Zimlovisertib

Zimlovisertib (PF-06650833) is a potent, selective and orally active inhibitor of interleukin-1 receptor associated kinase 4 (IRAK4) with IC₅₀s of 0.2 and 2.4 nM in the cell and PBMC assay, respectively. Zimlovisertib is used to treat diseases such as rheumatoid arthritis, lupus, and lymphomas^[1][2]. In Vitro: The kinome selectivity profile of Zimlovisertib (Compound 40) is assessed in a panel of 278 kinases (Invitrogen) at 200 nM inhibitor concentration using the ATP K_m for each kinase. Approximately 100% inhibition is observed for IRAK4^[1].
Lactam Zimlovisertib is assessed in a whole cell functional VEGF2R assay (PAE-KDR cell line). No activity is observed at concentrations up to and including 30 μM. In a voltage clamp assay, Zimlovisertib inhibits hERG current by 25% at 100 μM^[1].
The ability of Zimlovisertib to inhibit five major CYP450 enzymes is assessed using pooled human liver microsomes and probe substrates for the CYP450 enzymes. At a concentration of 3 μM of Zimlovisertib, less than 5% inhibition of CYPs 1A2, 2C8, 2C9, 2D6, and 3A4 is observed. Lactam Zimlovisertib is examined for time dependent inhibition effects on six major CYP450 enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C19, and 2D6) using pooled human liver microsomes and probe substrates. At 100 μM of Zimlovisertib, no time dependent CYP inhibition is observed. The potential induction of CYP3A by Zimlovisertib is assessed using cryopreserved human hepatocytes and afforded a 4.4-fold increase in mRNA at 10 μM^[1]. In Vivo: Zimlovisertib (0.3-30 mg/kg; oral administration; for 2.5 hours; male Sprague-Dawley rats) treatment significantly inhibits LPS-induced TNF-α in a dose dependent manner. Mean exposures of Zimlovisertib in plasma are 2.1 nM, 7.7 nM, 19 nM and 150 nM free, respectively, at 2.5 hours after oral administration of Zimlovisertib at 0.3, 1, 3, and 30 mg/kg. The fraction unbound in rat plasma of Zimlovisertib is 0.3^[1].