The introduction of cyclosporine (CsA) during the early 1980s resulted in a significant improvement in 1-year renal graft survival rates. Nevertheless, the use of CsA is associated with several side effects. Nephrotoxicity has emerged as a serious limiting factor for both transplanted and native kidneys (1–5). CsA is also associated with the development of posttransplantation hyperlipidemia and hypertension (6–8), which may ultimately affect both graft and patient survival.
Concerns about CsA toxicity have led numerous investigators to evaluate withdrawal of CsA, by either conversion from CsA to azathioprine (AZA) or withdrawal of CsA from an AZA-containing regimen. A first meta-analysis of 17 such studies showed that CsA withdrawal was associated with a trend to lower serum creatinine levels at the end of follow-up (9). A recent update of this initial meta-analysis, reporting on 13 studies of CsA withdrawal completed before 1999, found that the proportion of patients with acute rejection increased by 11% after CsA discontinuation (10). However, the relative risk of graft failure did not increase after CsA discontinuation, and in the six studies with at least 4 years of follow-up, there was a trend toward improved graft survival in patients weaned from CsA (relative risk: 0.92). Nevertheless, maintenance therapy with AZA and steroids has not become routine practice, mainly because of the concern about rejection after discontinuation of CsA.
Mycophenolate mofetil (MMF; CellCept) is a more potent immunosuppressive drug than AZA when used together with CsA and steroids in the posttransplantation period (11–13). MMF does not adversely affect kidney function, blood pressure, or lipid levels. MMF has been investigated in a number of small, uncontrolled studies with short-term follow-up in an attempt to improve the outcome of CsA withdrawal in renal transplantation (14–18). These studies demonstrated that the total or partial withdrawal of CsA in the presence of MMF resulted in an improvement in renal function. At the same time, in many cases serum lipid levels and blood pressure improved or became easier to control.
To obtain a clearer picture of the safety and benefits of CsA withdrawal in the presence of MMF, we conducted a multicenter, randomized, controlled trial of CsA withdrawal in stable kidney transplant recipients receiving MMF therapy. Patients were assessed at the 6-month primary endpoint.
In an open, multicenter, randomized, controlled trial, the immunosuppression in stable kidney transplant recipients receiving a CsA-based regimen was converted to MMF, corticosteroids, and CsA (Neoral, Novartis, Basel, Switzerland). One study arm had CsA slowly tapered and withdrawn (CsA withdrawal group), whereas the other continued with this regimen (CsA continuation group), as shown in Figure 1. The study was constructed as follows. The first phase (run-in phase) allowed the introduction of MMF (3 months) if the patient was not already receiving MMF. The second phase permitted the controlled reduction and final withdrawal of CsA from the test group (3 months). During the third phase (6 months), the main comparison between the CsA withdrawal group and the CsA continuation group was performed. Analyses were done on the intent-to-treat population, which comprises all patients randomized into the study, and on the per-protocol population, which is restricted to subjects who did not violate inclusion or exclusion criteria and who completed the third phase of the protocol.
All patients were given the opportunity to continue MMF treatment after study termination. Follow-up of key parameters such as renal function, serum lipids, hypertension, incidence of malignancy, and patient and graft survival rates will be continued for 5 years after trial entry to assess long-term outcome.
Recipients of first or second cadaveric or living donor kidney transplants, who were between 12 and 30 months posttransplantation and maintained on a CsA-based regimen, were considered for enrollment. To be enrolled, subjects must have had no more than one rejection episode after transplantation, no rejection episodes during the 3 months before enrollment, and stable renal function, defined as a serum creatinine level of less than 300 μmol/L, for at least 3 months before study entry.
Exclusion criteria included a white cell count less than 2.5×109/L or hemoglobin less 5 g/dL or serologic evidence of human immunodeficiency virus or hepatitis B surface antigen. Other exclusion criteria were severe diarrhea or severe gastrointestinal disorders that interfere with the absorption of oral medication; active peptic ulcer disease; malignancy or a history of malignancy, except successfully treated nonmetastatic basal or squamous cell carcinoma of the skin; pregnancy or lactation; panel-reactive antibodies greater than >50% at the time of transplantation; additional treatment with unlicensed, investigational drugs or other prohibited medication; and systemic infection (including cytomegalovirus) requiring therapy at the time of entry into the study.
The trial was performed in conformity with the Declaration of Helsinki (as amended in Tokyo, Venice, and Hong Kong), Good Clinical Practice guidelines, and all local laws and regulations concerning clinical trials. Informed consent, with complete and unambiguous freedom of refusal and withdrawal, was obtained from all patients. In addition, each center had to obtain independent approval from its applicable institutional review board or ethics committee.
Enrollment and Treatment Plan
Patients maintained on CsA and corticosteroids, with or without AZA, entered a 3-month run-in period during which they received MMF, CsA, and corticosteroids before randomization (Fig. 1). Patients already maintained on a triple-drug regimen of MMF, CsA, and corticosteroids were directly randomized. Thus, at randomization, all patients had been receiving triple-drug therapy with MMF, CsA, and corticosteroids for at least 3 months (Fig. 1). Patients were randomized either to gradual withdrawal of CsA during a further 3-month period (CsA withdrawal group) or to continued triple-drug therapy (CsA continuation group). Randomization was performed centrally by the minimization method, with frequency matching for the following variables: donor status (living, first cadaveric, second cadaveric), diabetes (yes or no), period of previous temporary interruption of CsA therapy (two groups: one consisting of patients who discontinued CsA for 0–10 days and the other for 11 or more days), renal function (creatinine clearance <50, 50–75, >75 mL/min), and proteinuria (<0.1, 0.1–1.0, >1.0 g/day). Those randomized to CsA withdrawal were tapered off CsA stepwise, by thirds of the baseline dosage, such that the dosage was reduced by one third immediately after randomization, by another third of the baseline dosage 6 weeks after randomization, and the final third (total discontinuation of CsA) 12 weeks after randomization.
A total of 187 patients entered the study. Seventeen of these were not randomized. The reasons for nonrandomization were as follows: adverse events (nine patients: abdominal pain, nausea and vomiting, gastrointestinal toxicity, diarrhea and constipation, gout, headache and vomiting, leukopenia, vomiting, and reason not given), patient request (three patients), administrative error (two patients), and other (three patients: islet transplantation, not eligible, and noncompliance). Thus, 170 patients were randomized to either the CsA withdrawal group or the CsA continuation group at visit 4 (85 patients per group). Patient demographics and characteristics at baseline are summarized in Table 1.
During the study, MMF was administered at a dose of 1 g twice per day, and CsA and corticosteroids were administered at a doses according to the practice followed at each center; however, all centers administered CsA at a dose to achieve a trough level of 100 to 200 ng/mL. For those patients who started MMF during the run-in period, dosage was increased in steps during the first 2 weeks of run-in, reaching 2 g per day at the start of the third week of run-in. During the CsA withdrawal phase, investigators were permitted to increase the dosage of corticosteroids (up to a maximum of 25 mg/day) for patients in the CsA withdrawal group to help prevent rejections; however, a minimum dose was not defined.
MMF could be increased to 3 g per day, corticosteroids could be increased, and CsA could be either increased (CsA continuation group) or reintroduced (CsA withdrawal group). It was possible to reduce or discontinue corticosteroids or CsA in cases of related, intractable adverse events. Patients in the CsA withdrawal group in whom CsA had to be reintroduced were excluded from the per-protocol population. Patients in whom MMF was reduced or withdrawn for a period longer than 3 days were also excluded from the per-protocol population. Study visits were scheduled monthly after trial entry, in addition to the baseline visit.
Primary and Secondary Endpoints
The primary endpoint was renal function 9 months after randomization (6 months after withdrawal of CsA), assessed by creatinine clearance (measured in 79% of patients, or calculated in 21% of patients, for whom no data were available for urine creatinine and urine volume). Serum creatinine level and calculated glomerular filtration rate were also noted (19). Secondary endpoints included the number and severity of acute rejection episodes in the first 9 months after randomization, serum lipid profile, blood pressure, adverse events, graft loss, and patient death.
A Banff grade of I, II, or III was accepted as evidence of biopsy-proven rejection (20). In two patients, needle biopsy specimens were also accepted as confirming rejection episodes. If a biopsy could not be performed, a clinical diagnosis of presumed rejection, which was considered an actual rejection for purposes of the analysis, could be made if one or more of the following were present: a rise in serum creatinine concentration of 30% or more, fever, graft enlargement, oliguria, administration of a full course of high-dose corticosteroids, or 1 or more days of antilymphocyte therapy. Patients with acute rejections were treated according to each center’s practice with high-dose corticosteroids, antilymphocyte antibodies, or both. In addition, for patients in the CsA continuation group, investigators were permitted to increase the dose of MMF (to 3 g/day), CsA, or both. In the case of patients with rejections in the CsA withdrawal group, the reintroduction of CsA was allowed. If serum creatinine failed to return to prerejection levels after 2 weeks of antirejection therapy, plus 3 g per day of MMF, these patients were excluded from per-protocol analysis because they did not fulfill per-protocol criteria.
At each study visit, all adverse events occurring since the previous visit that were not present at the initial visit were recorded. Patients were monitored for the following opportunistic infections: cytomegalovirus, Aspergillus/Mucor, Candida spp, Pneumocystis carinii, Cryptococcus spp, Listeriamonocytogenes, herpes simplex virus, and herpes zoster virus.
Statistical Methods and Power
After the run-in period, at randomization, both groups were receiving MMF 2 g per day, CsA, and corticosteroids, and this was determined to be the baseline. An analysis of covariance (ANCOVA) was used to analyze creatinine clearance, serum creatinine level, and glomerular filtration rate at 9 months after randomization. The ANCOVA method tested for differences between the two treatment groups and allowed a covariate to be incorporated into mean values. The baseline value of the variable (e.g., creatinine clearance) was used as the covariate, so that differences between the two groups already present at the start of the study were taken into account. The results obtained in this way are a more accurate estimate of the true difference between the treatment groups than could be obtained using a t test. Creatinine clearance was calculated according to the formula devised by Cockroft and Gault:EQUATION
Glomerular filtration rate was calculated using the formula devised by Nankivell et al. (19):EQUATION
Lipids (total cholesterol, high-density lipoprotein, low-density lipoprotein [LDL], and triglycerides) were also analyzed by ANCOVA, using the same model as that used for the primary analysis variable.
A sample size of 64 evaluable patients per group was calculated to have 80% power to detect an increase of creatinine clearance of 10 mL/min, assuming that the creatinine clearance in the CsA-treated group was 65 mL/min, with a common standard deviation of 20 mL/min. The number of patients eventually randomized to treatment in the study was 85 per treatment group. The corresponding power of the actual sample size is 89% (using the two-sample t test). The percentage of patients with acute rejections occurring during the 12 months of the study was analyzed by the log-rank statistic resulting from the Kaplan-Meier analysis.
Analyses were performed on intent-to-treat and per-protocol populations as determined in the protocol. The intent-to-treat population included 12 patients later found to be ineligible for the study. Six of them had panel-reactive antibodies greater than 50%, and six had received a transplant more than 30 months previously. The per-protocol population comprised the intent-to-treat population minus 39 patients (23 from the CsA withdrawal group; 16 from the CsA continuation group), giving a total of 131 patients in the per-protocol analyses (62 in the CsA withdrawal group; 69 in the CsA continuation group). Reasons for the exclusion of the 39 patients are given in Table 2.
The mean daily dose of CsA was similar in the CsA withdrawal group and the CsA continuation group during phase I (226 and 237 mg/day, respectively). Of note, the CsA dose decreased from 237 mg/day during phase I to 216 mg/day during phase III (P =0.0001) in patients who continued CsA.
The average daily dose of MMF was approximately 2 g in both treatment groups. Nine patients in the CsA withdrawal group and 10 patients in the CsA continuation group received doses lower than 2 g at some time during phase III of the study. Only three patients in the CsA withdrawal group and five in the CsA continuation group interrupted MMF dosing for 1 or more days. The mean daily dose of steroids throughout the study in the CsA continuation group and the CsA withdrawal group was 7.5 mg/day and 13.0 mg/day, respectively (P =0.0001).
Renal Function: Intent-to-Treat Population
The primary endpoint was creatinine clearance at 9 months after randomization. The difference in creatinine clearance and calculated glomerular filtration rate reached 4.5 mL/min (P =0.16) and 2.3 mL/min (P =0.24) in favor of the CsA withdrawal group (Figs. 2A and 3). None of these comparisons reached statistical significance. Creatinine clearance improved by more than 10% in 46% of patients in the CsA withdrawal group. Serum creatinine levels in the CsA withdrawal group showed a decrease from baseline at 9 months, whereas the CsA continuation group showed an increase (P =NS) (Table 3). The difference in serum creatinine levels reached −5.0 μmol/L in favor of the CsA withdrawal group (P =0.34). Serum creatinine levels were reduced by 10% in 31% of patients in the CsA withdrawal group.
Renal Function: Per-Protocol Population
At the end of the study, there was a statistically significant improvement in creatinine clearance (7.5 mL/min;P =0.02) in favor of the CsA withdrawal group (Fig. 2 B). A significant difference was also found for glomerular filtration rate as calculated by ANCOVA (6.0 mL/min;P =0.0002). The difference in serum creatinine levels reached −14 μmol/L in favor of the CsA withdrawal group (P =0.0003) (Table 3).
Lipid Profile: Intent-to-Treat Population
There was a significant difference in total and LDL cholesterol between the groups in favor of the CsA withdrawal group at 9 months after randomization (Fig. 4) (P =0.02 and P =0.015, respectively). There were no significant differences for high-density lipoprotein cholesterol or triglycerides (P =0.96 and P =0.1, respectively). Similar results were observed in the per-protocol population.
Systolic and diastolic blood pressure in both groups fell very slightly during the study. At the end of the study, systolic and diastolic pressures in the CsA withdrawal group had changed by −0.9 mm Hg and −0.5 mm Hg, respectively, from baseline values. In the CsA continuation group, the decrease from baseline was greater (−4.7 mm Hg systolic and −2.6 mm Hg diastolic [P =NS]).
The majority of patients received at least one concomitant medication during the study: 77 patients (91%) in the CsA withdrawal group and 78 patients (92%) in the CsA continuation group. The major medications prescribed are listed in Table 4. Although there was no significant change in blood pressure by the end of the study, 18% of patients in the CsA withdrawal group were receiving an angiotensin-converting enzyme inhibitor, compared with 28% of patients in the CsA continuation group. The number of patients on hypolipidemic drugs was not different between the two groups.
Overall, 72% of patients in the CsA withdrawal group and 74% of patients in the CsA continuation group reported at least one adverse event. The number and incidence of adverse events that were related to MMF were not significantly different in the treatment groups. Diarrhea was more frequent in the CsA withdrawal group, however (P =0.02). As expected, the incidence of adverse events related to CsA was higher in the CsA continuation group (42% vs. 31% in the CsA withdrawal group). Of note, the incidence of adverse events ascribed to steroids was higher in the group that continued CsA (42% vs. 36%), despite the greater use of steroids in the CsA withdrawal group.
Specific adverse events are listed in Table 5. Patients in the CsA continuation group had a higher incidence of infections and cancers, probably because of the greater immunosuppression with the combination of CsA, MMF, and steroids. Patients in the CsA withdrawal group had a higher incidence of diarrhea. The one patient who died during the study had a history of myocardial ischemia and died of a myocardial infarction. No patient died of a rejection-related cause, and no patient lost a graft.
Acute Rejection Episodes
After randomization, acute rejection episodes were more common in the CsA withdrawal group, occurring in nine patients versus two patients in the CsA continuation group (10.6% vs. 2.4%, P =0.03). Two patients, both in the CsA withdrawal group, suffered 2 acute rejections, for a total of 11 rejection episodes in the CsA withdrawal group and 13 rejection episodes overall. None of the patients who had a rejection in the withdrawal group had experienced prior rejections, but of the two who had rejections in the CsA continuation group, one had experienced a prior rejection.
In the CsA withdrawal group, two of the nine first-rejection episodes occurred late in the CsA taper period, when the CsA dosage was one third of baseline, and six of the remaining seven episodes occurred during the first 70 days after CsA was entirely discontinued. All acute rejections were confirmed by biopsy, except for two patients in whom fine-needle aspiration was performed. Of these nine first-rejection episodes, most were Banff grade I, and only one (occurring after discontinuation) was grade III (Fig. 5). Six were successfully treated with steroids, and three patients required antibody treatment.
There was a marked center effect among the rejections in the CsA withdrawal group, with 5 of the 9 rejections occurring in 2 of the 21 centers. A comparison of the characteristics of CsA withdrawal patients who did and did not have acute rejection episodes is given in Table 6. Because of the design of the study and sample sizes of the statistics in this table, the P values should be understood as being indicative only. An examination of individual dosing reveals that six of the patients experiencing acute rejection may have been underimmunosuppressed at the time of rejection (MMF <2 g/day, steroids <10 mg/day), but there were also patients receiving steroid doses of 10 mg per day or more in whom rejection occurred.
This is the first randomized, controlled, multicenter study comparing maintenance triple-drug therapy (CsA, MMF, and steroids) with dual therapy (MMF and steroids after CsA withdrawal). One of the rationales behind this trial was that the increased immunosuppressive potency of MMF, as compared with AZA, would contribute to the prevention of rejection episodes after CsA withdrawal. The incidence of rejection in the present study was 10.6% in the CsA withdrawal group. Although the lack of an AZA-steroid arm in our trial does not allow us to draw definitive conclusions, the rejection rates observed in our MMF-steroid patients compare favorably with those reported in the AZA-steroid groups of the three most recent randomized studies of CsA discontinuation: 16% (21), 17% (22), and 16% (23). Furthermore, a recent prospective, randomized trial comparing two groups that received either AZA-steroid or MMF-steroid dual therapy after CsA withdrawal supports the hypothesis that rejection rates are lower in MMF-treated patients. Rejection occurred in 12% of MMF-steroid recipients versus 36% of those in the AZA-steroid arm (P =0.04) (24).
In the present study, acute rejection episodes began to occur when CsA was reduced to one third of its initial dosage. Rejection episodes continued to occur for approximately 2 months after complete withdrawal. This suggests that the final one third of the CsA taper was critical for a minority subset of the patients. CsA reduces the total body clearance of steroids (25,26), and, therefore, the withdrawal of CsA may have been accompanied by a fall in the level of circulating steroids, precipitating acute rejection episodes in susceptible patients. This probably explains why patients in the CsA withdrawal group received higher doses of steroids to maintain the level of immunosuppression. The fact that rejection develops rapidly after discontinuation of CsA has been observed in several studies (23,24,27–29), stressing the need for close patient follow-up during this period.
An examination of the risk factors for rejection did not reveal any particular imbalance in the group experiencing rejections, except that some patients may have been underimmunosuppressed. Indeed, six of the nine patients were receiving less than 2 g per day of MMF, less than 10 mg per day of steroids, or both, at the time of rejection. Of note, this was associated with a center effect, because five of the nine acute rejections occurred in two of the participating centers. One may speculate that monitoring of mycophenolic acid area under the time-concentration curve or trough levels might have helped to avoid underimmunosuppression and would have contributed to prevent rejection in this setting (30). Until this kind of data become available, it may be wise to recommend complete CsA withdrawal only in those patients who tolerate an MMF dosage of 2 g per day and who are receiving at least 10 mg of steroids per day.
In this trial, CsA withdrawal initiated a strong trend toward improved renal function, as measured by the primary endpoint (creatinine clearance) and improved serum creatinine level and glomerular filtration rate. In the per-protocol population, which does not include patients with acute rejection episodes, differences between the groups in creatinine clearance, serum creatinine level, and glomerular filtration rate reached statistical significance in favor of the CsA withdrawal group at the 6-month endpoint, 9 months after randomization. The majority of these changes occurred fairly rapidly and probably represent a reversal of the renal vasoconstriction thought to be caused by CsA (31,32). The increased level of renal function remained stable after the last phase of the taper.
There was also a statistically significant treatment difference in total and LDL cholesterol levels in favor of the CsA withdrawal group at the 6-month endpoint in the intent-to-treat population, probably reflecting the hyperlipidemic effects of CsA. Cyclosporine has been shown to significantly elevate total and LDL cholesterol levels when used as monotherapy in nontransplantation patients (33) and is associated with increases in serum levels of total and LDL cholesterol in renal transplant recipients (6,7). The substitution of MMF for CsA thus reduces hyperlipidemia, which is a major management issue in transplantation. The CsA withdrawal study reported by Hollander et al. (22) found that the frequency of cardiovascular death with a functioning graft was 8% higher in the group remaining on CsA, this difference being apparent only 5 years after CsA discontinuation.
What alternative maintenance therapy could be proposed that would allow for calcineurin inhibitor sparing or discontinuation? Our data show that the largest increase in creatinine clearance occurred after reduction of CsA to one third of its baseline value, and clearance remained stable thereafter. The timing and extent of changes in serum lipid levels show a similar pattern. Coupled with the timing of the onset of the acute rejection episodes, these factors suggest that dose reduction of CsA to one third of the baseline dose in the presence of MMF and steroids may be an alternative regimen.
The successful reduction of CsA dose in the presence of MMF and steroids has been reported in two small studies with short-term follow-up (14,16). Both studies reported that patients with chronic allograft nephropathy displayed a significant improvement in renal function after CsA dose reduction. Nevertheless, the effectiveness of CsA dose reduction has recently been called into question. An animal study demonstrated that low doses of CsA may still promote interstitial fibrosis without any decrease in renal blood flow and concluded that chronic CsA nephrotoxicity may be very hard to prevent (34). Furthermore, in a 2-year follow-up study of patients with declining renal function and chronic allograft nephropathy, graft function stabilized or improved in more than 90% of those who were treated with MMF-steroid dual therapy, compared with less than 60% of those who also received a low dose of either CsA or tacrolimus (P <0.05) (35). Similarly, Schrama (17) recently observed that a complete switch from CsA to MMF was accompanied by statistically significant improvement in lipid profile and kidney graft function, whereas only trends were seen after partial CsA withdrawal.
Sirolimus is another nonnephrotoxic agent that has been investigated in a prospective, randomized trial of CsA elimination (36). In that study, patients treated at transplantation with a combination of CsA, sirolimus, and steroids were randomized at 3 months either to receive the same therapy or to discontinue CsA and to remain on dual treatment with sirolimus and steroids. Interestingly, the incidence of acute rejection after CsA discontinuation was 10%, a figure similar to that observed in the present trial. Although renal function significantly improved in the sirolimus-steroid arm, hyperlipidemia, a well-known side effect of sirolimus therapy (37), developed in the majority of patients. Indeed, 80% required therapy with either statins or fibrates (36). In the interest of definitively assessing which regimen achieves the most beneficial metabolic outcomes, it is clear that prospective, randomized studies comparing sirolimus-steroids with MMF-steroids as maintenance therapy are of major relevance in renal transplantation.
CsA withdrawal in the presence of MMF and steroids is associated with a small but significant risk of acute rejection. In the vast majority of patients, who remained rejection free, there was a significant improvement in renal function. In addition, CsA withdrawal is associated with a significant improvement in serum lipid levels.
Participants in the Cyclosporine Withdrawal Study Group
Prof. D. Abramowicz, Hôpital Erasme, Belgium; Dr. F. Behrend, Medizinische Hochschule Hannover, Germany; Dr. Maria del Rosario Brunnet, CEMIC, Argentina; Dr. Domingo Cassadei, INBA, Argentina; Dr. D. del Castillo, Hospitale Reina Sophia, Spain; Dr. Carlos Fasola, Catholic University of Chile, Chile; Dr. Agenor Spallini Ferraz, HCFMRP Camprio Universitário, Brazil; Dr. Josep Grinyó, Hospital de Bellvitge, Spain; Dr. U. Heeman, Universitätsklinikum Essen, Germany; Prof. Lameire, Universitair Ziekenhuis, Belgium; Prof. Mieczyslaw Lao, Warsaw Medical School, Poland; Dr. Nicole Lefrançois, Hôpital Edouard Herriot, France; Mr. Derek Manas, Freeman Hospital, UK; Dr. Raimund Margreiter, Universitätsklinik, Innsbruck, Austria; Dr. José Morales, Hospital 12 de Octobre, Spain; Dr. Alfredo Mota, Hospitais da Universidade de Coimbra, Portugal; Prof. G. Mourad, Hôpital Lapeyronie, France; Dr. Federico Oppenheimer, Hospital Clinico, Spain; Dr. Erich Pohanka, Universitätsklinik für Innere Medizin II, Wien, Austria; Prof. Yves Vanrenterghem, Universitair Ziekenhuis Gasthuisberg, Belgium; and Dr. Stefan Vitko, IKEM, Czech Republic.
1. Myers BD, Sibley R, Newton L, et al. The long-term course of cyclosporine-associated chronic nephropathy. Kidney Int 1988; 33: 590.
2. Zarifian A, Meleg-Smith S, O’Donovan R, et al. Cyclosporine-associated thrombotic microangiopathy in renal allografts. Kidney Int 1999; 55: 2457.
3. Bennett WM, DeMattos A, Meyer MM, et al. Chronic cyclosporine nephropathy: the Achilles’ heel of immunosuppressive therapy. Kidney Int 1996; 50: 1089.
4. Goldstein DJ, Zuech N, Sehgal V, et al. Cyclosporine-associated end-stage nephropathy after cardiac transplantation. Transplantation 1997; 63: 664.
5. Fioretto P, Steffes MW, Mihatsch MJ, et al. Cyclosporine associated lesions in native kidneys of diabetic pancreas transplant recipients. Kidney Int 1995; 48: 489.
6. Schorn TF, Kliem V, Bojanovski M, et al. Impact of long-term immunosuppression with cyclosporin A on serum lipids in stable renal transplant recipients. Transpl Int 1991; 4: 92.
7. Kasiske BL, Tortorice KL, Heim-Duthoy KL, et al. The adverse impact of cyclosporine on serum lipids in renal transplant recipients. Am J Kidney Dis 1991; 17: 700.
8. Mayer AD, Dmitrewski J, Squifflet JP, et al. Multicenter randomized trial comparing tacrolimus (FK506) and cyclosporine in the prevention of renal allograft rejection: a report of the European Tacrolimus Multicenter Renal Study Group. Transplantation 1997; 64: 436.
9. Kasiske BL, Heim-Duthoy K, Ma JZ. Elective cyclosporine withdrawal after renal transplantation. JAMA 1993; 269: 395.
10. Kasiske BL, Chakkera HA, Louis TA, et al. A meta-analysis of immunosuppression withdrawal trials in renal transplantation. J Am Soc Nephrol 2000; 11: 1910.
11. The Tricontinental Mycophenolate Mofetil Renal Transplantation Study Group. A blinded, randomized clinical trial of mycophenolate mofetil for the prevention of acute rejection in cadaveric renal transplantation. Transplantation 1996; 61: 1029.
12. Sollinger HW. Mycophenolate mofetil for the prevention of acute rejection in primary cadaveric renal allograft recipients. U. S. Renal Transplant Mycophenolate Mofetil Study Group. Transplantation 1995; 60: 225.
13. European Mycophenolate Mofetil Cooperative Study Group. Placebo-controlled study of mycophenolate mofetil combined with cyclosporin and corticosteroids for prevention of acute rejection. Lancet 1995; 345: 1321.
14. Weir MR, Anderson L, Fink JC, et al. A novel approach to the treatment of chronic allograft nephropathy. Transplantation 1997; 64: 1706.
15. Ducloux D, Fournier V, Bresson-Vautrin C, et al. Mycophenolate mofetil in renal transplant recipients with cyclosporine-associated nephrotoxicity: a preliminary report. Transplantation 1998; 65: 1504.
16. Hueso M, Bover J, Seron D, et al. Low-dose cyclosporine and mycophenolate mofetil in renal allograft recipients with suboptimal renal function. Transplantation 1998; 66: 1727.
17. Schrama YC, Joles JA, van Tol A, et al. Conversion to mycophenolate mofetil in conjunction with stepwise withdrawal of cyclosporine in stable renal transplant recipients. Transplantation 2000; 69: 376.
18. Houde I, Isenring P, Boucher D, et al. Mycophenolate mofetil, an alternative to cyclosporine A for long-term immunosuppression in kidney transplantation? Transplantation 2000; 70: 1251.
19. Nankivell BJ, Gruenewald SM, Allen RDM, et al. Predicting glomerular filtration rate after kidney transplantation. Transplantation 1995; 59: 1683.
20. Solez K, Axelsen RA, Benediktsson H, et al. International standardization of criteria for the histologic diagnosis of renal allograft rejection: the Banff working classification of kidney transplant pathology. Kidney Int 1993; 44: 411.
21. Pedersen EB, Hansen HE, Kornerup HJ, et al. Long-term graft survival after conversion from cyclosporine to azathioprine 1 year after renal transplantation: a prospective, randomized study from 1 to 6 years after transplantation. Nephrol Dial Transplant 1993; 8: 250.
22. Hollander AAM, van Saase JLCM, Kootte AMM, et al. Beneficial effects of conversion from cyclosporine to azathioprine after kidney transplantation. Lancet 1995; 345: 610.
23. MacPhee IAM, Bradley JA, Briggs JD, et al. Long-term outcome of a prospective randomized trial of conversion from cyclosporine to azathioprine treatment one year after renal transplantation. Transplantation 1998; 66: 1186.
24. Smak Gregoor PJ, van Gelder T, van Besouw NM, et al. Randomized study on the conversion of treatment with cyclosporine to azathioprine or mycophenolate mofetil followed by dose reduction. Transplantation 2000; 70: 143.
25. Langhoff E, Madsen S, Flachs H, et al. Inhibition of prednisolone metabolism by cyclosporine in kidney-transplanted patients. Transplantation 1985; 39: 107.
26. Ost L. Effects of cyclosporin on prednisolone metabolism. Lancet 1984; 1: 451.
27. Versluis DJ, Wenting GJ, Derkx FHM, et al. Who should be converted from cyclosporine to conventional immunosuppression in kidney transplantation, and why. Transplantation 1987; 44: 387.
28. Hall BM, Tiller DJ, Hardie I, et al. Comparison of three immunosuppressive regimens in cadaver renal transplantation: long-term cyclosporine, short-term cyclosporine followed by azathioprine and prednisolone, and azathioprine and prednisolone without cyclosporine. N Engl J Med 1988; 318: 1499.
29. Hilbrands LB, Hoitsma AJ, Koene RAP. Randomized, prospective trial of cyclosporine monotherapy versus azathioprine-prednisone from three months after renal transplantation. Transplantation 1996; 61: 1038.
30. van Gelder T, Hilbrands LB, Vanrenterghem Y, et al. A randomized double-blind, multicenter plasma concentration controlled study of the safety and efficacy of oral mycophenolate mofetil for the prevention of acute rejection after kidney transplantation. Transplantation 1995; 68: 261.
31. Radermacher J, Meiners M, Bramlage C, et al. Pronounced renal vasoconstriction and systemic hypertension in renal transplant patients treated with cyclosporin A versus FK 506. Transpl Int 1998; 11: 3.
32. Weir MR, Klassen DK, Shen SY, et al. Acute effects of intravenous cyclosporine on blood pressure, renal hemodynamics, and urine prostaglandin production of healthy humans. Transplantation 1990; 49: 41.
33. Ballantyne CM, Podet EJ, Patsch WP, et al. Effects of cyclosporine therapy on plasma lipoprotein levels. JAMA 1989; 262: 53.
34. Vieira JM Jr, Noronha IL, Malheiros DMAC, et al. Cyclosporine-induced interstitial fibrosis and arteriolar TGF-beta expression with preserved renal blood flow. Transplantation 1999; 68: 1746.
35. Weir MR, Ward MT, Blahut SA, et al. Long-term impact of discontinued or reduced calcineurin inhibitor in patients with chronic allograft nephropathy. Kidney Int 2001; 59: 1567.
36. Johnson R, Oberbauer R, Kreis H, et al. Sirolimus allows early cyclosporine free immunosuppression in renal transplantation resulting in improved renal function and lower blood pressure. Transplantation 2001; 72: 777.
37. Groth CG, Backman L, Morales JM, et al. Sirolimus (rapamycin)-based therapy in human renal transplantation: similar efficacy and different toxicity compared with cyclosporine. Sirolimus European Renal Transplant Study Group. Transplantation 1999; 67: 1036.