Automation in Busulfan Therapeutic Drug Monitoring: Evaluation of an Immunoassay on two Routine Chemistry Analyzers

Abstract

Background: Therapeutic drug monitoring (TDM) of busulfan is recommended for hematopoietic stem cell transplant recipients. Timely reporting of these TDM results is essential given the short administration period and the planned dose adjustments on day 2. The authors evaluated the performance of a new nanoparticle-based competitive immunoassay on two routine clinical chemistry analyzers and compared its performance to that of an in-house highresolution mass spectrometry (HRMS) method. Methods:The MyCare Oncology Busulfan Assay Kit (Saladax Biomedical) was applied on two routine clinical chemistry analyzers (Abbott Architect c8000 and Roche Cobas c502) with a linearity range of 187-2000 ng/mL. The study evaluation measured imprecision and accuracy, sample probe carry-over, and dilution integrity. Method comparison with liquid chromatography (LC)-HRMS was performed using samples from patients undergoing busulfan treatment.Results: Within-and between-run coefficient of variations for both analyzers were #5.23% and #8.45%, respectively, across the busulfan concentration range. The obtained biases were #10.3%. Both analyzers met the acceptance criteria for sample probe carry-over and dilution integrity. Agreement between the immunoassay and LC-HRMS was high: 92% and 89% of the samples measured on Architect and Cobas, respectively, were within the 615% limit compared to the corresponding LC-HRMS results.Conclusions: Overall, good analytical performance and high agreement with LC-HRMS results were obtained for the immunoassay installed on both routine clinical chemistry analyzers. Therefore, this assay could be implemented as a valid alternative for LC methods in clinical laboratories on different open-channel clinical chemistry analyzers, resulting in shorter turn-around times for reporting busulfan TDM results with subsequent faster dosage adjustments.

Busulfan Interlaboratory Proficiency Testing Program Revealed Worldwide Errors in Drug Quantitation and Dose Recommendations

“…This chemical disturbs the immunoagglutination reaction in certain automated analyzers, resulting in a result that is 3–10 times higher than LC-MS and reference values, as published previously. 15 In the current study, none of the participating laboratories used an immunoanalytic method. In addition to LC–MS/MS, a few laboratories have used HPLC-UV or GC–MS to quantify busulfan.…”

Therapeutic drug monitoring for cytotoxic anticancer drugs: Principles and evidence-based practices

“…These assays can be quickly performed without any sample processing steps. It has also been shown that they are in good conformity with the LC-MS/MS methods ( 20 , 66 ) and are gaining acceptance.…”

“…Though the use of oral busulfan was short-lived and it has now been replaced by intravenous use, it provided great insight to understand the pharmacokinetics (PK) of the drug and helped in the evolution of the TDM strategy. The PK profile of the drug is best described as a single compartment model, with rapid absorption and maximum plasma concentration achieved within 1 h. Majority of the drug is metabolized in the liver by the glutathione-S-transferase ( 20 ) enzyme and the metabolites are excreted via urine. A minimal amount of the drug (<2%) is excreted unchanged in the urine.…”