Expression and clinicopathologic significance of HER2 and PD-L1 in high grade urothelial carcinoma of the urinary tract.

Background: Urothelial carcinoma (UC) is an aggressive tumor with high recurrence rates and poses a great challenge for clinical management. Programmed death ligand-1 (PD-L1) inhibitors and human epidermal growth factor receptor 2 (HER2) blockers have been approved for the treatment of advanced urothelial carcinoma. PD-L1 and HER2 expression in UC will determine whether patients are likely to respond to these targeted treatments. This study assessed the expressions of HER2 and PD-L1 in UC at our institution and investigated their correlations with gender, tumor location (upper genitourinary (GU) tract vs. lower GU tract), tumor stage, and histologic divergent subtypes.

Design: Patients with UC who had PD-L1 or HER2 immunostains performed in the past 3 years at our institution were included in our analysis. A total of 97 cases were identified. PD-L1 and HER2 scores were provided by two experienced GU pathologists. HER2 scores were given according to the criteria used in breast cancer, while PD-L1 scores were reported as the combined positive score. We assessed correlation of the scores with the patients' gender, tumor location, tumor stage, and histologic divergent subtypes. The data for PD-L1 expression were analyzed using the Mann-Whitney U Test for gender and urinary tract location, and one-way analysis of variance (ANOVA) for stage and histology. The data for HER2 expression were analyzed using the chi-square test. For all analyses, significance was set at P<0.05.

Results: Of the 97 patients, the average age was 69 years. There were 95 patients who had previously reported HER2 results and 86 patients who had PD-L1 results. PD-L1 expression did not show a significant difference among the histological divergent subtypes (P=0.36). However, HER2 status exhibited a significant difference, with more HER2-positive cases observed in the conventional histology (P=0.008). No correlation between HER2 status and either gender or tumor stage was identified. The median PD-L1 combined positive score was significantly higher in lower urinary tract UC than upper (10 and 2, respectively; P=0.049). No significant differences were observed for gender or pathologic stage.

Conclusion: Our data suggest that HER2 is more frequently expressed in conventional UC than in divergent subtypes. Additionally, PD-L1 has a higher expression level in lower urinary tract UC compared to upper. However, PD-L1 and HER2 expression are not related to gender or tumor stage in UC.