Syndax Pharmaceuticals announced that the FDA has designated entinostat as a Breakthrough Therapy for the treatment of locally recurrent or metastatic estrogen receptor-positive (ER+) breast cancer when added to exemestane in postmenopausal women whose disease has progressed following non-steroidal aromatase inhibitor therapy.

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The Breakthrough Therapy designation for entinostat is based on data from the completed Phase 2 ENCORE 301 study. Entinostat was shown to extend both progression-free survival and overall survival when added to exemestane in postmenopausal women with ER+ metastatic breast cancer whose cancer had progressed after treatment with a nonsteroidal aromatase inhibitor.

Entinostat is an investigational oral histone deacetylase inhibitor (HDACi) set to begin Phase 3 testing in combination with exemestane in postmenopausal women with metastatic ER+ breast cancer who have progressed on hormonal therapy.

For more information call (781) 419-1400 or visit Syndax.com.