Multiple platforms are commercially available for the detection of circulating cell-free tumour DNA (ctDNA) from liquid biopsies. Since platforms have different input and output variables, deciding what platform to use for a given clinical or research question can be daunting. This study aimed to provide insight in platform selection criteria by comparing four commercial platforms that detect KRAS ctDnA hotspot mutations: Bio-Rad droplet digital PCR (ddPCR), BioCartis Idylla, Roche COBAS z480 and Sysmex BEAMing. Platform sensitivities were determined using plasma samples from metastatic colorectal cancer (mCRC) patients and synthetic reference samples, thereby eliminating variability in amount of plasma analysed and ctDNA isolation methods. The prevalence of KRAS nucleotide alterations was set against platform-specific breadth of target. Platform comparisons revealed that ddPCR and BEAMing detect more KRAS mutations amongst mCRC patients than Idylla and COBAS z480. Maximum sample throughput was highest for ddPCR and COBAS z480. Total annual costs were highest for BEAMing and lowest for Idylla and ddPCR. In conclusion, when selecting a platform for detection of ctDNA hotspot mutations the desired test sensitivity, breadth of target, maximum sample throughput, and total annual costs are critical factors that should be taken into consideration. Based on the results of this study, laboratories will be able to select the optimal platform for their needs. Patients with metastatic colorectal cancer (mCRC) may be treated with targeted therapies directed against epidermal growth factor receptor (EGFR). However, presence of a Kirsten rat sarcoma (KRAS) mutation in the tumour confers resistance to this type of therapy 1. In the current standard of care the presence of KRAS mutations is determined in tissue biopsies obtained from the tumour. Obtaining such biopsies is invasive to the patient, may not fully represent tumour heterogeneity 2 , and is cost and time intensive. Detection of KRAS mutations in circulating cell-free DNA (cfDNA) from liquid biopsies offers an attractive alternative 3. Yet, cfDNA testing has its challenges, including the small amounts of available cfDNA and low fractions of circulating tumour DNA (ctDNA) 4. Multiple commercial ctDNA detection platforms are available, ranging from PCR based hotspot analysis to broad targeted NGS applications. These platforms show considerable differences in the amount of plasma required as input, the DNA isolation method, quantitative versus semi-quantitative results, the breadth of target and the total cost per sample analysed. These differences complicate a straightforward comparison of platforms, which results in a knowledge gap in cfDNA testing 5. Attempts to perform such comparisons have been made 6-9 , but it cannot be excluded that the results were biased by using different amounts of plasma or cfDNA, different isolation methods 10 and/or the use of tissue biopsy results as the gold standard. In addition these studies did not evaluate factors influencing the choi...

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PURPOSE Comprehensive molecular profiling (CMP) plays an essential role in clinical decision making in metastatic non–small-cell lung cancer (mNSCLC). Circulating tumor DNA (ctDNA) analysis provides possibilities for molecular tumor profiling. In this study, we aim to explore the additional value of centralized ctDNA profiling next to current standard-of-care protocolled tissue-based molecular profiling (SoC-TMP) in the primary diagnostic setting of mNSCLC in the Netherlands. METHODS Pretreatment plasma samples from 209 patients with confirmed mNSCLC were analyzed retrospectively using the NGS AVENIO ctDNA Targeted Kit (Roche Diagnostics, Basel, Switzerland) and compared with paired prospective pretreatment tissue-based molecular profiling from patient records. The AVENIO panel is designed to detect single-nucleotide variants, copy-number variations, insertions or deletions, and tyrosine kinase fusion in 17 genes. RESULTS Potentially targetable drivers were detected with SoC-TMP alone in 34.4% of patients. Addition of clonal hematopoiesis of indeterminate potential–corrected, plasma-based CMP increased this to 39.7% ( P < .001). Concordance between SoC-TMP and plasma-CMP was 86.6% for potentially targetable drivers. Clinical sensitivity of plasma-CMP was 75.2% for any oncogenic driver. Specificity and positive predictive value were more than 90% for all oncogenic drivers. CONCLUSION Plasma-CMP is a reliable tool in the primary diagnostic setting, although it cannot fully replace SoC-TMP. Complementary profiling by combined SoC-TMP and plasma-CMP increased the proportion of patients who are eligible for targeted treatment.