XL765

XL765 (SAR245409) is an orally bioavailable small molecule targeting the phosphatidylinositol 3 kinase (PI3K) and mammalian target of rapamycin (mTOR) kinases in the PI3K/mTOR signaling pathway, with potential antineoplastic activity. XL765 inhibits both PI3K kinase and mTOR kinase, which may result in tumor cell apoptosis and growth inhibition in susceptible tumor cell populations. Activation of the PI3K/mTOR pathway promotes cell growth, survival, and resistance to chemotherapy and radiotherapy. mTOR, a serine/threonine kinase downstream of PI3K, may also be activated in a PI3K-independent fashion in response to nutrient and energy deprivation. XL765 significantly reduces phosphorylation of the mTOR targets S6, S6K, and 4EBP1, which is associated with greater apoptosis induction rather than to PI3K inhibition alone. In preclinical studies, XL765 slowed tumor growth or caused tumor shrinkage in multiple preclinical cancer models, including breast, lung, ovarian, prostate cancers, and gliomas.