Alpha and gamma interferon in the treatment of advanced renal cell carcinoma.

Thirty-two patients with proven progressive metastatic renal cell carcinoma were treated with the combination of 0.1 mg/m2 (2 X 10(6) IU/m2) r-interferon (r-IFN)-gamma and 6 micrograms/m2 (2 X 10(6) IU/m2) r-IFN-alpha. In case of progressive disease (PD) or stable disease (SD), after 8 weeks, the dose of r-IFN-alpha was escalated by 6 micrograms/m2 every 2 weeks until the maximum tolerable dose was reached, while r-IFN-gamma was maintained at the low dose. The rationale for this study is provided by the dose-related efficacy of IFN-alpha as a monotherapy, the potent immunostimulatory activity of IFN-gamma, and the alleged synergistic effect of the combination. Fourteen patients are evaluable for 8 weeks of low-dose combination treatment (7 X SD, 5 X PD, 2 X early progression), while so far 6 of 24 patients (25%) who started dose escalation of IFN-alpha have reached a partial response. These data indicate better efficacy with higher doses of IFN-alpha. Because of the infrequent administration and the relative low doses, compared to other trials, the treatment regimen was well tolerated. Although preliminary results are promising, definite efficacy remains to be proven.