Interferon alpha-2 is a genetically engineered, highly purified pharmaceutical agent that has undergone extensive phase I and phase II clinical study in more than 1000 patients. The material has biological activity by intravenous, intramus cular and subcutaneous routes. Clinical toxicity principally involves the 'influen za like' syndrome previously seen with native interferons. Other important toxi cities include anorexia, hepatitis, confusion and myelosuppression. Tolerable doses in multiple schedules and routes of administration have been determined. Phase II clinical trials with multiple...