Interferon therapy for renal cell carcinoma.

Recurrent or metastatic renal cell carcinoma (RCC) seldom and only briefly responds to hormonal therapy or chemotherapy, with little, if any, impact on overall survival; hence the prognosis is poor. Effects of both partially purified and recombinant interferons have been studied and have yielded response rates of 5% to 27%. In a review of 12 series, the complete and partial response rate was 16% (100 of 632 patients) with a 95% confidence interval of 13% to 19%. Response rates were similar for both partially purified and recombinant interferons. Although no dose-response effect has been clearly demonstrated, daily doses (5 to 10 megaunits) of interferon seem to be associated with the highest therapeutic index. Patient characteristics that suggest potential responsiveness to interferon include minimal or no prior therapy, good performance status, and pulmonary metastases. Although some investigators believe that patients with nephrectomy are more likely to be responsive, a careful review of published literature does not support this. Laboratory observations demonstrating synergistic activity of interferons combined with a variety of chemotherapeutic agents have led to clinical trials for exploring the potential of such treatment. Initial results of combining interferon and vinblastine are encouraging; further studies are under way. Substantial evidence now indicates that interferon is an effective agent in metastatic RCC.