title: In vitro and in vivo stability and anti-tumour efficacy of an anti-EGFR/anti-CD3 F(ab')2 bispecific monoclonal antibody.
abstract: The in vitro and in vivo stability and anti-tumour efficacy of the anti-EGFR/anti-CD3 bispecific monoclonal antibody (biMAb), M26.1, were analysed. The interaction of the intact biMAb with Fc receptor I (Fc gamma RI) present on human leucocytes was not observed when the antibody was used as an F(ab')2 fragment. A CD8+ T-cell clone coated with M26.1 F(ab')2 was as effective as the intact biMAb in inducing IGROV1 target cell lysis when tested in a 51Cr-release assay. Variable levels of reduction of F(ab')2 to monovalent F(ab') were observed upon incubation with human ovarian cancer ascitic fluid (OCAF) or with human glioblastoma cavity fluid (GCF), but not with mouse or human sera. Activated lymphocytes coated with F(ab')2 and incubated in vitro with GCF or OCAF for 24 and 48 h respectively maintained their targeting. Thus, the F(ab')2, when present as a soluble molecule, but not when bound to T cells, might lose some functional activity as a consequence of partial reduction to F(ab'). In normal mice, M26.1 F(ab')2 retained full cytotoxic activity in the circulation, and clearance values were similar to those obtained with parental and other MAb F(ab')2. Treatment of IGROV1 tumour-bearing mice with activated human lymphocytes coated with the M26.1 F(ab')2 significantly prolonged survival of the animals compared with tumour-bearing untreated and control mice treated with lymphocytes or F(ab')2 alone. Together, these results suggest the clinical usefulness of bispecific M26.1 F(ab')2 as a targeting agent for local treatment of tumours such as glioma and ovarian cancers that express variable levels of epidermal growth factor receptor (EGFR).
authors.affiliation: Division of Experimental Oncology E, Istituto Nazionale Tumori, Milan, Italy.
authors.forename: D R
authors.initials: DR
authors.lastname: Negri
authors.forename: E
authors.initials: E
authors.lastname: Tosi
authors.forename: O
authors.initials: O
authors.lastname: Valota
authors.forename: S
authors.initials: S
authors.lastname: Ferrini
authors.forename: A
authors.initials: A
authors.lastname: Cambiaggi
authors.forename: S
authors.initials: S
authors.lastname: Sforzini
authors.forename: A
authors.initials: A
authors.lastname: Silvani
authors.forename: P A
authors.initials: PA
authors.lastname: Ruffini
authors.forename: M I
authors.initials: MI
authors.lastname: Colnaghi
authors.forename: S
authors.initials: S
authors.lastname: Canevari
mesh_terms: D000818:Animals; D018033:Antibodies, Bispecific / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000493:pharmacokinetics / Q000627:therapeutic use*; D017252:CD3 Complex / Q000276:immunology*; D066246:ErbB Receptors / Q000276:immunology*; D005260:Female; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009374:Neoplasms, Experimental / Q000628:therapy*; D014407:Tumor Cells, Cultured
chemical_list: D018033:Antibodies, Bispecific; D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D007140:Immunoglobulin Fab Fragments; D066246:ErbB Receptors