PIK3CA and PTEN hamartoma tumor syndrome: mTORC1 inhibitor rapamycin reduces symptoms and excessive growth in PHTS patients.418–420 In fact, rapamycin has been tested in patients with PHTS in phase II open clinical trials.421 In addition, the upstream proteins of PTEN signaling pathway, PI3K and AKT for example, can also be used as drug inhibition candidates for PTEN mutant patients.