A comparison of Sarstedt S-Monovette cfDNA exact and streck cell-free DNA blood collecting tubes in liquid biopsies

Analysing cell-free DNA from a blood sample provides a minimally invasive alternative to a conventional tissue biopsy and enables molecular characterization of tumours. The performance of the new Sarstedt S-Monovette blood collection tube has not yet been formally evaluated against a reference standard. The performance of Streck and Sarstedt S-Monovette tubes were compared by their ability to yield cell-free DNA, cell-free DNA stability and cell-free DNA purity. Thirty patients undergoing liquid biopsy for clinical follow-up were enrolled. DNA yield was estimated by plasmatic DNA quantification and DNA purity was estimated by DNA fragments size and stability by the difference between day 7 and day 0. On day 0, the median cell-free DNA yield was significantly lower in Sarstedt S-Monovette tubes than in Streck tubes (paired Wilcoxon test, p = 0.00095, median 19.5 ng and 24.2 ng, respectively). The change in cell-free DNA yield change between days 7 and 0 was significantly higher in Sarstedt S-Monovette tubes than in Streck tubes (Wilcoxon test, p = 0.034). This study found that Sarstedt S-Monovette tubes yielded lower amounts of cell-free DNA than Streck tubes on day 0. Sarstedt S-Monovette tubes also found to increase in DNA yield after day 7 of storage, which may be compatible with an increased release of leukocyte DNA, although this mechanism was not assessed in this study. Further studies are required to determine the clinical significance of the observed differences in DNA yield and stability.