title: Novel recombinant human b7-h4 antibodies overcome tumoral immune escape to potentiate T-cell antitumor responses.
abstract: B7-H4 (VTCN1, B7x, B7s) is a ligand for inhibitory coreceptors on T cells implicated in antigenic tolerization. B7-H4 is expressed by tumor cells and tumor-associated macrophages (TAM), but its potential contributions to tumoral immune escape and therapeutic targeting have been less studied. To interrogate B7-H4 expression on tumor cells, we analyzed fresh primary ovarian cancer cells collected from patient ascites and solid tumors, and established cell lines before and after in vivo passaging. B7-H4 expression was detected on the surface of all fresh primary human tumors and tumor xenotransplants, but not on most established cell lines, and B7-H4 was lost rapidly by tumor xenograft cells after short-term in vitro culture. These results indicated an in vivo requirement for B7-H4 induction and defined conditions for targeting studies. To generate anti-B7-H4-targeting reagents, we isolated antibodies by differential cell screening of a yeast-display single-chain fragments variable (scFv) library derived from patients with ovarian cancer. We identified anti-B7-H4 scFv that reversed in vitro inhibition of CD3-stimulated T cells by B7-H4 protein. Notably, these reagents rescued tumor antigen-specific T-cell activation, which was otherwise inhibited by coculture with antigen-loaded B7-H4+ APCs, B7-H4+ tumor cells, or B7-H4- tumor cells mixed with B7-H4+ TAMs; peritoneal administration of anti-B7-H4 scFv delayed the growth of established tumors. Together, our findings showed that cell surface expression of B7-H4 occurs only in tumors in vivo and that antibody binding of B7-H4 could restore antitumor T-cell responses. We suggest that blocking of B7-H4/B7-H4 ligand interactions may represent a feasible therapeutic strategy for ovarian cancer.
authors.affiliation: Department of Obstetrics and Gynecology, Ovarian Cancer Research Center, and Departments of Pathology and Laboratory Medicine and Hematology/Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Denarda
authors.initials: D
authors.lastname: Dangaj
authors.forename: Evripidis
authors.initials: E
authors.lastname: Lanitis
authors.forename: Aizhi
authors.initials: A
authors.lastname: Zhao
authors.forename: Shree
authors.initials: S
authors.lastname: Joshi
authors.forename: Yi
authors.initials: Y
authors.lastname: Cheng
authors.forename: Raphael
authors.initials: R
authors.lastname: Sandaltzopoulos
authors.forename: Hyun-Jeong
authors.initials: HJ
authors.lastname: Ra
authors.forename: Gwenn
authors.initials: G
authors.lastname: Danet-Desnoyers
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Powell
authors.forename: Nathalie
authors.initials: N
authors.lastname: Scholler
mesh_terms: D000818:Animals; D001201:Ascites; D045744:Cell Line, Tumor; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D010051:Ovarian Neoplasms / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D057127:Single-Chain Antibodies / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D019139:Tumor Escape / Q000276:immunology*; D060907:V-Set Domain-Containing T-Cell Activation Inhibitor 1 / Q000276:immunology* / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: D057127:Single-Chain Antibodies; D060907:V-Set Domain-Containing T-Cell Activation Inhibitor 1; C475826:VTCN1 protein, human