MTOR and cancer: In view of the evidence implicating both PI3K and mTOR in cancer, as well as the potential to obtain synergism and address drug resistance (Stauffer et al., 2008; Ma and Hu, 2013; Beaufils et al., 2017; Ma et al., 2018), simultaneous inhibition of PI3K and mTOR is expected to provide therapeutic advantages over mono-inhibition of PI3K or mTOR.