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.