Cell-free DNA in the supernatant of pleural effusion as bio-source for diagnostic biomarker tests 213 6 Introduction In current practice, molecular profiling of tumors has become essential to offer targeted therapy for several types of metastasized malignancies. Especially in non-small cell lung cancer (NSCLC), targeted therapy has been shown to be highly effective, and multiple tyrosine kinase inhibitors (TKI) for activating mutations or rearrangements in genes like EGFR (epidermal growth factor receptor), BRAF (B-Raf proto-oncogene serine/threonine kinase), ALK (anaplastic lymphoma kinase) and ROS1 (Ros oncogene 1 receptor tyrosine kinase) have become available1. Also, early detection of resistance mutations like EGFR T790M is important as they can guide the next line of therapy2. Unfortunately, obtaining tumor tissue for molecular analysis can be challenging. The site of the tumor can be difficult to reach and it often requires invasive procedures to obtain adequate amounts of vital tumor. In this respect, pleural effusion could be an attractive alternative bio-source for molecular analysis, especially as approximately ~30% of NSCLC patients develop pleural effusion3. Usually, DNA is isolated from a cell block or a Giemsa slide, but analysis of cell-free (cfDNA) in the supernatant has shown promising results4-9. Moreover, since the amount of tumor cells or the tumor cell percentage is often insufficient for analysis, this cell-free compartment is highly interesting. Here we explore the diagnostic yield of cfDNA analysis in pleural effusion samples from patients with NSCLC and other cancer types for EGFR and KRAS (KRAS proto-oncogene GTPase) driver mutation detection, as well as for EGFR resistance mutations. Analyses of cfDNA from the supernatant were compared head-to-head with analyses of the cell pellets (figure 1).
RkJQdWJsaXNoZXIy MTk4NDMw