Evaluation of the MassTrak Immunosuppressant XE Kit for the determination of everolimus and cyclosporin A in human whole blood employing isotopically labeled internal standards.

BACKGROUND: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is widely used for therapeutic drug monitoring of immunosuppressants given to transplant recipients. This study evaluated the performance of the newly introduced MassTrak Immunosuppressant XE Kit (Waters Corporation; "the Kit") in the determination of everolimus and cyclosporin A (CsA) using LC-MS/MS. METHODS: The linearity, precision, detection limit, carryover and matrix effect of the Kit and comparison of the in-house method and Kit procedure were evaluated according to Clinical and Laboratory Standards Institute guidelines. RESULTS: The Kit afforded good linearity in the measurement of everolimus from 2 to 26 ng/mL (R² = 0.996) and of CsA from 42.6 to 1407 ng/mL (R² = 0.995). The between- and within-run assay coefficients of variation were 2.3% - 8.0% for everolimus and 1.1% - 3.1% for CsA. The lower limit of quantitation of everolimus and CsA were 1.1-4.1 ng/mL, respectively. A comparison of CsA values obtained using inhouse reagents indicated good correlation with Kit results (R = 0.9909). The average matrix effect ranged from 15% - 39% for everolimus and 3% -10% for CsA, and ion enhancement was mostly observed for the matrix effect. The effect on analyte/internal standard ratios ranged from 1%-8% for everolimus and 1%-16% for CsA. CONCLUSIONS: The Kit employing isotopically labeled internal standards provides reliable measurements of immunosuppressant levels over a broad range of concentrations.

Sirolimus- vs. paclitaxel-eluting stents in patients undergoing off-label percutaneous coronary intervention.

Studies of percutaneous coronary intervention (PCI) with drug-eluting stents in high-risk scenarios are often limited by short follow up and use definitions of "off-label" PCI which do not entirely mirror insert packages recommendations. We analyzed the incidence of cardiovascular events in 1050 consecutive patients undergoing off-label PCI with sirolimus- (n=581) or paclitaxel- (n=469) eluting stents. At 3 years, there were no differences between groups in terms of major cardiovascular events (adjusted hazard ratio 0.991; 95% CI, 0.758 to 1.295; p=0.945), despite slightly higher rates of myocardial infarction and late stent thrombosis seen among patients who received paclitaxel-eluting stents.

Safety of an immunosuppressant protocol based on sirolimus in liver transplant recipients with malignancies or high risk of tumor recurrence.

BACKGROUND: The mammalian target of rapamycin inhibitors are immunosuppressive agents with antiproliferative effects and consequent potential application as anticancer agents. The safety and tolerance of calcineurin inhibitor (CNI)-free sirolimus-based immunosuppressant protocols in liver transplant recipients with malignancies or high risk of tumor recurrence has been scarcely evaluated. PATIENTS AND METHODS: Fourteen liver transplant recipients, including 12 men, of overall mean age of 57.4 +/- 12.4 years were distributed into two groups: group I, corresponding to 11 patients with malignant neoplasia, eight de novo neoplasia, and three recurrent hepatocarcinoma and; group II, three patients with high risk of tumor recurrence due to cholangiocarcinoma. Sirolimus was initiated at 2 mg od, with target levels of 3 to 9 ng/mL. Withdrawal of CNI was performed after reaching target levels of sirolimus. Periodic examinations of weight, arterial pressure, liver function tests, serum creatinine, triglycerides, cholesterol, sirolimus blood levels, and creatinine clearance were performed at 30, 60, 90, 180, and 360 days. RESULTS: After a median follow-up of 221.5 days, eight group I patients (72.7%) were alive, including six with stable disease. All group II patients were alive without evidence of tumor recurrence after a median follow-up of 560 days. CNI was withdrawn in 11 patients (78.6%). Sirolimus was withdrawn in only one case due to severe symptomatic oral ulcers. No vascular complications or rejection episodes were observed. CONCLUSIONS: A sirolimus-based immunosuppressant protocol was well tolerated and safe in liver transplant recipients with malignancies or a high risk of recurrence of neoplastic disease.

Quantification of cyclosporine A in peripheral blood mononuclear cells by liquid chromatography-electrospray mass spectrometry using a column-switching approach.

As a potential alternative to cyclosporine A (CsA) monitoring in whole blood, a sensitive and selective method was developed for quantifying this immunosuppressive drug in human peripheral blood mononuclear cells (PBMCs) by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). PBMCs were isolated from whole blood by density gradient centrifugation. After purification, cell counts were performed to express CsA amounts per single cell. The pelleted cells were then lysed and CsA was extracted with methanol (MeOH) containing 27-demethoxy-sirolimus as internal standard. After evaporation of the supernatant under nitrogen, the residue was reconstituted in MeOH, further diluted with water and injected onto a column-switching unit. On-line solid-phase extraction was performed using a C8 column with an acidic aqueous mobile phase containing 5% MeOH. The analytes were transferred in the back-flush mode on a C18 column with 65% MeOH and the chromatographic separation performed with a MeOH gradient (65-90%). The detection was carried out with a single quadrupole analyzer and the sodium adducts [M+Na](+) were monitored for quantification. This sensitive method was fully validated in the range of 5-400 ng/mL. This allowed the measurement of very small CsA amounts present in cells up to 0.5 fg/PBMC in clinical samples. Trueness (95.0-113.2%), repeatability (5.1-9.9%) and intermediate precision (7.0-14.7%) were found to be satisfactory. This method represents a new potential tool for therapeutic drug monitoring of CsA and could be used in clinical conditions if the utility of intracellular measurements is confirmed in prospective clinical trials.

Determination of sirolimus in rabbit arteries using liquid chromatography separation and tandem mass spectrometric detection.

Sirolimus, an effective immunosuppressive agent, is used for drug eluting stents. During stent development, an analytical method for the determination of sirolimus in tissue needs to be established. Normally, tissue samples are homogenized and then analyzed against the calibration standards prepared in a tissue homogenate. This approach provides insufficient control of the homogenization process. In this paper, tissue quality control samples were introduced for the optimization of the homogenization process during method development, but also allowance for the performance evaluation of the entire analytical process. In addition, a new approach using rabbit blood as a homogenization medium was developed to stabilize sirolimus in rabbit tissue homogenates. Calibration standards and quality controls were prepared by spiking different sirolimus working solutions into rabbit blood. Homogenization quality control samples were prepared by injecting other sirolimus working solutions into empty test tubes and pre-cut arteries within pre-defined masses. A high-throughput homogenization procedure was optimized based on the specific chemical properties of sirolimus. The linear dynamic range was between 49.9 pg/mL and 31.9 ng/mL to accommodate the expected artery homogenate concentrations. Additionally, quality controls in rabbit blood were also used in the extraction to support the calibration standards. The accuracy and precision of the quality controls in rabbit blood reflect the extraction performance and the accuracy and precision of the homogenization tissue quality controls reflect the overall performance of the method. The mean bias was between -4.5 and 0.2% for all levels of quality controls in the blood and between 4.8 and 14.9% for all levels of the homogenization tissue quality controls. The CVs of all concentration levels were < or =5.3% for the quality controls in blood and < or =9.2% for the homogenization tissue quality controls. The method was successfully applied to determine the concentration of sirolimus in the rabbit arteries.

Recommendations for use of everolimus after heart transplantation: results from a Latin-American Consensus Meeting.

Despite improvements during the last decades, heart transplantation remains associated with several medical complications, which limit clinical outcomes: acute rejection with hemodynamic compromise, cytomegalovirus (CMV) infections, allograft vasculopathy, chronic renal failure, and neoplasias. Everolimus, a proliferation signal inhibitor, represents a new option for adjunctive immunosuppressive therapy. Everolimus displays better efficacy in de novo heart transplant patients than azathioprine for prophylaxis of biopsy-proven acute rejection episodes of at least ISHLT grade 3A (P < .001), of allograft vasculopathy (P < .01), and of CMV infections (P < .01). These findings suggest that everolimus potentially play an important role as part of immunosuppressive therapy in heart transplant recipients. Heart transplant investigators from Latin America produced recommendations for everolimus use in daily practice based on available data and their own experience.

Trace analysis of rapamycin in human blood by micellar electrokinetic chromatography.

A capillary electrophoretic method with UV detection at 278 nm has been developed for analysis of the immunosuppressant rapamycin (sirolimus) in human blood at low microgram per liter levels. Separation has been achieved in an acidic carrier electrolyte containing sodium dodecylsulfate and 30% (v/v) acetonitrile. For sample clean-up and preconcentration, an off-line solid-phase extraction step using a silica-based reversed-phase material and an on-capillary focussing technique were employed. The latter allows the injection of increased sample volumes without excessive band broadening. Although this new method is less sensitive than existing liquid chromatographic procedures combined with mass spectrometry, it is fully suited to routine analysis of rapamycin in blood from patients treated with this drug. Last but not least the low costs make it an attractive alternative to established methods.