Antiproliferative, antiangiogenic and proapoptotic activity of h‐R3: A humanized anti‐EGFR antibody

Abstract

The epidermal growth factor receptor (EGFR) proto-oncogene is frequently overexpressed in tumors of epithelial origin. This event is thought to be causative for tumor development and progression and henceforth associated with poor prognosis. The recent considerable interest in developing EGFR-targeting agents resulted in derivation of the monoclonal, humanized, neutralizing antibody h-R3, which binds to the extracellular domain of EGFR with high affinity and strongly inhibits EGFR-dependent cellular transformation. Thus, treatment of A431 squamous cell carcinoma cells with h-R3 in either 2-dimensional or 3-dimensional culture resulted in appreciable antimitotic effects through induction of the G1 arrest. Although h-R3 does not appear to have a direct proapoptotic activity in this setting, it inhibits production of the vascular endothelial growth factor (VEGF) by A431 cells both in vitro and in vivo. In the latter case, h-R3 treatment (0.25-1 mg/mouse; every other day per 2 weeks) not only significantly reduced VEGF mRNA expression of A431 tumors growing subcutaneously in SCID mice but also resulted in reduction of the overall microvascular density (MVD), disappearance of dilated "mother vessels," as well as in suppression of tumor growth followed by regression of established tumors. This apparent antiangiogenic activity of h-R3 was associated with reduction in Ki67-positive tumor cell fraction and (unlike in vitro) also with an elevated apoptotic index, the latter indicative of a cytotoxic mode of action in vivo. Taken together, h-R3 is a promising new antagonist of the EGFR oncogene, the anticancer properties of which are associated with combined and potent antiproliferative, antiangiogenic and proapoptotic activity.

Radiosensitisation of U87MG brain tumours by anti-epidermal growth factor receptor monoclonal antibodies

“…Further, a close relationship between EGFR/VEGF has been postulated to promote angiogenesis (Rak et al, 2000). Whereas earlier studies indicated that VEGF is induced in tumours after irradiation (Gorski et al, 1999), nimotuzumab has shown to downregulate VEGF expression at the RNA and protein level after treatment in A431 tumour xenografts in vivo (Crombet-Ramos et al, 2002). In agreement with that, we found a 60% of reduction in the total area of the vessels in tumour specimens from mice treated with nimotuzumab.…”

Enhancement of the antitumor activity of ionising radiation by nimotuzumab, a humanised monoclonal antibody to the epidermal growth factor receptor, in non-small cell lung cancer cell lines of differing epidermal growth factor receptor status

“…Together these results suggest that the efficacy of nimotuzumab monotherapy is a prerequisite for augmentation of radioresponse by this mAb. Nimotuzumab was previously shown to induce the regression of A431 tumour xenografts in vivo as a result of inhibition of both tumour cell proliferation and tumour angiogenesis (Crombet-Ramos et al, 2002). Immunohistochemical analysis of tumour specimens from head and neck cancer patients treated with the combination of nimotuzumab and radiation also showed evidence of antiproliferative and antiangiogenic effects (Crombet et al, 2004).…”

“…In a preclinical study, nimotuzumab showed marked antiproliferative, proapoptotic, and antiangiogenic effects in tumours that overexpress EGFR (Crombet-Ramos et al, 2002). In early clinical trials, nimotuzumab has shown a longer half-life and a greater area under the curve (AUC) in comparison with other anti-EGFR antibodies (Crombet et al, 2003).…”

Nimotuzumab, a promising therapeutic monoclonal for treatment of tumors of epithelial origin

“…The in vitro antiproliferative activity of nimotuzumab was tested in both two and three dimensional A431 squamous cell carcinoma cultures. 7 There was a dose dependent inhibition of vascular endothelial growth factor (VEGF) expression in A431 monolayer cultures. In studies with A431 subcutaneous tumor xenografts, northern blot analysis of the tumors confirmed VEGF inhibition by nimotuzumab.…”