8ZCA

Crystal structure of human CD47 ECD bound to Fab of Hu1C8

Summary for 8ZCA

• Entry DOI: 10.2210/pdb8zca/pdb
• Descriptor: 1C8 Fab light chain, 1C8 Fab heavy chain, Leukocyte surface antigen CD47, ... (7 entities in total)
• Functional Keywords: cd47, antibody, immune system
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 6
• Total formula weight: 126122.35

Authors

Chen, Z.,Ding, J. (deposition date: 2024-04-29, release date: 2025-05-07, Last modification date: 2025-08-06)

Primary citation

Lu, X.,Chen, Z.,Yi, C.,Ling, Z.,Ye, J.,Chen, K.,Cong, Y.,Sonam, W.,Cheng, S.,Wang, R.,Zhang, D.,Xu, J.,Yang, J.,Ma, L.,Duan, Q.,Sun, X.,Ding, J.,Sun, B.
An anti-CD47 antibody binds to a distinct epitope in a novel metal ion-dependent manner to minimize cross-linking of red blood cells.
J.Biol.Chem., 301:110420-110420, 2025

PubMed Abstract: Cluster of differentiation 47 (CD47) is a widely expressed transmembrane protein that plays a crucial role in immune self-recognition. Cancer cells upregulate CD47 expression to promote immune escape through activating the "don't eat me" signal via interactions with signal regulatory protein α (SIRPα) on macrophages. The effectiveness of anti-CD47 antibodies has been demonstrated in multiple tumour models. However, since CD47 is also expressed in human red blood cells (RBCs) and platelets, the clinical application of anti-CD47 antibodies requires careful consideration of blood toxicity. One major obstacle to the clinical application of CD47 antibodies is the haemagglutination caused by RBCs cross-linking. In this study, we generated Hu1C8, a humanized anti-CD47 monoclonal antibody that demonstrated increased selectivity for binding to CD47 on cancer cells and lacked haemagglutination activity. Epitope mapping and the crystal structure of the Hu1C8 Fab-CD47 extracellular domain (ECD) complex revealed that Hu1C8 binds to a distinct epitope of CD47 in a Ca-dependent manner. The unique recognition and binding mode allowed Hu1C8 to bind CD47 on RBCs with reduced haemagglutination activity while still maintaining effective antitumour activity. These findings demonstrate a feasible strategy for developing CD47 antibodies with high antitumor activity but low RBC haemagglutination activity. Our study elucidates how epitope-specific antibody influences antibody-induced cell cross-linking, offering innovative strategies for antibody design to either leverage or avoid cell cross-linking effects.

PubMed: 40578556
DOI: 10.1016/j.jbc.2025.110420

Experimental method

X-RAY DIFFRACTION (2.5 Å)