A tri-specific antibody engages T and myeloid cells to augment anti-tumor immunity [TCE_scRNA-seq]

Immunologically inert tumors often resist immune checkpoint inhibitors due to a scarcity of tumor-specific T cells and the immunosuppressive microenvironment, despite pronounced and functional bystander T cell infiltration. Here, we develop a novel tri-specific T cell engager (Tri-TCE) designed in a unique format to redirect T cells while mitigating immunosuppression. Our comprehensive studies utilizing co-culture systems, patient-derived tumor suspensions (PDTSs), patient-derived tumor fragments (PDTFs), and humanized mouse tumor models, demonstrate that Tri-TCE effectively activates T cells and induces tumor cell lysis. To elucidate the mechanisms underlying Tri-TCE treatment, we employed a clinical PDTS system. Clinical tumor samples (ovarian cancer) were digested with collagenase-II and DNase I. After filtration through a mesh strainer with 70-μm pores, single-cell suspensions were prepared and cultured for 3days treated with control-IgG or Tri-TCE. Using fluorescence-activated cell sorting to isolate CD45+ immune cells, we conducted single-cell transcriptome and TCR sequencing.