MSACL 2024 Abstract

Optimizing an Immunosuppressant Testing Workflow: Lessons Learned from Revisiting a Long-Established Assay

Meng Wang (1, 2), Junyan Shi (1, 2)
(1) Vancouver General Hospital, Vancouver, BC, Canada (2) Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada

Meng Wang, PhD (Presenter) Vancouver General Hospital

Presenter Bio: I am a Research & Development Scientist working at Vancouver General Hospital, specializing in mass spectrometry method development and quality improvement in the clinical laboratory.

I received my PhD in Chemistry from the University of British Columbia, with a research focus on discovering biologically active natural products for potential drug candidates. Following the completion of my doctorate, I transitioned to the role of Research Scientist at IntelliSyn Pharma, where I used mass spectrometry and NMR techniques to analyze and characterize drug-like small molecules across various drug discovery and medicinal chemistry projects. After working in the pharmaceutical industry for two years, I started my postdoctoral training at the University of British Columbia (St Paul's Hospital). During this period, my research focused on the development, optimization, and validation of targeted mass spectrometry protein assays.

Relevant Financial Disclosures (within past 24 months) No relevant financial relationship(s) to disclose. Conflict mitigation NOT REQUIRED.

Introduction: Immunosuppressants, such as tacrolimus (TAC), sirolimus (SRO), and cyclosporine A (CSA), are medications that suppress the immune system. Immunosuppressant is commonly used in transplant patients to prevent organ rejection. Due to the narrow therapeutic window of immunosuppressant and the variable pharmacokinetics among patients, routine drug monitoring is a standard clinical practice. In British Columbia, Canada, there has been a 29% increase in transplant recipients receiving follow-up care over the past five years. In our facility, the daily test volume for TAC increased from an average of 29 in 2005 to an average of 120 per day in 2021. Same-day result is ideal to provide information for dose adjustment, especially for new transplant patients and inpatients. With the manual sample preparation, the technologists spend approximately 5-7 hours hands on time on sample preparation and there have been 5.4% of results filed the following day, which are considered as delayed results. Given the increasing test volume, extended bench time, and result delays, revisiting and optimizing the workflow of immunosuppressant testing is essential to enhance efficiency.

Objectives: The primary goal of this quality improvement study was to revisit and enhance the efficiency of our existing immunosuppressant test, which has been in use for over a decade. Our focus was on optimizing the workflow to better align with the demands of our current test volume. This included an analysis of the pre-analytical processes, leading to adjustment in the batch volume and cut-off times. In addition, we assessed several analytical parameters in our workflow, including Hamilton programming, liquid handling robotics versus manual sample preparation, sample mixing, reagent selection, and instrument parameters.

Methods: TAC, SRO, and CSA concentrations were quantified in whole blood samples. With the new method, whole blood specimens were processed by the liquid handler. Samples were mixed, cleaned up through protein precipitation by zinc sulfate and acetonitrile incubation, and filtered, prior to analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Chromatographic separation was achieved using an Agilent Zorbax Eclipse Plus C18 UPLC column integrated into the Agilent 1290 Infinity LC system, coupled with an Agilent Ultivo Triple Quadrupole mass spectrometer. For pre-analytical workflow improvement, retrospective data analysis was done using the R open-source software.

Results: Pre-analytically, we set our cut-off batch time at 9AM and 12PM each day to facilitate same-day reporting based on the peak sample receiving time. Compared to our existing manual method, this optimized workflow demonstrated notable improvements, including (1) a double batch volume from 42 to 84 samples; (2) a streamlined robotic sample preparation, decreasing the hands on time from 5-7 hours to 3 hours per day; (3) a 23.7% reduction in instrument time per patient sample and a total reduction of 2 hours per batch; and 4) improved precision. The new workflow maintained comparable linearity, and the method comparison revealed R2 values of 0.99, 0.93, and 0.99 for TAC, SRO, and CSA, respectively.

Conclusion: This refined workflow not only enhances the precision of immunosuppressant measurements by eliminating user variations, but also contributes to streamlined laboratory processes, improved quality, and shorter turnaround time, ultimately benefiting patient care. Our experience also highlights the importance of incorporating prospective considerations when introducing laboratory developed tests to avoid extensive future re-validation.