pH-Responsive Polyethylene Glycol Engagers for Enhanced Brain Delivery of PEGylated Nanomedicine to Treat Glioblastoma.

The blood-brain barrier (BBB) remains a major obstacle for effective delivery of therapeutics to treat central nervous system (CNS) disorders. Although transferrin receptor (TfR)-mediated transcytosis is widely employed for brain drug delivery, the inefficient release of therapeutic payload hinders their efficacy from crossing the BBB. Here, we developed a pH-responsive anti-polyethylene glycol (PEG) × anti-TfR bispecific antibody (pH-PEG engager) that can complex with PEGylated nanomedicine at physiological pH to trigger TfR-mediated transcytosis in the brain microvascular endothelial cells, while rapidly dissociating from PEGylated nanomedicine at acidic endosomes for efficient release of PEGylated nanomedicine to cross the BBB. The pH-PEG engager significantly increased the accumulation of PEGylated nanomedicine in the mouse brain compared to wild-type PEG engager (WT-PEG engager). pH-PEG engager-decorated PEGylated liposomal doxorubicin exhibited an enhanced antitumor effect and extended survival in a human glioblastoma (GBM) orthotopic xenograft mice model. Conditional release of PEGylated nanomedicine during BBB-related receptor-mediated transcytosis by pH-PEG engager is promising for enhanced brain drug delivery to treat CNS disorders.