Efficient amyloid-β degradation in Alzheimer's disease using SPYTACs.

Clearance of aberrant cerebral amyloid-β (Aβ) deposits represents a promising therapeutic strategy for Alzheimer's disease (AD), yet current anti-Aβ immunotherapy raises safety concerns due to frequent adverse effects. Extracellular targeted protein degradation (eTPD) offers an approach for safe and efficient clearance of disease-causing proteins. Here, we develop a next-generation eTPD platform, synthetic peptide-programmed lysosome-targeting chimeras (SPYTACs), using entirely synthesized bispecific peptides. Leveraging low-density lipoprotein receptor-related protein 1 (LRP1), SPYTACs effectively facilitate targeted degradation of extracellular proteins and enable transcytosis across the blood-brain barrier. In vivo administration of SPYTACs effectively reduces peripheral and cerebral Aβ burden, attenuates synapse loss, and improves cognitive function in 5×FAD mice at both prodromal and symptomatic stages. Notably, SPYTAC treatment shows fewer side effects, including intracerebral hemorrhage and inflammation, compared with conventional immunotherapies. The high modularity and genetic encodability enable SPYTACs to target customized disease-causing proteins, underscoring their therapeutic versatility and translational promise across diverse diseases driven by pathogenic proteins.