XL388

XL388 is a novel class of highly potent and selective, ATP-competitive inhibitor of the mammalian target of rapamycin (mTOR). XL388 inhibited cellular phosphorylation of mTOR complex 1 (p-p70S6K, pS6, and p-4E-BP1) and mTOR complex 2 (pAKT (S473)) substrates. Furthermore, XL388 displayed good pharmacokinetics and oral exposure in multiple species with moderate bioavailability. Oral administration of XL388 to athymic nude mice implanted with human tumor xenografts afforded significant and dose-dependent antitumor activity.