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Blood samples versus tumor biopsies in patients with advanced NSCLC

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The latest analysis from the EURTAC trial explored the feasibility of using circulating free DNA (cfDNA) to identify EGFR mutations and predict patient outcomes in those with advanced non-small-cell lung cancer (NSCLC) – conclusions usually drawn from tumor biopsies. The results of the study were published recently in JAMA Oncology.

The EURTAC trial previously compared the efficacy of using erlotinib with standard chemotherapy as a first-line treatment for European advanced NSCLC patients with oncogenic EGFR mutations ( L858R mutations in exon 21 or exon 19 deletion) within the tumor tissue.

In the present study, researchers examined EGFR mutations in cfDNA isolated from 97 baseline blood samples. EGFR mutations in cfDNA were detected in 78% of patients.

Other notable findings include the survival difference between patients with L858R mutations and exon 19 deletion in cfDNA: the median overall survival for patients with L858R mutations was 13.7 months versus 30 months in patients with exon 19 deletion. Additionally, in  all those with disease with the L858R mutation, median overall survival for patients with L858R mutation detectable both in tissue and cfDNA was calculated at 13.7  and 27.7 months for those in whom the L858R mutation was not identified in cfDNA .

Finally, the study reported that erlotinib treatment was an independent predictor of longer disease progression-free survival in those 76 patients with EGFR mutations in cfDNA.

The study drew conservative conclusions from these findings, stating: “Testing of tumor tissue remains the recommended method for detecting the presence of oncogenic EGFR mutations; however, the amount of tumor tissue obtained by biopsy is often insufficient, especially in advanced NSCLC, raising the question of whether cfDNA may be used as a surrogate liquid biopsy for the noninvasive assessment of EGFR mutations.”

Roy Herbst (Yale School of Medicine, CT, USA) expanded on some of the implications of the study in a related commentary: “In conclusion, the updated EURTAC study demonstrates that mutations detected in cfDNA are prognostic and consistent with data obtained from tumor biopsies.… More broadly, the potential benefits of liquid biopsies include a better evaluation of the tumor genome landscape with the identification of a comprehensive set of targetable mutations and the serial noninvasive monitoring, which may allow the detection of additional mutations from emerging subclones, including those involved in the development of acquired resistance. Finally, the presence of specific mutations in cfDNA may help identify populations of patients who are likely to have worse (or better) outcomes and who may require alternative treatments.”

Source: JAMA Network press release

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