Entrectinib (previously known as RXDX-101, NMS-E628) is an investigational drug, potent inhibitor of ALK, ROS1, and, importantly, of TRK family kinases, which shows promise for therapy of tumors bearing oncogenic forms of these proteins. Entrectinib (RXDX-101) is a selective inhibitor for all three Trk receptor tyrosine kinases encoded by the three NTRK genes, as well as the ROS1 and ALKreceptor tyrosine kinases.This investigational drug is active at low nanomolar concentrations, allowing for once-daily oral administration to patients whose tumors have been shown to have gene rearrangements in NTRK, ROS1, or ALK. Nerviano Medical Sciences, the original sponsor for entrectinib (formerly referred to as NMS-1191372), initiated the first-in-human Phase 1 study ALKA-372-001 in Italy in October 2012. The study is currently ongoing in Italy. Entrectinib is currently being tested in a global phase 2 basket clinical trial called STARTRK-2. In the U.S., entrectinib has orphan drug designation and rare pediatric disease designation for the treatment of neuroblastoma and orphan drug designation for treatment of TrkA-, TrkB-, TrkC-, ROS1- and ALK-positive non-small cell lung cancer (NSCLC) and metastatic colorectal cancer (mCRC).