Anti-CD47 antibody eliminates bone tumors in rats

Bone tumor is a rare heterogeneous malignancy. Osteosarcoma is the most common bone tumor with no apparent underlying pathogenesis, and its peak incidence often occurs during puberty. The intensive application of chemotherapy rarely alters the poor prognosis of the patients in advanced stage. Despite intensive chemotherapy in clinical practice, patients still suffer from the poor prognosis, or even progression of bone tumor. We identified integrin-associated protein (IAP) Cluster of Differentiation 47 (CD47) as a target for monoclonal antibody, and use anti-CD47 antibody to block its expression in bone tumors. CD47 was highly expressed in the bone tumor rats when comparing to the healthy rats. Likewise, Western blotting assay revealed a higher protein expression of CD47 in the bone tumor cells when compared to the normal osteoblasts. Further studies have shown the association between the mRNA expression of CD47 and the disordered bone tumors development and decreased rate of overall survival of diseased rats. In addition, blocking the CD47 monoclonal antibody has been shown to drive macrophages to engulf bone tumor cells in vitro and thus inhibiting tumor metastasis in rats. Taken together, the results of this study suggested that CD47 is a key regulator of bone tumor cell metastasis and that targeting inhibition of anti-CD47 may be a new immunotherapy for bone tumors.