SOUTH SAN FRANCISCO, Calif.--(BUSINESS WIRE)--Exelixis, Inc. (Nasdaq:EXEL) announced today that the phase 3 registration trial of XL184 as a potential treatment for medullary thyroid cancer (MTC) has been initiated. XL184 is a small molecule anticancer compound targeting the MET, RET, and VEGFR2 receptor tyrosine kinases. Recently, Exelixis and the U.S. Food and Drug Administration (FDA) reached agreement on the phase 3 registration trial via the Special Protocol Assessment process. Exelixis has also discussed the trial design with European regulatory agencies.