Anti-epidermal growth factor receptor monoclonal antibody cetuximab augments radiation effects in glioblastoma multiforme in vitro and in vivo.
OBJECTIVE
Previously, we demonstrated that the anti-epidermal growth factor receptor (EGFR) antibody cetuximab alone was effective against EGFR-amplified glioblastoma multiforme (GBM) cells in vivo and in vitro. The purpose of the present work was to study further the effectiveness of cetuximab as a monotherapy as well as combining it with radiation therapy or chemotherapy.


METHODS
EGFR-amplified GBM cells were implanted either in the flanks of nude mice to determine the effectiveness of cetuximab on larger tumor burden or intracranially to assess the ability of cetuximab to cross the blood-brain barrier. Cells were also exposed to cetuximab in combination with radiation in vivo or chemotherapeutic agents in vitro.


RESULTS
Increasing tumor burden in the flanks of mice decreased the amount of tumor growth inhibition. For the first two intracranial models using cetuximab for 5 weeks, the treated mice had a significant increase in median survival compared with controls. When cetuximab was given indefinitely, the results were encouraging, with an increase in median survival for the treated group not yet reached but at least 900%. Mice with flank GBM exposed to cetuximab and radiation had a larger increase in median survival than those with either treatment alone. Preliminary in vitro experiments using cetuximab and chemotherapeutic agents showed increased cytotoxicity.


CONCLUSIONS
These results were encouraging, demonstrating the effectiveness of cetuximab against EGFR-amplified GBM. Surprisingly, cetuximab was effective when administered systemically in an intracranial model. Radiation augmented the effect of cetuximab on GBM in vitro and in vivo. In vitro analysis demonstrated additive effects for chemotherapeutic agents as well. These results confirm EGFR blockade with cetuximab as a potential treatment against human GBM.
Eller
Jorge L
JL
Department of Neurosurgery, State University of New York Upstate Medical University, Syracuse, New York 13210, USA.
Longo
Sharon L
SL
Kyle
Michele M
MM
Bassano
Daniel
D
Hicklin
Daniel J
DJ
Canute
Gregory W
GW
D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D000068818:Cetuximab; D003131:Combined Modality Therapy; D066246:ErbB Receptors / Q000502:physiology; D005260:Female; D005909:Glioblastoma / Q000188:drug therapy* / Q000532:radiotherapy*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D066246:ErbB Receptors; D000068818:Cetuximab