High dose alpha-2b interferon + folinic acid in the modulation of 5-fluorouracil. A phase II study in advanced colorectal cancer with evidence of an unfavourable cost/benefit ratio.

The combination of folinic acid (FA) and 5-fluorouracil (5FU) is the most active systemic chemotherapy against advanced colorectal cancer. Experimental and clinical studies have suggested that the activity of 5FU can be improved by the addition of alpha-interferon (IFN). To evaluate the possibility of a double modulation of 5FU, a pilot study was conducted in the period July 1989-December 1989 with the following regimen: FA (200 mg/m2 i.v. bolus x 5 days) + 5FU (400 mg/m2 i.v. in 15 min x 5 days) + alpha-2b IFN (10 x 10(6) IU subcutaneously on alternate days). FA and 5FU administrations were repeated every 28 days; IFN was administered every week. In the 16 treated patients, 4 partial responses, 4 no changes, and 8 with progression of disease were observed, with an objective response rate of 25% (95% CI, 7.8%-55.1%). Median duration of response was 9.5 months, as was overall survival. Toxicity (fever, fatigue, neurotoxicity, stomatitis and diarrhea) was considerable and led to a reduction in IFN doses in 10/16 patients. Due to the unfavorable cost/benefit ratio, the study was closed and a new trial, with different doses and schedule of IFN, was started within the GISCAD (Italian Group for the Study of Digestive Tract Cancer).