IS 3-HOUR CYCLOSPORINE BLOOD LEVEL SUPERIOR TO TROUGH LEVEL IN EARLY POST-RENAL TRANSPLANTATION PERIOD?

LC-MS/MS and EMIT measure the whole blood concentration of cyclosporine A: The two methods yield concordant results within the dynamic range of the latter, but the former shows broader application scenarios

Cyclosporine A (CsA) is a widely used immunosuppressive drug with a narrow therapeutic index and large individual differences. Its therapeutic and toxic effects are closely related to blood drug concentrations, requiring routine therapeutic drug monitoring (TDM). The current main methods for TDM of CsA are enzyme multiplied immunoassay technique (EMIT) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). However, few study on the method comparison of the EMIT and LC-MS/MS for the measurement of whole blood CsA concentration in children has been reported. In this study, we developed a simple and sensitive LC-MS/MS assay for the determination of CsA, and 657 cases of CsA concentrations were determined from 197 pediatric patients by a routine EMIT assay and by the validated in-house LC-MS/MS method on the same batch of samples, aimed to address the aforementioned concern. Consistency between the two assays was evaluated using linear regression and Bland-Altman analysis. The linear range of LC-MS/MS was 0.500-2000 ng/mL and that of the EMIT was 40-500 ng/mL, respectively. Overall, the correlation between the two methods was significant (r-value ranging from 0.8842 to 0.9441). Unsatisfactory consistency was observed in the concentrations < 40 ng/mL (r = 0.7325) and 200-500 ng/mL (r = 0.6851). Bland-Altman plot showed a mean bias of -18.0 % (±1.96 SD, -73.8 to 37.8 %) between EMIT and LC-MS/MS. For Passing-Bablok regression between EMIT and LC-MS/MS did not differ significantly (p > 0.05). In conclusion, the two methods were closely correlated, but the CsA concentration by LC-MS/MS assay was slightly higher than that by EMIT method. Switching from the EMIT assay to the LC-MS/MS method was acceptable, and the LC-MS/MS method will receive broader application in clinical settings due to its better analytical capabilities, but the results need to be further verified in different laboratories.

Fifty years in the vineyard of transplantation: looking back

The past 5 decades have documented remarkable advances in basic knowledge and clinical expertise in transplantation. The first 12 years of this half century of my participation in the enterprise were consumed with the isolation, chemical characterization, and application of histocompatibility antigens purified from mouse, guinea pig, and human tissues, demonstrating that their specificity was based on unique amino acid sequences in protein structures. Initial unsuccessful attempts to use native molecules to induce tolerance in rat renal or heart transplantation models were followed by limited success when they were administered with a brief perioperative course of cyclosporine (CsA). Production of allochimeric constructs of class I major histocompatibility complex molecules bearing donor-type amino acid substitutions into the host-type C-terminal portion of the α1 helix yielded tolerogens whose activity was not dependent on conditioning with CsA or total lymphoid irradiation (TLI). The allochimeric molecules serve as altered peptide ligands that induce an aberrant T-cell signal 1 response producing transplantation tolerance. The potent activity of CsA in this experimental model was extended to clinical settings. Pharmacologic tools were employed to explore intra- and interindividual variations in drug exposure leading to the development of a better drug formulation. However, the intrinsic nephrotoxicity of CsA necessitated marked 80% reductions in de novo drug exposure as were achieved by exploiting the synergistic pharmacodynamic and pharmacokinetic interactions of CsA with sirolimus. The final decade in this 50-year experience includes editorship of this journal with marked changes in its direction. These experiences have afforded insights into future avenues for preclinical exploration and therapeutic drug development.

Triple therapy with single daily dose of cyclosporine in Japanese patients with idiopathic membranous nephropathy

OBJECTIVE

The optimal therapeutic approach to patients with idiopathic membranous nephropathy (IMN) remains controversial. In this study, we assessed the efficacy of single daily dose cyclosporine (CsA) combined with low-dose prednisolone (PSL) and an angiotensin II receptor blocker (ARB) in patients with IMN.

METHODS

We studied 13 nephrotic patients (8 men, 5 women) with IMN diagnosed on biopsy. An initial single daily dose of 2 mg/kg, but not exceeding 150 mg, CsA was given for 12 months, tapered by a 25 mg reduction every 2 months. An initial twice-daily dose of 0.5 mg/kg PSL was given for 2 months and was also tapered. An ARB was given to all patients and the same dosage was used throughout the study. Patients were followed up for 6 to 66 months.

RESULTS

Nine patients achieved complete remission at 6.7±2.9 months, and incomplete remission was obtained in the remaining patients. After a follow-up period of 32.7±20.0 months, their serum creatinine and estimated glomerular filtration rate values were similar to baseline levels. The 9 patients who completed the treatment course have not relapsed. Moreover, there were no adverse effects requiring discontinuation of this triple therapy.

CONCLUSION

A single daily dose of CsA combined with a low dose of PSL and an ARB in new-onset nephrotic patients with IMN induced a high remission rate of nephrotic syndrome, with a low incidence of relapse and a low risk of adverse effects. The triple therapy and prospective follow-up shows potential as a treatment approach for patients with IMN.

Renal transplant immunosuppression impairs natural killer cell function in vitro and in vivo

Background

Despite an increasing awareness of the importance of innate immunity, the roles of natural killer (NK) cells in transplant rejection and antiviral and cancer immunity during immunosuppression have not been clearly defined.

Methods

To address this issue we have developed a quantitative assay of NK cell function that can be used on clinical samples and have studied the influence of immunosuppression on NK cell function. NK cell degranulation and intracellular interferon (IFN)-γ production were determined by flow cytometry of peripheral blood samples.

Results

Overnight ex vivo treatment of peripheral blood cells from healthy controls with ciclosporin or tacrolimus inhibited NK cell degranulation and IFN-γ production in a dose-dependent manner. A similar impairment of function was seen in NK cells from patients treated in vivo with calcineurin inhibitors. In the early post-transplant period, there was a variable reduction of NK cell counts after treatment with alemtuzumab and basiliximab.

Conclusions

The functional inhibition of NK cells in early transplant patients coincides with the period of maximum susceptibility to viral infections. The ability to assay NK cell function in clinical samples allows assessment of the impact of immunosuppression on these effector cells. This information may be helpful in guiding the titration of immunosuppression in the clinical setting.

C2 monitoring of cyclosporine in stable renal transplant patients results in lower costs and improved renal function

INTRODUCTION

C2 (2-hour post-absorption levels) monitoring of cyclosporine (CsA) seems to reduce the rate of acute rejection episodes (ARE) without increasing nephrotoxicity during the first months after transplant. There are a few reports on the impact of adopting this strategy in patients with stable renal transplants. We herein report a prospective trial in long-term renal transplant patients (>6 months) monitored by C0 or C3 who were switched to C2 monitoring.

METHODS

Seventy-six (mean age = 43 +/- 11 years) kidney transplant patients (mean = 37 +/- 21 months after transplant) receiving CsA, steroids, and azathioprine were switched to C2 monitoring, seeking to achieve a target range of 800 +/- 100 ng/mL. The patients were followed for at least 6 months.

RESULTS

At conversion the C2 values of 61% of the patients were above and 17% below the therapeutic range. Six months after conversion there was a significant reduction in BUN (29 +/- 11 vs 27 +/- 10, P < .01), Creatinine (Cr), cholesterol, and triglyceride levels were unchanged. Mean CsA dose was decreased 10% from 244 +/- 63 to 220 +/- 52 (P < .01), implying a net savings of 390 US dollars per patient per year. Among the group of patients who showed a high C2 level, there was also a reduction in BUN (30 +/- 12 vs 27 +/- 10, P < .01) and a nonsignificant decrease in Cr (1.53 +/- 0.6 vs 1.50 +/- 0.6).

CONCLUSIONS

C2 monitoring in stable kidney transplant recipients is feasible and safe. The strategy results in reduced drug costs and improved renal function.

Renal transplants with delayed graft function show decreased renal function despite monitoring with postabsorptive levels

Cyclosporine (CyA) monitoring with postabsorptive levels can predict the risk of an acute rejection episode (ARE). Large doses of CyA are needed to obtain adequate drug exposure. The impact of this strategy on renal function, especially in patients with delayed graft function (DGF), is unknown. We report our experience comparing C3 (3-hour postdose) monitoring with a historical series of cadaveric renal transplants. Sixty-three consecutive patients who received cadaveric renal transplants were followed for 1 year. Group A (historical n = 31) patients received 6 mg/kg/d CyA with the dose adjusted according to the trough level (target, 250-350 ng/mL), group B (study n = 32) received 10 mg/kg/d CyA with dose adjustments based upon C3 (target, 1100-1500 ng/mL). All patients received cyclosporine prednisone and a third agents. The general characteristics of the donors and recipients were comparable. The incidence of biopsy-proven ARE at 1 year in group A was 42% and 19% in group B (P <.05). Patients achieving C3 levels >1000 ng/mL at 1 week displayed significantly lower ARE rates (8% vs 50%; P <.05). The rate of DGF was similar in both groups, but the duration was longer in group B (15 vs 21 days, P <.05). The serum creatinine (SCr) level was significantly higher in group B at 3 months (1.47 mg/dL group A vs 1.76 mg/dL group B; P <.05). Patients in group B with DGF showed significantly higher SCr values at 1 year (1.18mg% vs 2.03 mg%; P <.05). C3 level monitoring of CyA yields excellent results in terms of decreased ARE, but an increased SCR was observed among patients with DGF.

Impact of cardiac transplantation on kidney function: a single- center experience

Long-term follow-up of cardiac transplant recipients reveals a progressive decline in kidney function in a significant number of patients. This complication is one of the most important prognostic parameters for the outcome of cardiac transplantation. The risk factors implicated in the pathogenesis of renal dysfunction following cardiac transplantation are numerous, with the immunosuppressive drug cyclosporine (CsA) playing a major role. This case-control study was designed to evaluate the role of different risk factors among patients who had been transplanted at the Northern General Hospital Cardiothoracic Centre (CTC) with the possibility of identifying modifiable risk factors that mitigate the nephrotoxicity of CsA. Over a 10-year period, heart transplantation was performed in 205 patients at the CTC. Seventeen patients who experienced chronic renal failure (CRF) and were treated at the outpatient clinic of the Sheffield Kidney Institute were randomly selected from those who had >2-year graft survival and follow-up after cardiac transplantation. As controls, 15 cardiac transplant patients were randomly selected from 32 with comparable survival and follow-up after transplantation and without evidence of significant renal dysfunction (serum creatinine </=150 micromol/L). The putative risk factors for development of renal insufficiency were retrospectively studied as well as those affecting the rate of progression of CRF. Seventy-five percent of the progressors (cases) had ischemic cardiomyopathy compared with 10% of nonprogressors (controls) (P <.05). CsA trough levels during the follow-up period were higher among the nonprogressors compared with the progressors (P =.03). Follow-up systolic blood pressure revealed a statistically significant correlation with the slope of serum creatinine in the progressor group (r = -.515 and P <.05). At the time of transplantation, ischemic cardiomyopathy as an underlying diagnosis seems to be a detrimental factor, contributing to the pathogenesis of renal dysfunction after heart transplantation. CsA trough levels alone do not seem to discriminate between progressors and nonprogressors. A randomized controlled study may be required to evaluate the possibility of replacing or reducing CsA to the lowest possible dose in the early posttransplant period for the subset of patients with ischemic cardiomyopathy.

Effect of cyclosporin pharmacokinetics on renal allograft outcome in African-Americans

African-Americans (A-As) experience inferior outcome after transplantation compared with other ethnic groups. Bioavailability of cyclosporin (CsA) has been implicated as a possible contributing factor. This paper describes the outcome of 32 A-A recipients of de novo renal allograft who received CsA-based triple immunotherapy according to individual pharmacokinetic profiles. Patients received CsA-microemulsion q 12 h, dosed initially at 3.5 mg/kg (8 am) and 3.0 mg/kg (8 pm). The am and pm doses were independently adjusted to achieve a 12-h area under the concentration-time curve (AUC0-12) of 6600-7200 nghr/mL and morning trough level (C0) of 250-325 ng/mL, respectively. Mean age was 43 +/- 12 yr, 37% (12) female. Mean AUC0-12 in 1 wk, 1, 3, 6, and 12 months were 7810 +/- 1880 nghr/mL, 9057 +/- 2097 nghr/mL, 7674 +/- 1912 nghr/mL, 7132 +/- 2040 nghr/mL, and 6503 +/- 1410 ngl/h with corresponding C0 of 301 +/- 79 ng/mL, 316 +/- 66 ng/mL, 275 +/- 59 ng/mL, 273 +/- 66 ng/mL, and 224 +/- 49 ng/mL, respectively. Acute rejection occurred in two patients (6%) 1 yr after transplantation. Prospective use of CsA pharmocokinetic profiles improves renal allograft outcome in A-As.

Adequate early cyclosporin exposure is critical to prevent renal allograft rejection: patients monitored by absorption profiling

This study used receiver operating characteristic analysis to investigate the properties of area under the concentration-time curve during the first 4h after cyclosporin-microemulsion dosing (AUC0-4) and cyclosporin (CyA) levels immediately before and at 2 and 3h after dosing (C0, C2 and C3) to predict the risk of biopsy-proven acute rejection (AR) at 6 months. Ninety-eight kidney transplant recipients treated with CyA-microemulsion-based triple therapy immunosuppression were studied on post-transplant days 3, 5, and 7, and at increasing intervals thereafter. The most sensitive and specific predictor of AR was AUC0-4. Of the single time-point measurements, the measurement properties of C2 were closest to those of AUC0-4, and superior to those of C3. The relationship between C0 and subsequent AR was weak and did not reach statistical significance. On day 3, CyA AUC0-4 > or = 4,400 ng.h/mL and C2 > or = 1,700 ng/mL were each associated with a 92% negative predictive value for rejection in the first 6months. Pharmacokinetic measurements on or after day 5, and measurements on day 3 in patients with delayed graft function, were not predictive of AR. Adequate exposure within the first 3days post transplantation may be critically important in preventing subsequent rejection.

Rapid Liquid Chromatography-Tandem Mass Spectrometry Method for Routine Analysis of Cyclosporin A Over an Extended Concentration Range

Background: Cyclosporin A (CsA) is commonly measured by immunoassay techniques that have a limited analytical range. The consequence of this is that low CsA concentrations that may be clinically significant are difficult to measure and that high concentrations require sample dilution, which introduces error and increases cost. More specific assays, such as HPLC, do not have the required turnaround times for busy transplant clinics.

Methods: CsA was measured in whole blood from 180 cardiac and lung transplant recipients by a liquid chromatography-tandem mass spectrometry (MS) assay, and the results were compared with the Dade Behring Emit assay. Proteins were precipitated with acetonitrile containing ascomycin as internal standard. We used isocratic elution on a Supelco CN column (33 × 3.0 mm; 3- μm bead size) with a mobile phase of 65% aqueous acetonitrile containing ammonium acetate (2 mmol/L) and formic acid (1 g/L), at a flow rate of 0.5 mL/min, with a sample injection volume of 6 μL. We used positive-ion electrospray MS to monitor the ammonium adducts of the compounds of interest decomposing under controlled conditions to the most dominant fragments of the individual molecules. Calibration curves used linear least-squares regression with 1/x weighting.

Results: Maximum sensitivity was obtained by monitoring fragmentation of the ammonium adducts m/z 1220→m/z 1203 for CsA and m/z 809→m/z 765 for ascomycin. Sample throughput, including preparation time, was 30 samples in 1.5 h with an injection-to-injection cycle time of 1.5 min. The calibration curve was linear to 5000 μg/L, with a detection limit of 0.03 μg/L and a limit of quantification of 1 μg/L. Regression analysis [tandem MS method (y) and Emit assay (x)] yielded a slope of 1.09 (± 0.03), an intercept of 6.2 (± 4.5) μg/L, and Sy|x = 27 μg/L.

Conclusions: Tandem MS assay is a realistic alternative to immunoassay for the routine monitoring of CsA in transplant recipients. Its wide dynamic range has utility for pharmacokinetic studies of CsA.

2,500 living donor kidney transplants: a single-center experience

OBJECTIVE

To review a single center's experience and outcome with living donor transplants.

SUMMARY BACKGROUND DATA

Outcome after living donor transplants is better than after cadaver donor transplants. Since the inception of the authors' program, they have performed 2,540 living donor transplants. For the most recent cohort of recipients, improvements in patient care and immunosuppressive protocols have improved outcome. In this review, the authors analyzed outcome in relation to protocol.

METHODS

The authors studied patient and graft survival by decade. For those transplanted in the 1990s, the impact of immunosuppressive protocol, donor source, diabetes, and preemptive transplantation was analyzed. The incidence of rejection, posttransplant steroid-related complications, and return to work was determined. Finally, multivariate analysis was used to study risk factors for worse 1-year graft survival and, for those with graft function at 1 year, to study risk factors for worse long-term survival.

RESULTS

For each decade since 1960, outcome has improved after living donor transplants. Compared with patients transplanted in the 1960s, those transplanted in the 1990s have better 8-year actuarial patient and graft survival rates. Death with function and chronic rejection have continued to be a major cause of graft loss, whereas acute rejection has become a rare cause of graft loss. Cardiovascular deaths have become a more predominant cause of patient death; infection has decreased. Donor source (e.g., ideally HLA-identical sibling) continues to be important. For living donor transplants, rejection and graft survival rates are related to donor source. The authors show that patients who had preemptive transplants or less than 1 year of dialysis have better 5-year graft survival and more frequently return to full-time employment. Readmission and complications remain problems; of patients transplanted in the 1990s, only 36% never required readmission. Similarly, steroid-related complications remain common. The authors' multivariate analysis shows that the major risk factor for worse 1-year graft survival was delayed graft function. For recipients with 1-year graft survival, risk factors for worse long-term outcome were pretransplant smoking, pretransplant peripheral vascular disease, pretransplant dialysis for more than 1 year, one or more acute rejection episodes, and donor age older than 55.

CONCLUSIONS

These data show that the outcome of living donor transplants has continued to improve. However, for living donors, donor source affects outcome. The authors also identify other major risk factors affecting both short- and long-term outcome.

Limited sampling strategies for estimating cyclosporin area under the concentration-time curve: review of current algorithms

Cyclosporin, the drug of first choice in transplantation surgery, is characterized by a low therapeutic index and variable absorption, so close monitoring of the drug is required to optimize the dosing. Predose blood cyclosporin levels are measured routinely for therapeutic monitoring, but this approach is not optimal because the area under the concentration-time curve (AUC) correlates better with clinical events. However, conventional methods of measuring AUC require many blood samples, which is not viable in a routine clinical setting. AUC monitoring can be simplified for use in a clinical setting by using a limited sampling strategy (LSS) that allows AUC to be estimated using a small number of blood samples collected at specific times. This article reviews the current literature on estimating cyclosporin AUC using LSS. Thirty-eight papers suggesting the use of specific time points were found. LSS has been developed for different transplant types, with different dosing regimens, and with different assays. Most authors suggested either two- or three-sample equations. Results from authors who validated their models suggest that equations defined on one transplant type may be applicable to other transplant types, to both adults and children, and to early or late after transplantation. Moreover, it seems that there is flexibility in the choice of equations available to clinicians. The number of samples to collect for accurate estimations is a matter of debate, but a wise choice can minimize the number. The choice of the optimal LSS and validation are discussed.