Introduction: Circulating tumor DNA analysis is an emerging genotyping strategy that can identify tumor‐specific genetic alterations in plasma including mutations and rearrangements. Detection of ROS1 fusions in plasma requires genotyping approaches that cover multiple breakpoints and target a variety of fusion partners. Compared to other molecular subsets of NSCLC, experience with detecting ROS1 genetic alterations in plasma is limited. Methods: To describe the spectrum of ROS1 fusions in NSCLC and determine sensitivity for detecting ROS1 fusions in plasma, we queried the Guardant Health plasma dataset and an institutional tissue database and compared plasma findings to tissue results. In addition, we used the Guardant360 NGS assay to detect potential genetic mediators of resistance in plasma from patients with ROS1‐positive NSCLC who were relapsing on crizotinib. Results: We detected seven distinct fusion partners in plasma, most of which (n = 6 of 7) were also represented in the tissue dataset. Fusions pairing CD74 with ROS1 predominated in both cohorts (plasma: n = 35 of 56, 63%; tissue: n = 26 of 52, 50%). There was 100% concordance between the specific tissue‐ and plasma‐detected ROS1 fusion for seven patients genotyped with both methods. Sensitivity for detecting ROS1 fusions in plasma at relapse on ROS1‐directed therapy was 50%. Six (33%) of 18 post‐crizotinib plasma specimens harbored ROS1 kinase domain mutations, five of which were ROS1 G2032R. Two (11%) post‐crizotinib plasma specimens had genetic alterations (n = 1 each BRAF V600E and PIK3CA E545K) potentially associated with ROS1‐independent signaling. Conclusions: Plasma genotyping captures the spectrum of ROS1 fusions observed in tissue. Plasma genotyping is a promising approach to detecting mutations that drive resistance to ROS1‐directed therapies.

中文翻译：

---

ROS1 阳性非小细胞肺癌患者血浆的分子分析

简介：循环肿瘤 DNA 分析是一种新兴的基因分型策略，可以识别血浆中肿瘤特异性基因改变，包括突变和重排。检测血浆中的 ROS1 融合需要覆盖多个断点并针对各种融合伙伴的基因分型方法。与非小细胞肺癌的其他分子亚群相比，检测血浆中 ROS1 基因改变的经验是有限的。方法：为了描述 NSCLC 中 ROS1 融合的谱并确定检测血浆中 ROS1 融合的灵敏度，我们查询了 Guardant Health 血浆数据集和机构组织数据库，并将血浆结果与组织结果进行了比较。此外，我们使用 Guardant360 NGS 检测检测了克唑替尼复发的 ROS1 阳性 NSCLC 患者血浆中潜在的耐药性遗传介质。结果：我们在血浆中检测到七个不同的融合伙伴，其中大部分（n = 6 个，共 7 个）也出现在组织数据集中。CD74 与 ROS1 配对的融合在两个队列中占主导地位（血浆：n = 56 中的 35，63%；组织：52 中的 n = 26，50%）。对于使用两种方法进行基因分型的 7 名患者，特定组织和血浆检测到的 ROS1 融合之间有 100% 的一致性。在 ROS1 定向治疗复发时检测血浆中 ROS1 融合的灵敏度为 50%。18 份克唑替尼后血浆样本中有 6 份（33%）含有 ROS1 激酶结构域突变，其中 5 份是 ROS1 G2032R。两个 (11%) 克唑替尼后血浆样本具有可能与 ROS1 独立信号传导相关的基因改变（BRAF V600E 和 PIK3CA E545K 各 n = 1）。结论：血浆基因分型可捕获组织中观察到的 ROS1 融合谱。血浆基因分型是检测导致对 ROS1 导向疗法产生抗性的突变的一种很有前景的方法。