Ziihera (zanidatamab-hrii) is a targeted therapy for HER2-positive biliary tract cancer (BTC) that has metastasized or cannot be surgically removed after prior treatment. It is a bispecific HER2-directed antibody that binds to two sites on HER2, reducing receptor presence on tumor cells and triggering immune responses that inhibit tumor growth and cause cancer cell death. Ziihera is administered as an intravenous infusion every two weeks and is not chemotherapy.