An Engineered IGF2 Mutant for Lysosomal Targeting Chimeras Development and Membrane Proteins Degradation

Lysosome-targeting chimeras (LYTACs) have emerged as a promising strategy for targeted degradation of membrane proteins, offering potential applications in drug development. Currently, two main methods for developing LYTACs exist: chemically modified antibodies [1-2] and wild-type insulin-like growth factor 2 (IGF2) fusion proteins (iLYTACs) [3]. However, the fusion of the IGF2 arm within iLYTACs carries the risk of activating IGF1R tyrosine kinase activity and promoting tumor development. To address this concern, we introduce eiLYTACs, a technology that employs engineered IGF2 fusion antibodies to induce degradation of endogenous membrane proteins. Compared to the wild-type IGF2, the engineered IGF2 mutant exhibited minimal binding affinity for IGF1R but demonstrated a significant 100-fold increase in its binding affinity for IGF2R. In contrast to wild-type IGF2, which promotes tumor growth, the cells incubated with the engineered IGF2 showed no stimulation of tumor growth. The eiLYTACs strategy effectively inhibits tumor cell proliferation by degrading specific targets, resulting in a significant reduction in xenograft tumor size in experimental nude mice. More interestingly, our research revealed that eiLYTACs simultaneously degrade both homo- and heterodimers of disease-relevant proteins,which offer a promising strategy to address the activation of compensatory bypass signaling pathways, drug resistance, and tumor heterogeneity.