Department of Pathology, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway.
Department of Clinical and Molecular Medicine, NTNU, Norwegian University of Technology and Science, Trondheim, Norway.
J Pathol Clin Res. 2021 May;7(3):209-219. doi: 10.1002/cjp2.200. Epub 2021 Jan 27.
Droplet digital polymerase chain reaction (ddPCR) is a highly sensitive and accurate method for quantification of nucleic acid sequences. We used absolute quantification of mutated v-Ki-ras2 Kirsten rat sarcoma viral oncogene homology gene (KRAS) by ddPCR to investigate the prognostic role of mutated KRAS in patients with KRAS-mutated lung adenocarcinomas. Pre-treatment plasma samples from 60 patients with stages I-IV KRAS-mutated lung adenocarcinomas were analysed for KRAS mutations. The associations between survival, detectable KRAS mutations in plasma, and the plasma concentration of mutated KRAS were assessed. Overall, 23 of 60 (38%) patients had detectable KRAS mutation in plasma. The percentage of patients with detectable mutation was 8% in stage I, 30% in stage II, 71% in stage III, and 73% in stage IV. Estimated overall median progression-free survival (PFS) and overall survival (OS) were 26.2 months [95% confidence interval (CI) 12.5-39.9] and 50.8 months (95% CI 0-107.3), respectively. Patients with detectable mutations in plasma had significantly worse median PFS compared to patients with undetectable mutation (13.1 versus 70.1 months) and shorter median OS (20.7 versus not reached). High circulating tumour DNA (ctDNA) concentrations of mutated KRAS were significantly associated with shorter PFS [hazard ratio (HR) 1.008, 95% CI 1.004-1.012] and OS (HR 1.007, 95% CI 1.003-1.011). All associations remained statistically significant in multivariable analyses. In conclusion, ddPCR is an accurate and easily feasible technique for quantification of KRAS mutations in ctDNA. The presence of detectable KRAS mutation in plasma at baseline was associated with worse PFS and OS. High concentration of mutated KRAS in ctDNA was an independent negative prognostic factor for both PFS and OS.
液滴数字聚合酶链反应（ddPCR）是一种高度敏感和准确的方法，用于定量核酸序列。我们使用 ddPCR 对突变的 v-Ki-ras2 Kirsten 大鼠肉瘤病毒癌基因同源基因（KRAS）进行绝对定量，以研究突变的 KRAS 在 KRAS 突变型肺腺癌患者中的预后作用。分析了 60 例 I-IV 期 KRAS 突变型肺腺癌患者的治疗前血浆样本，以检测 KRAS 突变。评估了生存、血浆中可检测到的 KRAS 突变与血浆中突变 KRAS 浓度之间的关系。总体而言，60 例患者中有 23 例（38%）在血浆中检测到 KRAS 突变。I 期、II 期、III 期和 IV 期患者中可检测到突变的比例分别为 8%、30%、71%和 73%。估计的总中位无进展生存期（PFS）和总生存期（OS）分别为 26.2 个月[95%置信区间（CI）12.5-39.9]和 50.8 个月（95%CI 0-107.3）。血浆中可检测到突变的患者与未检测到突变的患者相比，中位 PFS 明显更差（13.1 与 70.1 个月），OS 更短（20.7 与未达到）。高循环肿瘤 DNA（ctDNA）中突变的 KRAS 浓度与较短的 PFS 显著相关[风险比（HR）1.008，95%CI 1.004-1.012]和 OS（HR 1.007，95%CI 1.003-1.011）。多变量分析仍显示所有关联均具有统计学意义。总之，ddPCR 是一种准确且易于实施的 ctDNA 中 KRAS 突变定量技术。基线时血浆中可检测到 KRAS 突变与较差的 PFS 和 OS 相关。ctDNA 中高浓度突变的 KRAS 是 PFS 和 OS 的独立负预后因素。
