In-vitro assays to assess in-silico predictions!
Have you ever heard of Muromomab (anti-CD3)? It is a monoclonal antibody directed against the CD3 receptor, which is a membrane protein found on the surface of T cells. Muromomab is used as an immunosuppressant and serves to reduce acute rejection in transplanted patients. The first monoclonal antibody (mAb) was released on the market in 1986, it opened the era of biotherapeutics and biosimilars. More than 30 years later, 70 mAbs are currently on the market and over 500 are in clinical development. This represents a great success for pharmaceutical research and new possibilities for treating many diseases.
In the realm of chemical compounds, the main features that determine the future of compounds as potent drugs are synthesis, solubility, metabolism, and bio availability. The development of monoclonal antibodies conveys other challenges. mAbs are larger molecules, composed of hundreds of amino acids with specific conformation. Their synthesis using bioengineering techniques, as well as their tedious screening, stability, and ability to recognize specific epitopes in-vivo, present new challenges for researchers.
In this article, Thomas Bourquard introduces a new method for the epitope mapping needed for generating mAbs. MAbTope takes an in-silico approach, using docking-based prediction methods from 3D antibody and antigen structures, combined with a set of experimental assays to validate results. He tested two therapeutic mAbs targeting TNFα (certolizumab and golimumab) as case studies for validation. The epitope recognition motifs were assessed by site-directed mutagenesis. Interaction of certolizumab and golimumab with their respective antigen epitopes was confirmed by competition assays and in-vitro TR-FRET binding measurements.
MAbTope appears to be a very robust and promising method to identify epitopes for mAbs, fully integrating in-silico and predictive approaches combined with real-data in-vitro assays.
Consider this for your next biotherapeutic programs!
Abs are very efficient drugs, ∼70 of them are already approved for medical use, over 500 are in clinical development, and many more are in preclinical development. One important step in the characterization and protection of a therapeutic Ab is the determination of its cognate epitope. The gold standard is the three-dimensional structure of the Ab/Ag complex by crystallography or nuclear magnetic resonance spectroscopy. However, it remains a tedious task, and its outcome is uncertain. We have developed MAbTope, a docking-based prediction method of the epitope associated with straightforward experimental validation procedures. We show that MAbTope predicts the correct epitope for each of 129 tested examples of Ab/Ag complexes of known structure. We further validated this method through the successful determination, and experimental validation (using human embryonic kidney cells 293), of the epitopes recognized by two therapeutic Abs targeting TNF-α: certolizumab and golimumab.
Journal of Immunology. 2018 Nov 15;201(10):3096-3105.