3614 - Enhanced Access to EGFR Molecular Testing in NSCLC using a Cell-Free DNA Tube for Liquid Biopsy

Background

The clinical utility of non-invasive liquid biopsy and ability to accurately detect EGFR mutations in circulating-tumor DNA of patients with NSCLC has been well demonstrated. This expands the pool of patients eligible for molecular testing. The cobas^® EGFR Mutation Test v2 (cobas test) is a real-time PCR test for qualitative and semi-quantitative detection of 42 EGFR mutations in DNA from tissue and circulating free DNA (cfDNA) from K2 EDTA plasma. Blood collected in K2 EDTA requires plasma be separated within 8 hours, which can be a barrier to molecular testing and thus impact treatment decisions. The Roche Cell-Free DNA Collection Tube (Roche cfDNA) stabilizes blood up to 8 days, allowing greater flexibility in transportation and time to plasma separation. Here the suitability of plasma from Roche cfDNA tubes for use with the cobas test is demonstrated.

Methods

Test performance with Roche cfDNA plasma was verified with NSCLC patient specimens or surrogate samples (sheared cell line DNA in healthy donor plasma). Correlation was tested using paired draws in K2 EDTA and Roche cfDNA tubes for 51 NSCLC patients and 20 healthy donor surrogate samples. Limit of detection (LoD) and linearity established with K2 EDTA plasma were verified with Roche cfDNA plasma. Reproducibility was assessed using surrogate samples at two levels with multiple operators, Roche cfDNA tube lots, instruments, days and sites. Blood storage conditions were established at an external laboratory with 6 NSCLC patient specimens.

Results

Compared to K2 EDTA plasma, Roche cfDNA plasma had a PPA, NPA and OPA of 100.0% with the cobas test. LoD for EGFR mutation detection in Roche cfDNA plasma was verified as ≤ 100 cp/mL. Linearity for EGFR mutations in Roche cfDNA plasma was verified. The reproducibility study had a call agreement of ≥ 98.6%. Blood in Roche cfDNA tubes was stable for up to 8 days at 18-25ºC with one excursion of up to 24 hours at 15-30ºC prior to separation.

Conclusions

Use of the Roche cfDNA tube with the cobas^® EGFR Mutation Test v2 provides the flexibility to store blood for up to 8 days prior to separation, with equivalent performance to K2 EDTA plasma, and facilitates use of liquid biopsy for NSCLC patients needing molecular testing.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Roche Molecular Systems Inc.

Funding

AstraZeneca PLC.

Disclosure

T.E. May: Full / Part-time employment: Roche Molecular Solutions. S.A. Scudder: Shareholder / Stockholder / Stock options, Full / Part-time employment: Roche Molecular Solutions. S.J. Joshi: Full / Part-time employment: Roche Molecular Solutions. M. Kohlmann: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca, PLC. N. Shrestha: Full / Part-time employment: Roche Molecular Solutions. N. Lee: Full / Part-time employment: Roche Molecular Solutions. J. Lai: Full / Part-time employment: Roche Molecular Systems Inc. M. Tsourounis: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca PLC. A. Kohlmann: Shareholder / Stockholder / Stock options, Full / Part-time employment: AstraZeneca PLC. P. O’Donnell: Full / Part-time employment, Spouse / Financial dependant: Roche Molecular Systems. H. Halait: Shareholder / Stockholder / Stock options, Full / Part-time employment: Roche Molecular Systems. All other authors have declared no conflicts of interest.