Suppression of Extracellular Vesicle CD47 Induces Systemic Anti-DLBCL Immunity

• Published in: Blood 2021-11, Vol.138 (Supplement 1), p.716-716
• Main Authors: Zhuang, Wenzhuo, Li, Bingzong
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2021-152451

Purpose: Tumor cells evade the immune surveillance by up-regulating surface expression of CD47, which interacts with SIRPa on macrophages to elicit the immune checkpoint response. Anti-CD47 antibody (IBI188) has shown promise in treating tumors, including Diffuse large B cell lymphoma (DLBCL). The objective response rate among DLBCL was 73% (ClinicalTrials.gov number, NCT02953509.). The basis of differential therapeutic success between patients remains unknown. Extracellular vesicles (EVs) carry bioactive molecules that influence the immune system. CD47 has be found on surface of EVs. The purpose of this study is to explore whether EV CD47 contributes to immunosuppression and is associated with anti-CD47 response in DLBCL. Methods:  1.Kaplan-Meier curves and Cox regression models were used to analyze PFS and OS. The area under the ROC curve (AUC) was used to assess the predicted validity of the National Comprehensive Cancer Network-International Prognostic Index (NCCN-IPI) model and the NCCN-IPI+ CD47 model.2.Immunofluorescence experiment was used to detect the infiltration of M1 and M2 subtype macrophages in DLBCL tumor tissue. M1 and M2 macrophages were generated from peripheral blood mononuclear cells obtained from healthy donors. Immunoelectron microscopy, flow cytometry and western blot were performed to detect CD47 on the surface of the EVs derived from DLBCL cells. The activity of macrophage phagocytosis of DLBCL cells was detected by confocal-based phagocytosis assay and flow cytometry-based phagocytosis assay.3.In DLBCL xenografts, the IBI188 antibody was a macrophage immune checkpoint inhibitor blocking CD47 that induces tumor-cell phagocytosis.4.Peripheral blood mononuclear cells from DLBCL patients and healthy donors was collected for EVs purification and subsequent detection of human CD47 proteins by ELISA. Results  1.The elevated expression of CD47 in DLBCL is significantly correlated with poor PFS and OS in a univariate analysis, and is statistically significant after adjusting for the NCCN-IPI in the univariate and multivariate analysis (Figure 1A, B). AUC analysis with cross-validation showed that the combination of the CD47 signature and NCCN-IPI had a better prediction of PFS and OS than without the CD47 signature (Figure 1C). Thus, CD47 in DLBCL can be used as a biomarker of prognosis and developed the prognostic stratification of DLBCL patients.2.EV CD47 derived from DLBCL cells has the same membrane topology as the cell surface CD47,