HER2 gene (ERBB2) amplification is a low-frequency driver with potential predictive value in gallbladder carcinoma

Area of Science:

• Oncology
• Gastroenterology
• Molecular Biology

Background:

• Gallbladder carcinoma (GBC) is an aggressive malignancy with poor outcomes.
• Human epidermal growth factor receptor 2 (HER2) is a potential therapeutic target in biliary tract cancers, but its prevalence in GBC is unclear.

Purpose of the Study:

• To determine the frequency of HER2 positivity in a large European cohort of gallbladder adenocarcinoma.
• To investigate the clinical significance of HER2 status in GBC.
• To explore the role of HER2 amplification in early gallbladder carcinogenesis.

Main Methods:

• HER2 status was assessed in 186 gallbladder adenocarcinomas and 74 high-grade biliary intraepithelial neoplasias (BilIN) using immunohistochemistry and in situ hybridization.
• Testing followed current consensus guidelines for HER2 detection in gastric cancer.

Main Results:

• HER2 positivity was found in 5.4% (10/186) of GBC cases.
• HER2 amplification was observed in precursor lesions (high-grade BilIN) in some cases.
• HER2-positive GBC cases were more advanced (predominantly Stage IV) and showed a trend towards poorer survival.
• One patient with metastatic GBC achieved near-complete remission with dual HER2 inhibition therapy.

Conclusions:

• HER2 positivity is infrequent in GBC but may represent an early event in tumorigenesis.
• Targeted HER2 inhibition shows promise, as evidenced by a case report of significant clinical response.
• Further research, including prospective trials, is warranted to confirm HER2 status and evaluate targeted therapies in GBC.