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N. Normanno
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P3.02b - Poster Session with Presenters Present (ID 494)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.02b-043 - Inter-Laboratory Comparison of the Roche Cobas EGFR Mutation Test v2 in Plasma (ID 4277)
14:30 - 14:30 | Author(s): N. Normanno
- Abstract
Background:
Molecular testing of the EGFR gene is required to predict therapeutic response in non-small cell lung cancer (NSCLC). Although routinely performed, analysis of tumor tissue is subject to limitations. Analysis of circulating tumor DNA (ctDNA) in blood plasma may overcome these barriers, and techniques to detect and quantify variants in ctDNA are emerging. However, several key elements like sensitivity and specificity still need to be addressed. This study evaluates the inter-laboratory performance and reproducibility of the cobas[®] EGFR Mutation Test v2 for the detection of common EGFR variants in plasma.
Methods:
Fourteen laboratories from ten European countries received two identical panels of 27 single-blinded plasma members (Roche Molecular Systems, CA, USA). Samples were wild-type or spiked with plasmid DNA containing seven common EGFR variants at six predefined concentrations from 50-5000 target copies per mL (cp/mL). ctDNA was extracted by the Roche cobas[®] cfDNA Sample Preparation kit, followed by duplicate analysis with the Roche cobas[®] EGFR Mutation Test v2 kit. All sites received hands-on training and two obligatory proficiency samples to assure operator qualification. Statistical analyses were performed with SAS 9.4 (SAS Institute Inc., NC, USA).
Results:
In total, 0.8% (12/1512) and 0.2% (3/1512) of runs were excluded due to protocol deviations or technical failures respectively. The sensitivity was lowest for the c.2156G>C;p.(G719A) variant with values of 80.4%, 69.6% and 89.1% at 50, 100 and 250 cp/mL respectively. Besides 88.7% for the c.2573T>G;p.(L858R) variant at 50 cp/mL, sensitivities for all other variants or concentrations varied between 96.3-100.0% and improved for increasing cp/mL. Specificities were all 98.8%-100.0%. Coefficients of variation (CV) indicate good intra-laboratory repeatability and inter-laboratory reproducibility, but increased for decreasing concentrations. Highest CV’s were reported for c.2156G>C;p.(G719A), c.2307_2308ins;Ex20Ins, and c.2582T>A;p.(L861Q) at 50 cp/mL. Prediction models reveal a significant correlation between the observed semi-quantitative index values (SQI) and copy numbers in plasma for all variants. A systematic over- and underestimation was observed for four different variants at 1000 and 5000 cp/mL respectively.
Conclusion:
This study demonstrates an overall robust performance of the cobas® EGFR Mutation Test v2 in plasma, suggesting a valuable and convenient addition to molecular tumor analysis in NSCLC. Repeated tests are advisable in case of low SQI values to reduce the average variation. Prediction models could be applied by future users to estimate the plasma tumor load from the observed SQI value, taking into account the possibility of systematic errors for high target copies.
