The purpose of this study is to determine the efficacy of catumaxomab by determination of the rate of macroscopic complete remissions of peritoneal carcinomatosis after treatment with one cycle (four doses) of catumaxomab followed by six cycles of routine neoadjuvant chemotherapy.

Inclusion Criteria:

• Histologically confirmed diagnosis of resectable gastric adenocarcinoma or adenocarcinoma of the esophagogastric junction (type II and type III according to Siewerts classification)

• Macroscopic peritoneal carcinomatosis (stage P1-4 according to Gilly et al., appendix 1)

• Patients potentially eligible for gastrectomy after primary systemic (and intraperitoneal) treatment

• Signed and dated informed consent before the start of specific protocol procedures

• Age > 18 years

• ECOG Performance Status of 0 or 1

• Life expectancy of at least 12 weeks

• Adequate bone marrow, liver and renal function as assessed by the following laboratory requirements to be conducted within 7 days prior to screening

  • Hemoglobin > 10.0 g/dl
  • Leukocyte count > 4.000/μl; absolute neutrophil count (ANC) > 2.000/μl
  • Platelet count > = 100.000/µl
  • Total bilirubin < 1,5 times the upper limit of normal
  • ALT and AST < 3 x upper limit of normal
  • Alkaline phosphatase < 5 x ULN
  • Serum creatinine < 1.5 x upper limit of normal and creatinine clearance > 60 ml/min

• The patient is willing and able to comply with the protocol for the duration of the study, including hospital visits for treatment and scheduled follow-up visits and examinations

Exclusion Criteria:

• Distant metastasis other than peritoneal seedings

• Prior diagnosis of any malignancy not cured by surgery alone less than 5 years before study entry

• Clinically significant cardiovascular disease (incl. myocardial infarction, unstable angina, symptomatic congestive heart failure, serious uncontrolled cardiac arrhythmia) = < 1 year before enrolment

• History of HIV infection or chronic hepatitis B or C

• Active, clinically serious infections (> grade 2 NCI-CTC version 3.0)

• Pre-existing neuropathy > grade 1 (NCI CTCAE), except for loss of tendon reflex

• Patients with seizure disorder requiring medication (such as steroids or antiepileptics)

• History of organ allograft

• Patients undergoing renal dialysis

• Known hypersensitivity to any of the drugs given in the study; known hypersensitivity to murine (rat and/or mouse) proteins

• Any condition that is unstable or could jeopardize the safety of the patient and their compliance in the study

• Excluded therapies and medications, previous and concomitant:

  • Prior anti-cancer chemotherapy or immunotherapy.
  • Investigational drug therapy outside of this trial during or within 4 weeks of study entry
  • Major surgery within 4 weeks of starting the study, and patients must have recovered from effects of major surgery

• Pregnant or breast-feeding patients, or planning to become pregnant within 6 months after the end of treatment. Women of childbearing potential must have a negative pregnancy test performed within 7 days of the start of treatment. Women enrolled in this trial must use adequate barrier birth control measures during the course of the trial and for 6 months after the end of treatment

• Substance abuse, medical, psychological or social conditions that may interfere with the patient's understanding of the informed consent procedure, participation in the study or evaluation of the study results