In a paper presented at this year’s European Society of Medical Oncology (ESMO) 2020 virtual congress, Dr Zeynep Zengin from City of Hope Hospital, Los Angeles, USA presented the results of a study using a commercially available circulating tumour DNA (ctDNA) assay. Assessment of ctDNA is a non-invasive method to assess genetic alterations in tumours.
The researchers identified 847 patients with advanced renal cell carcinoma (RCC) who underwent ctDNA testing. The most commonly identified genetic alterations were TP53 (37%), VHL (22%), and EGFR (6%) and there were increased mutation rates, particularly in EGFR and PTEN, over time.
Forty-six patients also had DNA analysis of tumour tissue. In these patients, the most commonly identified genetic alterations were VHL (64%), PBRM1 (45%), and SETD2 (32%). Notably, the agreement between ctDNA and tissue DNA was 96.2%. Concordance was higher among patients for whom ctDNA and tissue-based testing was performed within 6 months of each other.
The authors conclude that ctDNA analysis is possible in patients with metastatic RCC. They also highlight the concordance between ctDNA analysis and tissue-based analysis. Discrepancies between ctDNA and tissue-based analysis suggest tumour evolution as a result of time and treatment pressures.