CD47-blocking Antibody ZL-1201 Promotes Tumor-associated Macrophage Phagocytic Activity and Enhances the Efficacy of the Therapeutic Antibodies and Chemotherapy

Tumor-associated macrophages (TAM) are the most abundant immune cells in the tumor microenvironment. They consist of various subsets but primarily resemble the M2 macrophage phenotype. TAMs are known to promote tumor progression and are associated with poor clinical outcomes. CD47 on tumor cells and SIRPα on TAMs facilitate a “don't-eat-me” signal which prevents cancer cells from immune clearance. Therefore, blockade of the CD47–SIRPα interaction represents a promising strategy for tumor immunotherapy. Here, we present the results on ZL-1201, a differentiated and potent anti-CD47 antibody with improved hematologic safety profile compared with 5F9 benchmark. ZL-1201 enhanced phagocytosis in combination with standards of care (SoC) therapeutic antibodies in in vitro coculture systems using a panel of tumor models and differentiated macrophages, and these combinational effects are Fc dependent while potently enhancing M2 phagocytosis. In vivo xenograft studies showed that enhanced antitumor activities were seen in a variety of tumor models treated with ZL-1201 in combination with other therapeutic mAbs, and maximal antitumor activities were achieved in the presence of chemotherapy in addition to the combination of ZL-1201 with other mAbs. Moreover, tumor-infiltrating immune cells and cytokine analysis showed that ZL-1201 and chemotherapies remodel the tumor microenvironment, which increases antitumor immunity, leading to augmented antitumor efficacy when combined with mAbs. SIGNIFICANCE: ZL-1201 is a novel anti-CD47 antibody that has improved hematologic safety profiles and combines with SoC, including mAbs and chemotherapies, to potently facilitate phagocytosis and antitumor efficacy.