RESUMO
BACKGROUND: High-dose interleukin (IL)-2 is an effective agent for the treatment of metastatic malignant melanoma and renal cell carcinoma. This study evaluated the outcomes of patients receiving two commonly used intravenous IL-2 schedules that have never been directly compared. METHODS: Forty-seven metastatic malignant melanoma and renal cell carcinoma patients were identified from a prospective database who underwent high-dose IL-2 therapy (720,000 or 600,000 IU/kg) during 1999 to 2003. Disease-specific survival (DSS) was calculated by the Kaplan-Meier method with the log-rank test on an intention-to-treat basis. Multivariate Cox regression analysis of prognostic variables associated with outcome was performed. Factors associated with initial response and prevention of disease progression were determined. RESULTS: Objective response (5 partial and 5 mixed) or disease stabilization was noted in 9 (20%) and 10 (22%), respectively, of 46 assessable patients after 1 course of therapy. Four patients (22%) achieved disease-free status after the third course of IL-2 (n = 1) or surgical resection of confined metastatic disease (n = 3). At 19.1 months' median follow-up, factors associated with improved DSS included an initial clinical response to IL-2 therapy (P < .001) and a higher administered dose (P = .04). Patients who received 720,000 IU/kg were more likely to experience an initial major objective response (P = .03) and disease stabilization (P = 0.03) independent of the tumor treated. Objective response early in the course of therapy was the only independent predictor of tumor-related mortality (P = .004). CONCLUSIONS: The initial clinical response to IL-2 therapy is an independent predictor of improved outcome associated with DSS and the 720,000 IU/kg dose. These results support further prospective trials with increased IL-2 dose schedules in a larger cohort of patients.
