Efficacy of intraperitoneal treatment with the trifunctional antibody catumaxomab in patients with GI-tract cancer and peritoneal carcinomatosis: A matched-pair analysis
2544 Background: Peritoneal carcinomatosis (PC) due to GI-tract cancer is an advanced tumor stage with poor survival. At present, no standard therapy has been recommended, as chemotherapy and surgery showed only limited efficacy in affected patients. When applied intraperitoneally (i.p.), the trifunctional antibody catumaxomab could be shown to destroy intraperitoneal tumor cells in patients with malignant ascites due to ovarian cancer. While binding simultaneously to EpCAM (on tumor cells), CD3 (T cells) and, via the Fc region, to Fc gamma receptor 1 and 3 on accessory cells, it induces a complex immunoreaction against epithelial tumor cells. The aim of this study was to investigate clinical efficacy of i.p. catumaxomab therapy in patients with PC compared to a matched control group. Methods: Between 2003 and 2005, 22 patients with PC due to cancer of colon (n=10), stomach (8), pancreas (3) and CUP (1) received treatment with catumaxomab within a phase I study. Treatment consisted of 3 to 4 i.p. applications (10–200 μg) of escalating catumaxomab doses. The survival was compared with patients receiving conventional therapies in a matched-pair analysis regarding sex, age, tumor surgery, chemotherapy, and extent of PC. Patients with existing ileus and clinically significant ascites were not included. Results: Follow up of patients receiving catumaxomab showed a median survival of 12.2 months (range 2–34) after first diagnosis of peritoneal carcinomatosis vs. 9.7 months (range 1–40) in patients with conventional treatment (p=0.005; log-rank). These data will be updated at presentation. Conclusion: Intraperitoneal treatment with the trifunctional antibody catumaxomab may be an attractive option for treatment of patients with peritoneal carcinomatosis due to GI-tract cancer. The convincing results have to be further investigated in clinical phase II/III trials. [Table: see text]