Epidermal growth factor receptor

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Iressa (gefitinib), a EGFR inhibitor, originally received fast track approval from the U.S. Food &
Drug Administration for non-small cell lung cancer (NSCLC) in 2003 amid much brouhaha.  Two years later, AstraZeneca (AZN)
were forced to stop marketing the drug in the U.S. because it failed in the phase III clinical trial to extend patients lives and improve survival.

Doctors continued to research the drug, however, which is how doctors at M.D. Anderson Cancer Center in Houston made the interesting discovery that Iressa can significantly delay the spread of
breast cancer when given along with standard hormone therapy.  The results were reported at the 2008 annual ASCO meeting.

The idea behind the study was that preclinical data provide evidence that suggests crosstalk between
growth factor receptor pathways and the estrogen receptor (ER). 
Inhibition of both epidermal growth factor receptor and ER signalling
may therefore be a potential intervention to overcome hormonal resistance.

A total of 94 women with newly diagnosed hormone sensitive (ER+) metastatic breast cancer (mBC) were randomized to receive Arimidex (anastrozole) 1
mg/day and either gefitinib 250 mg/day or placebo. The goal was to measure progression-free survival (PFS) in the phase II setting. 

The results were interesting – Arimidex plus Iressa was well tolerated and associated with a
marked advantage in PFS compared with Arimidex plus placebo.  Further trials may be forthcoming to determine if the combined inhibition of both epidermal growth factor receptor and ER signalling will extend lives in postmenopausal
women with newly diagnosed hormone sensitive mBC.

{UPDATE: the 2009 ASCO meeting starts tomorrow and it will be interesting to see what new data will be coming out on both Iressa and also other EGFR inhibitors.}

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