Abstract P60: CD47 in Osteosarcoma: Correlation with Metastasis and Macrophage-Mediated Phagocytosis

CD47 is expressed on cell surfaces and act as “don’t eat me” signal by interacting with SIRPα of the macrophage surface. In certain types of cancer, cancer cells express CD47 protein and are presumed to evade macrophage phagocytosis. In this study, we evaluated the feasibility of targeting CD47 for osteosarcoma by analyzing its expression patterns, clinicopathological correlations, and immunotherapeutic potential. We performed a retrospective analysis on 24 biopsy samples from osteosarcoma patients to investigate correlations between CD47 protein positivity and clinicopathologic characteristics. CD47 protein expression was identified in 20.8% of the biopsy samples, with a correlation between CD47 positivity and metastasis at diagnosis (P=0.04). Patients with CD47-positive tumors tended to be older than those with CD47-negative tumors (P=0.07). However, no association was found between CD47 protein expression and sex, tumor size, or histologic response to preoperative chemotherapy. In vitro, CD47 antibody (B6H12) did not significantly affect osteosarcoma cell proliferation or apoptosis. In a wound-healing assay, CD47 antibody (B6H12) inhibited the migration of osteosarcoma cells. Furthermore, differentiated macrophages exhibited significantly higher phagocytic activity against osteosarcoma cells when pretreated with CD47 antibodies (B6H12), compared to isotype control (P<0.01). Taken together, our preliminary data suggest a possible interaction between CD47 protein and macrophage phagocytosis in metastasis of osteosarcoma. Further studies are necessary for a better understanding the role of CD47 in osteosarcoma and an innovative immunotherapy approach against this formidable malignancy. Citation Format: Yunmi Ko, Heejung Na, Jun Ah Lee. CD47 in Osteosarcoma: Correlation with Metastasis and Macrophage-Mediated Phagocytosis [abstract]. In: Proceedings of Frontiers in Cancer Science 2024; 2024 Nov 13-15; Singapore. Philadelphia (PA): AACR; Cancer Res 2025;85(15_Suppl):Abstract nr P60.