PURPOSE: EphA2 overexpression is frequently observed in endometrial cancers and is predictive of poor clinical outcome. Here, we use an antibody drug conjugate (MEDI-547) composed of a fully human monoclonal antibody against both human and murine EphA2 (1C1) and the tubulin polymerization inhibitor monomethylauristatin F.
EXPERIMENTAL DESIGN: EphA2 expression was examined in endometrial cancer cell lines by Western blot. Specificity of MEDI-547 was examined by antibody degradation and internalization assays. Viability and apoptosis were investigated in endometrial cancer cell lines and orthotopic tumor models.
RESULTS: EphA2 was expressed in the Hec-1A and Ishikawa cells but was absent in the SPEC-2 cells. Antibody degradation and internalization assays showed that the antibody drug conjugate decreased EphA2 protein levels and was internalized in EphA2-positive cells (Hec-1A and Ishikawa). Moreover, in vitro cytotoxicity and apoptosis assays showed that the antibody drug conjugate decreased viability and increased apoptosis of Hec-1A and Ishikawa cells. In vivo therapy experiments in mouse orthotopic models with this antibody drug conjugate resulted in 86% to 88% growth inhibition (P < 0.001) in the orthotopic Hec-1A and Ishikawa models compared with controls. Moreover, the mice treated with this antibody drug conjugate had a lower incidence of distant metastasis compared with controls. The antitumor effects of the therapy were related to decreased proliferation and increased apoptosis of tumor and associated endothelial cells.
CONCLUSIONS: The preclinical data for endometrial cancer treatment using MEDI-547 show substantial antitumor activity.
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