X0306 4 2017-03-20 false 0001395937 Syndax Pharmaceuticals Inc SNDX 0001026765 ROYSTON IVOR C/O SYNDAX PHARMACEUTICALS, INC. 35 GATEHOUSE DRIVE, BUILDING D, FLOOR 3 WALTHAM MA 02451 true false false false Common Stock 2017-03-20 4 D false 125000.00 13.75 D 625545.00 I See footnote The securities are owned directly by Forward Ventures V, LP ("Forward V"), Forward Ventures IV, LP ("Forward IV") and Forward Ventures IVB, LP ("Forward IVB" and collectively, the "Forward Entities"). Dr. Royston is a member of Forward V and a managing member of Forward IV Associates, LLC which is the general partner of each of Forward IV and Forward IVB. As a result, Dr. Royston shares voting and investment power over the shares owned by the Forward Entities. Dr. Royston disclaims beneficial ownership of all shares held by the Forward Entities, except to the extent of his actual pecuniary interest therein. /s/ Michael A. Metzger, Attorney-in-Fact 2017-03-22