Already Approved Chemotherapeutic Drugs Shrink Some Types of Brain Tumor

After reexamining two chemotherapeutic drugs, cancer researchers have concluded that they can be used to treat certain types of glioblastoma multiforme (GBM) that harbor a mutation in the gene that codes for epidermal growth factor receptor (EGFR).

GBM tumors are aggressive and resistant to current treatments, such as surgery, radiation, and chemotherapy. The two drugs, the anti-EGFR specific monoclonal antibody cetuximab and the small molecule inhibitor erlotinib, have already been approved by the US Food and Drug Administration (FDA) for treatment of metastatic colorectal cancer and squamous cell carcinoma of the head and neck (cetuximab) and lung and pancreatic cancers (erlotinib).

In the current study, investigators at the University of California, San Diego (USA) reexamined the effect of the two drugs on GBM. They reported in the October 14, 2011, online edition of the journal Cancer Research that while not being terribly effective in stopping GBM overall, they were quite good at inhibiting a form of GBM characterized by a specific exon 27 deletion mutation within the EGFR carboxyl-terminus domain (CTD). Cetuximab in particular prolonged the survival of intracranially xenografted mice with oncogenic EGFR CTD deletion mutants, compared to untreated control mice.

“In the past when we treated brain cancer patients with these drugs, the response rate was very small,” said contributing author Dr. Santosh Kesari, professor of neurooncology at the University of California, San Diego. “What we now show is that the tumors with CTD mutations respond best to these EGFR targeted agents. If we knew this beforehand, we might have been able to select patients most likely to respond to these agents. We are now trying to put together a prospective clinical trial to prove this. We would select only patients with these tumor mutations and treat them. This kind of research gets us closer to identifying genetic subtypes, to doing better biomarker-based clinical trials, and to personalizing treatments in brain cancers.”

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University of California, San Diego