Abstract Text: Tailoring of IgG antibodies for specific and improved effector functions is crucial to secure optimal targeted treatment of diseases. We recently reported on an IgG Fc-engineering approach, the REW Fc technology, which is based three amino acids substitutions in the Fc that improves the pharmacokinetic properties of IgG antibodies due to enhanced pH dependent binding to the human form of the neonatal Fc receptor (FcRn). However, this technology also enhances the ability to recruit and activate the complement system via a mechanism that is postulated to be via increased Fc-Fc clustering upon antigen binding. Naturally, we have four human IgG subclasses with very distinct ability to engage different effector molecules, such as the complement system. As such, which IgG subclass to be used as a scaffold to build a therapeutic will depend on the need for which effector function that should be activated to secure efficient therapy while at the same time consider the potential for induction of severe side effects. Thus, in this project we aim to gain an in-depth understanding of how the REW Fc technology is behaving in the context of the four IgG subclasses, designed with specificity for the hapten DNP (dinitrophenol), by bridging biochemical assays with cryogenic electron microscopy (cryo-EM) studies where both Fc-Fc clustering and the ability to engage the complement system will be addressed. A detailed structural understanding will guide further engineering strategies with the purpose to develop IgG antibodies with fine-tunned complement activation capacity.
