Feasibility of prolonged use of interferon-alpha in metastatic kidney carcinoma: a phase II study

Interferon-alpha has proven effective in the treatment of metastatic renal cell carcinoma. However, the optimal schedule has not yet been determined. The authors have studied the efficacy and toxicity of prolonged use interferon-alpha2a (IFN-alpha) in metastatic renal cell carcinoma (RCC). Interferon-alpha was administered intermittently for outpatients.

Seventy-five patients with metastatic RCC without prior biochemotherapy were treated. During the first month, the IFN-alpha dose was increased from 4.5 to 18 million units (MU) 3 times a week to define the individual maximal tolerated dose for each patient. The treatment was continued at the maximal tolerated dose with a 1-week pause each month until either progression or intolerable toxicity was observed or up to 2 years.

The overall response rate (5 complete response [CRs] and 8 partial responses [PRs]) was 17% (95% confidence interval, 10-28%). Stable disease was observed in 32 patients (43%). Three late objective responses (4%) occurred after 12 months treatment. The median progression free time of all patients was 12.3 months, and median survival time was 19.3 months. The median duration of response in CR/PR patients was 16 months. In multivariate analysis independent prognostic factors were poor performance status (P = 0.004), presence of bone metastases (P = 0.001), and time to metastases less than 24 months (P = 0.003), which predicted poor survival. Six patients (8%) discontinued the treatment because of fatigue, elevation of liver enzymes, or cardiac arrhythmias. No life-threatening side effects were observed.

Prolonged and intermittently administered IFN-alpha2a three times per week in 3 weekly cycles in metastatic RCC is a feasible and effective therapy. A prolonged treatment duration of more than 12 months for stable and responding patients is beneficial and may improve the outcome of patients with RCC.