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. Voxtalisib 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. Accordingly, this agent maybe more potent compared to an agent that inhibits either PI3K kinase or mTOR kinase alone.