Laboratory of Circulating Tumor Biomarkers, Institut Curie, PSL Research University, SiRIC, Paris, France.
Department of Medical Oncology, San Gerardo Hospital, Monza, Italy.
Clin Chem. 2017 Mar;63(3):691-699. doi: 10.1373/clinchem.2016.262337. Epub 2017 Jan 10.
In nonmetastatic triple-negative breast cancer (TNBC) patients, we investigated whether circulating tumor DNA (ctDNA) detection can reflect the tumor response to neoadjuvant chemotherapy (NCT) and detect minimal residual disease after surgery.
Ten milliliters of plasma were collected at 4 time points: before NCT; after 1 cycle; before surgery; after surgery. Customized droplet digital PCR (ddPCR) assays were used to track tumor protein p53 () mutations previously characterized in tumor tissue by massively parallel sequencing (MPS).
Forty-six patients with nonmetastatic TNBC were enrolled. mutations were identified in 40 of them. Customized ddPCR probes were validated for 38 patients, with excellent correlation with MPS ( = 0.99), specificity (≥2 droplets/assay), and sensitivity (at least 0.1%). At baseline, ctDNA was detected in 27/36 patients (75%). Its detection was associated with mitotic index ( = 0.003), tumor grade ( = 0.003), and stage ( = 0.03). During treatment, we observed a drop of ctDNA levels in all patients but 1. No patient had detectable ctDNA after surgery. The patient with rising ctDNA levels experienced tumor progression during NCT. Pathological complete response (16/38 patients) was not correlated with ctDNA detection at any time point. ctDNA positivity after 1 cycle of NCT was correlated with shorter disease-free ( < 0.001) and overall ( = 0.006) survival.
Customized ctDNA detection by ddPCR achieved a 75% detection rate at baseline. During NCT, ctDNA levels decreased quickly and minimal residual disease was not detected after surgery. However, a slow decrease of ctDNA level during NCT was strongly associated with shorter survival.
在非转移性三阴性乳腺癌（TNBC）患者中，我们研究了循环肿瘤 DNA（ctDNA）检测是否能反映肿瘤对新辅助化疗（NCT）的反应，并在手术后检测微小残留病灶。
在 4 个时间点采集 10 毫升血浆：NCT 前；1 个周期后；手术前；手术后。使用定制的液滴数字 PCR（ddPCR）检测方法来跟踪肿瘤组织中通过大规模平行测序（MPS）之前表征的肿瘤蛋白 p53（）突变。
共纳入 46 例非转移性 TNBC 患者。其中 40 例存在突变。对 38 例患者进行了定制 ddPCR 探针验证，与 MPS 具有极好的相关性（=0.99），特异性（≥2 个液滴/检测）和敏感性（至少 0.1%）。在基线时，36 例患者中有 27 例（75%）检测到 ctDNA。其检测与有丝分裂指数（=0.003）、肿瘤分级（=0.003）和分期（=0.03）相关。在治疗过程中，我们观察到所有患者的 ctDNA 水平均下降，但有 1 例患者除外。在 NCT 期间，1 例 ctDNA 水平升高的患者出现肿瘤进展。病理完全缓解（38 例患者中有 16 例）与任何时间点的 ctDNA 检测均无相关性。NCT 第 1 周期后的 ctDNA 阳性与无病生存期（<0.001）和总生存期（=0.006）较短相关。
通过 ddPCR 进行定制的 ctDNA 检测在基线时的检出率为 75%。在 NCT 期间，ctDNA 水平迅速下降，手术后未检测到微小残留病灶。然而，NCT 期间 ctDNA 水平的缓慢下降与较短的生存时间密切相关。
