Animal experiment:

Rats[1]In vivo pharmacokinetics is tested in Sprague Dawley male rats. Compounds (e.g., Nemiralisib) are administered discretely by the oral or intravenous routes, at a dose level of 3 and 1 mg/kg respectively (n=2 rats/route). Compounds (e.g., Nemiralisib) are formulated as a solution in DMSO:PEG200:water (5:45:50 v/v/v) at a dose volume of 6 (oral) and 2 (intravenous) mL/kg. All animals are serially bled from the tail vein and blood samples collected over a time-course of 0-7 h are submitted to LC-MS/MS analysis for the quantification of the parent compound. The main pharmacokinetic parameters are estimated by non-compartmental analysis.

Nemiralisib (GSK2269557 free base) is a potent and highly selective PI3Kδ inhibitor with a pKi of 9.9. PI3Kδ|9.9 (pKi)|PI3Kγ|5.2 (pIC50)|PI3Kα|5.3 (pIC50)|PI3Kβ|5.8 (pIC50)

Nemiralisib (GSK2269557 free base) is highly selective for PI3Kδ, with >1000-fold selectivity over the closely related isoforms PI3Kα (pIC50=5.3), PI3Kβ (pIC50=5.8) and PI3Kγ (pIC50=5.2). Nemiralisib inhibits IFNγ in the peripheral blood mononuclear (PBMC) assay with an pIC50 of 9.7[1].

To assess the suitability of the series for inhaled delivery clearance data in rat microsomes and subsequently in vivo pharmacokinetic data from Sprague Dawley male rats is obtained. Compounds (e.g., Nemiralisib) are administered by the oral or intravenous routes, at a dose level of 3 and 1mg/kg respectively (n=2 rats/route). Nemiralisib free base is active in a disease relevant brown norway rat acute OVA model of Type 2 helper T-cells (Th2)-driven lung inflammation[1].

[1]. Down K et al. Optimization of Novel Indazoles as Highly Potent and Selective Inhibitors of Phosphoinositide 3-Kinase δ for the Treatment of Respiratory Disease.J Med Chem. 2015 Sep 24;58(18):7381-99.