A Four-Part Peptide Vehicle That Delivers Therapeutic Proteins Inside Cells — and Treats Liver Failure in Mice

The researchers designed and synthesized a four-module chimeric peptide, tested protein delivery efficiency in cell culture (in vitro), and validated therapeutic efficacy in two mouse models: TNF-α-induced systemic inflammatory response and acetaminophen-induced acute liver failure. The therapeutic protein PTP1B was fused to the chimeric peptide and delivered via intravenous injection.

Many promising drug targets sit inside cells, but getting large protein drugs through cell membranes and out of endosomal traps has been a major barrier. This modular peptide system demonstrates that combining multiple functional peptide elements can overcome both challenges simultaneously, opening the door to a new class of protein-based drugs that work against intracellular targets.

Published in Nature Communications, this work addresses one of the fundamental bottlenecks in biologics development: intracellular delivery. Most antibody and protein drugs can only hit targets on cell surfaces or in the bloodstream. A reliable system for delivering proteins to intracellular targets could unlock therapies for diseases driven by signaling pathways inside cells — including many cancers, inflammatory conditions, and metabolic disorders.

This is a mouse study — efficacy and safety in humans are unknown. The specific therapeutic protein used (PTP1B) may behave differently than other cargo proteins. Manufacturing complexity of a four-module chimeric construct could pose challenges for clinical development. Long-term effects and immunogenicity were not assessed.