PURPOSE Biliary tract cancers (BTCs), particularly gallbladder carcinoma (GBC), are highly aggressive and exhibit significant geographical disparity, with a high incidence in Northern India. Human epidermal growth factor receptor 2 (HER2) amplification represents a key targetable alteration in a subset of patients. This study evaluates the real-world outcomes of trastuzumab in combination with chemotherapy for HER2-positive BTCs. METHODS A retrospective analysis of 91 patients with HER2-positive (immunohistochemistry 2+ amplified or 3+) BTCs was conducted. Patient characteristics and treatment details were summarized using descriptive statistics. The primary end points were progression-free survival (PFS) and overall survival (OS), estimated using the Kaplan-Meier method and compared with the log-rank test. RESULTS The median age was 50 years, with a female predominance (70.3%). Nearly all patients had GBC (98.9%) and HER2 3+ positivity (91.2%); 76.9% had metastatic disease. Trastuzumab was administered to 49 patients (53.8%), mostly in the first line (38.5%). The median PFS was 11.8 months (95% CI, 7.7 to 15.8) with trastuzumab versus 2.8 months (95% CI, 2.4 to 3.1) without ( P < .001). The median OS was 17.3 months (95% CI, 13.5 to 21.1) with trastuzumab versus 5.8 months (95% CI, 4.3 to 7.3) without ( P < .001). The 2-year OS rate was 32.7% for the trastuzumab group versus 11.8% for the control group. CONCLUSION In this real-world cohort from a high-incidence region, trastuzumab-based therapy was associated with a significant and clinically meaningful improvement in survival outcomes for HER2-positive BTCs. These findings strongly support routine HER2 testing and the integration of trastuzumab into the treatment arsenal for this molecularly defined subgroup.
Gupta et al. (Wed,) studied this question.