Antibody-IL2 Fusion Protein Delivery by Gene Transfer

摘要

The immunotherapeutic potential of the antibody-cytokine fusion proteins has been investigated as an alternative means of the therapy for refractory breast cancer. These novel molecules contain the antibody portion recognizing the tumor associated antigen and is covalently linked to a potent immune stimulator. Experiments were performed to elucidate the mechanisms of targeting tumor cells for destruction and mechanisms of stimulation immune effector cells by these molecules, to ultimately translate these findings to clinical application. Initially new delivery approach of fusion protein was studied, based on particle-mediated gene transfer (PMGT), and most effective expression vectors were developed. Animal model for tumor immunotherapy was established, using cancer cell lines engrafted to syngeneic animals. After gene delivery detectable expression of fusion protein was achieved. Despite of lack of therapeutic effect of this approach in animal model, substantial progress has been made in studies with fusion protein used as a protein reagent. In vitro was demonstrated that fusion protein can specifically bind to cancer cells and deliver IL-2 to their surface. It can activate IL-2 responsive cells and induce tumor specific ADCC. Sensitive assays for detection of fusion protein and its components in animal and patients serum were developed. It was shown that after administration this molecule is stable for several hours in animal and human serum (confirmed also on clinical samples from separate trial of similar fusion protein of different specificity), retains its functional activity and induces immune activation. These findings will provide a model for bringing novel immunocytokines to the clinic to improve effectiveness of human cancer treatment.