Phase I study of combined alpha Interferon,alpha difluoromethylornithine (DFMO), and doxorubicin in advanced malignancy

Interferon (IFN) and conventional cytotoxic chemotherapeutic agents have been successfully combined in various studies. Alpha difluoromethylornithine (DFMO) is a novel antitumor agent which is an inhibitor of polyamine metabolism. A phase I study of IFN 24 × 10⁶ U/m²/day IM (days 3–7), DFMO 9 gm/m² p.o. daily (days 1–7), and a variable dose of doxorubicin starting at 20 mg/m² (day 6), of each 28 day cycle was performed. The aim of the study was to determine the maximally tolerable dose of doxorubicin in this combination. Three patients were treated with doxorubicin at 20 mg/m² and six patients at 40 mg/m². The dose limiting toxicities were neutropenia, fatigue and fever. All other toxicities were mild and there was no grade IV toxicity. A doxorubicin dose of 40 mg/m² produced tolerable toxicity and is recommended for phase II studies. No major antitumor effects were seen.