Phase II trial of pegylated interferon-alpha 2b in patients with advanced renal cell carcinoma.

Pegylated interferon (IFN) has a longer serum half-life compared with standard IFN, and this allows for weekly dosing. In this study, the efficacy and toxicity of pegylated IFN was assessed in patients with metastatic renal cell carcinoma (mRCC).Thirty-two patients with previously untreated mRCC were treated with pegylated IFN-alpha 2b in a prospective, single-arm phase II trial. Pegylated IFN was given by subcutaneous administration on a weekly schedule at a dose of 4.5 microg/kg.Of the 32 assessable patients, 29 (91%) had a nephrectomy previously, and none had been treated previously with systemic therapy. Forty-one percent had good-risk, 53% had intermediate-risk, and 6% had poor-risk features per Memorial Sloan-Kettering Cancer Center risk criteria. The best response was a complete response (CR) in 1 patient (3%). Nine patients (28%) had a partial response. Fifteen patients (47%) had stable disease. The median progression-free survival (PFS) was 5 months (95% CI, 3-7 months), and median overall survival was 31 months (95% CI, 18 months to not reached). Five patients had a prolonged PFS of > or = 17 months, 1 of whom achieved a CR. There were no grade 4 toxicities; primary grade 3 toxicities were hematologic (11 of 32 patients; 34%) and fatigue (4 of 32 patients; 13%).Pegylated IFN administered weekly has antitumor activity in patients with mRCC with predominantly good- and intermediate-risk features. This study suggests comparable efficacy and safety compared with standard IFN-alpha.