title: Purging of epithelial tumor cells from peripheral blood stem cells by means of the bispecific antibody BIS-1.
abstract: Peripheral blood stem cell (PBSC) support in breast cancer patients allows high-dose chemotherapy, but tumor cell contamination of the PBSCs is a potential source of relapse. Specific carcinoma cell killing can be obtained by retargeting activated T cells with bispecific antibody BIS-1, directed against epithelial glycoprotein-2 and CD3. To purge epithelial tumor cells from the PBSCs of breast cancer patients, activation of T cells in PBSCs and T-cell retargeting by BIS-1 was studied. PBSCs, obtained by leukapheresis after chemotherapy and recombinant human granulocyte colony-stimulating factor, were cultured in the presence of PBS, interleukin-2, OKT3, or interleukin-2/OKT3 for induction of T-cell activation. Subsequently, lysis of epithelial tumor cell lines by activated T cells of PBSCs in the presence or absence of BIS-1 was assessed with the 51Cr-release assay or immunocytochemical staining. The effect on PBSC hematopoietic colony formation (HCF) was evaluated by the granulocyte macrophage colony-stimulating units assay. Prior to activation, PBSCs from breast cancer patients contained higher levels of CD8+ T cells than peripheral blood from healthy volunteers (P < 0.05). The potential of PBSCs to sustain tumor cell lysis was increased after all prior activations and was further enhanced by BIS-1. Maximal BIS-1 effect was observed after OKT3 activation of PBSCs for 72 h (P < 0.0005), inducing a >3 log depletion of tumor cells. HCF was not affected by prior OKT3 activation and/or BIS-1. In conclusion, specific tumor cell lysis by PBSCs can be obtained in vitro by OKT3 activation and BIS-1 retargeting of T cells, without affecting HCF. At present, studies are evaluating this format for future clinical application.
authors.affiliation: Department of Internal Medicine, University Hospital Groningen, The Netherlands.
authors.forename: C P
authors.initials: CP
authors.lastname: Schröder
authors.forename: B J
authors.initials: BJ
authors.lastname: Kroesen
authors.forename: L F
authors.initials: LF
authors.lastname: de Leij
authors.forename: E G
authors.initials: EG
authors.lastname: de Vries
mesh_terms: D000906:Antibodies / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000097:blood / Q000276:immunology* / Q000628:therapy*; D017252:CD3 Complex / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D002860:Chromium Radioisotopes / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006023:Glycoproteins / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000627:therapeutic use; D006801:Humans; D007150:Immunohistochemistry; D007167:Immunotherapy / Q000379:methods; D007376:Interleukin-2 / Q000494:pharmacology; D008175:Lung Neoplasms / Q000276:immunology / Q000628:therapy; D008213:Lymphocyte Activation; D009375:Neoplasms, Glandular and Epithelial / Q000097:blood / Q000276:immunology* / Q000628:therapy*; D013234:Stem Cells / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D002860:Chromium Radioisotopes; D006023:Glycoproteins; D007376:Interleukin-2; D016178:Granulocyte-Macrophage Colony-Stimulating Factor