High T-cell infiltration in tumor tissue and younger age predict the response to pembrolizumab in recurrent urothelial cancer.

Targeting the programmed cell death-1 signaling pathway has been approved for the anti-cancer therapy in several cancers including urothelial cancer. To determine predictive factors of the responsiveness to pembrolizumab in urothelial cancer patients, a retrospective study that used clinical information and paraffin-embedded samples obtained from patients diagnosed with urothelial cancer between 2015 and 2020 were performed. Seventeen patients who underwent total cystectomy or nephroureterectomy of the primary lesion and were treated with pembrolizumab for chemo-resistant disease were enrolled, and immunohistochemical analysis was performed. A key difference in the characteristics between the non-responder group and the responder group was the age of the patients (74 vs. 63 years, p = 0.0194). Although there was no statistically significant difference, the histological subtype with sarcomatoid and micropapillary components was only seen in the non-responder group, and squamous differentiation and lymph node metastasis were only seen in cases with a complete response. In the results of immunohistochemistry, the density of CD8-positive T-cells and Tregs was significantly increased in the responder group than in the non-responder group. In conclusion, younger age and a high number of tumor-infiltrating lymphocytes were predictive factors of a good response to immune checkpoint inhibitors, although further studies with more enrolled patients are necessary.