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PubMed2005

Economic evaluation of sirolimus-eluting stents.

BACKGROUND: Sirolimus-eluting stents have recently been shown to reduce the risk of restenosis among patients who undergo percutaneous coronary intervention (PCI). Given that sirolimus-eluting stents cost about 4 times as much as conventional stents, and considering the volume of PCI procedures, the decision to use sirolimus-eluting stents has large economic implications. METHODS: We performed an economic evaluation comparing treatment with sirolimus-eluting and conventional stents in patients undergoing PCI and in subgroups based on age and diabetes mellitus status. The probabilities of transition between clinical states and estimates of resource use and health-related quality of life were derived from the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) database. Information on effectiveness was based on a meta-analysis of randomized controlled clinical trials (RCTs) comparing sirolimus-eluting and conventional stents. RESULTS: Cost per quality-adjusted life year (QALY) gained in the baseline analysis was Can58,721 dollars. Sirolimus-eluting stents were more cost-effective in patients with diabetes and in those over 75 years of age, the costs per QALY gained being 44,135 dollars and 40,129 dollars, respectively. The results were sensitive to plausible variations in the cost of stents, the estimate of the effectiveness of sirolimus-eluting stents and the assumption that sirolimus-eluting stents would prevent the need for cardiac catheterizations in the subsequent year when no revascularization procedure was performed to treat restenosis. INTERPRETATION: The use of sirolimus-eluting stents is associated with a cost per QALY that is similar to or higher than that of other accepted medical forms of therapy and is associated with a significant incremental cost. Sirolimus-eluting stents are more economically attractive for patients who are at higher risk of restenosis or at a high risk of death if a second revascularization procedure were to be required.

Age Factors↗
PubMed2005

Effects of calcineurin inhibitors on sirolimus pharmacokinetics during staggered administration in renal transplant recipients.

STUDY OBJECTIVE: To compare the effects of different calcineurin inhibitors on sirolimus pharmacokinetics during long-term, staggered administration in kidney transplant recipients. Design. Randomized, open-label, parallel-group trial. SETTING: A medical center and one of its teaching hospitals in Taiwan. PATIENTS: Twenty-two de novo kidney transplant recipients. INTERVENTION: Patients received cyclosporine microemulsion or tacrolimus capsules twice/day in combination with once-daily sirolimus solution and corticosteroids. Sirolimus was administered 6 hours after the morning dose of cyclosporine or tacrolimus. After receiving a 6-mg loading dose of sirolimus, participants received sirolimus 2 mg/day for at least 7 days. Neither the cyclosporine nor the tacrolimus dosage was adjusted for at least 3 days before and during blood sampling for pharmacokinetic profiling. MEASUREMENTS AND MAIN RESULTS: One patient dropped out because of trimethoprim-sulfamethoxazole-related hepatotoxicity. We observed no differences between the two patient groups in terms of their demographic data, renal and liver function, or dosage of sirolimus during the study. During multiple-dose administration, the area under the whole-blood concentration-time curve and the peak and trough concentrations of sirolimus in the cyclosporine group were, respectively, 1.46 (95% confidence interval [CI] 1.21-1.71), 1.42 (95% CI 1.08-1.76), and 1.42 (95% CI 1.09-1.76) times higher than those of the tacrolimus group, even though sirolimus was administered 6 hours after the other agents. CONCLUSION: Sirolimus pharmacokinetics may change significantly when calcineurin inhibitors are switched, even with staggered administration, which may not completely prevent a drug interaction between cyclosporine and sirolimus solution.

Adult↗
PubMed2006

Sirolimus-associated proteinuria and renal dysfunction.

Sirolimus is a novel immunosuppressant with potent antiproliferative actions through its ability to inhibit the raptor-containing mammalian target of rapamycin protein kinase. Sirolimus represents a major therapeutic advance in the prevention of acute renal allograft rejection and chronic allograft nephropathy. Its role in the therapy of glomerulonephritis, autoimmunity, cystic renal diseases and renal cancer is under investigation. Because sirolimus does not share the vasomotor renal adverse effects exhibited by calcineurin inhibitors, it has been designated a 'non-nephrotoxic drug'. However, clinical reports suggest that, under some circumstances, sirolimus is associated with proteinuria and acute renal dysfunction. A common risk factor appears to be presence of pre-existing chronic renal damage. The mechanisms of sirolimus-associated proteinuria are multifactorial and may be due to an increase in glomerular capillary pressure following calcineurin inhibitor withdrawal. It has also been suggested that sirolimus directly causes increased glomerular permeability/injury, but evidence for this mechanism is currently inconclusive. The acute renal dysfunction associated with sirolimus (such as in delayed graft function) may be due to suppression of compensatory renal cell proliferation and survival/repair processes. Although these adverse effects occur in some patients, their occurrence could be minimised by knowledge of the molecular effects of sirolimus on the kidney, the use of sirolimus in appropriate patient populations, close monitoring of proteinuria and renal function, use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers if proteinuria occurs and withdrawal if needed. Further long-term analysis of renal allograft studies using sirolimus as de novo immunosuppression along with clinical and laboratory studies will refine these issues in the future.

Animals↗
PubMed1998

Metabolism and transport of the macrolide immunosuppressant sirolimus in the small intestine.

Small intestinal metabolism and transport of sirolimus, a macrolide immunosuppressant with a low and highly variable oral bioavailability, were investigated using small intestinal microsomes and intestinal mucosa in the Ussing chamber. After incubation of sirolimus with human and pig small intestinal microsomes, five metabolites were detected using high performance liquid chromatography/electrospray-mass spectrometry: hydroxy, dihydroxy, trihydroxy, desmethyl and didesmethyl sirolimus. The same metabolites were generated by human liver microsomes and pig small intestinal mucosa in the Ussing chamber. Anti-CYP3A antibodies, as well as the specific CYP3A inhibitors troleandomycin and erythromycin, inhibited small intestinal metabolism of sirolimus, confirming that, as in the liver, CYP3A enzymes are responsible for sirolimus metabolism in the small intestine. Of 32 drugs tested, only known CYP3A substrates inhibited sirolimus intestinal metabolism with inhibitor constants (Ki) equal to those in human liver microsomes. The formation of hydroxy sirolimus by small intestinal microsomes isolated from 14 different patients ranged from 28 to 220 pmol.min-1.mg-1 microsomal protein. In the Ussing chamber, >99% of the sirolimus metabolites reentered the mucosa chamber against a sirolimus gradient, indicating active countertransport. Intestinal drug metabolism and countertransport into the gut lumen, drug interactions with CYP3A substrates and inhibitors in the small intestine and an 8-fold interindividual variability of the intestinal metabolite formation rate significantly contribute to the low and highly variable bioavailability of sirolimus.

Animals↗
PubMed2005

Tirofiban and sirolimus-eluting stent vs abciximab and bare-metal stent for acute myocardial infarction: a randomized trial.

CONTEXT: Bare-metal stenting with abciximab pretreatment is currently considered a reasonable reperfusion strategy for acute ST-segment elevation myocardial infarction (STEMI). Sirolimus-eluting stents significantly reduce the need for target-vessel revascularization (TVR) vs bare-metal stents but substantially increase procedural costs. At current European list prices, the use of tirofiban instead of abciximab would absorb the difference in cost between stenting with sirolimus-eluting vs bare-metal stents. OBJECTIVE: To evaluate the clinical and angiographic impact of single high-dose bolus tirofiban plus sirolimus-eluting stenting vs abciximab plus bare-metal stenting in patients with STEMI. DESIGN, SETTING, AND PATIENTS: Prospective, single-blind, randomized controlled study (Single High Dose Bolus Tirofiban and Sirolimus Eluting Stent vs Abciximab and Bare Metal Stent in Myocardial Infarction [STRATEGY]) of 175 patients (median age, 63 [interquartile range, 55-72] years) presenting to a single referral center in Italy with STEMI or presumed new left bundle-branch block and randomized between March 6, 2003, and April 23, 2004. INTERVENTION: Single high-dose bolus tirofiban regimen plus sirolimus-eluting stenting (n = 87) vs standard-dose abciximab plus bare-metal stenting (n = 88). MAIN OUTCOME MEASURES: The primary end point was a composite of death, nonfatal myocardial infarction, stroke, or binary restenosis at 8 months. Secondary outcomes included freedom, at day 30 and month 8, from major cardiac or cerebrovascular adverse events (composite of death, reinfarction, stroke, and repeat TVR). RESULTS: Cumulatively, 14 of 74 patients (19%; 95% confidence interval [CI], 10%-28%) in the tirofiban plus sirolimus-eluting stent group and 37 of 74 patients (50%; 95% CI, 44%-56%) in the abciximab plus bare-metal stent group reached the primary end point (hazard ratio, 0.33; 95% CI, 0.18-0.60; P<.001 [P<.001 by Fischer exact test]). The cumulative incidence of death, reinfarction, stroke, or TVR was significantly lower in the tirofiban plus sirolimus-eluting stent group (18%) vs the abciximab plus bare-metal stent group (32%) (hazard ratio, 0.53; 95% CI, 0.28-0.92; P = .04), predominantly reflecting a reduction in the need for TVR. Binary restenosis was present in 6 of 67 (9%; 95% CI, 2%-16%) and 24 of 66 (36%; 95% CI, 26%-46%) patients in the tirofiban plus sirolimus-eluting stent and abciximab plus bare-metal stent groups, respectively (P = .002). CONCLUSION: Tirofiban-supported sirolimus-eluting stenting of infarcted arteries holds promise for improving outcomes while limiting health care expenditure in patients with myocardial infarction undergoing primary intervention.

Abciximab↗
PubMed2005

Sirolimus-eluting stent or paclitaxel-eluting stent vs balloon angioplasty for prevention of recurrences in patients with coronary in-stent restenosis: a randomized controlled trial.

CONTEXT: In patients with de novo coronary lesions, drug-eluting stents have drastically reduced restenosis risk compared with bare metal stents and conventional balloon angioplasty. It is less clear whether drug-eluting stents are superior to conventional balloon angioplasty for the treatment of patients with in-stent restenosis. OBJECTIVES: To assess if drug-eluting stents are a more effective treatment of in-stent restenosis than conventional balloon angioplasty, and to assess the relative merits of 2 drug-eluting stents, a sirolimus-eluting stent and a paclitaxel-eluting stent. DESIGN, SETTING, AND PARTICIPANTS: Randomized, open-label, active-controlled trial conducted among 300 patients with angiographically significant in-stent restenosis in 2 tertiary German centers from June 1, 2003, to October 20, 2003. INTERVENTIONS: After pretreatment with 600 mg of clopidogrel for at least 2 hours before intervention, all patients were randomly assigned to 1 of 3 treatment groups: sirolimus stent, paclitaxel stent, or balloon angioplasty (100 patients in each group). MAIN OUTCOME MEASURES: Primary end point: angiographic restenosis (diameter stenosis > or =50%) at 6-month follow-up angiography based on "in-segment" analysis. Primary analysis was comparison between stent groups and balloon angioplasty groups; a secondary analysis compared sirolimus and paclitaxel stents. RESULTS: Follow-up angiography was performed in 275 (92%) of 300 patients. The incidence of angiographic restenosis was 44.6% (41/92) in the balloon angioplasty group, 14.3% (13/91) in the sirolimus stent group (P<.001 vs balloon angioplasty), and 21.7% (20/92) in the paclitaxel stent group (P = .001 vs balloon angioplasty). When compared with balloon angioplasty, receiving a sirolimus stent had a relative risk (RR) of angiographic restenosis of 0.32 (95% confidence interval [CI], 0.18-0.56); a paclitaxel stent had an RR of 0.49 (95% CI, 0.31-0.76). The incidence of target vessel revascularization was 33.0% (33/100) in the balloon angioplasty group, 8.0% (8/100) in the sirolimus stent group (P<.001 vs balloon angioplasty), and 19.0% (19/100) in the paclitaxel stent group (P = .02 vs balloon angioplasty). The secondary analysis showed a trend toward a lower rate of angiographic restenosis (P = .19) and a significantly lower rate of target vessel revascularization (P = .02) among sirolimus stent patients compared with paclitaxel stent patients. CONCLUSIONS: In patients with in-stent restenosis, a strategy based on sirolimus- or paclitaxel-eluting stents is superior to conventional balloon angioplasty for the prevention of recurrent restenosis. Sirolimus-eluting stents may be superior to paclitaxel-eluting stents for treatment of this disorder.

Aged↗
PubMed2006

Sirolimus-eluting stents vs vascular brachytherapy for in-stent restenosis within bare-metal stents: the SISR randomized trial.

CONTEXT: Although vascular brachytherapy is the only approved therapy for restenosis following bare-metal stent implantation, drug-eluting stents are now being used. Data on the relative merits of each are limited. OBJECTIVE: To determine the safety and efficacy of the sirolimus-eluting stent compared with vascular brachytherapy for the treatment of patients with restenosis within a bare-metal stent. DESIGN, SETTING, AND PATIENTS: Prospective, multicenter, randomized trial of 384 patients with in-stent restenosis who were enrolled between February 2003 and July 2004 at 26 academic and community medical centers. Data presented represent all follow-up as of June 30, 2005. INTERVENTIONS: Vascular brachytherapy (n = 125) or the sirolimus-eluting stent (n = 259). MAIN OUTCOME MEASURE: Target vessel failure (cardiac death, myocardial infarction, or target vessel revascularization) at 9 months postprocedure. RESULTS: Baseline patient characteristics were well matched. Lesion length was similar between vascular brachytherapy and sirolimus-eluting stent patients (mean [SD], 16.76 [8.55] mm vs 17.22 [7.97] mm, respectively; P = .61). Procedural success was 99.2% (124/125) in the vascular brachytherapy group and 97.3% (250/257) in the sirolimus-eluting stent group (P = .28). The rate of target vessel failure was 21.6% (27/125) with vascular brachytherapy and 12.4% (32/259) with the sirolimus-eluting stent (relative risk [RR], 1.7; 95% confidence interval [CI], 1.1-2.8; P = .02). Target lesion revascularization was required in 19.2% (24/125) of the vascular brachytherapy group and 8.5% (22/259) of the sirolimus-eluting stent group (RR, 2.3 [95% CI, 1.3-3.9]; P = .004). At follow-up angiography, the rate of binary angiographic restenosis for the analysis segment was 29.5% (31/105) for the vascular brachytherapy group and 19.8% (45/227) for the sirolimus-eluting stent group (RR, 1.5 [95% CI, 1.0-2.2]; P = .07). Compared with the vascular brachytherapy group, minimal lumen diameter was larger in the sirolimus-eluting stent group at 6-month follow-up (mean [SD], 1.52 [0.63] mm vs 1.80 [0.63] mm; P<.001), reflecting greater net lumen gain in the analysis segment (0.68 [0.60] vs 1.0 [0.61] mm; P<.001) due to stenting and no edge restenosis. CONCLUSION: Sirolimus-eluting stents result in superior clinical and angiographic outcomes compared with vascular brachytherapy for the treatment of restenosis within a bare-metal stent. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT00231257.

Aged↗
PubMed1996

Pharmacokinetics of prednisolone during administration of sirolimus in patients with renal transplants.

The pharmacokinetic interaction of multiple oral doses of sirolimus (rapamycin) and prednisone were evaluated in 40 stable patients with renal transplants receiving concomitant multiple doses of cyclosporine. Nine sirolimus dosage levels from 1 mg/m2/day to 13 mg/m2/day were studied and compared with placebo. Plasma concentrations of prednisone, prednisolone, and cortisol were measured by high-performance liquid chromatography and analyzed by noncompartmental methods. Mean pharmacokinetic values of prednisolone found before sirolimus administration were as follows: peak plasma concentration (Cmax) was 187 ng/mL; time to peak plasma concentration (tmax) was 2.03 hours; rate of reaching peak plasma concentration (Cmax divided by the area under the concentration-time curve [AUC]) was 0.149 hour-1; terminal half-life (t1/2) was 3.60 hours; AUC was 1206 ng.hour/mL; and apparent clearance (Cl/F) was 0.094 L/hour/kg. During the 2 weeks of concomitant administration, prednisolone elimination decreased in relation to sirolimus dosages. These changes were modest, with mean increases of 18% in Cmax and 27% in t1/2 and mean decreases of 27% in Cl/F for the groups receiving 6 mg/m2/day to 13 mg/m2/day. Most patients initially had plasma cortisol concentrations indicative of adrenal suppression. With sirolimus treatment, the Cmax of cortisol did not decrease further, but the AUC (8:00 AM-8:00 PM) values were significantly lower, independent of sirolimus exposure. The AUC for cyclosporine did not correlate with sirolimus and prednisolone exposure. A 2-week course of sirolimus showed a slight pharmacokinetic interaction between sirolimus and prednisolone/prednisone/cortisol in stable patients with renal transplants.

Adult↗
PubMed2002

Combination therapy with low dose sirolimus and tacrolimus is synergistic in preventing spontaneous and recurrent autoimmune diabetes in non-obese diabetic mice.

AIMS/HYPOTHESIS: Sirolimus and tacrolimus are immunosuppressive drugs that prevent rejection of pancreatic islet allografts transplanted into patients with Type I (insulin-dependent) diabetes mellitus. This study aimed to determine whether sirolimus and tacrolimus can prevent autoimmune beta-cell destruction, and if so, what the mechanisms of action are. METHODS: Sirolimus and tacrolimus were given separately and together to female non-obese diabetic (NOD) mice from age 12 to 35 weeks. Diabetes incidence was determined and pancreatic insulitis and insulin content were measured. Sirolimus and tacrolimus were also given separately and together to diabetic NOD mice from the time of syngeneic islet transplantation until the reappearance of hyperglycaemia. Islet grafts were examined by RT-PCR assay for expression of interferon (IFN)- gamma, interleukin (IL)-2, IL-4, IL-10 and transforming growth factor (TGF)- beta1. RESULTS: Low doses of sirolimus (0.1 mg/kg) and tacrolimus (0.1 mg/kg) were synergistic in reducing insulitis, preserving pancreatic insulin content and preventing diabetes in female NOD mice (8 % diabetes incidence at 35 weeks vs 66 % in vehicle-treated mice). Also, the combination of sirolimus and tacrolimus prolonged syngeneic islet graft survival (median 34 days vs 13 days for vehicle-treated mice). Islet grafts from sirolimus plus tacrolimus-treated mice expressed significantly decreased mRNA contents of Th1-type cytokines (IFN- gamma and IL-2) and the highest ratio of TGF- beta1/IFN- gamma mRNA. CONCLUSION/INTERPRETATION: These findings suggest that combination therapy with sirolimus and tacrolimus prevent autoimmune beta-cell destruction by upregulating expression of the immunoregulatory cytokine, TGF- beta1 and reducing Th1 cytokines (IFN- gamma and IL-2) expressed in the islets. Low-dose sirolimus and tacrolimus combination therapy could warrant consideration for prevention or early treatment of human Type I diabetes.

Animals↗
PubMed2006

The impact of the mTOR inhibitor sirolimus on the proliferation and function of pancreatic islets and ductal cells.

AIMS/HYPOTHESIS: The Edmonton Protocol for islet transplantation has provided hope for type 1 diabetic patients. However, this protocol requires lifelong immunosuppression, specifically sirolimus, a cellular antiproliferate. The effect of sirolimus on human pancreatic ductal cells (HDCs) is not known. This may be important since HDCs are believed to be islet precursors. Since neonatal porcine islets (NPIs), which contain many ductal precursor cells, could be a potential clinical source of islets, we also tested the effects of sirolimus on this tissue. METHODS: HDCs (n=4), NPIs (n=9) and human islets (n=5) were cultured with and without sirolimus (20 ng/ml) for 6 days. RESULTS: HDCs and NPIs cultured with sirolimus showed a 50 and 28% decrease, respectively, in cell number relative to control (p<0.05). Control cultures expanded 1.65- and 2.44-fold relative to time 0. Decreases in cell number of sirolimus-treated HDCs were not due to apoptosis as measured by TUNEL staining. No functional effects on human islets or NPIs were observed following static incubation with high glucose. Treatment of syngeneically transplanted and naïve BALC/c mice with sirolimus resulted in altered OGTT profiles with prolonged elevation of hyperglycaemia and weight gain. There was no difference in graft and organ insulin content between treatment groups. CONCLUSIONS/INTERPRETATION: Our results indicate that sirolimus decreases ductal cell numbers in culture and alters glucose-stimulated insulin secretion in vivo. The administration of sirolimus to islet transplant recipients is likely to impair graft function as a result of decreasing ductal neogenesis and induction of insulin resistance.

Animals↗
PubMed2006

Multi-center evaluation of analytical performance of the microparticle enzyme immunoassay for sirolimus.

OBJECTIVES: This study evaluated the analytical characteristics of the new Abbott microparticle enzyme immunoassay (MEIA) for sirolimus. DESIGN AND METHODS: The protocol consisted of nine sections: evaluation of antibody specificity, linearity, detection limit, quantification limit, endogenous interferents, exogenous interferents, precision, proficiency testing panel, and method comparison. RESULTS: The mean analytical detection limit was 0.68 microg/L. The sirolimus concentration corresponding to a total CV of 20% was 1.5 microg/L. Linearity of response was demonstrated across the dynamic range of the assay. Total precision (CVs) at QC control levels from 5 to 22 microg/L ranged from 5.7 to 12.6%. Assay standardization was found to be in good agreement with LC/MS/MS as compared with target values for spiked sirolimus proficiency samples from an international sirolimus proficiency testing program. Good correlations (R values) of the immunoassay were observed in comparisons to LC/MS/MS. R values tended to be lower in comparisons with LC/UV methods. Across both LC-based methods and all study sites, there was approximately 25% overall positive slope bias due to cross reactivity of the MEIA antibody to metabolites of sirolimus. The assay cross-reactivity to metabolites of sirolimus parent drug ranged from 6 to 63%. Assay interferences were minimal with the exception of hematocrit, which presented a negative relationship to measured sirolimus concentration. CONCLUSIONS: The MEIA demonstrated acceptable analytical characteristics for use for routine monitoring of sirolimus immunosuppressive therapy, and is a viable alternative to HPLC-based methods for sirolimus monitoring.

Calibration↗
PubMed2005

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.

Adolescent↗
PubMed2006

Reccurence of Kaposi's sarcoma after increased exposure to sirolimus.

UNLABELLED: The conversion to sirolimus treatment is recently indicated as an effective therapy of Kaposi's sarcoma (KS) in transplant patients. We present two treatment modalities in patients with KS and recurrence of the disease after increasing sirolimus dose. Among 1034 renal transplants performed at our center, three (0.3%) suffered from KS. Initial immunosuppression consisted of cyclosporine, azathioprine and prednisone in one patient; and tacrolimus, mycophenolate mofetil and prednisone in two patients. KS symptoms appeared within one year post-transplantation. Two patients developed cutaneous tumor; one disseminated disease, including the skin, mediastinal lymph nodes and both lungs. After histological confirmation of KS immunosuppression was minimized: Two were converted to sirolimus (1-2 mg/day, level 5-8 ng/ml) treatment; the third patient discontinued tacrolimus and was administered 1 g/day mycophenolate mofetil. Gradual regression of KS was observed in all the patients. In one patient, 8 months after regression of lung KS, the dose of sirolimus was increased to 2 mg/day (level raised to 13.8 ng/ml). Recurrent disease developed afterwards involving diffuse interstitial infiltrates with nodular changes in both lungs. For the second time the dose of sirolimus was reduced to 1 mg/day (level 4-5 ng/ml) and lung lesions regressed 5 months later. Renal function was stable (creatinine 1.3-1.9 mg/dl) in all patients, 24 months from KS onset. IN CONCLUSION: treatment by low sirolimus or mycophenolate mofetil doses caused regression of KS. Recurrence of KS after increasing sirolimus dose suggests that regression of KS is a result of diminished immunosuppression, not the direct antineoplastic effect of sirolimus. Careful maintenance of low sirolimus levels is suggested.

Drug Therapy, Combination↗
PubMed2005

Preservation of renal function after heart transplantation: initial single-center experience with sirolimus.

BACKGROUND: Long-term survivors of heart transplantation are often confronted with chronic kidney disease, by definition related to the intake of calcineurin-inhibitors. Sirolimus is increasingly proposed as an alternative immunosuppressive agent due to its absence of nephrotoxicity. METHODS: Between November 2002 and November 2003, 9 adult heart transplant candidates with moderate to severe chronic renal disease were switched from cyclosporine to sirolimus. The conversion scheme consisted of an immediate stop of cyclosporine and an 8-mg loading dose of sirolimus, followed by 3 mg/d; after 1 week, the sirolimus dose was adjusted to maintain trough levels between 5 and 15 microg/L. The majority of patients were on corticosteroids, and on either azathioprine or mycophenolate mofetil. At conversion, the mean serum creatinine level was 2.11 (+/-0.4) mg/dL and the mean glomerular filtration rate (GFR) was 32 (+/-7) mL/min/1.73 m(2). Prior to conversion, the renal dysfunction was predominantly stable. RESULTS: After conversion, there were 7 dropouts (75%) due to several side effects related to sirolimus: edema (n = 2), general discomfort (n = 2), delayed wound healing (n = 1), cardiac thrombus (n = 1), and diarrhea (n = 1). The median treatment time with Sirolimus, therefore, was only 4.0 months. While on sirolimus, the renal function of all patients remained unchanged or showed even some improvement. Retrospective nephrological review revealed severe renal artery stenoses in 2 patients and serious generalized abdominal and renal atheromatosis in 7 patients. No cardiac dysfunction was seen. CONCLUSION: Conversion from cyclosporine to sirolimus was problematic due to sirolimus side effects, occurring at any time after the switch. One should also question whether chronic kidney disease after heart transplantation is routinely caused by the administration of calcineurin-inhibitors, in view of the generalized renal and abdominal atheromatosis.

Aged↗
PubMed2006

Resolution of sirolimus-induced pneumonitis after conversion to everolimus.

BACKGROUND: Sirolimus-induced pneumonitis usually requires the complete cessation of sirolimus. Herein we have reported five cases of recovery from sirolimus pneumonitis after conversion from sirolimus to everolimus. PATIENTS: All five cases were comparable with regard to their clinical conditions. The ages were between 46 and 64 years. They had received kidney transplants 3 to 18 years earlier. In four cases, the reason for sirolimus therapy was toxicity due to calcineurin inhibitors on a transplant biopsy; three of the patients also displayed malignant tumors: renal cell carcinoma, spinocellular carcinoma, or melanoma. Their serum creatinine levels were elevated between 150 and 350 micromol/L. In all five cases, bronchoscopy disclosed lymphocytic pneumonitis and bronchiolitis obliterans. The immunosuppressive co-medications were prednisolone in three, azathioprine in one, and mycophenolate mofetil in four cases. The previous sirolimus dose was 1 to 4 mg/day, with sirolimus trough levels between 5 and 12 ng/mL. The patients were switched to everolimus at doses between 1 x 0.25 and 2 x 0.75 mg/day to achieve trough concentrations between 3 and 8 ng/mL. Pulmonary symptoms and radiological findings resolved completely within 1 to 4 weeks. CONCLUSION: Everolimus is more hydrophilic by virtue of differing from sirolimus by one hydroxyl group. Sirolimus-induced pneumonitis improved after conversion to everolimus.

Aged↗
PubMed2006

Sirolimus attenuates chronic allograft nephropathy in an experimental rat kidney transplantation model.

Chronic allograft nephropathy (CAN) is the primary reason for late allograft loss in kidney transplantation. The use of calcineurin inhibitors is suggested to be a risk factor for the development of CAN. Thus, calcineurin-inhibitor-free immunosuppressive protocols are needed to improve long-term graft outcome. Sirolimus affects the immune response by interfering with postreceptor interleukin-2 signaling. Safety profile of sirolimus is different from that of calcineurin inhibitors. We investigated the long-term effects of sirolimus on kidney allografts and fibrogenic growth factor expression and compared it to cyclosporine A. Kidney transplantations were performed from DA to WF rats and syngenic controls were done between DA rats. Allograft recipients were immunosuppressed daily with sirolimus 2 p.o. or CsA 1.5 mg/kg s.c. In addition, sirolimus-treated animals were treated with cyclosporine 1.5 mg/kg s.c. for the first 7 days after transplantation. Serum creatinine levels were measured once a week. Grafts were harvested 90 days after transplantation for histology and immunohistochemistry. Histological changes were scored according to the chronic allograft damage index (CADI). No signs of CAN were seen in syngenic grafts, CADI 0.8 +/- 0.2 (mean +/- SEM). In cyclosporine-treated allografts moderate to intense chronic changes were seen; CADI 10.3 +/- 0.6. Sirolimus significantly ameliorated the development of CAN compared to cyclosporine, CADI 3.0 +/- 0.5 (P < .05). Creatinine values of sirolimus-treated allografts were lower compared to the cyclosporine-treated allografts and were nearly similar to the syngenic grafts. Our results demonstrate that sirolimus attenuates the development of CAN and restores kidney function. Based on our findings, sirolimus improves the long-term kidney graft outcome.

Animals↗
PubMed2006

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.

Bronchiolitis Obliterans↗
PubMed2003

Sirolimus: its discovery, biological properties, and mechanism of action.

Sirolimus is the USAN-assigned generic name for the natural product rapamycin. Sirolimus is produced by a strain of Streptomyces hygroscopicus, isolated from a soil sample collected from Rapa Nui commonly known as Easter Island. Although sirolimus was isolated as an antifungal agent with potent anticandida activity, subsequent studies revealed impressive antitumor and immunosuppressive activities. Sirolimus demonstrates activity against several murine tumors, such as B16 43 melanocarcinoma, Colon 26 tumor, EM ependymoblastoma, and mammary and colon 38 solid tumors. Sirolimus is a potent inhibitor of antigen-induced proliferation of T cells, B cells, and antibody production. Demonstration of the potent immunosuppressive activity of sirolimus in animal models of organ transplantation led to clinical trials and subsequent approval by regulatory authorities for prophylaxis of renal graft rejection. Interest in sirolimus as an immunosuppressive therapy in organ transplantation derives from its unique mechanism of action, its unique side-effect profile, and its ability to synergize with other immunosuppressive agents. The molecular mechanism underlying the antifungal, antiproliferative, and immunosuppressive activities of sirolimus is the same. Sirolimus forms an immunosuppressive complex with intracellular protein, FKBP12. This complex blocks the activation of the cell-cycle-specific kinase, TOR. The downstream events that follow the inactivation of TOR result in the blockage of cell-cycle progression at the juncture of G1 and S phase.

Animals↗