xB3-001

**xB3-001** is a fusion protein developed by Bioasis Technologies combining the proprietary xB3 peptide—a 12-amino-acid sequence derived from melanotransferrin—with trastuzumab (Herceptin), a monoclonal antibody targeting HER2. The xB3 platform enables receptor-mediated transcytosis via low-density lipoprotein-related protein 1 (LRP1) to transport the antibody across the blood-brain barrier (BBB), achieving significantly higher brain exposure (up to 4-6% injected dose per gram) compared to trastuzumab alone, while preserving peripheral pharmacokinetics and efficacy. Preclinical studies in HER2+ breast cancer brain metastasis mouse models demonstrated a 68% reduction in tumor number, 46% smaller remaining tumors, and 10-fold higher drug levels in brain regions, with no effect from trastuzumab alone. It retains anti-tumor activity in peripheral models and shows potential for accelerated approval due to addressing unmet need in CNS metastases.[1][2][3][5][7][11]

Other names

xB3-HerceptinxB-3-HerceptinxB 3-HerceptinBT2111BT-2111BT 2111