Phase II study of alpha interferon on renal cell carcinoma. Summary of three collaborative trials.

A cooperative study was carried out in 44 institutions in Japan to evaluate the clinical efficacy of two kinds of recombinant human leukocyte interferon (Ro 22-8181 and Sch 30500) and a human lymphoblastoid interferon (MOR-22) on metastatic lesions of renal cell carcinoma. Of 226 evaluable cases, efficacy was observed in 40 cases; complete response (CR) in 4 cases, and partial response (PR) in 36 cases, indicating an overall response rate of 17.7%. Although there were no statistically significant differences in age range, sex distribution, and performance status between responders and nonresponders, the incidence of poor response was significantly higher among patients in whom primary renal cell carcinoma had remained or in those who had prior chemotherapy and/or radiation therapy. When response was assessed with regard to individual metastatic sites of renal cell carcinoma, pulmonary metastasis was significantly susceptible to interferon treatment, compared to other metastatic sites. The median period to achieve CR or PR was 45 days (range, 22-211 days) and the median length to maintain CR or PR was 79 days (range, 29-278 days). The median of pulmonary metastatic area that was measured by the sum of the products of the largest perpendicular diameters was 7.2 cm2 (0.5-107.8 cm2), which was reduced to 1.1 cm2 (0-48.8 cm2) by alpha interferons. Cumulative survival of all responder patients was significantly longer than that of other patients with poor response.