5-Fluorouracil and recombinant alpha interferon-2a in the treatment of advanced colorectal carcinoma: a dose optimization study.

A dose optimization study was carried out with the aim of identifying the maximally tolerated dose of recombinant alpha interferon-2a (raIFN-2a) in combination with 5-fluorouracil (5FU). 5FU was given at the dose of 750 mg/m2 over a 4-hour infusion on day 1- - greater than 5 followed by 750 mg/m2 weekly i.v. bolus. Recombinant aIFN-2a was started at 3 x 10(6) IU subcutaneously three times/week. 12 patients with advanced colorectal carcinoma were included in the study. 10 patients had previously received chemotherapy for advanced disease. Severe fatigue, most likely attributable to rIFN, was the dose-limiting toxicity. The dosage of raIFN-2a could not be further escalated above 12 x 10(6) IU. At this dose level all patients required dose reduction due to fatigue, fever, myalgia and severe reduction of performance status.