Study Shows Abbott’s Tacrolimus Assay Demonstrates Consistent Organ Transplant Drug Monitoring

A new study published in the journal Clinical Chemistry reported Abbott’s ARCHITECT® Tacrolimus assay provides accurate and consistent medication monitoring for patients taking tacrolimus, an immunosuppressive medication, after receiving solid organ transplantation.

Tacrolimus is a calcineurin inhibitor often used in patients to help prevent organ rejection. For continued organ survival, a transplant patient must be monitored accurately and precisely to ensure the medication level is sufficient to prevent organ rejection and to help the organ remain functional. Currently, test methods used to monitor tacrolimus concentration in the blood are not standardized which may lead to varying results for patients. Underestimating tacrolimus levels could result in prescribing unnecessarily high doses of medication that could be toxic to the transplanted organ over time and may cause side effects contributing to a poor quality of life for the patient. Overestimating tacrolimus levels could lead to insufficient dosing, poor immunosuppression and subsequent organ rejection.

“A transplant patient might receive an organ at one facility and be monitored somewhere else. If that location uses an assay with poorer accuracy and precision, it could result in incorrect dosage decisions, so it is critical that test results measuring tacrolimus medication levels be comparable from site-to-site,” said Dr. David Holt, co-author of the paper and Emeritus Professor of Bioanalytics at the University of London and director of Analytical Services International Ltd. in the United Kingdom.

“The absence of standardization between the various assay techniques could result in the clinician receiving misleading information. Current low-dose regimens for tacrolimus and other anti-rejection medications require drug-monitoring assays with both high precision and sensitivity,” he added.

“Minimizing drug toxicity over time is considered one way to help improve long-term graft survival and preserve quality of life for transplant patients,” said Daniel M. Levine, Ph.D., lead author of the study and director of the Iris and B. Gerald Cantor Clinical Research Laboratory at The Rogosin Institute in New York City. “To reduce toxicity risk, current guidelines suggest prescribing immunosuppressive drugs at the lowest levels possible without risking rejection,” he added.

The ARCHITECT Tacrolimus assay is used for the quantitative determination of tacrolimus in human whole blood, as an aid in managing liver and kidney transplant patients receiving tacrolimus therapy. It is the only automated transplant monitoring test that meets published international guidelines for low-level monitoring. It is accurate and precise at low levels and shows consistent results between laboratories.

“Kidney-transplant patients have a high incidence of cardiovascular complications which may be exacerbated by the long-term effects of taking calcineurin inhibitors,” said Gregory Maine, Ph.D., co-author and associate research fellow, Diagnostics, Abbott. “The ARCHITECT Tacrolimus assay addresses an unmet clinical need for consistent site-to-site patient results by providing uniform instrumentation, test kits, calibrators and controls across the world.”

According to the National Organ Procurement and Transplant Network, between January through October 2011, nearly 24,000 organ transplants were performed in the United States.

About the Study

The global tacrolimus proficiency study compared the performance of the Abbott ARCHITECT Tacrolimus assay with a candidate reference method exact-matching isotope-dilution mass spectrometry (EM-IDMS), laboratory developed LC-MS (liquid chromatography tandem mass spectrometry) assays and another commercially available immunoassay. Panels of whole blood samples containing patient specimens and spiked samples with tacrolimus concentrations ranging from 0-30 µg/L were tested at 22 laboratories in 14 countries. This study showed tacrolimus values were not comparable between laboratories and across methods, but the ARCHITECT assay was close to the target values and comparable from lab to lab. Today, the ARCHITECT Tacrolimus assay is used by 10 of the 19 U.S. hospitals recently named as the nation’s top organ transplant centers by HealthGrades, the leading independent health care ratings company.

The study authors concluded that harmonization of tacrolimus assay results for patient samples is a worthwhile aim in clinical practice and an important step forward in providing uniform global care for transplant patients. The authors also encouraged professional associations and academics to take a leadership role and work collaboratively with pharmaceutical and diagnostics companies to fund and promote assay standardization.

Intended Use and Important Safety Information:

For In Vitro Diagnostic Use

Intended Use: The ARCHITECT Tacrolimus assay is a chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of tacrolimus in human whole blood on the ARCHITECT iSystem. The ARCHITECT Tacrolimus assay is to be used as an aid in the management of liver and kidney allograft patients receiving tacrolimus therapy.

Important Safety Information: Caution must be used in sample preparation for the Tacrolimus assay, specific handling instructions may be found in the assay package insert. No firm therapeutic range exists for tacrolimus in whole blood. Individual tacrolimus values cannot be used as the sole indicator for making changes in treatment regimen and each patient should be thoroughly evaluated clinically before changes in treatment regimens are made. Each user must establish his or her own ranges based on clinical experience. This product contains human sourced and/or potentially infectious components. It is recommended that these reagents and human specimens be handled in accordance with the OSHA Standard on Bloodborne Pathogens. This material contains sodium azide; material and its container must be disposed of in a safe way.

CAUTION: United States Federal law restricts this device to sale and distribution by or on the order of a physician or to a clinical laboratory.

For complete information, see the assay specific package insert on www.abbottdiagnostics.com