Department of Chemistry, Stanford University, Stanford, CA, USA.
Department of Chemical Engineering, Stanford University, Stanford, CA, USA.
Clin Chem. 2021 Mar 1;67(3):534-542. doi: 10.1093/clinchem/hvaa307.
Liquid biopsy circulating tumor DNA (ctDNA) mutational analysis holds great promises for precision medicine targeted therapy and more effective cancer management. However, its wide adoption is hampered by high cost and long turnaround time of sequencing assays, or by inadequate analytical sensitivity of existing portable nucleic acid tests to mutant allelic fraction in ctDNA.
We developed a ctDNA Epidermal Growth Factor Receptor (EGFR) mutational assay using giant magnetoresistive (GMR) nanosensors. This assay was validated in 36 plasma samples of non-small cell lung cancer patients with known EGFR mutations. We assessed therapy response through follow-up blood draws, determined concordance between the GMR assay and radiographic response, and ascertained progression-free survival of patients.
The GMR assay achieved analytical sensitivities of 0.01% mutant allelic fraction. In clinical samples, the assay had 87.5% sensitivity (95% CI = 64.0-97.8%) for Exon19 deletion and 90% sensitivity (95% CI = 69.9-98.2%) for L858R mutation with 100% specificity; our assay detected T790M resistance with 96.3% specificity (95% CI = 81.7-99.8%) with 100% sensitivity. After 2 weeks of therapy, 10 patients showed disappearance of ctDNA by GMR (predicted responders), whereas 3 patients did not (predicted nonresponders). These predictions were 100% concordant with radiographic response. Kaplan-Meier analysis showed responders had significantly (P < 0.0001) longer PFS compared to nonresponders (N/A vs. 12 weeks, respectively).
The GMR assay has high diagnostic sensitivity and specificity and is well suited for detecting EGFR mutations at diagnosis and noninvasively monitoring treatment response at the point-of-care.
液体活检循环肿瘤 DNA（ctDNA）突变分析为精准医学靶向治疗和更有效的癌症管理带来了巨大的希望。然而，由于测序分析的高成本和长周转时间，或者由于现有便携式核酸检测对 ctDNA 中突变等位基因分数的分析灵敏度不足，其广泛采用受到了阻碍。
我们使用巨磁电阻（GMR）纳米传感器开发了一种 ctDNA 表皮生长因子受体（EGFR）突变分析。该分析在 36 份已知 EGFR 突变的非小细胞肺癌患者的血浆样本中进行了验证。我们通过随访采血评估治疗反应，确定 GMR 分析与影像学反应的一致性，并确定患者的无进展生存期。
GMR 分析的分析灵敏度达到 0.01%突变等位基因分数。在临床样本中，该分析对 Exon19 缺失的敏感性为 87.5%（95%CI=64.0-97.8%），对 L858R 突变的敏感性为 90%（95%CI=69.9-98.2%），特异性为 100%；我们的分析检测 T790M 耐药的特异性为 96.3%（95%CI=81.7-99.8%），敏感性为 100%。在 2 周的治疗后，10 名患者的 GMR 检测到 ctDNA 消失（预测应答者），而 3 名患者没有（预测无应答者）。这些预测与影像学反应完全一致。Kaplan-Meier 分析显示，与无应答者相比，应答者的无进展生存期明显更长（分别为 N/A 与 12 周，P<0.0001）。
GMR 分析具有高诊断灵敏度和特异性，非常适合用于诊断时检测 EGFR 突变，并在护理点进行非侵入性监测治疗反应。
