Abstract Targeted degradation of extracellular proteins via endo-lysosomal pathways constitutes a promising therapeutic strategy by enabling irreversible target removal and potentially reducing systemic effects of antigen accumulation. In this study, we present a systematic approach for the design and evaluation of Biological Degraders (BioDegs) that leverage receptor-mediated uptake through triantennary N-acetylgalactosamine (TGN) induced activation of the asialoglycoprotein receptor (ASGPR). While this principle has been established, there is still a lack about molecular determinants that influence uptake efficiency. Using interleukin-6 (IL-6) and its soluble receptor (sIL-6R) as therapeutically relevant model antigens, we systematically compared a range of BioDeg formats, including full-length antibodies (siltuximab, tocilizumab), a VHH against IL-6, and an IL-6 binding decoy-receptor design, with respect to binding affinity, thermal stability, cellular uptake, lysosomal trafficking, and degradation efficiency in HepG2 cells. Our results demonstrate that combined properties of scaffold architecture and receptor engagement critically influence degradation outcomes. This work provides a comparative framework for BioDeg design and highlights key parameters for developing lysosome-targeting degraders for extracellular proteins.
Seifert et al. (Sat,) studied this question.