Are There Any Ethnic Differences in Molecular Predictors of Erlotinib
Efficacy in Advanced Non-Small Cell Lung Cancer?
- Affiliated Author(s)
- Alternative Author(s)
- Song, Hong Suk
- Journal Title
- Clinical Cancer Research
- Issued Date
- Purpose: This study investigated possible molecular predictors of outcome in Korean patients
with advanced non-small cell lung cancer treated with erlotinib.
Experimental Design: One hundred and twenty patients received erlotinib and were followed
prospectively. Ninety-two tissue samples were analyzed for epidermal growth factor receptor
(EGFR) gene mutations (exons 18, 19, and 21), 88 for EGFR gene amplification by real-time
PCR, and 75 for EGFRprotein expressionby immunohistochemistry.
Results:The overall tumor response ratewas 24.2%(complete response, 4; partial response, 25)
with 56.7% of disease control rate.With a median follow-up of 23.6 months, the median time to
progression (TTP) was 2.7 months and the median overall survival was12.9 months. EGFR gene
mutations were found in 26.1% (24 of 92), EGFR gene amplification in 40.9% (36 of 88), and
EGFR protein expression in 72% (54 of 75).There was a strong association between EGFR gene
mutations and gene amplification (c = 0.241). Patients with EGFR gene mutations or gene amplification
showed both better response rate (58.3% versus 16.2%, P < 0.001; 41.7% versus 17.3%,
P = 0.012) and TTP (8.6 versus 2.5 months, P = 0.003; 5.8 versus 1.8 months, P < 0.001) and
overall survival (not reached versus 10.8 months, P = 0.023; not reached versus 10.1months,
P = 0.033). By multivariate analysis, EGFR gene mutation was the only significant molecular
predictor for TTP (hazard ratio, 0.47; 95% confidence interval, 0.25-0.89).
Conclusions: Our findings indicate that EGFR gene mutation is a more predictive marker for improved
TTP than EGFR gene amplification in erlotinib-treated Korean non-small cell lung cancer
patients. Prospective studies fromdiverse ethnic backgrounds are required to determine the exact
role of these molecular markers.
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