A phase I trial of intermittent high-dose α-interferon and dexamethasone in metastatic renal cell carcinoma

Background: Evidence exists that the toxic effects of a-interferon can be ameliorated by co-administration of dexamethasone without compromise of therapeutic efficacy. We therefore conducted a phase I trial to determine the maximum tolerated dose of intermittent interferon when combined with oral dexamethasone. Patients and methods: Thirty patients with metastatic renal cell carcinoma were enrolled. The starting dose of interferon was 20 million IU/m²/day given as a subcutaneous injection days 1 to 4 of each 14 day cycle. Dose levels were escalated at increments of 5 million IU/m². Dexamethasone 4 mg was administered orally every 6 hours during administration of high-dose interferon. Low-dose maintenance interferon, 3 million lU/m²/day, was administered without dose escalation on days 5 to 14 of each cycle. Results: The maximum tolerated dose of intermittent high-dose interferon was 40 million IU/m²/day. The dose limiting toxicity was fatigue. EEG abnormalities developed in five patients and neuropsychiatric parameters deteriorated significantly in seventeen. Conclusions: We conclude that co-administration of dexamethasone improves the tolerance of intermittent high-dose interferon. The results of this trial may be useful in designing high-dose interferon regimens for renal cell carcinoma and other interferon-sensitive diseases.