Abstract
ABSTRACT
CDC‐like kinases (CLK) and dual‐specificity tyrosine‐regulated kinases (DYRK) are protein kinases involved in various cellular functions, mRNA splicing, and DNA damage repair. CLK/DYRK kinases have been implicated in many disorders such as diabetes, neurodegenerative diseases, and cancer. Cirtuvivint (SM08502) is an orally bioavailable, first‐in‐class pan‐CLK and pan‐DYRK inhibitor that modulates pre‐mRNA splicing and has shown the ability to inhibit cancer cell growth in vitro and reduce tumor burden in vivo. This has led to the administration of cirtuvivint in phase I clinical trials. To quantitate cirtuvivint, we have developed and validated an LC–MS/MS method in human plasma. The assay is simple and robust and consists of a protein precipitation, dilute‐and‐shoot extraction method using 20 μL of plasma, chromatographic separation with a Phenomenex Kinetex C18, and a gradient mobile phase system consisting of 0.1% formic acid in water and acetonitrile. The chromatographic method is followed by mass spectrometric detection with a SCIEX 4500 tandem mass spectrometer. The method has a 5‐min run time and is linear from 5 to 1000 ng/mL. The assay met the criteria outlined by the US Food and Drug Administration guidance for bioanalytical method validation and will support ongoing and future clinical studies defining cirtuvivint pharmacokinetics.