Combining SiRPα decoy–coengineered T cells and antibodies augments macrophage-mediated phagocytosis of tumor cells
Evangelos Stefanidis, … , George Coukos, Melita Irving
Evangelos Stefanidis, … , George Coukos, Melita Irving
Published June 3, 2024
Citation Information: J Clin Invest. 2024;134(11):e161660. https://doi.org/10.1172/JCI161660.
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Combining SiRPα decoy–coengineered T cells and antibodies augments macrophage-mediated phagocytosis of tumor cells

Abstract

The adoptive transfer of T cell receptor–engineered (TCR-engineered) T cells (ACT) targeting the HLA-A2–restricted cancer-testis epitope NY-ESO-1157–165 (A2/NY) has yielded favorable clinical responses against several cancers. Two approaches to improve ACT are TCR affinity optimization and T cell coengineering to express immunomodulatory molecules that can exploit endogenous immunity. By computational design we previously developed a panel of binding-enhanced A2/NY-TCRs including A97L, which augmented the in vitro function of gene-modified T cells as compared with WT. Here, we demonstrated higher persistence and improved tumor control by A97L–T cells. In order to harness macrophages in tumors, we further coengineered A97L–T cells to secrete a high-affinity signal regulatory protein α (SiRPα) decoy (CV1) that blocks CD47. While CV1-Fc–coengineered A97L–T cells mediated significantly better control of tumor outgrowth and survival in Winn assays, in subcutaneous xenograft models the T cells, coated by CV1-Fc, were depleted. Importantly, there was no phagocytosis of CV1 monomer–coengineered T cells by human macrophages. Moreover, avelumab and cetuximab enhanced macrophage-mediated phagocytosis of tumor cells in vitro in the presence of CV1 and improved tumor control upon coadministration with A97L–T cells. Taken together, our study indicates important clinical promise for harnessing macrophages by combining CV1-coengineered TCR–T cells with targeted antibodies to direct phagocytosis against tumor cells.

Authors

Evangelos Stefanidis, Aikaterini Semilietof, Julien Pujol, Bili Seijo, Kirsten Scholten, Vincent Zoete, Olivier Michielin, Raphael Sandaltzopoulos, George Coukos, Melita Irving

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Figure 3

SiRPα-Fc decoys are efficiently produced by gene-modified T cells.

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SiRPα-Fc decoys are efficiently produced by gene-modified T cells. (A) S...
(A) Schematic of retroviral constructs encoding inSiRPα-Fc, wtSiRPα-Fc, or CV1-Fc proteins with an EGFP reporter gene, and of a lentiviral construct encoding the A97L-TCR. (B) Strategy for T cell activation, dual virus transduction, and expansion. (C) Expression of SiRPα-Fc and A97L-TCR in cotransduced rested human CD8+ T cells as detected by EGFP and anti–human Vβ13.1 Ab, respectively (data are representative of 12 independent donors). (D) CD47-based ELISA detection of SiRPα-Fc secreted by engineered CD8+ T cells (n = 3). (E) Quantification of CD8+ T cell–secreted CV1-Fc by CD47-based ELISA after 24 hours of culture (n = 3). (F) Quantification of CV1-Fc accumulated in culture supernatants of engineered CD8+ T cells over time (representative results for 3 donors). (G) Binding of CD8+ T cell–secreted CV1-Fc on different CD47+ tumor cell lines (data are representative of 3 donors). (H) Frequency of effector and memory phenotypes of transduced and rested CD8+ T cells (n = 3) (TE, effector; TEM, effector memory; TCM, central memory; TN/SCM, naive/stem cell–like memory). (I) Expansion of engineered CD8+ T cells (n = 3). Statistical analysis was done by 1-way ANOVA (D and H), unpaired 2-tailed t test (E), or 2-way ANOVA (I) with correction for multiple comparisons by post hoc Tukey’s test on pooled donors (D, H, and I). ****P< 0.0001.