Clinical outcome of combined immunotherapy with interferon-α and low-dose interleukine-2 for Japanese patients with metastatic renal cell carcinoma

The objective of this study was to retrospectively investigate clinical outcomes of combined immunotherapy with interferon-α (IFN-α) and low-dose interleukin-2 (IL-2) in Japanese patients with metastatic renal cell carcinoma (RCC). This study included a total of 52 patients with metastatic RCC who were treated by combined immunotherapy with IFN-α and low-dose IL-2 following radical nephrectomy. These patients received a subcutaneous injection of IFN-α (5 to 6 million U/d) three times per week and intravenous injection of IL-2 (1.4 million U/d) twice per week. Tumor response was evaluated every 16 weeks, and as a rule, this weekly regimen was repeated 50 times in patients with evidence of objective response or stable disease. In this series, complete response and partial response were achieved in 1 and 11 patients, respectively; however, the remaining 20 and 20 patients were diagnosed as showing stable disease and progressive disease, respectively. Of several parameters examined, presence of metastases at diagnosis and C-reactive protein (CRP) level were significantly associated with response to this combined therapy. The 1-, 3-, and 5-year cancer-specific survival rates of these 52 patients were 80.4%, 51.7%, and 38.8%, respectively. Furthermore, cancer-specific survival was significantly associated with performance status, presence of metastases at diagnosis, metastatic organ and CRP level on univariate analysis; however, only performance status and presence of metastases at diagnosis appeared to be independent predictors of cancer-specific death by multivariate analysis. Toxicities related to this therapy were generally mild and tolerable, limited to World Health Organization (WHO) grade 1 or 2 in the majority of patients. Collectively, these findings suggest that combined immunotherapy with IFN-α and low-dose IL-2 could achieve comparatively acceptable oncological outcomes in patients with metastatic RCC; however, other therapeutic options should be considered in patients with unfavorable performance status and/or those positive for metastatic diseases at diagnosis.