Entinostat is an oral, highly selective histone deacetylase (HDAC) inhibitor with epigenetic and immunomodulatory activity that is being evaluated in multiple combination regimens for the treatment of patients with therapy-resistant cancers. Entinostat has been designated a Breakthrough Therapy by the FDA when used in combination with exemestane in HR+ advanced (locally advanced or metastatic) breast cancer. A pivotal Phase 3 clinical study, being conducted under a special protocol assessment (SPA), combining entinostat with exemestane for the treatment of hormone receptor-positive metastatic breast cancer is currently enrolling. Syndax is also developing an immuno-oncology platform to improve responsiveness to checkpoint inhibitors based on entinostat’s ability to down-regulate immune suppressor cells.

Entinostat targets cancer cell growth and the primary and acquired resistance pathways that limit the effectiveness and durability of cancer therapies. We observed in clinical trials that entinostat, in combination with other cancer therapies, may enhance and extend their therapeutic benefit resulting in prolonged progression-free survival and overall survival. We believe that our approach with entinostat is applicable to a broad range of cancer therapies and across a wide spectrum of tumor types. We have collected clinical data in both advanced breast and lung cancer, which we believe supports this approach and demonstrates the significant clinical and commercial potential for entinostat in targeting resistance to cancer therapies.