The pretreatment neutrophil-to-lymphocyte ratio is a novel biomarker for predicting clinical responses to pembrolizumab in platinum-resistant metastatic urothelial carcinoma patients.

<bold>Purpose: </bold>We investigated the relationship between pretreatment neutrophil-to-lymphocyte ratio (pre-NLR) levels just before the initiation of treatment with pembrolizumab and clinical outcomes in platinum-resistant metastatic urothelial carcinoma (UC) patients treated with pembrolizumab.<bold>Methods: </bold>Our study population comprised 78 patients diagnosed with metastatic UC and treated with pembrolizumab after platinum-based chemotherapy at our institutions between December 2017 and April 2019. We examined the relationships between pre-NLR levels just before pembrolizumab treatment and clinical outcomes. A pre-NLR level of ≥3.35 was defined as elevated according to a calculation by a receiver-operating curve analysis.<bold>Results: </bold>The high pre-NLR group consisted of 33 patients (42.3%). Overall, 29.5% of patients had a clinical response and the sum of the target lesion longest diameter was decreased in 18.8% of the high pre-NLR group, which was significantly lower than that in the low pre-NLR group (58.1%, P = 0.005). Six-month progression-free survival and cancer-specific survival rates for the high pre-NLR group were 9.1 and 58.0%, which were significantly lower than those for their counterpart (45.9 and 89.1%, P < 0.001 and P = 0.002, respectively). The pre-NLR level was an independent indicator of disease progression and cancer-specific death (P < 0.001 and P = 0.003). Furthermore, patients with a postpembrolizumab NLR level that had decreased ≥25% from the pre-NLR level had significantly lower disease progression and cancer-specific death rates than their counterparts (P = 0.01 and P = 0.022, respectively).<bold>Conclusions: </bold>Elevated pre-NLR may be a novel biomarker for identifying poor responders to pembrolizumab among platinum-resistant metastatic UC patients. [ABSTRACT FROM AUTHOR]