Background The majority of metastatic melanoma patients initially do not respond or acquire resistance to anti-programmed cell death 1 (PD-1) immunotherapy. Liquid biopsy biomarkers might provide useful early response information and allow for personalized treatment decisions. Methods We prospectively assessed circulating cell-free SHOX2 DNA methylation (SHOX2 ccfDNAm) levels and their dynamic changes in blood plasma of melanoma patients by quantitative methylation-specific polymerase chain reaction. Patients were treated with either palliative (n = 42) or adjuvant (n = 55) anti-PD-1 immunotherapy. Moreover, we included n = 126 control patients without evidence of malignant disease. We analyzed SHOX2 ccfDNAm status prior to and 4 weeks after palliative treatment initiation with regard to outcome [objective response, progression-free survival (PFS), and overall survival (OS)]. In the adjuvant setting, we associated longitudinal SHOX2 ccfDNAm status with disease recurrence. Results Sensitivity was 60% with 25/42 melanoma patients showing increased SHOX2 ccfDNAm levels, whereas specificity was 98% with 123/126 (P < 0.001) control patients having SHOX2 ccfDNAm levels below cut-off. Pretreatment SHOX2 ccfDNAm status did not correlate with outcome; however, SHOX2 ccfDNAm negativity 4 weeks after palliative treatment initiation was strongly associated with improved survival [PFS: hazard ratio (HR) = 0.25, P = 0.002; OS: HR = 0.12, P = 0.007]. Pretreatment positive patients who reached SHOX2 ccfDNAm clearance after 4 weeks of immunotherapy showed an exceptionally beneficial outcome. SHOX2 ccfDNAm testing allowed for an early detection of distant metastases in adjuvant-treated melanoma patients. Conclusions Our study suggests SHOX2 ccfDNAm to be an early predictor of outcome in anti-PD-1 treated melanoma patients. SHOX2 ccfDNAm testing may aid individualized treatment decision-making.

中文翻译：

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循环游离 SHOX2 DNA 甲基化是辅助和姑息性抗 PD-1 治疗黑色素瘤的预测、预后和监测生物标志物

背景 大多数转移性黑色素瘤患者最初对抗程序性细胞死亡 1 (PD-1) 免疫疗法没有反应或产生耐药性。液体活检生物标志物可能提供有用的早期反应信息并允许个性化的治疗决策。方法 我们通过定量甲基化特异性聚合酶链反应前瞻性评估黑色素瘤患者血浆中循环游离 SHOX2 DNA 甲基化 (SHOX2 ccfDNAm) 水平及其动态变化。患者接受姑息性 (n = 42) 或辅助 (n = 55) 抗 PD-1 免疫疗法。此外，我们纳入了 n = 126 名没有恶性疾病证据的对照患者。我们分析了姑息治疗开始前和开始后 4 周的 SHOX2 ccfDNAm 状态的结果 [客观缓解、无进展生存期 (PFS) 和总生存期 (OS)]。在辅助治疗中，我们将纵向 SHOX2 ccfDNAm 状态与疾病复发相关联。结果 25/42 名黑色素瘤患者显示 SHOX2 ccfDNAm 水平升高，敏感性为 60%，而特异性为 98%，123/126 (P < 0.001) 对照患者的 SHOX2 ccfDNAm 水平低于截止值。治疗前 SHOX2 ccfDNAm 状态与结果无关；然而，姑息治疗开始后 4 周，SHOX2 ccfDNAm 阴性与生存率改善密切相关[PFS：风险比 (HR) = 0.25，P = 0.002； OS：HR = 0.12，P = 0.007]。经过 4 周免疫治疗后达到 SHOX2 ccfDNAm 清除率的治疗前阳性患者显示出异常有益的结果。 SHOX2 ccfDNAm 测试可以及早发现接受辅助治疗的黑色素瘤患者的远处转移。结论 我们的研究表明 SHOX2 ccfDNAm 是抗 PD-1 治疗黑色素瘤患者预后的早期预测因子。 SHOX2 ccfDNAm 测试可能有助于个体化治疗决策。