BACKGROUND Longitudinal evaluation of mutations in blood samples was a pre-specified secondary objective in the BELIEF trial of erlotinib/bevacizumab in advanced EGFR-positive NSCLC. Here we report the testing results and explore the correlation of EGFR status in blood with clinical outcomes. METHODS Blood samples were prospectively collected from patients at baseline, response evaluation and progression and sent to a central laboratory. Circulating free DNA (cfDNA) was purified and EGFR mutations were analyzed with a validated real-time quantitative PCR assay. RESULTS EGFR exon-19/21 mutations were detected in 55/91 (60.4%) baseline blood samples and correlated with a significantly worse PFS: 11.4m (95%CI:9.0-14.8m) for the positive patients vs. 22.9m (95%CI:9.5-33.9m) for the negatives, (log-rank.p=0.0020). Among the 74 samples at response, exon-19/21 mutations were detected only in three cases (4.1%). In contrast, 29/58 patients (50.0%) were exon 19/21 positive at progression and showed a significantly worse median OS of 21.7m (95%CI:17.0-30.9m), compared to 37.4m (95%CI:22.6-53.1m) for negatives (log-rank.p=0.011). Blood samples at the three timepoints were available for 48 patients. Of those, among 14 exon-19/21 EGFR-negative at presentation, 13 (93%) were persistently negative for the sensitizing mutations after progression and the p.T790M could only be detected in the blood of two. CONCLUSIONS Longitudinal testing of EGFR mutations in blood can offer valuable clinical information. In patients of the BELIEF study, detection of EGFR mutations in cfDNA at presentation was associated with shorter PFS, while positivity at progression correlated with shorter OS. Finally, patients negative in blood at presentation were almost invariably negative at relapse.

中文翻译：

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BELIEF 试验中循环游离 DNA 中 EGFR 突变的演变和临床影响

背景 在厄洛替尼/贝伐单抗治疗晚期 EGFR 阳性 NSCLC 的 BELIEF 试验中，血液样本中突变的纵向评估是预先指定的次要目标。在这里，我们报告测试结果并探讨血液中 EGFR 状态与临床结果的相关性。方法 前瞻性地从基线、反应评估和进展时的患者收集血液样本，并将其送往中心实验室。纯化循环游离 DNA (cfDNA) 并使用经验证的实时定量 PCR 检测分析 EGFR 突变。结果 在 55/91 (60.4%) 基线血液样本中检测到 EGFR exon-19/21 突变，并且与显着更差的 PFS 相关：阳性患者为 11.4m（95%CI：9.0-14.8m）与 22.9m（ 95%CI:9.5-33.9m) 为负数，(log-rank.p=0.0020)。在响应时的 74 个样本中，仅在 3 例 (4.1%) 中检测到外显子 19/21 突变。相比之下，29/58 患者 (50.0%) 在进展时外显子 19/21 呈阳性，中位 OS 为 21.7m（95%CI：17.0-30.9m），而 37.4m（95%CI：22.6 -53.1m) 为负数 (log-rank.p=0.011)。3 个时间点的血液样本可供 48 名患者使用。其中，在就诊时 14 个外显子 19/21 EGFR 阴性的患者中，13 个（93%）在进展后的致敏突变持续呈阴性，并且 p.T790M 只能在两个人的血液中检测到。结论 血液中 EGFR 突变的纵向检测可以提供有价值的临床信息。在 BELIEF 研究的患者中，就诊时检测到 cfDNA 中的 EGFR 突变与较短的 PFS 相关，而进展时的阳性与较短的 OS 相关。最后，