Anti‐tumor efficacy of an anti‐epidermal‐growth‐factor‐ receptor monoclonal antibody and its F(ab′)₂ fragment against high‐ and low‐egfr‐expressing carcinomas in nude mice

Abstract

Monoclonal antibody (MAb) MINT5 specifically detects the epidermal-growth-factor receptor (EGFR). In vitro analyses of intact MINT5 (IgG1) and its F(ab')2 fragment indicated that both forms of the MAb inhibited binding of 125I-mEGF to EGFR, induced receptor internalization and blocked EGF-induced EGFR tyrosine-kinase activation in A431 cells. Both forms of the MAb also inhibited to the same extent the proliferation of the carcinoma cell lines A431 and IGROVI, despite the difference in EGFR levels on the cells. The detection of TGF alpha mRNA and the inhibition of cell growth in EGF-free conditions by anti-EGFR MAb indicated the involvement of an EGFR/TGF alpha autocrine/paracrine pathway in the in vitro growth of both cell lines. Analysis of mice xenotransplanted s.c. with A431 cells and treated with MINT5 revealed a block in A431 tumor take in 6 of 10 animals when intact MAb was administered from day 0 to day 11. On a molar basis, F(ab')2 at the same dose was ineffective, although at a 7-fold higher dose F(ab')2 reduced s.c. tumor growth by 80%. At the same dose, intact MINT5 MAb reduced s.c. growth of the EGFR-negative MeWo cell line by 5%. Survival of mice bearing IGROVI i.p. xenotransplants and treated locally with either form of MAb was significantly prolonged even when treatment was initiated on day 3. Corrected doses of intact and F(ab')2 fragment, which accounted for the difference in serum half-lives of the MAb forms, resulted in similar survival rates in the tumor-bearing mice. These pre-clinical results suggest that MINT5 MAb might be safely used for systemic therapy of EGFR-over-expressing tumors. Loco-regional therapy might be contemplated in the case of tumors with moderate/low EGFR expression.

Reversion of transformed phenotype in ovarian cancer cells by intracellular expression of anti folate receptor antibodies

“…Mabs MOV18 (IgG 1 ) and MOV19 (IgG 2a ) directed to FR, 9,36 MINT5 and MGR6 directed, respectively, against HER-1 and HER-2 37,38 and 9E10 (IgG 1 ) directed to a myc sequence 39 present in the C-terminus of scFv protein were affinity-purified from hybridoma supernatants on protein A-Sepharose Cl-4B (Pharmacia Biotech).…”

Targeting the epidermal growth factor receptor

“…Cetuximab (IMC-C225, Erbitux ImClone Systems Inc, New York, NY, USA), ABX-EGF (Abgenics, San Francisco, CA, USA), and EMD 72000 are monoclonal antibodies directed against the EGFR that are currently in clinical trials. Another class of monoclonal antibodies consists of bispecific antibodies that can bind the EGFR and an immunologic effector cell Tosi et al, 1995;Curnow, 1997). Examples of this class of agents include M26.1, MDX-447, and H22-EGF.…”

“…Examples of this class of agents include M26.1, MDX-447, and H22-EGF. These agents have shown promising activity in early clinical trials Tosi et al, 1995;Curnow, 1997).…”

Generation and phenotypic characterization of new human ovarian cancer cell lines with the identification of antigens potentially recognizable by HLA-restricted cytotoxic T cells

“…Other MAbs used in the study (obtained commercially) were antiintercellular adhesion molecule-1 (ICAM-1; Immunotech, Marseille, France), anti-B7.1 (BB1/B7-PE, Becton Dickinson, Mountain View, CA) and anti-cytokeratin MAbs CK18, CK7 (Sigma). Antibodies to FR-␣ (MOv18, Miotti et al, 1987), p185 HER-2/neu (MGR6, Centis et al, 1992) and EGFR (MINT5, Tosi et al, 1995) were obtained from the authors. All determinations were carried out by flow cytometry on a FACScan analyzer (Becton Dickinson).…”