Trastuzumab Plus Chemotherapy vs Chemotherapy Alone in First-line HER2 Positive Advanced Biliary Tract Cancer Patients

This is a randomized, open-label, two-arm, Phase III clinical trial evaluating the efficacy and safety of trastuzumab plus chemotherapy versus chemotherapy alone as first-line treatment in patients with HER2-positive advanced or metastatic biliary tract cancers (BTC). HER2-positive BTCs represent a molecular subset of these rare cancers, associated with poor prognosis and limited treatment options. Eligible patients with histologically confirmed HER2-positive (IHC 3+ or IHC 2+ with FISH amplification) unresectable or metastatic biliary tract adenocarcinoma-including gallbladder cancer, intrahepatic, and perihilar cholangiocarcinoma-will be randomized in a 1:1 ratio. Participants in the intervention arm (Arm A) will receive either gemcitabine and cisplatin with or without nab-paclitaxel plus trastuzumab, while those in the control arm (Arm B) will receive chemotherapy alone (gemcitabine + cisplatin with or without nab-paclitaxel). Treatment will continue until disease progression, unacceptable toxicity, withdrawal of consent, or death. The primary endpoint is 6-month progression-free survival (PFS). Secondary endpoints include overall survival (OS), response rate (RR), quality of life (QOL), and adverse event (AE) profiles. The study aims to enroll 196 patients across a single center in India over a period of 5 years, with an additional 6-month follow-up. This trial builds on earlier Phase II findings suggesting improved outcomes with trastuzumab in HER2-positive BTC and aims to provide the first randomized evidence for the benefit of HER2-targeted therapy in this setting.