Feasibility of HER2-Targeted Therapy in Advanced Biliary Tract Cancer: A Prospective Pilot Study of Trastuzumab Biosimilar in Combination with Gemcitabine Plus Cisplatin

Simple Summary Unresectable or metastatic biliary tract cancer (BTC) has a poor prognosis with the standard gemcitabine and cisplatin (GemCis) regimen. Given the considerable incidence of HER2-overexpressing tumours (e.g., >10% of gallbladder cancer), HER2 is a potential therapeutic target in advanced BTC. In this prospective study, 7 out of 41 (17.1%) patients had HER2-positive tumours, and 4 patients (9.8%) subsequently proceeded to receive HER2-targeted therapy. The combination of trastuzumab-pkrb, an anti-HER2 monoclonal antibody, and GemCis resulted in high overall response (50%) and disease control (100%) rates in HER2-positive advanced BTC patients without new safety issues. This is the first prospective study that suggested the feasibility of HER2-targeted combination chemotherapy in advanced BTC patients. Future prospective randomised trials using HER2-targeted agents are warranted. The prognosis of advanced biliary tract cancer (BTC) is poor with the standard gemcitabine and cisplatin (GemCis) regimen. Given that the rates of human epidermal growth factor receptor 2 (HER2) positivity in BTC reaches around 15%, HER2-targeted therapy needs further investigation. This study aims to evaluate the preliminary efficacy/safety of first-line trastuzumab-pkrb plus GemCis in patients with advanced BTC. Patients with unresectable/metastatic HER2-positive BTC received trastuzumab-pkrb (on day 1 of each cycle, 8 mg/kg for the first cycle and 6 mg/kg for subsequent cycles), gemcitabine (1000 mg/m(2) on day 1 and 8) and cisplatin (25 mg/m(2) on day 1 and 8) every 3 weeks. Of the 41 patients screened, 7 had HER2-positive tumours and 4 were enrolled. The median age was 72.5 years (one male). Primary tumour locations included extrahepatic (N = 2) and intrahepatic (N = 1) bile ducts, and gallbladder (N = 1). Best overall response was a partial response in two patients and stable disease in two patients. Median progression-free survival (PFS) was 6.1 months and median overall survival (OS) was not reached. The most common grade 3 adverse event was neutropenia (75%), but febrile neutropenia did not occur. No patient discontinued treatment due to adverse events. Trastuzumab-pkrb with GemCis showed promising preliminary feasibility in patients with HER2-positive advanced BTC.

Automated summary

Unresectable or metastatic biliary tract cancer (BTC) has a poor prognosis with the standard gemcitabine and cisplatin (GemCis) regimen, but HER2-targeted therapy shows promising preliminary feasibility in patients with HER2-positive advanced BTC. This prospective study suggests the potential benefits of HER2-targeted combination chemotherapy in improving outcomes for patients with advanced BTC, warranting further investigation through future prospective randomised trials.