Tumor necrosis factor (TNF) induces hemorrhagic necrosis in the Meth A mouse tumor model and has shown cytostatic and cytotoxic antitumor effects against a wide range of human tumors both in vitro and as human tumor xenografts in nude mice. Because of in vitro activity against colorectal tumors and antitumor responses in colon cancer patients in phase I trials, this phase II study was undertaken. Patients were treated with TNF administered daily for 5 days/week every other week at a dose of 150 micrograms/m2/day as a 30-min i.v. infusion. One cycle consisted of 4 weeks of treatment over an 8-week period. Twenty-five patients have been entered into this study with three patients ineligible. The 22 eligible patients ranged in age from 38-73 years and had initial performance status of 0 in 10 patients, 1 in 10 patients, and 2 in 2 patients. No complete or partial responses were seen. Two patients had stable disease (no response) and 18 patients progressed. Two patients had no evaluation and were assumed to have had no response. The response rate is therefore 0%, with a 95% exact confidence interval of 0% to 15%. There was one grade 4 toxicity consisting of nausea and vomiting. Most common grade 3 toxicities were chills and fever in four patients, nausea and vomiting in three patients, and anemia and elevated liver enzymes in two patients. Headache, myalgia/arthralgia, and elevated serum triglycerides were frequently seen. Mildly elevated levels of fibrin split products were seen after TNF treatment in 5/13 evaluable patients and one ineligible patient.(ABSTRACT TRUNCATED AT 250 WORDS)