Combining SiRPα decoy–coengineered T cells and antibodies augments macrophage-mediated phagocytosis of tumor cells
Evangelos Stefanidis, Aikaterini Semilietof, Julien Pujol, Bili Seijo, Kirsten Scholten, Vincent Zoete, Olivier Michielin, Raphael Sandaltzopoulos, George Coukos, Melita Irving
Evangelos Stefanidis, Aikaterini Semilietof, Julien Pujol, Bili Seijo, Kirsten Scholten, Vincent Zoete, Olivier Michielin, Raphael Sandaltzopoulos, George Coukos, Melita Irving
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Research Article Immunology

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 6

Tumor-targeted monoclonal Abs synergize with T cell-secreted CV1 monomer to augment tumor cell phagocytosis by macrophages in vitro.

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Tumor-targeted monoclonal Abs synergize with T cell-secreted CV1 monomer...
(A) Schematic of retroviral vectors encoding SiRPα monomers and of lentiviral vector encoding A97L-TCR. (B and C) Expression of SiRPα monomer and A97L-TCR in transduced CD8+ (B) and CD4+ (C) T cells, detected by EGFP and anti-Vβ13.1 Ab staining, respectively (data are representative of 11 donors). (D) Flow cytometric detection of CV1 monomer binding on CD8+ and CD4+ T cells by comparison of anti-CD47 Ab staining to CV1- versus inSiRPα-engineered T cells (data are representative of 11 donors). (E) Frequency of annexin V+ DAPI+ tumor cells in 24-hour cocultures with SiRPα monomer–coengineered A97L–T cells at E/T = 1:1, corrected to tumor alone (n = 3). (F) Schematic of macrophage-mediated tumor cell phagocytosis assay in the presence of SiRPα monomer and cetuximab and/or avelumab. (G) Human MDM phagocytosis of A375 tumor cells in the presence of T cell–secreted SiRPα monomer alone versus in combination with cetuximab and/or avelumab (representative results from n ≥3 donors). (H) NSG murine BMDM phagocytosis of A375 tumor cells in the presence of T cell–secreted SiRPα monomer alone versus in combination with cetuximab and/or avelumab (n = 3). Statistical analysis was done by 1-way ANOVA (E and H) with correction for multiple comparisons by post hoc Tukey’s test (E and H). *P < 0.05; **P < 0.01; ***P < 0.001; ****P< 0.0001.