Predictive utility of serum cytokine levels in patients with metastatic renal cell carcinoma (MRCC) treated with interferon alfa (IFNa)

14503 Background: IFNa may prolong survival in MRCC patients (pts) due to stimulation of cell-mediated immunity. We hypothesized that IFNa exerts an anti-tumor effect by upregulation of Th1 cytokines and that patients (pts) with elevated serum levels of Th1 cytokines either at baseline (BL) or after treatment with IFNa would have a superior clinical outcome. Methods: Cytokine profiling was performed on 104 pts with MRCC treated in a randomized phase III trial with IFNa 0.5 million units (MU) subcutaneously (SC) twice daily or 5 MU SC daily. Serum samples were collected at BL (n = 104) and after 8 weeks of IFNa therapy (C1) (n = 89). Cytokine concentrations were determined using a 16-plex immunoassay. The linear mixed-effect model was fit to assess the change of cytokine levels from BL to C1. Cox proportional hazards model was fit to evaluate the effect of BL cytokine levels or change of cytokine levels from BL to C1 on the risk of death. Results: Of 16 cytokines evaluated (IL-1b, IL-2, IL-4, IL-5, IL-6, I...