Mustang Bio is an American clinical-stage biopharmaceutical company founded in 2015 and headquartered in Worcester, MA, U.S.[1][2][3] Operating as a partner company of Fortress Biotech, Mustang Bio develops CAR-T immunotherapies and gene therapies for multiple diseases, including hematologic cancers, solid tumors, and X-linked severe combined immunodeficiency (X-SCID).[4][5][6]