()-4-(Difluoromethyl)-5-(4-(3-methylmorpholino)-6-morpholino-1,3,5-triazin-2-yl)pyridin-2-amine (PQR530), a Potent, Orally Bioavailable, and Brain-Penetrable Dual Inhibitor of Class I PI3K and mTOR Kinase.

The phosphoinositide 3-kinase (PI3K)/mechanistic target of rapamycin (mTOR) pathway is frequently overactivated in cancer, and drives cell growth, proliferation, survival, and metastasis. Here, we report a structure-activity relationship study, which led to the discovery of a drug-like adenosine 5'-triphosphate-site PI3K/mTOR kinase inhibitor: ()-4-(difluoromethyl)-5-(4-(3-methylmorpholino)-6-morpholino-1,3,5-triazin-2-yl)pyridin-2-amine (PQR530, compound ), which qualifies as a clinical candidate due to its potency and specificity for PI3K and mTOR kinases, and its pharmacokinetic properties, including brain penetration. Compound showed excellent selectivity over a wide panel of kinases and an excellent selectivity against unrelated receptor enzymes and ion channels. Moreover, compound prevented cell growth in a cancer cell line panel. The preclinical in vivo characterization of compound in an OVCAR-3 xenograft model demonstrated good oral bioavailability, excellent brain penetration, and efficacy. Initial toxicity studies in rats and dogs qualify for further development as a therapeutic agent in oncology.