Clinical update on the role of fluorouracil and recombinant interferon alfa-2a in the treatment of colorectal carcinoma.

Recombinant interferon alfa-2a (rIFN alpha-2a) synergistically augments the cytotoxic effects of the antimetabolite fluorouracil (5-FU) against two human colon cancer cell lines. A pilot clinical trial was initiated to determine whether this same combination of agents would show clinical utility greater than that expected with 5-FU alone in patients with advanced colorectal carcinoma. 5-FU was administered at 750 mg/m2/d for 5 days as a continuous intravenous infusion followed by weekly bolus therapy. rIFN alpha-2a was administered at 9 million units subcutaneously three times per week starting on day 1. Doses of 5-FU were modified for mucosal toxicities and myelo-suppression, and doses of rIFN alpha-2a were modified for fatigue and neurologic toxicities. Thirty-two previously untreated patients with advanced colorectal carcinoma were entered into a clinical trial. With the exception of one patient with a destructive lesion of the sacrum, all patients had metastases to visceral organs, abdominal wall, or pelvis. Twenty patients (63%) achieved a partial response, seven remained stable, and five had progressive disease. Mucosal toxicities limited delivery of full projected dose. Two patients died following episodes of watery diarrhea progressing to sepsis. A third died suddenly, secondary to an interstitial pneumonitis. The remainder of the toxicities were managed with dose reductions. At the median follow-up of 8 months, 23 of 32 patients remain alive. Nine are alive at 16 to 30+ months. The early results of this single-institution study are promising, but will require confirmation in a multi-institutional setting currently being conducted by the Eastern Cooperative Oncology Group.