More Evidence to Support Personalized Cancer Care as Researchers Show EGFR Biomarkers Correlate with Response to Gefinitib

May 29, 2009
Christin Melton

In yet another example of the need to personalize cancer care, researchers from the Kinki University School of Medicine in Osaka, Japan, found that endothelial growth factor receptor mutations predicted treatment response in Asian patients with non-small cell lung cancer.

In yet another example of the need to personalize cancer care, researchers from the Kinki University School of Medicine in Osaka, Japan, found that endothelial growth factor receptor (EGFR) mutations predicted treatment response in Asian patients with non-small cell lung cancer (NSCLC). They analyzed tissue samples from 406 patients enrolled in the IPASS (IRESSA Pan-Asia Study) to determine whether there was a correlation between EGFR-related biomarkers and tumor growth and progression-free survival (PFS) in patients treated with gefitinib (Iressa).

Earlier results from the IPASS study found that Asian patients with stage IIIB/IV lung cancer who were nonsmokers or light smokers at the time of diagnosis demonstrated slower disease progression when treated initially with gefitinib compared to those who received standard chemotherapy. Researchers questioned why PFS was better in the chemotherapy group for the first 6 months of the study and favored the gefitinib group in the second 6 months. Using fluorescence in situ hybridization (FISH), they determined that of the 406 evaluable tumor tissue samples, 261 were positive for EGFR mutations. In the subgroup of patients with EGFR mutations, median PFS was 9.5 months with gefitinib versus 6.3 months with chemotherapy. Conversely, patients without the mutations responded significantly better to chemotherapy than to treatment with gefitinib (5.5 mo vs. 1.5 mo, respectively). An interim analysis found no significant difference between those with mutations and those without in overall survival, but Mashiro Fukuoka, MD, PhD, said it was too early in the study to draw solid conclusions on survival.

This is not the first study to document an apparent correlation between EGFR mutations in NSCLC tumors and response to gefitinib. As Richard L. Schilsky, MD, president of ASCO and professor of medicine at University of Chicago, Illinois, noted in a press conference on the results, “The important thing about this study is that it really affirms, in a large randomized trial, much of what we’ve been seeing coming out in smaller studies over the past several years.” He suggested this evidence, added to prior data, indicate it may be time to consider NSCLC as 2 different types of cancer and tailor treatment based on the patient‘s biomarkers.

This is not unlike the recent developments in metastatic colorectal cancer, where KRAS biomarkers were found to predict response to EGFR-inhibiting agents. It is possible that these sorts of discoveries may be made in other types of cancers, as well. It is clear oncologists must increasingly consider the individual patient’s tumor and genetic/biomarker profile rather than the basic malignant condition when selecting a treatment regimen most likely to be effective.

ASCO Abstract 8006.