Department of Medical Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands.
Department of Neurology, The Brain Tumor Center at Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands.
Clin Cancer Res. 2021 May 15;27(10):2798-2806. doi: 10.1158/1078-0432.CCR-20-3954. Epub 2021 Jan 29.
Detection of leptomeningeal metastasis is hampered by limited sensitivities of currently used techniques: MRI and cytology of cerebrospinal fluid (CSF). Detection of cell-free tumor DNA in CSF has been proposed as a tumor-specific candidate to detect leptomeningeal metastasis at an earlier stage. The aim of this study was to investigate mutation and aneuploidy status in CSF-derived cell-free DNA (cfDNA) of patients with breast cancer with a clinical suspicion of leptomeningeal metastasis.
cfDNA was isolated from stored remnant CSF and analyzed by targeted next-generation sequencing (NGS; = 30) and the modified fast aneuploidy screening test-sequencing system (mFAST-SeqS; = 121). The latter method employs selective amplification of long interspaced nuclear elements sequences that are present throughout the genome and allow for fast and cheap detection of aneuploidy. We compared these results with the gold standard to diagnose leptomeningeal metastasis: cytology.
Leptomeningeal metastasis was cytology proven in 13 of 121 patients. Low DNA yields resulted in insufficient molecular coverage of NGS for the majority of samples (success rate, 8/30). The mFAST-SeqS method, successful in 112 of 121 (93%) samples, detected genome-wide aneuploidy in 24 patients. Ten of these patients had cytology-proven leptomeningeal metastasis; 8 additional patients were either concurrently diagnosed with central nervous system metastases by radiological means or developed these soon after the lumbar puncture. The remaining six cases were suspected of leptomeningeal metastasis, but could not be confirmed by cytology or imaging. Aneuploidy was associated with development of leptomeningeal metastasis and significantly worse overall survival.
Aneuploidy in CSF-derived cfDNA may provide a promising biomarker to improve timely detection of leptomeningeal metastasis.
目前使用的技术（MRI 和脑脊液细胞学）对检测脑膜转移的灵敏度有限，这一问题限制了脑膜转移的检测。人们已经提出检测脑脊液中无细胞肿瘤 DNA 作为一种肿瘤特异性候选物，以更早地检测脑膜转移。本研究旨在调查怀疑脑膜转移的乳腺癌患者脑脊液中游离细胞 DNA (cfDNA) 的突变和非整倍体状态。
从储存的残余 CSF 中分离 cfDNA，并用靶向下一代测序（NGS；n=30）和改良快速非整倍体筛选-测序系统（mFAST-SeqS；n=121）进行分析。后一种方法采用长散布核元件序列的选择性扩增，这些序列存在于整个基因组中，允许快速且廉价地检测非整倍体。我们将这些结果与诊断脑膜转移的金标准（细胞学）进行了比较。
121 例患者中有 13 例经细胞学证实为脑膜转移。由于 DNA 产量低，大多数样本的 NGS 分子覆盖率不足（成功率为 8/30）。mFAST-SeqS 方法在 121 例样本中的 112 例（93%）中成功，在 24 例患者中检测到全基因组非整倍体。这 10 例患者经细胞学证实有脑膜转移；另外 8 例患者通过影像学检查同时诊断为中枢神经系统转移，或在腰椎穿刺后很快出现这些转移。其余 6 例患者怀疑有脑膜转移，但无法通过细胞学或影像学检查证实。非整倍体与脑膜转移的发生和总生存显著相关。
CSF 衍生 cfDNA 中的非整倍体可能提供一个有前途的生物标志物，以提高脑膜转移的及时检测。
