Addition of induction therapy offsets the hazard of marked calcineurin minimization among renal transplant recipients treated with sirolimus.

AIMS: We sought to examine the improvement in renal function with preserved immunosuppression consequent to reducing de novo cyclosporine (CsA) doses combined with sirolimus and induction antibody treatment. MATERIALS AND METHODS: 408 renal recipients treated de novo with CsA-sirolimus included 91 patients who received high (> 5); 125, medium (2.5-5.0); or 192, low CsA doses (< 2.5 mg/kg/day) together with induction antibody among 5, 48 and 68% of subjects, respectively. At 2 years we excluded 21 (23), 30 (24) and 49 (25%) subjects who experienced the composite end-point, yielding 70 (71), 95 (76) and 143 (74%) cases, whose mean de novo CsA C2 values were 725, 400 and 306 ng/ml; for all cohorts, sirolimus C0 = 10-15 de novo and 8-12 ng/ml during maintenance treatment. The primary end-point--mean 4-year GFR by aMDRD--ascribed "0" to patients who experienced death or graft loss after 2 years. RESULTS: Although low-dose subjects were older (p = 0.008) and heavier (p < 0.001) with grafts exposed to longer cold ischemia times (p < 0.001), they displayed greater GFR: 64.8 versus 48.4 among the high and 54.1 ml/min/1.73 m(2) in the medium dose arms (p = 0.002). Polychotomous logistic regression revealed significant GFR predictors to be CsA dose (p = 0.015) and younger donor age (p < 0.001). Between 2 and 4 years, the incidences of the composite end-point were 17, 14 and 16%; including 13, 10 and 11% rejections. CONCLUSION: 80% reduction in de novo CsA exposure with antibody induction improved renal function at 4 years compared with 50 or 66% reductions.

The impact of conversion from mycophenolate mofetil to mycophenolate sodium among renal transplant recipients on a sirolimus-based regimen.

OBJECTIVE: To examine the benefits of conversion from mycophenolate mofetil (MMF) to mycophenolic acid sodium (MPS) among renal transplant patients on sirolimus-based immunosuppression. METHODS: Alternate renal transplant recipients who were converted from MMF to MPS immediately (group A, n = 21) or 90 days thereafter (group B, n = 19) completed the Gastrointestinal Symptom Rating Scale and the Gastrointestinal Quality of Life Index (GIQLI) questionnaires at days 90 and 180. Similarly, at the completion of the study 20 members of groups A plus B (converted to MPS) and 19 patients who initially declined to participate (continuous MMF) completed the questionnaires. RESULTS: At 90 days after conversion, members of group A showed fewer responses to "feeling unwell" and to flatulence, which regressed in group B at 180 days, although more persons in the latter cohort complained of bloating. The average scores of cohort A on the GIQLI at day 180 were significantly better than those at day 90. Compared with a control cohort of continuous MMF treatment, members of cohorts A plus B showed lower incidences of diarrhea, dysphagia, and eructations but greater incidences of constipation and not feeling fit. CONCLUSION: Conversion from MMF to MPS offers subjective benefits for patients on maintenance therapy with mycophenolic acid in combination with sirolimus.

Use of sirolimus to facilitate steroid withdrawal from a cyclosporine regimen.

OBJECTIVE: Chronic steroid therapy has been associated with many comorbidities of transplant immunosuppression. Because sirolimus blocks one of the sites affected by steroids, we sought to examine whether substituting this drug mitigated these toxicities. METHODS: We used intent-to-treat methodology to compare the clinical outcomes and laboratory results between 30 renal transplant recipients converted from steroids to sirolimus with a cohort of demographically matched subjects who were transplanted concurrently with the study group and maintained on steroids. All patients received ongoing cyclosporine-based immunosuppression. To compensate for pharmacokinetic interactions with sirolimus, the cyclosporine exposure was markedly reduced in the study group. Statistical comparisons utilized analysis of variance, chi-square tests, and log rank evaluation of Kaplan-Meier curves. RESULTS: Conversion from prednisone to sirolimus was accomplished without difficulty in 27 of 30 patients. Treatment failures among the converted patients were due to chronic allograft nephropathy (n = 1), recurrence of original disease (n = 1), or chronic rejection (n = 2). By intent-to-treat analysis, the outcomes were similar in the study versus concurrent control groups. Laboratory values showed triglyceridemia as an adverse reaction to sirolimus, and reduced leukocytes, to steroid withdrawal. The observed clinical benefits solely reflected the markedly reduced cyclosporine exposure. Based on responses to a questionnaire administered prior to versus 12 and 24 months after steroid withdrawal, several domains revealed improvements in subjective complaints. CONCLUSION: Conversion from prednisone to sirolimus in combination with cyclosporine was easily accomplished in most renal transplant recipients. Although a 2-year follow-up failed to reveal objective benefits of the maneuver (other than those consequent to reduced cyclosporine exposure), most patients reported a subjectively improved health status.

Immunosuppressive effects and safety of a sirolimus/cyclosporine combination regimen for renal transplantation.

BACKGROUND: Sirolimus, a novel immunosuppressant that inhibits cytokine-driven cell proliferation and maturation, prolongs allograft survival in animal models. After a phase I trial in stable renal transplant recipients documented that cyclosporine and sirolimus have few overlapping toxicities, we conducted an open-label, single-center, phase I/II dose-escalation trial to examine the safety and efficacy of this drug combination. METHODS: Forty mismatched living-donor renal transplant recipients were sequentially assigned to receive escalating initial doses of sirolimus (0.5-7.0 mg/m2/day), in addition to courses of prednisone and a concentration-controlled regimen of cyclosporine. We conducted surveillance for drug-induced side effects among sirolimus-treated patients and compared their incidence of acute rejection episodes as well as mean laboratory values with those of a historical cohort of 65 consecutive, immediately precedent, demographically similar recipients treated with the same concentration-controlled regimen of cyclosporine and tapering doses of prednisone. RESULTS: The addition of sirolimus reduced the overall incidence of acute allograft rejection episodes to 7.5% from 32% in the immediately precedent cyclosporine/prednisone-treated patients. At 18- to 47-month follow-up periods, both treatment groups displayed similar rates of patient and graft survival, as well as morbid complications. Although sirolimus-treated patients displayed comparatively lower platelet and white blood cell counts and higher levels of serum cholesterol and triglycerides, sirolimus did not augment the nephrotoxic or hypertensive proclivities of cyclosporine. The degree of change in the laboratory values was more directly associated with whole blood trough drug concentrations than with doses of sirolimus. CONCLUSIONS: Sirolimus potentiates the immunosuppressive effects of a cyclosporine-based regimen by reducing the rate of acute rejection episodes.

Stability of renal allograft glomerular filtration rate associated with long-term use of cyclosporine A.

Renal allograft glomerular filtration rate (GFR) was measured at 4-month intervals for up to 1 year in 43 CsA-treated patients using x-ray fluorescence determination of plasma iohexol clearance. Study patients were divided into cohorts based on time (years) after transplantation at study entry (0-1; 1-2; 2-3; and > 3 years) and entry GFR levels (20-29; 30-39; 40-49; and > or = 50 ml/min/1.73 m2). GFR at study entry was 42 +/- 2 and was comparable in CAD (n = 31) versus LRD (n = 12) allografts (42 +/- 2 and 44 +/- 4 ml/min/1.73 m2, respectively). Range of entry GFR levels was similar in each of the "time at entry" cohorts defined above. Serum creatinine concentrations of 1.5-2.5 mg% were associated with GFR levels of 20-60 ml/min/1.73 m2. Serial GFR levels obtained at 4-month intervals for 1 year (n = 34 patients) were not consistent with a pattern of progressively declining GFR occurring as a function of either time after transplantation or absolute GFR level at study entry (intraindividual coefficient of variation 10.3 +/- 1.0%). Patients in the lower quartile of "entry GFR" levels (< 34 ml/min/1.73 m2) were more likely than their counterparts to have had a history of acute rejection. Results are consistent with retrospective population studies of aggregate serum creatinine levels, indicating that long-term CsA use is not uniformly associated with accelerated loss of renal allograft function consequent to a progressive, toxic nephropathy. The data also suggest that neither absolute GFR level nor time after transplantation represent indications for routine dose reduction or conversion to AZA.

Influence of HLA matching on rejections and short- and long-term primary cadaveric allograft survival.

Distribution of cadaveric donor kidneys, based upon the donor-recipient HLA match grade, remains one of the major controversies in transplantation. To determine whether matching results in fewer rejection episodes and better graft survival, we retrospectively studied our single-center patient population of 683 cyclosporine-prednisone-treated primary cadaveric renal allograft recipients. For 237 recipients of well-matched HLA A, B kidneys (< or = 2 HLA A, B mismatches [MM]) the 1-, 3-, 5-, and 7-year graft survivals of 76%, 66%, 62%, and 61%, respectively, were not significantly different from those of 71%, 65%, 63%, and 63%, respectively, for the 446 poorly matched HLA A, B (> 2 HLA A, B MM) recipients. Similarly, the 1-, 3-, 5-, and 7-year graft survivals for the 307 recipients of well-matched HLA-DR kidneys (0 or 1 DR MM) of 74%, 65%, 63%, and 61%, respectively, were not significantly different from those of 72%, 65%, 63%, and 62%, respectively, for the 366 poorly matched (2 DR MM) recipients. Patient survivals were comparable at each time point for well- vs. poorly matched recipients. Similarly, donor-recipient HLA A, B, and DR matching was not beneficial in retransplant recipients who were transplanted following negative NIH and antiglobulin (AHG) crossmatches when testing both historical (high-PRA) and pretransplant sera. Since rejection episodes may be a more sensitive indicator of immune response than graft loss, we also analyzed the relationship between donor-recipient HLA match grade and posttransplant rejections. A total of 60% (n = 413) of recipients experienced no rejections and had 1-, 3-, 5-, and 7-year graft survivals of 82%, 78%, 74%, and 73%, respectively; 32% (n = 215) of patients who experienced 1 rejection had 1-, 3-, 5-, and 7-year graft survivals of 58%, 48%, 44%, and 43%, respectively (P < 0.001 for graft survival of 0 vs. 1 rejection). The remaining 8% (n = 55) of recipients experienced more than 1 (> 1) rejection and had 1-, 3-, 5-, and 7-year graft survivals of 62%, 38%, 36%, and 36%, respectively (P < 0.001 for graft survival of 0 vs. > 1 rejection and P < 0.01 for graft survival of 1 vs. > 1 rejection). The mean numbers of rejections/patient experienced by well-matched vs. poorly matched recipients were comparable and not significantly different.(ABSTRACT TRUNCATED AT 400 WORDS)

Use of sirolimus in kidney transplantation.

Sirolimus, which has a distinctive mechanism of action that inhibits cytokine-driven cell proliferation and maturation, provides an exciting addition to the immunosuppressive regimen for organ transplantation. A significant decrease in the number and severity of rejection episodes has been noted when sirolimus is used; it also offers the potential for patients to be withdrawn from steroids, making kidney transplantation an option for many more potential recipients. Toxic conditions such as hyperlipidemia, thrombocytopenia, and leukopenia become transient and manageable with reduction of the sirolimus dose and/or countermeasure therapy.

Spin-wave interference in microscopic rings.

We have studied the spin excitations of ferromagnetic rings and observed a distinct series of quantized modes in the vortex state. We attribute them to spin waves that circulate around the ring and interfere constructively. They form azimuthal eigenmodes of a magnetic ring resonator which we resolve up to the fourth order. The eigenfrequencies are calculated semianalytically and classified as a function of magnetic field by a quantization rule which takes into account a periodic boundary condition. Strikingly each mode exists only below a characteristic field.

Sirolimus improves the two-year outcome of renal allografts in African-American patients.

The present study evaluated whether the addition of sirolimus to a cyclosporine (CyA)/prednisone (Pred) regimen mitigated the greater proclivity to acute rejection episodes and graft loss characteristic of African-American renal transplant recipients. Using Kaplan-Meier and log-rank tests, African-American renal transplant recipients treated with either CyA/Pred (n = 90) or sirolimus/CyA/Pred (n = 47) were compared with 120 Caucasian patients treated with sirolimus/CyA/Pred for 2-year rates of patient and graft survival as well as acute rejection episodes. Mean laboratory values were compared using analysis of variance and F-tests. Addition of sirolimus to the CyA/Pred regimen reduced the incidence of acute rejection episodes in African-Americans from 43.3% to 19.2% (P = 0.004), a value similar to Caucasian patients. The 97.9% 2-year graft survival rate among 47 African-American patients treated with sirolimus/CyA/Pred was significantly higher than the 85.6% rate shown among the 90 CyA/Pred-treated African-American transplant recipients (P = 0.0479) and similar to that in Caucasians. The 95.7% patient survival rate among the African-American sirolimus/CyA/Pred group was similar to the 97.8% rate in the African-American CyA/Pred cohort. Interestingly, there was no evident toxicity from the addition of sirolimus. The addition of sirolimus to a CyA-based regimen reduced acute rejection episodes and graft loss experienced by African-American renal transplant recipients.

Therapeutic drug monitoring of sirolimus: correlations with efficacy and toxicity.

UNLABELLED: We sought to examine the potential benefits of therapeutic drug monitoring of sirolimus, a potent immunosuppressive agent that displays a pleiotropic array of side effects. METHODS: A high-performance liquid chromatography (LC) procedure combined with ultraviolet detection (UV) was used to measure serial concentrations of parent compound sirolimus in 150 renal transplant recipients over a period of 4 yr. Drug concentrations in whole blood at trough time, as well as within pharmacokinetic profiles, were correlated with clinical events using contingency tables, logistic regression analysis, and receiver operating characteristic (ROC) curves. RESULTS: The LC/UV method showed an excellent correlation with detection of LC-resolved components by tandem mass spectrometry, demonstrating that the LC/UV method selectively detected parent compound. Sirolimus displayed the characteristics of a critical-dose drug: Its concentration could not be predicted by a standard body or demographic measure, or by dose, and it showed high degrees of intra- and inter-individual variability. However, there was a good correlation between trough and area-under-the-curve measurements. There was a significant association between trough values expressed as either observed ( < 5 ng/mL) or dose-corrected parameter ( < 1.7 ng/mL per mg administered drug) and the occurrence and severity of acute rejection episodes - despite the low overall incidence of 23 episodes among the cohort of 150 patients. Similarly, ROC functions showed a correlation of the occurrence of hypertriglyceridemia, thrombocytopenia, and leukopenia, but not hypercholesterolemia, with trough concentrations above 15 ng/mL. CONCLUSION: Due to its behavior as a critical-dose drug, therapeutic monitoring to measure sirolimus concentrations by a LC/UV method may provide clinicians with a tool to optimize outcomes.