RATIONALE: Interleukin-12 may kill tumor cells by stimulating a person's white blood cells to kill cancer cells.

PURPOSE: Phase I trial to study the effectiveness of interleukin-12 in treating patients with cancer in the abdomen.

OBJECTIVES: I. Determine the maximum tolerated dose of intraperitoneal interleukin-12 in patients with Mullerian carcinoma (closed to accrual as of 8/23/01), gastrointestinal carcinoma, or peritoneal mesothelioma (closed to accrual as of 8/23/01). II. Determine the qualitative and quantitative toxicity and reversibility of toxicity of this regimen in these patients.

OUTLINE: This is a dose-escalation, multicenter study. Patients receive intraperitoneal interleukin-12 over 30 minutes once weekly for 4 weeks. Treatment repeats every 4 weeks for up to 6 courses in the absence of unacceptable toxicity or disease progression. Patients with stable or responsive disease may receive an additional 6 courses. Patients receive escalating doses of intraperitoneal interleukin-12 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity. Once the MTD is established, additional patients are accrued to receive interleukin-12 at the recommended dose.

PROJECTED ACCRUAL: Approximately 20-40 patients will be accrued for this study within 2 years.

• Anal Cancer
• Carcinoma of the Appendix
• Colorectal Cancer
• Extrahepatic Bile Duct Cancer
• Gallbladder Cancer
• Gastric Cancer
• Gastrointestinal Carcinoid Tumor
• Malignant Mesothelioma
• Pancreatic Cancer
• Small Intestine Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed Mullerian carcinoma (ovarian epithelial or peritoneal carcinoma) (closed to accrual as of 8/23/01) OR Gastrointestinal cancer with abdominal carcinomatosis OR Peritoneal mesothelioma (closed to accrual as of 8/23/01) Must have received an adequate course of any platinum-based chemotherapy regimen for ovarian cancer with evidence of intraabdominal disease Must have received an adequate course of fluorouracil-based treatment for metastatic colon cancer Intact primary gastrointestinal tumor allowed if not at risk of obstruction and/or bleeding Abdominal lesions must be less than 10 cm Extraperitoneal lesions must be less than 2 cm No hepatic disease No clinically significant pleural effusion (controlled by pleurodesis allowed) No brain metastases No significant adhesions or symptoms of obstruction

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 Life expectancy: Not specified Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9 g/dL (transfusion allowed) Lymphocyte count at least 800/mm3 Hepatic: See Disease Characteristics Bilirubin no greater than 1.5 mg/dL SGOT or SGPT less than 2.5 times upper limit of normal Albumin at least 3.5 g/dL Hepatitis B and C negative Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No significant heart disease Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception Loss of no more than 10% of body weight over a 4 month period No overt autoimmune disease No active ulcer disease No prior inflammatory bowel disease (e.g., Crohn's disease or ulcerative colitis)

PRIOR CONCURRENT THERAPY: Biologic therapy: No other concurrent immunotherapy Chemotherapy: At least 3 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and recovered No concurrent chemotherapy Endocrine therapy: No chronic steroid therapy Radiotherapy: At least 3 months since prior localized radiotherapy (e.g., pelvic or small field) and recovered No radiotherapy to whole abdomen No concurrent radiotherapy Surgery: Recovered from prior surgery At least 3 weeks since prior major abdominal surgery At least 2 weeks since prior laparoscopy