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IPASS: EGFR mutation predicted response to gefitinib in NSCLC
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2009 ASCO Annual Meeting
A clinically selected group of patients with non–small cell lung cancer and mutations in the EGFR gene who were treated with gefitinib had slower cancer progression than patients without the mutation, according to data from IPASS.
“The IPASS biomarker results show EGFR mutation status was a strong predictive biomarker for differential PFS and overall response rate benefit with gefitinib vs. carboplatin/paclitaxel in this clinically selected first-line setting, indicating that a molecularly defined population will benefit most from first-line treatment with gefitinib,” said Masahiro Fukuoka, MD, PhD, professor of medicine at Kinki University School of Medicine in Osaka, Japan.
Previous data from the IPASS study demonstrated that first-line treatment with gefitinib was more effective for slowing cancer growth than conventional chemotherapy in Asian patients with stage IIIb/IV lung adenocarcinoma who had been nonsmokers or lights smokers.
In this biomarker study, Fukuoka and colleagues examined which EGFR-related biomarkers predicted significantly delayed tumor growth and OS.
They compared 261 patients with an EGFR mutation to 176 patients without the mutation. Patients were assigned to either conventional chemotherapy with carboplatin/paclitaxel or gefinitib (Iressa, AstraZeneca). Sixty-five percent of patients were mutation positive.
Patients positive for the EGFR mutation had a median PFS of 9.5 months with gefitinib vs. 6.3 months with carboplatin/paclitaxel (P<.0001). However, patients negative for the EGFR mutation had a significantly longer PFS when assigned to carboplatin/paclitaxel (5.5 months) vs. gefitinib (1.5 months; P<.0001). – by Leah Lawrence
You may remember that some years ago both IRESSA and a related drug Tarceva, or erlotinib, were FDA approved for the use in treatment of NSCLC and both drugs produced fairly modest improvement for unselected patients. We subsequently came to realize that the patients who would be most likely to benefit from these treatments had a particular appearance to them. That is, they tended to be Asian women who had never smoked or were only light smokers. They had a particular type of NSCLC called adenocarcinoma, one of the more common subtypes. Those were the people who were actually included in this study, so the study was highly enriched for people most likely to benefit from drugs like gefitinib or Tarceva. This population of patients is also most likely to have these mutations in the epidermal growth factor receptor gene, and again, we know that those are the mutations that tend to make the cancer respond much better to these particular kinds of treatments.
The really important thing about this study, in my mind, is that it
really now affirms in a large randomized study much of what we have been seeing
coming out in smaller studies over the last several years. That is that we now
need to think about NSCLC as at least two distinct types of cancer. Those types
that have either a mutation or an increase in the number of the EGFR genes
— those patients are probably best treated with drugs like gefitinib
— or a type of NSCLC that does not have mutations in the EGFR gene and
those people clearly are better treated with standard chemotherapy. 
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– Richard L. Schilsky, MD
President of ASCO
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