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P2.14 - Targeted Therapy (ID 183)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Targeted Therapy
- Presentations: 1
- Now Available
- Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
P2.14-21 - Liquid Biopsy in Lung Cancer: Comparison Between Real-Time PCR and MALDI-TOF for ctDNA Molecular Profiling (Now Available) (ID 1798)
10:15 - 18:15 | Author(s): Nicolas Lozano
Circulating cell free DNA (cfDNA) could now be used for lung cancer molecular testing when tissue is limited and/or insufficient. Tests’ sensitivity and mutation coverage could have a great implication for the patient care. In this study we analyzed and compared results of cfDNA from lung carcinoma patients tested with different technologies.Method
100 cfDNA samples were extracted from blood plasma (Qiagen), DNA quality and quantity were assessed using the LabChip GX Touch 24 (PerkinElmer).
We used PCR based Cobas® EGFR Mutation Test v2 (Roche) that identifies 42 mutations in the EGFR gene and UltraSEEK™ Lung Panel on MALDI-TOF based MassARRAY® (Agena Bioscience): 67 mutations in 5 oncogenes: EGFR (43), BRAF (4), ERBB2 (2), KRAS (14) and PIK3CA (4) with a sensitivity down to 0.1%. For UltraSEEK we used 11-40 µl cfDNA (avg. 8.87 ng). For Cobas we initially used 70 µl (avg. 24.39 ng) and re-tested a subset (63 samples) with lower input volumes as were used for UltraSEEK.
All samples showed the expected fragment-size distribution and no significant abundance of genomic DNA on the LabChip.
With high cfDNA input on Cobas we detected EGFR activating mutations in 60 patients with Cobas and in 57 with UltraSEEK and 16 and 18 EGFR T790M with Cobas and UltraSEEK, respectively. In addition, with the UltraSEEK Lung Panel 9*KRAS and 2*BRAF V600E were identified and one more double mutations (G719A/L861QR).
For the subset of 63 samples with the same cfDNA input between technologies 4 (6%) were invalid for analysis on Cobas. None were invalid with USK. 85% of patients (50/59) had concordant results for overlapping markers in EGFR. The EGFR T790M mutation was detected in 7 and 10 samples with Cobas and UltraSEEK, respectively (70% concordance). In total, with UltraSEEK 10 additional EGFR mutations (4*Exon 19 deletion, 3*T790M, 1*Exon 20 insertion, 1*L861Q/R, 1*G917A) were detected in 8 of 59 patients (14%). Conversely, 1 EGFR Exon 19 deletion (2%) was detected by Cobas (wild-type in initial analysis by Cobas). The UltraSEEK Lung Panel identified 7 non-EGFR mutations (6*KRAS, BRAF) in 6 patients (10%).Conclusion
This study showed that the MassARRAY UltraSEEK Lung Panel improved sensitivity for ctDNA analysis especially for samples with low input in comparison to Cobas EGFR Mutation Test v2, a method widely used in clinical routine. The UltraSEEK Lung Panel could detect more EGFR primary or secondary resistance mutations. Additional mutations to EGFR (KRAS, BRAF) could also be detected in ctDNA and used as guidance for therapy.