Current therapeutics antibodies, such as Trastuzumab and Pertuzumab, have marked significant success in disease treatment, particularly for Her2 positive cancers. However, side effects are sometimes associated with such targeted therapies due to the nature of the antigen binding, e.g. autoimmune diseases or cardiac failure. To address these issues, our work focuses on antibody structural modifications such as manipulating heavy-chain constant region to affect localization. In addition, we also explore both light-chain constant and framework (VL-FWR) manipulation to induce allosteric effects onto the antigen binding regions (i.e. CDRs).
By modulating VL-CDR3 exposure on the scaffold through serendipitous deletions in the VL-FWR3 of a Trastuzumab model, we found selective synergic effects of the mutations on abolishing the Her2 binding. Interestingly, we also found an allosteric effect on the Protein L binding site (impacting purification and superantigen binding) exerted by these distant deletions.
Similarly, in our work on the antibody constant engineering, we found allostery-driven structural changes elicited by substitution mutations in the constant region to also affect antigen binding in both Trastuzumab and Pertuzumab models.
In conclusion, our work studies allosteric effects of various often-neglected regions (constant and framework) of the antibodies in overall antigen recognition. With such knowledge, it may be possible to engineer therapeutic antibodies in their localization as well as antigen binding capabilities for mitigating systemic side effects and for fine-tuning antigen binding.