Fine Tuning Antibody Conjugation Methods using SNAP-tag Technology

Background Targeted imaging and therapy (theranostics) is a promising approach for the simultaneous improvement of cancer diagnosis, prognosis and management. Therapeutic and imaging reagents are coupled to tumor-targeting molecules such as antibodies, providing a basis for truly personalized medicine. However, the development of antibody-drug conjugates with acceptable pharmaceutical properties is a complex process and several parameters must be optimized, such as the controlled conjugation method and the drug-to-antibody ratio. Objective The major aim of this work is to address fundamental key challenges for the development of versatile technology platform for generating homogenous immunotheranostic reagent. Method We conjugated the theranostics reagent IRDye700dx to a recombinant antibody fusion protein containing a self-labeling protein (SNAP-tag) which provides a unique reaction site. Results The resulting conjugate was suitable for the imaging of cancer cells expressing the epidermal growth factor receptor and demonstrated potent phototherapeutic and imaging activities against them. Conclusion Here, we describe a simple, rapid and robust site-directed labeling method that can be used to generate homogeneous immunoconjugate with defined pharmacological properties.