Directed protein engineering identifies a human TIM-4 blocking antibody that enhances anti-tumor response to checkpoint inhibition in murine colon carcinoma

Abstract

Background: T-cell immunoglobulin and mucin domain containing molecule-4 (TIM-4) is a scavenger receptor best known for its role in recognizing dying cells. TIM-4 orchestrates phagocytosis allowing for cellular clearance of apoptotic cells, termed efferocytosis. It was previously shown that TIM-4 directly interacts with AMPKα1, activating the autophagy pathway, leading to degradation of ingested tumors, and effectively reducing antigen presentation. Methods: This study sought to identify a novel human TIM-4 antibody that can prevent phagocytosis of tumor cells thereby allowing for more antigen presentation resulting in anti-tumor immunological response. Using phage display panning directed against human TIM-4, we engineered a novel human TIM-4 antibody (SKWX301). Combination of in vitro phagocytosis assays and cell viability assays were used to test functionality of SKWX301. To examine the effect of SKWX301 in mouse models, we employed a syngeneic mouse model. CT26 cells were subcutaneously injected into BALB/c mice and tumor growth and mouse survival were analyzed. Results: SKWX301 can prevent human macrophage phagocytosis of cancer cells in vitro. Combination of low dose SKWX301 and antiPD1 antibody significantly inhibited tumor growth and increased overall survival in mice. This demonstrates that SKWX301 is effective in both human in vitro models and mouse in vivo models. Conclusion: Our study has demonstrated a rapid antibody discovery approach and identified a novel human TIM-4 antibody that can serve as a therapeutic for antitumor immunity to improve cancer therapy.