title: Cancer immunotherapy using a bispecific NK receptor fusion protein that engages both T cells and tumor cells.
abstract: T-cell immunotherapy is a promising strategy to treat cancer, but its efficacy, complexity, and costs may pose challenges. In this study, we report the results of an investigation of a new approach to selectively activate a T-cell attack against tumor cells. The immunotherapeutic approach we developed utilizes a bifunctional fusion protein that binds tumor cells through NK (natural killer)-activating receptor NKG2D and that recruits and stimulates T cells through an anti-CD3 single-chain variable fragment (scFv-NKG2D). In vitro, this scFv-NKG2D fusion protein engaged both T cells and tumor cells, stimulating T cells to produce IFN-γ, and cytotoxicity against NKG2D ligand-positive tumor cells. In vivo, expression of scFv-NKG2D by NKG2D ligand-positive tumor cells reduced tumor burden and, in some cases, led to tumor-free survival. Administration of scFv-NKG2D in vivo also promoted survival in a murine lymphoma model. Tumor-free mice were resistant to rechallenge with cognate tumor cells, suggesting that a host-specific immunologic memory response had been generated. Host adaptive immunity including γδ T cells was required for scFv-NKG2D-mediated therapeutic efficacy. ScFv-NKG2D also inhibited the growth of NKG2D ligand-negative B16F10 tumors, reduced the percentage of myeloid-derived suppressor cells and regulatory T cells, and increased the infiltration of T cells, suggesting that scFv-NKG2D may target these immune suppressive cells. Together, these results establish scFv-NKG2D as a promising biological fusion protein to induce effective antitumor immunity.
authors.affiliation: Department of Microbiology and Immunology, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA. Tong.Zhang@dartmouth.edu
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.forename: Charles L
authors.initials: CL
authors.lastname: Sentman
mesh_terms: D056704:Adaptive Immunity / Q000187:drug effects / Q000276:immunology; D000818:Animals; D017252:CD3 Complex / Q000276:immunology / Q000378:metabolism; D045744:Cell Line, Tumor; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D007167:Immunotherapy / Q000379:methods; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055655:NK Cell Lectin-Like Receptor Subfamily K / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D009369:Neoplasms / Q000276:immunology* / Q000473:pathology / Q000628:therapy; D009374:Neoplasms, Experimental / Q000276:immunology / Q000473:pathology / Q000628:therapy; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000276:immunology* / Q000378:metabolism / Q000627:therapeutic use; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D059016:Tumor Microenvironment / Q000187:drug effects / Q000276:immunology
chemical_list: D017252:CD3 Complex; C485468:Cd3e protein, mouse; C527086:Klrk1 protein, mouse; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D007371:Interferon-gamma