Efficacy of Antibodies to Epidermal Growth Factor Receptor Against KB Carcinoma In Vitro and in Nude Mice

Abstract

Iodine-125-labeled monoclonal antibody 108.4 (108.4 mAb), raised against the extracellular domain of the epidermal growth factor (EGF) receptor, was shown to visualize sc xenografts of human oral epidermoid carcinoma (KB) cells in nude mice. In vitro, although EGF caused an increase in the number of KB cell colonies (150% at a concentration of 160 mM), the anti-EGF receptor antibodies reduced clone formation. At a concentration at which EGF caused a 50% increase in colony number, the addition of a 100-fold molar excess of 108.4 mAb resulted in a decrease in the number of cell colonies to 20% of the original value. Therefore, the effect of antibody on the KB tumor was studied in vivo in three different modes of tumor transplantation. Antitumor activity was demonstrated first by retardation (versus controls) of the growth of tumor cells as sc xenografts (P greater than .017), then by prolongation of the life span of animals with the ip form of the tumor (P less than .001), and finally on an experimental lung metastasis by a reduction in the number and size of tumors (P less than .05). When the anti-EGF receptor antibodies were added together with cisplatin, the antitumor effect was greatly enhanced, suggesting that the toxic activity of these agents is synergistic (P less than .007). The antitumor effect persisted when animals were treated with the F(ab)'2 fragment of the antibody, although it was less efficient. The Fab fragment of the antibody, whose ability to bind to the cell-associated receptor was completely conserved, did not affect the growth of the tumor. The activity manifested by the F(ab)'2 fragment of the anti-EGF receptor antibodies suggested that the antitumor effect was not due to immune mechanisms requiring the Fc portion of the antibody.

The EGF receptor family as targets for cancer therapy

“…Production and characterization of Anti-EGF receptor monoclonal antibodies A series of anti-EGF receptor MAbs were produced with inhibitory activity against cells bearing EGF receptors Sato et al, 1983;Rodeck et al, 1987;Aboud-Pirak et al, 1988). In collaboration with Dr Sato, our laboratory produced two murine MAbs, 225 IgG1 and 528 IgG2a, which bind to the receptor with a nity comparable to the natural ligand (K d =1.5 ± 2 nM), compete with ligand binding, and block activation of receptor tyrosine kinase by EGF or TGF-a Sato et al, 1983;Gill et al, 1984).…”

8-Cl-cAMP antagonizes mitogen-activated protein kinase activation and cell growth stimulation induced by epidermal growth factor

“…8-Cl-cAMP alone induced up to 70% growth inhibition after 96 h (Figure 1), which occurred without citotoxicity as demonstrated by Trypan blue assay (data not shown). Since KB cells can be growth-stimulated by EGF even in the presence of serum (Aboud-Pirak et al, 1988) and in order to mimic more physiological conditions, cells were allowed to grow in 10% serum throughout this and all further experiments. Moreover, when cells were starved for 24 h and treated in serum-free medium, while the kinetic of EGF stimulation appeared different, probably because the interference of autocrine growth factor stimulation activated by the starvation stress, similar results were obtained for 8-Cl-cAMP effect (data not shown).…”

“…We have selected as experimental model the KB epidermoid carcinoma cell line that is responsive to the mitogenic stimulus induced by EGF (Aboud-Pirak et al, 1988;Caraglia et al, 1995) and is growth inhibited by 8-Cl-cAMP treatment. We have found that the growth-promoting activity of EGF on KB cells was completely abolished by 8-Cl-cAMP.…”

Emerging anti-cancer antibodies and combination therapies targeting HER3/ERBB3

“…27 Sela and colleagues later demonstrated that anti-EGFR antibodies can synergize with platinum-based chemotherapy, when administered to tumorbearing animals. 28 Mendelsohn's murine antibody is the father of cetuximab (Erbitux TM ), a chimeric human/mouse mAb that inhibits binding of EGF and downstream signaling. 29 The antibody was clinically developed and eventually approved in 2004, together with chemotherapy, for the treatment of metastatic colorectal cancer (mCRC).…”