The inter- and intra-tumoral heterogeneity is a well-known phenomenon which with the explosion of personalized medicine has become a challenge. Although the liquid biopsy is recognized as a promissory tool for prognostic, molecular profiling and monitoring of cancer disease, we are still far from incorporate it alone into the routine oncology practice. Here we analyze the application into the clinical routine of a new integrated approach that combines the analysis of both solid (FFPE block) and liquid (blood sample) biopsy in patients with different metastatic cancer types.
Materials and Methods:
We analysed 112 samples of metastatic patients, with different cancers types, using the OncoSTRAT&GO™ solution (OncoDNA SA, Gosselies, Belgium); that allows i) sequencing of more than 200 genes, identification of 350 genes fusion and evaluation of the expression level of tens of proteins in solid biopsy and ii) sequencing of hotspot mutations of a 27-gene panel in liquid biopsy.
We focus the analysis on those actionable variants that could be detected in both solid and liquid biopsies. A complete concordance of 60.7% was observed between both types of biopsies variants. The concordant and discordant variant allele frequencies (VAFs) were compare showing similar distributions, no significant statistical differences were found: mean values of 7.8/9.4% (P= 0.58; Mann-Whitney test) and 34.9/25.7% (P= .08; Mann-Whitney test) in liquid and solid biopsy, respectively.
Discordance variants cannot be put down to the sensibility of the analysis and consequently should be associated to tumor heterogeneity, low tumor burden and/or treatment response. Our results show the usefulness of the combination of solid and liquid biopsies in clinical practice providing additional information in 39.3% (81.8 and 18.2% due to differentiated variations in solid and liquid biopsy, respectively) of the cases, resulting in a better characterization of the tumor molecular profile and wider treatment options.