Phase I study of human leukocyte interferon in patients with advanced cancer.

Seventeen patients with disseminated cancer were treated with a human leukocyte interferon preparation in doses ranging from 3 X 10(6) to 50 X 10(6) IU daily for 30 days. Doses above 18 X 10(6) IU were considered intolerable in this schedule of administration due to severe fatigue and weight loss. Serum concentrations of interferon were lower than those achieved with either partially pure native or recombinant leukocyte interferon. Three of 17 patients in this study showed minimal evidence of tumor regression. Two patients treated at doses of 18 X 10(6), 36 X 10(6), and 50 X 10(6) IU also received a 5 X 10(6)-IU dose of a second human leukocyte interferon preparation. The latter resulted in less toxicity but similar serum levels. These results suggest that human leukocyte interferons prepared in the same manner may differ significantly in their in vivo biologic properties.