Combining interferon with cytotoxic chemotherapy in patients with advanced breast cancer.

Laboratory studies have suggested therapeutic synergy between alpha-interferons and various cytotoxic agents. The present study set out to monitor the toxicity of giving a standard cytotoxic drug regimen with a well evaluated, low-dose, schedule of lymphoblastoid interferon. The combined treatment resulted in significantly greater leucopenia than was seen with cytotoxics alone and two patients developed severe infections. Although total numbers were small there was no evidence of increased therapeutic response in the combined treatment group. We would therefore suggest caution in future studies combining cytotoxic drugs and interferons as dose reductions of one or other modality is probably necessary.