Discovery and Development of SPR519 as a Potent, Selective, and Orally Bioavailable Inhibitor of PI3Kα and mTOR Kinases for the Treatment of Solid Tumors

Herein, we report the identification and preclinical profile of a lead compound 10, (SPR519) as an equally potent dual inhibitor of PI3Kα and mTOR kinases. SPR519 exhibits an EC50 of low sub-micromolar range among various tested cancer cell lines such as A2780 (0.23 μM), PC3 (0.48 μM), and SKOV3 (0.50 μM). When administrated orally, it shows a considerably high plasma exposure (area under curve: 26,858 nM/h at 1 mg/kg) in mice. Moreover, it is found to be safe in animals with a dose of 30 mg/kg BID for 12 days in the dose tolerance study. SPR519 did not show any CYP or hERG liability. The identified lead compound demonstrates significant efficacy and bioavailability in ovarian and colon cancer xenograft models when evaluated for dose-ranging efficacy studies, at a dose as low as 2.5 mg/kg.