Combined treatment with low-dose interferon plus vinblastine is associated with less toxicity than conventional interferon monotherapy in patients with metastatic renal cell carcinoma.

The outcome of treatment of advanced renal cell carcinoma is disappointing. In interferon (IFN)-treated patients, the high incidence of adverse effects causes many patients to withdraw from treatment. This 12-week randomized study compared the incidence of toxicity associated with high-dose IFN monotherapy (15 x 10(6) U thrice weekly) and treatment with the combination of low-dose IFN (5 x 10(6) U thrice weekly) and 6 mg/m2 vinblastine (VBL) every 14 days in 100 consecutive patients. There was no significant difference in response rate between treatment arms (42% IFN vs. 34% IFN + VBL) or between subgroups (by tumor location). Combined treatment was associated with a significantly lower incidence of fever, fatigue, and weight loss but with a higher incidence of leukopenia. There was no significant difference in the incidence of other events. More patients treated with IFN monotherapy required bed rest, and overall treatment costs were 60% higher than for combined treatment. It is concluded that combined treatment with low-dose IFN and VBL, without loss of short-term efficacy, is better tolerated and less expensive than high-dose IFN monotherapy.