OSI-420

OSI-420 is an active metabolite of erlotinib which is an orally active EGFR tyrosin kinase inhibitor with IC50 of 2 and 20 nM for the inhibition of human EGFR and EGFR autophosphorylation in tumor cells. Erlotinib disappearance from plasma after a short IV infusion was biexponential with a mean terminal half-life of 5.2 h and a mean clearance of 128 ml/min per m2. OSI-420 exposure (AUC) in plasma was 30% (range 12–59%) of erlotinib, and OSI-420 clearance was more than 5-fold higher than erlotinib. Erlotinib and OSI-420 were detectable in CSF. The CSF penetration (AUCCSF:AUCplasma) of erlotinib and OSI-420 was