ERBB2 Amplification as a Predictive and Prognostic Biomarker in Upper Tract Urothelial Carcinoma

Abstract

Upper tract urothelial carcinomas (UTUCs) occur in about 5-10% of all urothelial carcinomas and are frequently discovered in high-stage disease. We aimed to evaluate human epidermal growth factor receptor 2 (ERBB2) protein expression immunohistochemically and ERBB2 amplification in UTUCs by fluorescence in situ hybridization, applying a tissue microarray technique. ERBB2 overexpression and ERBB2 amplification were defined according to the recommendations of the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) for breast cancer and gastric carcinoma (GC), revealing scores of 2+ and 3+ in 10.2% and 41.8% of UTUCs, respectively. The performance parameters showed obviously higher sensitivity of ERBB2 immunoscoring according to the ASCO/CAP criteria for GC. ERBB2 amplification was detected in 10.5% of UTUCs. ERBB2 overexpression was more likely to be found in high-grade tumors and was associated with tumor progression. Univariable Cox regression analysis revealed a significantly lower progression-free survival (PFS) in cases with ERBB2 immunoscores of 2+ or 3+ according to the ASCO/CAP guidelines for GC. UTUCs with ERBB2 amplification showed a significantly shorter PFS in the multivariable Cox regression analysis. Irrespective of their ERBB2 status, patients with UTUC treated with platin showed a significantly lower PFS than UTUC patients who had not received any platin-based therapy. In addition, UTUC patients with a normal ERBB2 gene status who had not received platin-based therapy showed significantly longer overall survival. The results suggest that ERBB2 is a biomarker for progression in UTUCs and may define a distinct subgroup of UTUCs. As previously shown, ERBB2 amplification is infrequent. However, the small number of patients diagnosed with ERBB2-amplified UTUC might benefit from ERBB2-targeted cancer therapy. In clinical-pathological routine diagnostics, the determination of ERBB2 amplification is an established method in some defined entities and also successful in small samples. Still, the simultaneous use of ERBB2 immunohistochemistry and ERBB2 in situ hybridization would be important in order to record the low rate of amplified UTUC cases as completely as possible.

Keywords: ERBB2; fluorescence in situ hybridization; survival analysis; tissue microarray; upper tract urothelial carcinoma.

Figure 1

ERBB2 protein expression and ERBB2 amplification in upper tract urothelial carcinoma. (A) Detail of solid and papillary high-grade (G3) UTUC (20×, hematoxylin and eosin). (B) In the same case, weak to moderate incomplete ERBB2 staining in >10% of tumor cells was seen (ERBB2/HER2 immunoscore of 2+ in accordance with ASCO/CAP 2017 guidelines for ERBB2/HER2 testing in GC). The heterogeneity of ERBB2 staining is illustrated (ERBB2 immunohistochemistry/DAKO, 40×). (C) FISH analysis revealed a low ERBB2 amplification rate with an ERBB2/CEN17 ratio of 2.55 and an average ERBB2 copy number of 6.45 (100×).

Figure 2

Survival analysis in upper tract urothelial carcinoma. (A) Upper tract urothelial carcinoma with ERBB2 amplification or gain displayed a trend toward shorter OS compared to UTUC without ERBB2 amplification or gain. (B) Comparing different groups, UTUC patients diagnosed with normal ERBB2 gene status and without adjuvant platin-based treatment showed a significantly longer OS. (C) There was a highly significant shorter PFS in UTUCs with ERBB2 immunoscores of 2+ and 3+ in contrast to UTUC with an ERBB2 immunoscore of 0 or 1+. (D) A significantly shorter PFS in UTUC with ERBB2 amplification compared to UTUC with normal ERBB2 gene status was revealed.