Anti-CD47 Antibody (InnoBation Bio)

Although Kirsten rat sarcoma virus (KRAS) G12C inhibitors alter the treatment strategy for patients with KRAS G12C-mutant lung cancer, their efficacy remains insufficient to eliminate tumors. Here, we identify that inhibition of mutant KRAS promotes escape from macrophage phagocytosis by upregulating the expression of cluster of differentiation 47 (CD47) and CD24. These proteins are induced by the binding of FOXA1 to the super-enhancer of CD47 and grainyhead-like transcription factor 2 (GRHL2) to the promoter of CD24, respectively. Whereas the addition of an anti-CD47 antibody restores macrophage phagocytosis, phagocytic macrophages induce programmed death-ligand 1 (PD-L1) expression, resulting in the suppression of CD8 T cell activation. Combination of a KRAS inhibitor with anti-CD47 and anti-PD-L1 antibodies achieves long-term survival in an orthotopic murine model recalcitrant to KRAS inhibition with immune checkpoint therapy. These results suggest that targeting KRAS with an anti-CD47 antibody and immune checkpoint blockade is a promising strategy, especially in immune-cold lung tumors.

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 tumor 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 hemagglutination 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 hemagglutination 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 Ca²⁺-dependent manner. The unique recognition and binding mode allowed Hu1C8 to bind CD47 on RBCs with reduced hemagglutination activity while still maintaining effective antitumor activity. These findings demonstrate a feasible strategy for developing CD47 antibodies with high antitumor activity but low RBC hemagglutination 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.