Phase I/II trial of human recombinant beta-interferon serine in patients with renal cell carcinoma.

Beta-interferon serine (IFN-beta ser) is a genetically altered recombinant IFN with a specific activity of 2 X 10(8) IU/mg protein. We undertook a Phase I trial of this agent in 18 patients with metastatic renal cell carcinoma. IFN-beta ser was given by a 4-h intravenous infusion twice weekly (Monday and Thursday). Three patients were placed on escalating dose levels. Doses were also escalated in each patient if no unacceptable toxicity was detected on the previous treatment. The maximum initial tolerated dose was less than or equal to 150 million units/m2. However, development of patient tolerance allowed escalation beyond this dose and chronic therapy at this or higher doses in most patients. Toxicity was largely limited to the symptom complex of fever, malaise, mild hypotension, and anorexia. One patient developed reversible proteinuria (10 g/24 h) with no change in serum creatinine. Limited or no renal, hepatic, or hematological toxicity was observed. Six of 16 patients developed anti-IFN antibody levels. Fifteen patients received twice weekly treatments at near their maximum tolerated dose for greater than or equal to 4 weeks and were evaluable for response. Two patients developed a partial and one patient a minor response. We conclude that IFN-beta ser is a well tolerated IFN with minimal renal, hepatic, and bone marrow toxicity. It has apparent activity in metastatic renal cell carcinoma.