Fei Xiao from the Beijing Hospital in China presented at London Calling 2023 a lightning talk on “Small extrachromosomal circular DNAs as biomarkers for potential pan-cancer diagnosis and prognosis.” Xiao noted that extrachromosomal circular DNA (eccDNA) are circular DNA molecules that are independent of conventional chromosomes and most are smaller than 10 kb. The study aimed to create a custom process for using Oxford Nanopore Technologies to sequence naturally occurring extrachromosomal circular DNA in cancer patients. Xiao and the team developed a process for using Nanopore sequencing to sequence only eccDNAs. Their work helped identify eccDNA sequences specific to cancer. For example, there was a higher frequency of certain sequences. Xiao emphasized the potential of using eccDNA from plasma samples as a liquid biopsy marker for tumors.
