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T. Mekhail
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MA 15 - Lung Cancer Biology II (ID 670)
- Event: WCLC 2017
- Type: Mini Oral
- Track: Biology/Pathology
- Presentations: 1
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MA 15.02 - Plasma CfDNA next Generation Sequencing in Non-Small Cell Lung Cancer: Clinical Outcomes and Comparison to Tissue (ID 9502)
15:50 - 15:55 | Author(s): T. Mekhail
- Abstract
- Presentation
Background:
Next-generation sequencing (NGS) of cell-free DNA (cfDNA) in plasma can be an alternative or complement to tissue biopsy for genomic analysis of non-small cell lung cancer (NSCLC), particularly for identifying driver and resistance alterations. We presented preliminary data in 67 patients comparing NGS in plasma vs. tissue (Santos et al. JTO; 11:10, S199-200) and found EGFR mutation agreement of 68% between plasma and tissue. We now present an expanded patient cohort with more extensive concordance analysis, longer follow-up, and clinical outcomes.
Method:
We analyzed data from advanced (stage III/IV) NSCLC patients seen at three cancer centers in Florida (US; Memorial Cancer Institute, Florida Hospital Cancer Center, Mount Sinai Cancer Center) that had alterations detected on Guardant360 (G360) testing through January 2017. G360 is a plasma cfDNA NGS assay that detects single nucleotide variations, amplifications, fusions, and indels in targeted genes using massively parallel digital sequencing; panel composition expanded from 54 to 73 genes over the course of the cohort. NGS performed on solid tumor biopsies from each subject were reviewed for comparison where available but may not have been collected contemporaneously to the plasma samples. Treatment information and clinical outcomes were collected for those patients with actionable mutations per NCCN guidelines (v3.2017).
Result:
A total of 190 G360 test results on 171 unique patients were identified (some patients underwent serial testing at multiple clinical timepoints, e.g. progression). Forty percent of patients were male; the median age was 65 (32-94). Excluding variants of uncertain significance, patients were most likely to have cfDNA alterations in TP53 (44%), EGFR (21%), KRAS (19%), BRAF (8%), and MET (8%). Forty-seven patients (28%) had at least one actionable mutation identified on G360, including SNVs, indels, fusions, and amplifications. Preliminary clinical outcomes data include durable (³10 months) partial responses on targeted therapy based on multiple plasma-detected alterations in EGFR and BRAF V600E; complete analysis will be presented at the meeting.
Conclusion:
Liquid biopsy plays an important role in genomic analysis of NSCLC, offering reliable information to guide therapeutic decision-making. Results in our cohort include a noteworthy proportion of patients with highly actionable mutations, like EGFR drivers and targetable resistance mutations, and G360 offers an alternative to tissue biopsy in these patients.
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