Primary evaluation of the safety, tolerability and feasibility regarding specific postoperative complications of an adjuvant treatment with catumaxomab administered after curative tumor resection subsequent to a neoadjuvant chemotherapy.

An open-label, multi-center phase II study in surgically resectable patients after neoadjuvant ECX-chemotherapy, with confirmed diagnosis of gastric adenocarcinoma and with a high risk of disseminated tumor cells due to serosal infiltration or positive lymph nodes after curative gastrectomy.

Treatment with catumaxomab will consist of an initial dose of 10 µg given intraoperatively as an intraperitoneal bolus and of four postoperative ascending doses (10-20-50-150 µg)which will be administered as an i.p.-infusion using an installed abdominal i.p.-port on the postoperative days 7, 10, 13 and 16.

Catumaxomab is a trifunctional antibody targeting EpCAM on tumor cells and CD3 on T cells. Trifunctional antibodies represent a new concept for targeted anticancer therapy. This new antibody class has the capability to redirect T cells and accessory cells (e.g. macrophages, dendritic cells [DCs] and natural killer [NK] cells) to the tumor site. According to preclinical data, trifunctional antibodies activate these different immune effector cells, which can trigger a complex anti-tumor immune response.

Inclusion Criteria:

• signed and dated informed consent
• male or female patient at an age of 18 years or older
• patient has a primary diagnosis of a histologically confirmed gastric adenocarcinoma (including GE junction Siewert-Type 2 or 3)
• TNM-staging at screening of T3/T4, N+/-, M0 or T2, N+, M0
• indication and eligibility for a neoadjuvant chemotherapeutic regimen featuring three cycles of ECX with 21 days per cycle
• intended curative gastrectomy
• Karnofsky index > 70

Exclusion Criteria:

• Exposure to prior cancer therapy or planned adjuvant chemo- or radiotherapy of the current gastric cancer
• prior diagnosis of any malignancy not cured by surgery alone less than 5 years before study entry
• previous use of non-humanized monoclonal mouse or rat antibodies
• treatment with another investigational product during this study or during the last 30 days prior to study start
• presence of distant metastases
• presence of constant immunosuppressive therapy
• history of pancreas resection (also partial) or thoracotomy
• presence of any acute or chronic systemic infection
• patient with a bowel obstruction within the last 30 days
• known contraindications to any of the planned ECX chemotherapeutics