Adjuvant Low-Dose Interleukin-2 (IL-2) Plus Interferon-α (IFN-α) in Operable Renal Cell Carcinoma (RCC): A Phase III, Randomized, Multicentre Trial of the Italian Oncology Group for Clinical Research (GOIRC)

There is currently no standard therapy to reduce the recurrence rate after surgery for renal cell carcinoma (RCC). The aim of this study was to assess efficacy and safety of adjuvant treatment with low doses of interleukin-2 (IL-2) + interferon-alpha (IFN-alpha) in operable RCC. The patients were randomized 1:1 to receive a 4-week cycle of low-dose IL-2 + IFN-alpha or observation after primary surgery for RCC. Treatment cycles were repeated every 4 months for the first 2 years and every 6 months for the subsequent 3 years. The primary endpoint was recurrence-free survival (RFS); safety; and overall survival (OS) were secondary endpoints. ClinicalTrials.gov registration number was NCT00502034. 303/310 randomized patients (156 in the immunotherapy arm and 154 in the observation group) were evaluable at the intention-to-treat analyses. The 2 arms were well balanced. At a median follow-up of 52 months (range, 12-151 mo), RFS, and OS were similar, with an estimated hazard ratio (HR) of 0.84 [95% confidence interval (CI), 0.54-1.31; P = 0.44] and of 1.07(95% CI, 0.64-1.79; P = 0.79), respectively in the 2 groups. Unplanned, subgroup analysis showed a positive effect of the treatment for patients with age 60 years and younger, pN0, tumor grades 1-2, and pT3a stage. Among patients with the combined presence of >= 2 of these factors, immunotherapy had a positive effect on RFS (HR = 0.44; 95% CI, 0.24-0.82; P <= 0.01), whereas patients with <2 factors in the treatment arm exhibited a significant poorer OS (HR = 2.27; 95% CI, 1.03-5.03 P = 0.037). Toxicity of, immunotherapy was mild and limited to World Health Organization grade 1-2 in most cases. Adjuvant immunotherapy with IL-2 + IFN-alpha showed no RFS or OS improvement in RCC patients who underwent radical surgery. The results of subset analysis here presented are only hypothesis generating.