EpCAM is an attractive target for
cancer therapy and the
EpCAM-specific antibody
catumaxomab has been used for intraperitoneal treatment of
EpCAM-positive
cancer patients with malignant
ascites. New prognostic markers are necessary to select patients that mostly benefit from
catumaxomab. Recent data showed that soluble
EpCAM (sEpCAM) is capable to block the effect of
catumaxomab in vitro. This exploratory retrospective analysis was performed on archived
ascites samples to evaluate the predictive role of sEpCAM in
catumaxomab-treated patients. Sixty-six
catumaxomab-treated patients with an available archived
ascites sample were included in this study and tested for sEpCAM by sandwich ELISA. All probes were sampled before treatment start and all patients received at least one
catumaxomab infusion. Overall survival,
puncture-free survival and time to next
puncture were compared between sEpCAM-positive and -negative patients. We detected sEpCAM in
ascites samples of 9 patients (13.6%). These patients showed a significantly shorter overall survival. The prognostic significance of sEpCAM in
ascites was particularly strong in patients with
ovarian cancer.
Puncture-free survival and time to next
puncture were not significantly different between sEpCAM-positive and -negative patients. We propose sEpCAM in malignant
ascites as a potential predictive marker in
cancer patients treated with
catumaxomab. Prospective studies with larger patients samples are urgently needed to confirm these findings and studies testing dose-intensified
catumaxomab in patients with sEpCAM-positive
ascites should be envisaged.