Harnessing the Power of Antibodies to Fight Bone Metastasis

Abstract

Over the past 20 years, antibody-based therapies have proved to be of great value in cancer treatment. Despite the clinical success of these biopharmaceuticals, reaching targets in the bone micro-environment has proved to be difficult perhaps due to the relatively low vascularization of bone tissue and the presence of physical barriers that impair drug penetration. Here, we have used an innovative bone targeting (BonTarg) technology to generate a first-in-class bone-targeting anti-body. Moreover, we have used two xenograft models to demonstrate the enhanced therapeutic efficacy of this bone-targeting antibody against bone metastases, compared to the efficacy of traditional antibodies. Our strategy involves the use of pClick antibody conjugation technology to chemically couple the bone-targeting moiety bisphosphonate to the human epidermal growth factor receptor 2 (HER2)-specific antibody trastuzumab. Bisphosphonate modification of therapeutic antibodies results in delivery of higher conjugate concentrations to the bone metastatic niche, relative to other tissues. In both HER2-positive and negative xenograft mice models, this strategy provides enhanced inhibition of experimental bone metastases as well as multi-organ secondary metastases that arise from the bone lesions. Specific delivery of therapeutic antibodies to the bone therefore represents a promising strategy for the treatment of bone metastatic cancers and other bone diseases.