Advances in preclinical and clinical development have demonstrated that monoclonal antibodies and immuno-activating cytokines have a beneficial role in certain clinical oncology settings. Genetic engineering has now been used to create 'immunocytokines (ICs)'. These are fusion proteins that consist of an immune-activating cytokine linked to a tumor-reactive monoclonal antibody. Preclinical data demonstrate that ICs are far more effective in murine tumor models than the separate molecules from which they are derived. Clinical testing of ICs has recently begun using an anti-GD2 monoclonal antibody linked to interleukin-2 (IL-2) (hu14.18-IL-2), and using an antibody directed against the human epithelial cell adhesion molecule linked to IL-2 (KS-IL-2).