Regression of liver metastases after treatment with intraperitoneal catumaxomab for malignant ascites due to breast cancer.

Malignant ascites is quite rare in breast cancer and is mainly associated with a lobular histology. To date, no studies have evaluated locoregional therapy for malignant ascites in breast cancer. The anti-epithelial cell adhesion molecule (EpCAM), trifunctional antibody catumaxomab was approved in the European Union for the intraperitoneal (i.p.) treatment of malignant ascites in patients with EpCAM-positive carcinomas where standard therapy is not available or no longer feasible. We report the case of a 69-year-old female with pretreated breast cancer who received i.p. catumaxomab for the treatment of malignant ascites and showed a regression of liver metastases. The patient originally underwent a left mastectomy and ipsilateral axillary lymph node dissection for an invasive ductal carcinoma in 1995. Following several lines of treatment, she was enrolled in February 2010 in a phase IIIb study (CASIMAS) investigating the safety of a 3-h i.p. catumaxomab infusion. In addition to a local benefit, as shown by an improvement in malignant ascites and a prolongation of the paracentesis-free interval with i.p. catumaxomab, a computed tomography scan, performed some weeks after catumaxomab administration, showed a regression of liver metastases. In addition to a locoregional effect on EpCAM-positive disease, i.p. catumaxomab may also show systemic effects. The use of i.p. catumaxomab for the treatment of malignant ascites due to breast cancer should be explored further in appropriate clinical studies and its possible systemic effects should also be further investigated.