Immune checkpoint inhibitors (ICIs) are commonly used to treat patients with advanced urothelial cancer. However, a significant number of patients do not respond to ICI, and the lack of validated predictive biomarkers impedes the success of the ICI strategy alone or in combination with chemotherapy or targeted therapies. In addition, some patients experience potentially severe adverse events with limited clinical benefit. Therefore, identifying biomarkers of response to ICI is crucial to guide treatment decisions. The most evaluated biomarkers to date are programmed death ligand 1 expression, microsatellite instability/defective mismatch repair phenotype, and tumor mutational burden. Other emerging biomarkers, such as circulating tumor DNA and microbiota, require evaluation in clinical trials. This review aims to examine these biomarkers for ICI response in urothelial cancer and assess their analytical and clinical validation.

中文翻译：

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尿路上皮癌免疫检查点抑制剂反应的预测生物标志物。

免疫检查点抑制剂（ICIs）通常用于治疗晚期尿路上皮癌患者。然而，大量患者对 ICI 没有反应，并且缺乏经过验证的预测生物标志物阻碍了单独 ICI 策略或与化疗或靶向治疗相结合的 ICI 策略的成功。此外，一些患者可能会经历严重的不良事件，但临床获益有限。因此，识别 ICI 反应的生物标志物对于指导治疗决策至关重要。迄今为止评估最多的生物标志物是程序性死亡配体 1 表达、微卫星不稳定性/缺陷错配修复表型和肿瘤突变负荷。其他新兴生物标志物，例如循环肿瘤 DNA 和微生物群，需要在临床试验中进行评估。本综述旨在检查这些尿路上皮癌 ICI 反应的生物标志物，并评估其分析和临床验证。