—▼TOPICS—グリオーマの低侵襲的診断法—Liquid biopsyの現状および展望

The Present and Future of Less-invasive Liquid Biopsy for the Diagnosis of Gliomas and Brain Tumors

Point

・脳腫瘍の低侵襲診断法liquid biopsyには，ddPCRによるctDNAの解析が有用である．

・ctDNAの検出精度を向上させるためには，脳脊髄液サンプル採取後に適正な処理が重要である．

・将来的には次世代シーケンスゲノムパネル検索や融合遺伝子解析が可能となると期待される．

　There is growing interest in liquid biopsy, the less-invasive detection of circulating tumor DNA（ctDNA）or circulating tumor cells（CTCs）from cerebrospinal fluid（CSF）and/or serum of patients, for the diagnosis of brain tumors. We share our experience of detecting hot spot point mutations using droplet digital PCR（ddPCR）in ctDNA obtained from the CSF of patients with brain tumors. The detection of mutations such as IDH1 R132H, BRAF V600E, and TERT promoter mutations in gliomas can be diagnostic. For optimal detection of ctDNA, which is only seen at very low concentrations, proper handling and storage of CSF, high-yield extraction of ctDNA, and usage of sensitive PCR methods for detection are imperative. We discuss which mutations can be assessed when diagnosing brain tumors, with a specific focus on gliomas. Finally, we look at what the near future holds for liquid biopsy of brain tumor patients, including next-generation sequencing panel analysis and accurate assessment of fusion genes.