PQR-309 is an orally bioavailable pan inhibitor of phosphoinositide-3-kinases (PI3K) and inhibitor of the mammalian target of rapamycin (mTOR), with potential antineoplastic activity. PI3K/mTOR kinase inhibitor PQR-309 inhibits the PI3K kinase isoforms alpha, beta, gamma and delta and, to a lesser extent, mTOR kinase, which may result in tumor cell apoptosis and growth inhibition in cells overexpressing PI3K/mTOR. By inhibiting mTOR to a lesser extent than PI3K, PQR-309 does not interfere with the mTOR-mediated negative feedback loop on PI3K signaling. Blocking the negative feedback loop would potentially increase PI3K signaling and decrease therapeutic efficacy. PQR-309 is in phase II clinical trial for the treatment of glioblastoma, head and neck cancer, lymphoma and breast cancer. Common adverse events included fatigue, hyperglycemia, nausea, diarrhea, constipation, rash, anorexia and vomiting.