Isolation of specific single chain antibodies against three immunodominant epitops of HER-2 antigen for immunotherapy of breast cancer

Introduction: Breast cancer is the most common cancer among women. Overexpression of human epidermal growth factor receptor 2 (HER2), a cell membrane receptor tyrosine kinase, in breast cancer is often associated with advanced disease and poor prognosis. Recombinant single-chain antibodies (scFvs) which are composed of VH and VL domains, have been introduced as effective alternatives to full-length antibodies in cancer-targeted therapy. In this study we selected specific scFvs against immunodominant epitopes of HER-2 and evaluated the reactivity of the selected scFvs with the corresponding epitopes. Methods: A phage antibody display library of scFv was used for selection of specific scFvs against three HER2 epitopes using panning process. PCR and DNA fingerprinting were applied to show the common patterns and isolation specific clones. The specificity of the clones were tested with ELISA. Results: Four specific clones were selected against three epitopes of HER2 with the frequencies 25%, 45%. 25% and 25%. The ELISA test demonstrated that the selected scFvs reacted with the corresponding epitopes significantly higher than the negative controls. Conclusion: Immunotherapy is a new strategy against different cancers. The human anti-mouse antibody response (HAMA) has reduced the efficacy of the monoclonal Abs. Due to scFvs properties including human origin, high specificity and affinity, these antibodies are useful agents for cancer immunotherapy. In this study four specific scFVs were selected against HER2 antigen. The specificity of the selected scFvs was shown in ELISA. This study suggests further investigation of the selected scFvs for their clinical use.

Keywords:

ScFv , HER2 , Immunotherapy