Exhibit 99.1 Syndax Pharmaceuticals Reports First Quarter 2024 Financial Results and Provides Clinical and Business Update – NDA filing for revumenib in R/R KMT2Ar acute leukemia granted Priority Review under RTOR; PDUFA action date set for September 26, 2024 – – BLA filing for axatilimab in chronic GVHD granted Priority Review; PDUFA action date set for August 28, 2024 – – Enrollment completed in AUGMENT-101 mNPM1 cohort; topline data expected in 4Q24 to potentially support sNDA filing in 1H25 – – Company ...