Robiya Joseph, Santosh K. Dasari, Sujanitha Umamaheswaran, Lingegowda S. Mangala, Emine Bayraktar, Cristian Rodriguez-Aguayo, Yutuan Wu, Nghi Nguyen, Reid T. Powell, Mary Sobieski, Yuan Liu, Mark Seungwook Kim, Sara Corvigno, Katherine Foster, Pahul Hanjra, Thanh Chung Vu, Mamur A. Chowdhury, Paola Amero, Clifford Stephan, Gabriel Lopez-Berestein, Shannon N. Westin, and Anil K. Sood
Endometrial cancer is the most frequent malignant tumor of the female reproductive tract but lacks effective therapy. EphA2, a receptor tyrosine kinase, is overexpressed by various cancers including endometrial cancer and is associated with poor clinical outcomes. In preclinical models, EphA2-targeted drugs had modest efficacy. To discover potential synergistic partners for EphA2-targeted drugs, we performed a high-throughput drug screen and identified panobinostat, a histone deacetylase inhibitor, as a candidate. We hypothesized that combination therapy with an EphA2 inhibitor and panobinostat leads to synergistic cell death. Indeed, we found that the combination enhanced DNA damage, increased apoptosis, and decreased clonogenic survival in Ishikawa and Hec1A endometrial cancer cells and significantly reduced tumor burden in mouse models of endometrial carcinoma. Upon RNA sequencing, the combination was associated with downregulation of cell survival pathways, including senescence, cyclins, and cell cycle regulators. The Axl-PI3K-Akt-mTOR pathway was also decreased by combination therapy. Together, our results highlight EphA2 and histone deacetylase as promising therapeutic targets for endometrial cancer.