This technology includes a first-in-class synthetic peptide, angubindin-1, designed to temporarily relax the blood-brain barrier (BBB)—the tightly sealed network of brain blood vessel cells that normally blocks most drugs—from the inside. By binding the tricellular tight-junction protein angulin-1/LSR, the peptide creates a reversible “molecular doorway” that lets cancer medicines such as liposomal doxorubicin (Doxil®) reach tumors in the central nervous system (CNS). In rodent models of malignant glioma, co-administration of angubindin-1 increased drug penetration into the brain, cut tumor volume, and significantly prolonged survival compared with chemotherapy alone. The opening of the BBB is short-lived and spatially restricted, minimizing exposure of healthy brain tissue and avoiding the hardware, ultrasound, or high-dose osmotic agents required by competing methods.