Strategy to effectively and efficiently implement voriconazole pharmacogenetics in clinical practice

Stability and Analytical Characterization of Voriconazole as Measured by Immunoassay

BACKGROUND

Voriconazole is a broad-spectrum triazole antifungal agent recommended for invasive fungal diseases, including invasive aspergillosis. Therapeutic drug monitoring via voriconazole target trough concentration is important to ensure efficacy while preventing toxicity. Our aim was to determine the stability of voriconazole as adapted and measured by an immunoassay.

METHODS

Plasma from patient samples (n = 45) evaluated by a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was compared against an ARK immunoassay method, adapted and optimized on the Abbott Alinity c analyzer. Stability of voriconazole and analytical performance of ARK immunoassay was assessed, including functional sensitivity, limit of blank (LoB), limit of detection (LoD), and limit of quantification (LoQ), linearity, and precision.

RESULTS

ARK voriconazole immunoassay was highly correlated (Pearson R = 0.988) to the LC-MS/MS method, with an average bias of 0.09 mg/L (2%). CV at LoQ of 0.5 mg/L was 3.7% while the functional sensitivity was established at 0.05 mg/L. Overall imprecision with liquid quality control material obtained from ARK was 5.0%, 6.3%, and 5.9% at 1 mg/L, 5 mg/L, and 10 mg/L, respectively. Limit of blank and LoD were 0.02 mg/L and 0.05 mg/L, respectively. Voriconazole in lithium heparin plasma separator tube declines over time, with a decrease that is more evident near or above toxic concentrations.

CONCLUSION

Voriconazole collected in gel separation tubes declines over time, possibly due to absorptive properties. Voriconazole measurements by immunoassay and LC-MS/MS demonstrated acceptable comparability with sufficient level of sensitivity and precision.

Advancing pharmacogenetic testing in a tertiary hospital: a retrospective analysis after 10 years of activity

The field of pharmacogenetics (PGx) holds great promise in advancing personalized medicine by adapting treatments based on individual genetic profiles. Despite its benefits, there are still economic, ethical and institutional barriers that hinder its implementation in our healthcare environment. A retrospective analysis approach of anonymized data sourced from electronic health records was performed, encompassing a diverse patient population and evaluating key parameters such as prescribing patterns and test results, to assess the impact of pharmacogenetic testing. A head-to-head comparison with previously published activity results within the same pharmacogenetic laboratory was also conducted to contrast the progress made after 10 years. The analysis revealed significant utilization of pharmacogenetic testing in daily clinical practice, with 1,145 pharmacogenetic tests performed over a 1-year period and showing a 35% growth rate increase over time. Of the 17 different medical departments that sought PGx tests, the Oncology department accounted for the highest number, representing 58.47% of all genotyped patients. A total of 1,000 PGx tests were requested for individuals susceptible to receive a dose modification based on genotype, and 76 individuals received a genotype-guided dose adjustment. This study presents a comprehensive descriptive analysis of real-world data obtained from a public tertiary hospital laboratory specialized in pharmacogenetic testing, and presents data that strongly endorse the integration of pharmacogenetic testing into everyday clinical practice.

Randomised multicentre clinical trial to evaluate voriconazole pre-emptive genotyping strategy in patients with risk of aspergillosis: vorigenipharm study protocol

INTRODUCTION

Invasive aspergillosis is the most important cause of morbidity and mortality in patients with haematological diseases. At present, voriconazole is the first-line treatment for invasive fungal disease. The pharmacokinetic interindividual variability of voriconazole depends on genetic factors. CYP450 is involved in 70%-75% of total metabolism of voriconazole, mainly CYP3A4 and CYP2C19, with the remaining 25%-30% of metabolism conducted by monooxygenase flavins. CYP2C19 single nucleotide polymorphisms could explain 50%-55% of variability in voriconazole metabolism.

MATERIALS AND METHODS

The main objective is to compare efficiency of pre-emptive voriconazole genotyping with routine practice. The primary outcome is serum voriconazole on the fifth day within the therapeutic range. The secondary outcome is the combined variables of therapeutic failure and adverse events within 90 days of first administration, associated with voriconazole. A total of 146 patients at risk of invasive aspergillosis who will potentially receive voriconazole will be recruited, and CYP2C19 will be genotyped. If the patient ultimately receives voriconazole, they will be randomised (1:1 experimental/control). In the experimental arm, patients will receive a dose according to a pharmacogenetic algorithm, including CYP2C19 genotype and clinical and demographic information. In the control arm, patients will receive a dose according to clinical practice guidelines. In addition, a Spanish National Healthcare System (NHS) point-of-view cost-effectiveness evaluation will be performed. Direct cost calculations for each arm will be performed.

CONCLUSION

This trial will provide information about the viability and cost-effectiveness of the implementation of a pre-emptive voriconazole genotyping strategy in the Spanish NHS.

ETHICS AND DISSEMINATION

A Spanish version of this protocol has been evaluated and approved by the La Paz University Hospital Ethics Committee and the Spanish Agency of Medicines and Medical Devices. Trial results will be submitted for publication in an open peer-reviewed medical speciality-specific publication.

TRIAL REGISTRATION NUMBER

Eudra-CT: 2019-000376-41 and NCT04238884; Pre-results.