轉移性泌尿道上皮癌 (metastatic urothelial carcinoma, mUC) 經第一線使用含鉑類 (platinum) 化療失敗後，後續治療藥物的效果並不理想。2016 年5 月至2017 年5月，美國食品藥物管理局 (Food and Drug Administration, FDA) 陸續核准5 個免疫檢查點抑制劑 (immune checkpoint inhibitors, ICIs) 用於治療mUC，其藥物機轉是作用於programmed cell death protein 1 (PD-1) 或programmed cell death ligand 1 (PD-L1)。這5 個ICIs 為atezolizumab、durvalumab、avelumab、nivolumab、pembrolizumab，它們皆被核准用於mUC 第二線及其後線治療，其中atezolizumab 和pembrolizumab亦核准可作為不適合以cisplatin 為起始治療之mUC 病人的第一線藥物。本文將總結這5 個ICIs 治療mUC的臨床試驗，檢視其療效和安全性，以及探討PD-L1 表現百分比做為生物標記 (biomarker) 的限制。

The efficacy of subsequent systemic therapy in patients with metastatic urothelial carcinoma (mUC) is reduced after failure of first-line platinum-based chemotherapy. From May 2016 to May 2017, U.S. Food and Drug Administration (FDA) successively approved five immune checkpoint inhibitors (ICIs) of programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) blockade, including atezolizumab, durvalumab, avelumab, nivolumab, and pembrolizumab as second-line therapy and beyond for mUC treatment. The U.S. FDA also approved atezolizumab and pembrolizumab for first-line therapy in cisplatin-ineligible patients with mUC. This article summarizes the efficacy and safety of the five ICIs in the mUC clinical trials, and discuss the limitations of the PD-L1 expression as a biomarker.