Memorial Sloan Kettering Cancer Center, New York, NY, USA.
ETH Zurich, Basel, Switzerland.
Cancer Med. 2020 Sep;9(17):6093-6101. doi: 10.1002/cam4.3144. Epub 2020 Jul 7.
The enucleation rate for retinoblastoma has dropped from over 95% to under 10% in the past 10 years as a result of improvements in therapy. This reduces access to tumor tissue for molecular profiling, especially in unilateral retinoblastoma, and hinders the confirmation of somatic RB1 mutations necessary for genetic counseling. Plasma cell-free DNA (cfDNA) has provided a platform for noninvasive molecular profiling in cancer, but its applicability in low tumor burden retinoblastoma has not been shown. We analyzed cfDNA collected from 10 patients with available tumor tissue to determine whether sufficient tumorderived cfDNA is shed in plasma from retinoblastoma tumors to enable noninvasive RB1 mutation detection.
Tumor tissue was collected from eye enucleations in 10 patients diagnosed with advanced intra-ocular unilateral retinoblastoma, three of which went on to develop metastatic disease. Tumor RB1 mutation status was determined using an FDA-cleared tumor sequencing assay, MSK-IMPACT. Plasma samples were collected before eye enucleation and analyzed with a customized panel targeting all exons of RB1.
Tumor-guided genotyping detected 10 of the 13 expected somatic RB1 mutations in plasma cfDNA in 8 of 10 patients (average variant allele frequency 3.78%). Without referring to RB1 status in the tumor, de novo mutation calling identified 7 of the 13 expected RB1 mutations (in 6 of 10 patients) with high confidence.
Plasma cfDNA can detect somatic RB1 mutations in patients with unilateral retinoblastoma. Since intraocular biopsies are avoided in these patients because of concern about spreading tumor, cfDNA can potentially offer a noninvasive platform to guide clinical decisions about treatment, follow-up schemes, and risk of metastasis.
由于治疗方法的改进，过去 10 年来，视网膜母细胞瘤的眼内容剜除率已从超过 95%降至 10%以下。这使得肿瘤组织进行分子分析的机会减少，尤其是在单侧视网膜母细胞瘤中，并且阻碍了遗传咨询所需的体细胞 RB1 突变的确认。无细胞游离 DNA（cfDNA）为癌症的非侵入性分子分析提供了一个平台，但它在低肿瘤负荷的视网膜母细胞瘤中的适用性尚未得到证实。我们分析了来自 10 名有肿瘤组织可供分析的患者的 cfDNA，以确定在来自视网膜母细胞瘤肿瘤的血浆中是否有足够的肿瘤衍生 cfDNA 脱落，从而能够进行非侵入性 RB1 突变检测。
从 10 名诊断为晚期眼内单侧视网膜母细胞瘤的患者的眼球摘除术中采集肿瘤组织，其中 3 例随后发生转移性疾病。使用经 FDA 批准的肿瘤测序检测（MSK-IMPACT）来确定肿瘤 RB1 突变状态。在眼球摘除术前采集血浆样本，并使用靶向 RB1 所有外显子的定制面板进行分析。
肿瘤指导的基因分型在 10 名患者中的 8 名（平均变异等位基因频率为 3.78%）中检测到了血浆 cfDNA 中 13 个预期的体细胞 RB1 突变中的 10 个。在不参考肿瘤中 RB1 状态的情况下，新突变检测以高可信度在 10 名患者中的 6 名中鉴定出了 13 个预期的 RB1 突变中的 7 个。
血浆 cfDNA 可检测单侧视网膜母细胞瘤患者的体细胞 RB1 突变。由于这些患者由于担心肿瘤扩散而避免了眼内活检，cfDNA 可能为指导治疗、随访方案和转移风险的临床决策提供非侵入性平台。
