with sirolimus (p = 0.013). PTE was examined using logistic regression analysis. Sirolimus use correlated negatively with PTE (odds ratio with sirolimus = 0.33, 95% CI: 0.12 to 0.89, p = 0.028). Our results indicate that, compared to treatment with MMF, treatment of kidney or kidney-pancreas recipients with sirolimus is associated with a higher prevalence of anemia, lower hemoglobin levels and lower incidence of PTE.     

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.     

Sirolimus immunosuppression in pediatric heart transplant recipients: a single-center experience.

BACKGROUND: Sirolimus has been used in heart transplant recipients for treatment of rejection, alternative immunosuppression (IS) and promotion of regression and prevention of graft vasculopathy (coronary artery disease [CAD]). This study reports on our center's experience with 16 children who underwent heart transplantation. METHODS: Data were obtained by retrospective review. RESULTS: Median age at time of review was 12.3 years (n = 16, 5.1 to 18.0 years; 9 boys, 7 girls), and at time of transplant 7.5 years (6 months to 18.0 years). Median time of sirolimus introduction was 2.7 years (1 month to 8.2 years) post-transplant. Fifteen patients were on steroids, 10 on tacrolimus (FK) and mycophenolate mofetil (MMF), 5 on FK and 1 on MMF with no calcineurin inhibitors (CNIs). The average dose of sirolimus was 0.25 mg/kg or 7.0 mg/m(2) to maintain a target level of 5 to 15 mug/liter. Sirolimus was started for CAD in 6 patients (38%), rejection in 5 (31%), and in 5 with combinations of CNI intolerance, CAD, renal dysfunction and rejection. All 6 who received sirolimus for rejection (International Society for Heart and Lung Transplantation [ISHLT] Grade 3A) showed improvement on follow-up biopsies. Two of 3 who received sirolimus for renal dysfunction showed improvement (glomerular filtration rate [GFR] 43 to 67 and 32 to 106 ml/min per 1.73 m(2), respectively). Side effects included hyperlipidemia (38%), abdominal pain (31%), mouth ulcers (26%), anemia or neutropenia (12.5%), persistent pericardial effusion (6%) and interstitial lung disease (6%). Sirolimus therapy was discontinued in 3 patients due to side effects. CONCLUSIONS: In this study sirolimus was found to be a valuable IS agent for the management of rejection, significant renal dysfunction and CNI side effects. These results support the need for prospective studies of the role of sirolimus in primary rejection prophylaxis, primary CAD prophylaxis and CAD regression. There also exists a need to establish an adverse event profile for this drug.     

Sirolimus: A Switch Option for Mycophenolate Mofetil–Induced Leukopenia in Renal Transplant Recipients

Mycophenolate mofetil (MMF) is a potent immunosuppressive agent used to prevent acute and chronic rejection in kidney transplantation or for rescue therapy. One side effect of MMF is bone marrow toxicity, including leukopenia, which may necessitate drug withdrawal. We report 2 patients who underwent kidney transplantation and developed leukopenia while receiving MMF and safely switched to sirolimus. A 35-year-old woman underwent deceased donor kidney transplantation. She received basiliximab, tacrolimus, MMF, and a corticosteroid. On postoperative day (POD) 75, her white blood cell (WBC) count was 1800/μL. A 44-year-old women underwent deceased donor kidney transplantation and received basiliximab, tacrolimus, MMF, valganciclovir, and a corticosteroid. On POD 88, her WBC count was 1320/μL. MMF was switched to sirolimus, resulting in recovery of WBC count without rejection. Switch from MMF to sirolimus is safe and favorable in MMF-induced leukopenia in renal transplant recipient.     

肝移植术后西罗莫司的替换治疗

目的 探讨肝移植术后应用西罗莫司的抗排斥替换治疗效果。方法 回顾性分析50例肝移植或肝肾联合移植患者替换西罗莫司前后肝肾功能的改善情况及副作用和排斥反应的发生率。34例联合应用小剂量FK506，9例联合应用骁悉，2例联合应用新山地明。5例术后远期患者，替换前仅用FK506，替换后单用西罗莫司。结果 24例患者因肝功能不良而替换西罗莫司，其中16例（66．7％）肝功能明显改善；18例患者肾功能不良，其中13例（72．2％）在2个月内肾功能明显好转；8例患者因大剂量应用FK506但其浓度未达到6ng／ml而替换西罗莫司，移植术后肝肾功能恢复良好，未出现排斥反应。本组中应用西罗莫司后出现急性排斥反应3例（6％），改用FK506后急性排斥反应治愈。11例（22％）出现白细胞及血小板减少，9例（18％）胆固醇和甘油三酯升高。这些副作用均在西罗莫司应用1月后出现，当停药或对症处理后消失。本组中未出现肝动脉血栓形成、伤口愈合不良等并发症。结论 肝移植术后应用钙调磷酸酶抑制剂发生肝肾功能不良或不能达到理想药物浓度时，西罗莫司是有效的抗排斥替代药物。     

Sirolimus-Associated Heavy Proteinuria in a Renal Transplant Recipient: Evidence for a Tubular Mechanism

Sirolimus is a new and potent immunosuppressive agent. Recently, increased proteinuria has been recognized as an important complication. However, the mechanism thereof has remained unclear. We describe a patient who received sirolimus as standard therapy after living donor kidney transplantation. Within 10 days the patient developed a severe proteinuria that disappeared completely after substituting tacrolimus for sirolimus. Renal biopsy disclosed normal glomeruli even without effacement of the podocytic foot processes. Using FITC labeled anti-albumin antibodies we noted complete absence of albumin in the proximal tubules, whereas an abundant albumin staining was observed in a control patient with a comparable level of proteinuria due to a recurrence of focal segmental glomerulosclerosis after transplantation. Our data suggest that sirolimus can induce severe proteinuria, and that reduced tubular protein reabsorption contributes to the protein loss.     

Sirolimus and tacrolimus trough concentrations and dose requirements after kidney transplantation in relation to CYP3A5 and MDR1 polymorphisms and steroids

BACKGROUND: CYP3A5 and MDR1 polymorphisms have been shown to influence tacrolimus blood concentrations and dose requirements. The aim is to determine whether these polymorphisms also affect sirolimus trough concentrations and dose requirements after kidney transplantation. METHODS: Eighty-five renal transplant recipients receiving sirolimus were included. Twenty-four were treated with a combined sirolimus-tacrolimus regimen. Eighty-one patients received steroids. Sirolimus and tacrolimus were adjusted to a target therapeutic window. CYP3A5 (intron 3) and MDR1 (exons 12, 21, 26) genotypes were correlated to the adjusted trough concentrations and dose requirements for both sirolimus and tacrolimus. RESULTS: There were no significant correlation between adjusted sirolimus trough concentrations or dose requirements and genetic polymorphisms. In a multiple regression model, adjusted-prednisone dose was involved with a positive or negative effect when considering sirolimus dose requirements or adjusted concentrations, respectively. In the subgroup of patients treated by tacrolimus and sirolimus, adjusted tacrolimus doses were higher in patients carrying at least one CYP3A5 *1 allele (median 0.083 vs. 0.035 mg/kg for CYP3A5*3/*3 patients, P<0.05). Adjusted-prednisolone dose and CYP3A5 polymorphism explained up to 61% of the variability in tacrolimus dose requirements. CONCLUSIONS: Unlike tacrolimus, sirolimus adjusted trough concentrations and dose requirements seem not affected by CYP3A5 and MDR1 polymorphisms. Adjusted-prednisone dose has a significant impact on tacrolimus and sirolimus dose requirements.