Animal experiment:

Mice[1] To determine the effects of CZ415 on its pharmacological target, dose-dependent changes in phosphorylation levels of S6 Ribosomal Protein and Akt - both downstream targets of mTOR are assessed. CZ415 is administered orally at 1, 3 and 10 mg/kg to mice 1 h before anti-CD3 stimulus. 15 min after stimulation, spleens are dissected and analyzed for pS6RP and pAKT levels. A dose related significant inhibition of phosphorylation of both S6RP and Akt are observed after compound administration. In particular, 1 and 3 mg/kg CZ415 could fully inhibit S6RP phosphorylation induced by anti-CD3 stimulation and 10 mg/kg additionally decreased the constitutive phosphorylation levels as measured in the control group.

CZ415 is a potent and highly selective mTOR inhibitor with a pIC50 of 8.07. CZ415 inhibits mTORC1 and mTORC2 protein complex.

Inhibition of phosphorylation for both downstream targets results in 14.5 nM IC50 for pS6RP and 14.8 nM for pAKT. The immunosuppressive effect of CZ415 is measured by detecting secreted IFNγ after 18 hours in stimulated human whole blood and the resulting IC50 is 226 nM. As a predictor for cardiotoxicity, the activity of CZ415 against the human cardiac ion channel hERG is assessed in a whole-cell patch-clamp assay in HEK293 cells resulting in an IC50 of 48 uM[1].

CZ415 is a highly selective mTOR inhibitor showing in vivo efficacy in a collagen induced arthritis (CIA) model. For full characterization of CZ415 and to enable improved dose predictions, the pharmacokinetic (PK) profile is assessed in rat. PK and oral bioavailability are determined after of 1 mg/kg intravenous (iv) bolus and 3 mg/kg oral (po) administration. The observed plasma clearance, corresponding to 45% liver blood flow, suggests that sufficient levels of free compound are circulating in the animal over time. The oral uptake is rapid with a Tmaxmax of 0.5 h and bioavailability F = 44% indicates very good absorption from the gut[1].

References:
[1]. Cansfield AD, et al. CZ415, a Highly Selective mTOR Inhibitor Showing in Vivo Efficacy in a Collagen Induced Arthritis Model. ACS Med Chem Lett. 2016 Jun 10;7(8):768-73.