OSI-027 is a potent mammalian target of rapamycin (mTOR) kinase inhibitor with potential antineoplastic activity. It binds to and inhibits both the raptor-mTOR (TOR complex 1 or TORC1) and the rictor-mTOR (TOR complex 2 or TORC2) complexes of mTOR, which may result in tumor cell apoptosis and a decrease in tumor cell proliferation.