Concordance between comprehensive cancer genome profiling in plasma and matched tumor specimens.

Abstract

e23146 Background: The importance and clinical use of liquid biopsies to identify somatic, targetable alterations in the plasma of cancer patients is steadily increasing. However, their concordance with alterations identified in cancer specimens tested in routine diagnostics is not being monitored. In a cohort of non-squamous cell lung cancer patients, our aim was to systematically compare alterations found by a massively parallel sequencing liquid biopsy assay covering 39 cancer related genes (NEOliquid) with alterations identified by routine diagnostics in a certified central pathology laboratory. Methods: Routine Diagnostics: DNA mutational analysis was performed using cobas or Sanger-Sequencing. Rearrangements were identified using immunohistochemistry or FISH. NEOliquid assay: Cell-free DNA from plasma was subjected to hybrid-capture based next-generation sequencing to detect point mutations, small insertions and deletions, copy number alterations and genomic translocations in 39 clinically relevant genes in a single assay. To evaluate and compare the performance of liquid biopsies, we applied the NEOliquid tests on blood samples of 82 non-squamous NSCLC patients and correlated them with results of routine diagnostics of matched tissue samples. Results: Routine diagnostics for lung cancer related oncogenes (EGFR, ALK, ROS1, KRAS, BRAF) identified a total of 50 somatic alterations of which 37 were point mutations, 11 InDels and 2 gene fusions. NEOliquid analysis of the corresponding plasma sample revealed a total of 34 alterations, including 21 targetable driver alterations. Overall, the concordance of mutation calls between routine diagnostic testing and NEOliquid was 97.6%, with a sensitivity of > 70% and a specificity of 100%. Importantly, NEOliquid identified additional clinically relevant genomic alterations, not covered by routine testing. Conclusions: We have shown high concordance of genomic alterations identified from liquid biopsies and tumor tissue specimens. The excellent specificity of actionable alterations identified by NEOliquid offers analytical performance for routine diagnostic use.