Over the past year our team has been actively investigating the immunotherapeutic potential of the antibody-cytokine fusion proteins. These molecules contain the antibody portion recognizing the tumor associated antigens, and is covalently linked to a potent immune stimulator. HuKS-1L2 fusion protein which is highly reactive with breast cancer cells became available to us for in vitro and in animal in vivo studies. We are still actively pursuing experiments to elucidate the mechanisms of targeting tumor cells for destruction and mechanisms of stimulation immune effector cells by this molecule, to ultimately translate these findings to clinical application. At this time similar fusion protein (hul4.l8-1L2) became available for clinical testing and we decided to refocus our efforts in this direction. At the UW-CCC we are currently performing an initial Phase I clinical trial involving an administration of this novel immunocytokine to the patients with GD-2 positive tumors, delivered as a single agent therapy. We are collecting serum specimens as well as cells from these patients. Studies are underway to assess the effects of this treatment, its safety and future applications. Findings from these studies will provide a baseline for clinical testing of other immunocytokines targeting human cancers.