PF-04691502 is an ATP-competitive PI3K/mTOR dual inhibitor with IC50 of 32 nM. PF-04691502 is also an agent targeting the phosphatidylinositol 3 kinase (PI3K) and mammalian target of rapamycin (mTOR) in the PI3K/mTOR signaling pathway, with potential antineoplastic activity. PI3K/mTOR kinase inhibitor PF-04691502 inhibits both PI3K and mTOR kinases, which may result in apoptosis and growth inhibition of cancer cells overexpressing PI3K/mTOR. 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 independent of PI3K. PF-04691502 is currently in Phase II clinical trials in patients with recurrent endometrial cancer and Breast Cancer. A Phase II clinical trials in patients with solid tumors has been completed.