Systemic HER3 ligand-mimicking bioparticles cross the blood–brain barrier reducing intracranial triple-negative breast cancer growth

Abstract Triple-negative breast cancer (TNBC) lacks selective biomarkers targeted by current clinical therapies and often metastasizes to the brain. Crossing the blood-brain barrier (BBB) and reaching intracranial tumors is a clinical challenge contributing to poor prognoses for patients. The human epidermal growth factor receptor HER3 has emerged as a biomarker of metastasis and may provide a means of therapeutically targeting TNBC. We have developed HER3-targeted biological particles (bioparticles) that exhibit systemic homing to resistant and metastatic breast tumors. Here we show that HER3 is expressed on the brain endothelium and can mediate the passage of bioparticles across the BBB and into intracranial TNBC. Our findings show that the extravasation of systemic bioparticles in mice and in human induced pluripotent stem cell-based BBB chips corresponds to HER3 levels. Furthermore, systemically delivered bioparticles carrying tumoricidal agents reduced the growth of intracranial TNBC in mice and exhibited improved therapeutic profile compared to current therapies.