Engineering of single domain antibody-based Bispecifics

Britta Lipinski

Merck KGaA, Darmstadt

Bispecific antibodies offer a targeted approach for cancer treatments by simultaneously engaging two different antigens. The ability to recruit and conditionally activate a targeted immune cell population enhances specificity and efficacy while minimising off-target effects in the absence of the tumour-associated antigen. The use of camelid-derived single-domain antibodies (VHHs) offer several advantages, such as their small size and high stability, but more importantly, in the context of complex multi-specific antibodies, they allow the possibility of multiple ‘plug-and-play’ reformatting options and easy combination with Fab-based paratopes, as they do not require an additional light chain. The main master thesis project focuses on the generation of potent NKCE (natural killer cell engagers) formats that bridge NKp46 on NK cells with EGFR on tumor cells to redirect NK cell cytotoxicity against EGFR-positive tumor cells (Lipinski et al 2023, NKp46-specific single domain antibodies enable facile engineering of various potent NK cell engager formats). In an additional project, single domain antibodies were used as surrogate agonists to mimic the cytokine functionality of IL-18 (Lipinski et al 2023, Generation and engineering of potent single domain antibody-based bispecific IL-18 mimetics resistant to IL-18BP decoy receptor inhibition.). For both projects the impact of valencies and the spatial orientation of individual paratopes within the overall design architecture were further explored by antibody engineering to augment the desired functionality.

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