Novel clinical assay to rapidly monitor posaconazole levels in plasma - SUMMARY/ABSTRACT
Invasive fungal infections (IFIs) contribute to more than 1.5 million deaths worldwide each year and pose a
serious and continuous health risk to immunocompromised individuals. The rate of mortality associated with IFI
is high, and there are only four major classes of antifungal drugs available to treat IFI, of which the triazoles find
greatest use. Posaconazole (PCZ; Noxafil®) is the newest triazole and is the broadest spectrum, demonstrating
activity against Aspergillus, Candida and Cryptococcus species.
PCZ is indicated in the U.S. for prophylaxis of invasive Aspergillus and Candida infections in patients at
high risk for these infections, including hematopoietic stem cell transplant recipients, those with hematologic
malignancies, and other immunocompromised patients. It is also indicated for treatment of oropharyngeal
candidiasis (OTC), a condition common among HIV patients. While PCZ is not associated with significant
toxicities, it displays high inter- and intra-individual variation in plasma drug concentrations, with subtherapeutic
levels associated with poor efficacy. There is significant evidence to demonstrate that inadequate exposure to
antifungals is independently associated with increased hospital mortality, and the Infectious Diseases Society of
America recommends therapeutic drug monitoring (TDM) of PCZ to ensure adequate treatment. Unfortunately,
there are currently no FDA approved assays available for performing PCZ TDM. Available assays remain limited
to institutions or laboratories that have developed in-house laboratory-developed tests that rely on high-
performance liquid chromatography (HPLC) or HPLC with mass spectrometry. These complex assays are
expensive and lack harmonization, making it impossible to compare results from one test to the next. Most
importantly, the turnaround time can range from several days to a week, making routine dose adjustments based
on timely results impossible. Affinergy plans to develop a novel locking assay for the direct measurement
of PCZ levels in plasma that is compatible with common clinical chemistry analyzers to facilitate routine
TDM. Our assay with its lower cost and rapid turnaround will open access to a majority of patients to ensure that
therapeutic levels are achieved to prevent life-threatening breakthrough infections and help control the rise of
resistant strains.