Predicting the response to PD-1/PD-L1 immune checkpoint blockade in patients with metastatic melanoma remains challenging. In this study, we have investigated for the relationships between PD-L1 expression, PD-L1 copy number variations, and the response to anti-PD-1 therapies. We studied the formalin-fixed paraffin-embedded tumor samples of 36 patients with metastatic melanoma using PD-L1 immunohistochemistry (IHC) and PD-L1/chromosome 9 fluorescent in situ hybridization (FISH). PD-L1 IHC was positive in 3 patients (8.33%, with >5% stained tumor cells) and PD-L1 FISH test revealed 5 (13.8%) PD-L1 amplifications, 8 (22.2%) PD-L1 gains, and 2 (5.5%) PD-L1 losses. Among 14 responders and 13 nonresponders to anti-PD-1 immunotherapy, we concluded that there was no significant relationship between PD-L1 expression, PD-L1 copy number variations, and the response to anti-PD-1 therapies. In our study, the determination of PD-L1 expression using IHC and PD-L1 copy number using FISH was insufficient to predict the response to PD-1/PD-L1 immune checkpoint blockade in patients with advanced melanomas.

中文翻译：

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PD-L1 拷贝数变异与晚期黑色素瘤患者的 PD-L1 表达或对抗 PD-1 免疫疗法的反应无关

预测转移性黑色素瘤患者对 PD-1/PD-L1 免疫检查点阻断的反应仍然具有挑战性。在这项研究中，我们调查了 PD-L1 表达、PD-L1 拷贝数变异和对抗 PD-1 疗法的反应之间的关系。我们使用 PD-L1 免疫组织化学 (IHC) 和 PD-L1/染色体 9 荧光原位杂交 (FISH) 研究了 36 名转移性黑色素瘤患者的福尔马林固定石蜡包埋肿瘤样本。3 名患者（8.33%，染色肿瘤细胞 >5%）的 PD-L1 IHC 呈阳性，PD-L1 FISH 检测显示 5 名（13.8%）PD-L1 扩增、8 名（22.2%）PD-L1 获得和 2 名(5.5%) PD-L1 损失。在抗 PD-1 免疫治疗的 14 名应答者和 13 名无应答者中，我们得出结论，PD-L1 表达、PD-L1 拷贝数变异、以及对抗 PD-1 疗法的反应。在我们的研究中，使用 IHC 确定 PD-L1 表达和使用 FISH 确定 PD-L1 拷贝数不足以预测晚期黑色素瘤患者对 PD-1/PD-L1 免疫检查点阻断的反应。