Phase II trial of high-dose recombinant leukocyte alpha-2 interferon for metastatic colorectal cancer without previous systemic treatment.

Ten patients with metastatic colorectal cancer after resection of the primary tumor were treated with high-dose recombinant leukocyte alpha-2 interferon. For a period of 12 weeks the patients received up to 20 X 10(6) IU/m2 im twice weekly. Follow-up varied from 6 to 11 months after stopping treatment. All ten patients were evaluable for tumor response and toxicity. There was one partial response. Nine patients showed growth of metastatic marker lesions. Only three of these patients qualified as having progressive disease (greater than 25% increase in tumor mass). The response rate was 10%, with a 95% confidence interval of 0.3%-44.5%. Toxicity proved considerable and consisted of flu-like symptoms, fatigue, anorexia, and weight loss. Fatigue was the single most important dose-limiting factor. There were no drug-related deaths. Three patients died 3, 5, and 7 months after stopping treatment. Median survival was 18 months.