Selective protein degradation platforms have afforded new development opportunities for therapeutics and tools for biological inquiry. The first lysosome targeting chimeras (LYTACs) targeted extracellular and membrane proteins for degradation by bridging a target protein to an endogenous lysosome targeting receptor, the cation-independent mannose-6-phosphate receptor (CI-M6PR). Here we developed LYTACs that engage the asialoglycoprotein receptor (ASGPR), a liver-specific lysosomal targeting receptor, to degrade membrane proteins in a tissue-specific manner. We conjugated antibody-based binders targeting cell-surface proteins to a tri-GalNAc motif that engages ASGPR. The resulting LYTACs directed lysosome trafficking of the bound targets and subsequent degradation. Degradation mediated by an EGFR-targeted GalNAc-LYTAC resulted in significant functional effects on the downstream kinase signaling of EGFR compared to canonical inhibition with a monoclonal antibody. Furthermore, we demonstrated that a small target binder, a 3.4 kDa peptide, can be linked to a single tri-GalNAc ligand to degrade integrins and significantly reduce cell proliferation. Site-specific chemical conjugation of one or two tri-GalNAc ligands to antibody scaffolds improved the pharmacokinetic profile of GalNAc-LYTACs in vivo compared to non-specific chemical conjugation. GalNAc-LYTACs represent an exciting new paradigm for cell-type restricted degradation of proteins.

选择性蛋白质降解平台为生物学上的治疗方法和工具提供了新的开发机会。第一个溶酶体靶向嵌合体（LYTAC）通过将靶蛋白桥接到内源性溶酶体靶向受体，非阳离子依赖的甘露糖6磷酸受体（CI-M6PR），将细胞外和膜蛋白靶向降解。在这里，我们开发了LYTAC，该LYTAC与去唾液酸糖蛋白受体（ASGPR）（一种肝脏特异性溶酶体靶向受体）结合，以组织特异性方式降解膜蛋白。我们将针对细胞表面蛋白的基于抗体的结合剂缀合到参与ASGPR的tri-GalNAc基序。所得的LYTAC指导溶酶体运输结合的靶标并随后降解。与使用单克隆抗体的规范抑制相比，由EGFR靶向的GalNAc-LYTAC介导的降解导致对EGFR下游激酶信号传导的显着功能作用。此外，我们证明了一个小的目标结合剂，一个3.4 kDa的肽，可以与单个tri-GalNAc配体相连，以降解整联蛋白并显着降低细胞增殖。一种或两种tri-GalNAc配体与抗体支架的位点特异性化学偶联改善了GalNAc-LYTAC的药代动力学体内相比非特异性化学偶联。GalNAc-LYTAC代表了一种激动人心的新范例，适用于蛋白质的细胞类型限制性降解。