Proteinuria in Transplant Patients Associated With Sirolimus

Renal

Proteinuria in Transplant Patients Associated With Sirolimus A.F.V. Franco, D. Martini, H. Abensur, and I.L. Noronha ABSTRACT Sirolimus (SRL) is a potent immunosuppressive drug used in organ transplantation for prophylaxis of acute allograft rejection. Conversion from calcineurin inhibitors to SRL has become an important alternative in patients with chronic allograft nephropathy. Recently, some reports have described the appearance of proteinuria after the use of SRL. The aim of the present study was to describe the incidence of proteinuria in transplant recipients receiving SRL in our transplant center. We studied 78 patients receiving SRL either de novo or after conversion. Eighteen transplant recipients (23.1%) developed proteinuria after SRL treatment. Proteinuria was diagnosed at 11.2 ⫾ 2.1 months after the initiation of SRL; in eight patients (44.4%) it occurred in the first 6 months. The mean value of proteinuria was 2.6 ⫾ 0.6 g/24 hours. In 5 patients (27.8%), proteinuria reached nephrotic levels, and in 13 patients (72.2%) was associated with edema. Renal allograft biopsies were performed before conversion to SRL, and a new biopsy, after the appearance of proteinuria. The light microscopy of biopsies performed after the onset of proteinuria showed no specific glomerular changes, except in 2 cases wherein the diagnosis was focal segmental glomerulosclerosis. Immunofluorescence was negative in all cases. In conclusion, in this study proteinuria was observed in 21.3% of patients receiving SRL therapy either as de novo protocol or after conversion to SRL. Proteinuria occurred early after the initiation of SRL therapy and in these cases, withdrawal of SRL was associated with reversion of proteinuria.

S

IROLIMUS (SRL) is a potent immunosuppressive drug used for the prevention of acute allograft rejection after transplantation. Conversion to SRL has become an important therapeutic alternative for patients with chronic allograft nephropathy (CAN). In addition, some studies have demonstrated the potential benefit of a switch to SRL for patients with biopsy-proven calcineurin inhibitor (CNI) toxicity.1– 6 The occurrence of proteinuria has been recently recognized among patients on SRL-based therapy.7–11 Proteinuria related to the use of SRL can occur de novo or as worsening of preexisting proteinuria.12,13 The incidence of © 2007 by Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010-1710 Transplantation Proceedings, 39, 449 – 452 (2007)

From the Laboratory of Molecular and Cellular Nephrology, University of São Paulo (A.F.V.F., I.L.N.) and the Nephrology Clinic, Beneficencia Portuguesa Hospital (D.M.F., H.A., I.L.N.), São Paulo, Brazil. Address reprint requests to Andréia Fabiana do Vale Franco, MSc, Laboratory of Molecular and Cellular Nephrology, University of São Paulo, Av. Dr. Arnaldo, 455 - 3° andar – Lab 3342, CEP: 01246-903, São Paulo - Brazil. E-mail: afvfranco@gmail. com 0041-1345/07/$–see front matter doi:10.1016/j.transproceed.2007.01.038 449

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this unexpected event is still not entirely established. Because proteinuria is considered to be an important marker for the progression of chronic renal disease, the appearance of proteinuria associated with SRL has clinical relevance, and the mechanisms involved in its development should be elucidated. The aim of the present study was to describe the incidence of proteinuria among transplant recipients receiving SRL in our transplant center. PATIENTS AND METHODS Patients Seventy-eight patients received SRL either as a de novo immunosuppressive protocol or in a conversion protocol. The 43 male and 35 female subjects had an overall age of 37 ⫾ 1.3 years (range, 18 to 61 years). Of these 78 patients, 35 received kidney, 24 kidney– pancreas, 12 pancreas alone, 6 islet alone, and 1 kidney–liver transplant. Fifteen patients (19.2%) received SRL-based therapy from the time of transplantation (de novo protocol) associated with CNI or with mycophenolate mofetil (MMF) and prednisone. SRL doses were adjusted to maintain SRL trough levels between 8 and 12 ng/mL. Sixty-three transplant patients (80.8%) were converted to SRL. The conversion protocol consisted of a gradual discontinuation in the majority of cases (92.1%) and abrupt replacement in five patients (7.9%). Gradual conversion occurred at 4 to 6 weeks characterized by a 50% reduction in CNI or MMF after introduction of SRL over 2 weeks, followed by a progressive reduction and withdrawal when the target SRL was achieved. The causes for conversion were CNI nephrotoxicity, CNI neurotoxicity, cancer, and adverse effects (diarrhea and hyperglycemia) related to other drugs.

Proteinuria Only patients who developed de novo proteinuria after SRL were included in this analysis. Patients presenting any degree of proteinuria before conversion to SRL were not enrolled in the study. Proteinuria was diagnosed by 24-hour urine collections performed routinely or when patients showed edema or when detected on urinalysis (and, then, confirmed with a 24-hour urine collection). Only eight patients (10.3%) were using angiotensin converting enzyme inhibitor or angiotensin II receptor blockers concomitant with the immunosuppressive therapy.

FRANCO, MARTINI, ABENSUR ET AL with Welch’s correction when necessary. Pearson correlation coefficient was used for correlation analysis. All analyses were realized through the Graph Pad Prism 4.0® software. Values were considered significant when P ⬍ .05.

RESULTS

Of 78 transplant recipients on SRL-based therapy, 18 (23.1%) developed proteinuria. Only 2 of 15 patients (13.3%) receiving SRL de novo developed proteinuria (Table 1). Of 63 patients converted from CNI⫹MMF⫹steroids to SRL, 16 (25.4%) displayed proteinuria (13 cases were switched to a CNIsparing protocol and in 3 cases MMF was withdrawn). Data on these 18 transplant recipients are shown in Table 2. These cases included 13 men and 5 women of overall mean age 39 ⫾ 1.6 years (range, 32 to 51 years). For the 16 converted patients, conversion to SRL occurred 40 ⫾ 9.6 months (range, 4 to 154 months) after transplantation. Proteinuria was diagnosed 11 ⫾ 2.1 months after the initiation of SRL (range, 1 to 32 months), including seven patients (38.9%) in whom it occurred in the first 6 months. The mean value of proteinuria was 2.6 ⫾ 0.6 g/24 hours, ranging from 0.5 to 9.6 g/24 hours. In 5 patients (27.8%), proteinuria reached nephrotic levels, and in 13 patients (72.2%) it presented as edema. Angiotensin-converting enzyme inhibitor or angiotensin II receptor antagonists were used in five patients (27.8%) concomitant with the immunosuppressive therapy. In the six patients (33%) that SRL was withdrawn we observed reversion of proteinuria and edema. The doses of SRL at time of proteinuria ranged from 2 to 6 mg/day (mean, 3.2 ⫾ 0.3 mg/day), with SRL trough blood levels ranging from 4.4 to 15.3 ng/mL (mean, 7.4 ⫾ 0.7 ng/mL). There was no correlation between proteinuria levels and SRL doses (r ⫽ ⫺0.3; P ⫽ NS), or SRL trough blood levels (r ⫽ 0.2; P ⫽ NS). There were no significant changes in serum creatinine levels before SRL or at the moment of proteinuria. Of 18 patients with proteinuria, 14 patients (77.8%) underwent a renal allograft biopsy after the diagnosis of Table 1. Transplant Recipients on De Novo SRL Protocol and Converted to SRL That Developed Proteinuria n

Proteinuria

%

Renal Allograft Biopsies Before conversion to SRL, all patients underwent a kidney allograft biopsy. Patients under SRL-based therapy who developed proteinuria additionally underwent a kidney biopsy. Renal tissue samples were obtained by percutaneous needle biopsy under ultrasound guidance. The histologic diagnoses were established by light microscopy using paraffin sections (4 ␮m) stained with hematoxylin and eosin, and periodic acid Schiff. Immunofluorescence techniques were performed for immunoglobulin and complement system components.

Statistical Analysis Data were presented as mean values ⫾ SEM. Differences between groups were tested using the paired and unpaired Student’s t-test

de novo SRL Kidney Islets Pancreas Subtotal Converted to SRL Kidney/pancreas Kidney Pancreas Islets Kidney-liver Subtotal Total *Pancreas after kidney. † Pancreas after kidney (n ⫽ 4).

10 4 1* 15

2 0 0 2

20 0 0 13.3

25 24 11† 2 1 63 78

9 5 0 2 0 16 18

36 17 0 100 0 25.4 23.1

SIROLIMUS-ASSOCIATED PROTEINURIA

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Table 2. Clinical and Laboratory Data of Transplant Recipients Converted to SRL or With De Novo SRL Protocol Who Developed Proteinuria

Transplant Patients

n

Age (yr)

Time of Conversion After Tx (mos)

Kidney–pancreas (n ⫽ 9)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

47 37 32 37 38 34 33 39 37 45 33 32 33 46 49 51 42 50 39 ⫾ 1.6

47 20 19 20 23 6 26 32 16 4 52 11 46 83 80 154 — — 40 ⫾ 9.6

Kidney (n ⫽ 5)

Islets (n ⫽ 2) De novo (n ⫽ 2) Mean ⫾ SEM

Time of Proteinuria Appearance After SRL (mos)

Levels of Proteinuria (g/24 h)

6 24 9 10 7 1 3 19 3 8 1 24 2 32 18 16 6 12 11 ⫾ 2.1

3.9 3.9 0.9 0.9 3.2 1.3 1.2 2.4 9.6 1.7 1.0 0.5 6.5 0.8 0.9 0.9 0.6 6.5 2.6 ⫾ 0.6

SRL Dose* (mg/day)

SRL Through Level* (ng/mL)

SCr Before SRL (mg/dL)

SCr After SRL* (mg/dL)

3.0 6.0 3.0 3.0 4.5 5.0 3.0 2.0 2.0 3.0 2.0 5.0 2.0 2.0 3.0 3.0 4.0 2.0 3.2 ⫾ 0.3

4.5 7.7 11.2 6.1 5.5 4.4 10.3 5.5 7.5 7.8 5.6 5.8 4.4 10.7 6.4 5.0 10.3 14.0 7.4 ⫾ 0.7

2.2 2.8 2.1 1.0 1.7 2.5 2.0 1.7 1.8 1.9 1.8 2.1 2.9 1.5 1.2 1.4 — — 1.9 ⫾ 0.1

2.6 2.3 2.3 1.2 1.8 2.0 1.4 2.1 1.8 2.3 1.7 1.7 4.6 1.8 1.7 1.4 1.2 2.2 2 ⫾ 0.2

Abbreviations: SCr, serum creatinine; SEM, standard error of the mean; SRL, sirolimus. *At the appearance of proteinuria.

proteinuria. Of these biopsies, 10 (71.4%) were classified as CAN in the biopsy performed before conversion to SRL therapy. In five patients (50%) the renal histology ameliorated or remained stable after SRL inception, whereas in five patients (50%) the biopsies disclosed a worsened degree of the lesions. Interestingly, the CAN cases with favorable histologic outcomes were converted earlier after transplantation compared to those who presented a worse outcome (48.8 ⫾ 12.5 versus 8.8 ⫾ 2.8 months, respectively; P ⬍ .05). The other four cases (28.6%) included 2 patients from the de novo protocol and 2 other cases, who showed only mild changes in the renal biopsy before conversion (they were converted due to adverse effects of other immunosuppressive drugs). Concerning the glomerular changes in biopsies performed after proteinuria, various degrees of mesangial proliferation and mesangial expansion were commonly associated with CAN cases. However, in two cases (14.3%), the glomerular changes fulfilled the criteria for the histologic diagnosis of focal segmental glomerulosclerosis. There were no specific tubular interstitial changes beside the findings of tubular casts in some biopsies. Immunofluorescence was negative in all cases. DISCUSSION

The present study analyzed the occurrence of de novo proteinuria in transplant patients receiving SRL-based immunosuppression. Proteinuria was observed in 21.8% of patients, developing prominently in the first 6 months after

the initiation of SRL. The occurrence of proteinuria associated with SRL has been reported by other authors.7–11 In this study, the level of proteinuria ranged from 0.5 to 9.6 g/24 hours, reaching nephrotic levels in almost 28% of the cases. The increased urinary protein loss was associated with clinical signs, such as edema, which was observed in 70% of patients. No significant correlation was observed between the development of proteinuria and SRL dose or blood level. It has been reported that the use of angiotensinconverting enzyme inhibitor or angiotensin II receptor antagonists promotes reduction of urinary protein losses in these cases.14 –16 However, proteinuria reverts when SRL is withdrawn,13,17,18 strongly suggesting that SRL has a direct effect to induce proteinuria. It is notable that the development of proteinuria occurred predominantly in patients converted to SRL rather than those treated in a de novo SRL protocol. These findings suggest that the withdrawal of CNI in patients with CAN could trigger the development of proteinuria, as already suggested by some authors.9,10 However, proteinuria also occurred in patients receiving CNI⫹SRL; it has not been observed in conversion protocols to MMF with CNI withdrawal. Another evidence of the direct role of proliferation signal inhibitors to induce proteinuria is the reversal upon SRL withdrawal. Except for two cases, renal biopsies performed in patients that developed proteinuria did not reveal any specific changes. However, established morphologic lesions might not yet be detected due to the fact that the biopsies were

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performed at the time of development of proteinuria. In this context, an analysis of structural changes by electron microscopy would be of great interest; this evaluation is currently being performed. In conclusion, in this study proteinuria was observed in 21.3% of patients receiving SRL therapy either in a de novo protocol or after conversion to SRL. Proteinuria occurred early after the initiation of SRL therapy and in these cases, withdrawal of SRL was associated with reversion of proteinuria. ACKNOWLEDGMENTS The authors thank Carla Marotti and Natascha Camaroske from the Nephrology Clinic, Beneficencia Portuguesa Hospital, São Paulo, for assistance with data collection.

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FRANCO, MARTINI, ABENSUR ET AL neoplasia after renal transplantation. A single-center experience. Transplant Proc 37:3727, 2005 7. Dervaux T, Caillard S, Meyer C, et al: Is sirolimus responsible for proteinuria? Transplant Proc 37:2828, 2005 8. Ruiz JC, Diekmann F, Campistol JM, et al: Evolution of proteinuria after conversion from calcineurin inhibitors (CNi) to sirolimus (SRL) in renal transplant patients: a multicenter study. Transplant Proc 37:3833, 2005 9. Letavernier E, Peraldi M, Pariente A, et al: Proteinuria following a switch from calcineurin inhibitors to sirolimus. Transplantation 80:1198, 2005 10. Saurina A, Campistol JM, Piera C, et al: Conversion from calcineurin inhibitors to sirolimus in chronic allograft dysfunction: changes in glomerular haemodynamics and proteinuria. Nephrol Dial Transplant 21:488, 2006 11. Boratynska M, Banasik M, Watorek E, et al: Conversion to sirolimus from cyclosporine may induce nephrotic proteinuria and progressive deterioration of renal function in chronic allograft nephropathy patients. Transplant Proc 38:101, 2006 12. Fervenza FC, Fitzpatrick PM, Mertz J, et al. Acute rapamycin nephrotoxicity in native kidneys of patients with chronic glomerulopathies. Nephrol Dial Transplant 19:1288, 2004 13. Dittrich E, Schmaldienst S, Soleiman A, et al: Rapamycinassociated post-transplantation glomerulonephritis and its remission after reintroduction of calcineurin-inhibitor therapy. Transplant Int 17:215, 2004 14. Morelon E, Kreis H: Sirolimus therapy without calcineurin inhibitors: Necker Hospital 8-year experience. Transplant Proc 35:52S, 2003 15. Sennesael JJ, Bosmans JL, Bogers JP, et al: Conversion from cyclosporine to sirolimus in stable renal transplant recipients. Transplantation 80:1578, 2005 16. van der Akker JM, Wetzels JFM, Hoitsma AJ: Proteinuria following conversion from azathioprine to sirolimus in renal transplant recipients. Kidney Int 70:1355, 2006 17. Senior PA, Paty BW, Cockfield SM, et al: Proteinuria developing after clinical islet transplantation resolves with sirolimus withdrawal and increases tacrolimus dosing. Am J Tranplant 5:2318, 2005 18. Straathof-Galema L, Wetzels JF, Dijkman HB, et al: Sirolimus-associated heavy proteinuria in a renal transplant recipient: evidence for a tubular mechanism. Am J Transplant 6:429, 2006