Prospective randomized trial of natural interferon-alpha versus natural interferon-alpha plus cimetidine in advanced renal cell carcinoma with pulmonary metastasis

Purpose: In a preliminary non-randomized study, combination therapy with natural (i.e. non-recombinant) interferon-alpha plus cimetidine obtained a high response rate in patients with advanced renal cell carcinoma. We conducted a prospective randomized phase III trial to determine whether combination therapy with natural interferon-alpha plus cimetidine is superior to natural interferon-alpha alone in patients with advanced renal cell carcinoma with pulmonary metastasis. Methods: Patients received 5 million units (MU) natural interferon-alpha per day, five times a week, or the 5 MU natural interferon-alpha regimen plus a daily oral cimetidine. The primary and secondary end points were the response rate, and the time to progression (TTP), respectively. Results: Between April 1998 and March 2002, 71 patients from 32 institutions were randomly assigned to the 2 treatment groups. One patient in each group did not receive any natural interferon-alpha whatsoever. Two patients in the natural interferon-alpha alone group stopped treatment: on day 9 and on day 10, respectively. In the intent-to-treat analysis, 1 complete response (CR), 4 partial responses (PRs), 16 no changes (NCs), and 12 progressive diseases (PDs) were observed among the 36 patients in the interferon-alpha alone group with a response rate of 13.9%. Of the 35 patients in the natural interferon-alpha plus cimetidine group, there were two CRs, 8 PRs, 13 NCs, and 11 PDs, yielding a response rate of 28.6% (P=0.13). TTP ranged from 9 to 845 days (median 112 days) in the natural interferon-alpha-alone group, and from 31 to 1,568 days (median 125 days) in the natural interferon-alpha plus cimetidine group (P=0.87). Conclusions: Combined treatment with natural interferon-alpha plus cimetidine for advanced renal cell carcinoma did not result in a significant improvement in response rates or TTP compared to natural interferon-alpha therapy alone.