High-grade, chemotherapy-resistant ovarian carcinomas overexpress epithelial cell adhesion molecule (EpCAM) and are highly sensitive to immunotherapy with MT201, a fully human monoclonal anti-EpCAM antibody.

Abstract

We evaluated the expression of epithelial cell adhesion molecule (EpCAM) and the potential of MT201 (adecatumumab), a human-monoclonal-antibody that targets EpCAM against chemotherapy-resistant ovarian disease. EpCAM expression was evaluated by real-time polymerase chain reaction and flow cytometry. Sensitivity to MT201 antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity was tested in 4-hour chromium-release assays. The effect of interleukin-2 on MT201 ADCC was also studied. High messenger RNA expression by real-time polymerase chain reaction and high EpCAM surface expression by flow cytometry was detected in 71% of ovarian cancers (5 of 7 cell lines). Although these cell lines were highly resistant to complement-dependent cytotoxicity and natural killer-dependent cytotoxicity in vitro (range of killing, 0-7%), EpCAM-positive cell lines showed high sensitivity to MT201 ADCC (range of killing, 27-66%). Incubation with interleukin-2 further increased the cytotoxic activity against EpCAM-positive ovarian cancer cell lines. MT201 may represent a novel, potentially highly effective treatment option for patients with ovarian carcinoma whose body is harboring disease refractory to chemotherapy.