A phase I trial of recombinant interferon-alpha and alpha-difluoromethylornithine in metastatic melanoma.

Both interferon-alpha (IFN-alpha) and alpha-difluoromethylornithine (DFMO) have shown modest activity as single-agent therapy in the treatment of malignant melanoma. Several investigators have demonstrated true synergism in vitro of the combination of DFMO and IFN-alpha against human tumor cells, including melanoma. We have investigated this combination in 17 patients with malignant melanoma in a Phase I trial. Patients were treated with 4 or 6 g/m2/day of oral DFMO in 3 divided doses for 11 days, followed by a 3-day rest period. Concomitant administration of 1.5, 3.0, 6.0 or 9.0 x 10(6) U/m2 IFN-alpha intramuscularly was given. The maximum tolerated dose was 4 g/m2/day of DFMO plus 6 x 10(6) U/m2/day of IFN-alpha. Dose-limiting toxicity occurred in 3 of 3 patients receiving 9 x 10(6) U/m2 IFN-alpha and consisted of leukopenia, fatigue, and weight loss. Other toxicities were mild and included reversible hearing loss, diarrhea, nausea, and vomiting. Three responses were seen, including one partial response (PR) of soft tissue metastases, one PR of lung and liver, and one complete response of liver metastases without clearance of carcinomatous meningitis. A Phase II trial has been initiated based on these encouraging results.