Clinical and immunological evaluation of 20 patients with advanced colorectal cancer treated with high dose recombinant leukocyte interferon-αA (rIFNαA)

A total of 20 patients with advanced colorectal cancer received recombinant leukocyte interferon-αA (rIFNαA) either chronically (group I: twice a week up to 20×10⁶ IU/m² i.m.) or cyclically (group II: 1-4 periods of 8 consecutive days up to 20×10⁶ IU/m² i.m. daily at 20-days intervals) over a period of 12 weeks. There was 1 partial response, 1 mixed response and 1 patient with stable disease, whilst 17 patients had progressive disease. Median survival was 15.5 months. Survival was significantly shorter when the extent of hepatic disease was >25% (P=0.05), extrahepatic disease was extensive (P<0.005), alkaline phosphatase level was >2× normal (P<0.02), or performance status was <100% (P<0.001). Toxicity consisting mainly of fever, fatigue, anorexia and weight loss was serious in group I and minimal in group II. Administration of rIFNαA led to a "short lived" augmentation of natural killer (NK) cell activity. In the cyclically treated group this was a recurrent phenomenon whereas a marked lasting depression of NK cell activity was seen in chronically treated patients. Interferon-γ production capacity was significantly stimulated during rIFNαA therapy. The differences in toxicity and immunostimulatory effects between the two schedules may be of importance in the design of further studies.