Treatment Outcome of Low-dose Interleukin-2 Therapy in Patients with Metastatic Renal Cell Carcinoma

Renal cell carcinoma (RCC) is one of the most fatal urological malignancies. Approximately 30% of patients with RCC have metastasis at initial diagnosis and another 30% have metastasis after radical nephrectomy. Immunotherapy using interferon-α (IFN-α) and interleukin-2 (IL-2) has been the main treatment for metastatic RCC (mRCC) patients, with this therapy being still occasionally recommended. The aims of this study were to evaluate the efficacy of low-dose IL-2 and to investigate the prognosis of the patients. Study subjects included 37 patients who were clinically diagnosed with mRCC and received low-dose IL-2 therapy between December 1999 and October 2014. We investigated the relationship between prognosis and clinical features. The median overall survival (OS), that was calculated from the first use of cytokine therapy, was 19.8 months, while the median progression-free survival (PFS) was 3.82 months. PFS was prolonged in patients who received IL-2 as first-line therapy or second-line therapy following IFN-α therapy. IL-2 therapy should be used as a first- or second-line therapy following IFN-α therapy. IL-2 may have a lower response if it is used after molecular-targeted therapy or other treatments.