Elimination of tumor by CD47/PD-L1 dual-targeting fusion protein that engages innate and adaptive immune responses

Abstract

The host immune system generally serves as a barrier against tumor formation. Programmed death-ligand 1 (PD-L1) is a critical "don't find me" signal to the adaptive immune system, whereas CD47 transmits an anti-phagocytic signal, known as the "don't eat me" signal, to the innate immune system. These and similar immune checkpoints are often overexpressed on human tumors. Thus, dual targeting both innate and adaptive immune checkpoints would likely maximize anti-tumor therapeutic effect and elicit more durable responses. Herein, based on the variable region of atezolizumab and consensus variant 1 (CV1) monomer, we constructed a dual-targeting fusion protein targeting both CD47 and PD-L1 using "Knobs-into-holes" technology, denoted as IAB. It was effective in inducing phagocytosis of tumor cells, stimulating T-cell activation and mediating antibody-dependent cell-mediated cytotoxicity in vitro. No obvious sign of hematological toxicity was observed in mice administered IAB at a dose of 100 mg/kg, and IAB exhibited potent antitumor activity in an immune-competent mouse model of MC38. Additionally, the anti-tumor effect of IAB was impaired by anti-CD8 antibody or clodronate liposomes, which implied that both CD8+ T cells and macrophages were required for the anti-tumor efficacy of IAB and IAB plays an essential role in the engagement of innate and adaptive immune responses. Collectively, these results demonstrate the capacity of an elicited endogenous immune response against tumors and elucidate essential characteristics of synergistic innate and adaptive immune response, and indicate dual blockade of CD47 and PD-L1 by IAB may be a synergistic therapy that activates both innate and adaptive immune response against tumors.

Therapeutic Targeting of the Macrophage Immune Checkpoint CD47 in Myeloid Malignancies

“…Therefore, combinations with T-cell checkpoint inhibitors (with anti-PD-1 or PD-L1 agents) may further augment T cell responses and enhance efficacy. Several pre-clinical studies have demonstrated that CD47 blockade in combination with T cell checkpoint inhibitors can enhance antitumor activity (37)(38)(39). A clinical trial evaluating magrolimab in combination with atezolizumab (an anti-PD-L1 antibody) has been initiated in R/R AML (NCT03922477).…”

Role of CD47 in Hematological Malignancies

“…Boussiotis extensively reviewed the PD-1/PD-L1 axis and its potential role in cancer therapy [74]. Previous studies showed enhanced anti-tumor effect with dual targeting of both CD47 and PD-L1 in melanoma and colon carcinoma [75,76]. Lian and colleagues designed an Ep-CAM (epithelial cell adhesion molecule) liposome containing both CD47 and PD-L1 arms.…”

“…Anti-SIRPα antagonists have also been combined with tumor-opsonizing antibodies such as rituximab showed anti-tumor efficacy in vitro [ 82 ] and in xenograft lymphoma and colon cancer models [ 86 ]. Similarly, targeting CD47 and PD-L1 [ 75 , 76 ].…”

The Neutrophil: The Underdog That Packs a Punch in the Fight against Cancer

“…This therapeutic activity required simultaneous binding to CD20 and CD47 and was not detected in single CD47-positive cells [ 195 ]. Several other IgG-based CD47-targeting bispecific antibodies have been developed, among others CD20-CD47 [ 196 ] and CD70-KWAR23 [ 166 ] CD47-CD19 [ 197 , 198 ], CD47-MSLN [ 197 ], CD47-PDL1 [ 199 , 200 ], and PD-L1-SIRPα [ 201 ]. However, the impact of these bispecific antibodies on neutrophil-mediated phagocytosis and trogocytosis has not been delineated yet.…”