The Medicines and Healthcare products Regulatory Agency (MHRA) has approved zanidatamab, marketed as Ziihera, for the treatment of adults with advanced biliary tract cancer whose tumours express high levels of the HER2 protein and have progressed following prior therapy.
The decision, announced on 19 February 2026, provides a new treatment option for patients with locally advanced or metastatic disease that cannot be removed surgically and has spread to surrounding tissues or distant organs. Biliary tract cancer affects the structures responsible for storing and transporting bile, including the bile ducts and gallbladder.
Zanidatamab is administered intravenously once every two weeks. The approval is based on findings from a clinical study involving 80 patients with unresectable, locally advanced or metastatic biliary tract cancer. Among the 62 patients whose tumours had high HER2 expression, approximately 52% experienced tumour shrinkage or complete disappearance of detectable disease after an average follow-up period of 34 months.
The study was single-arm and did not include a comparison with placebo or another active treatment.
The regulator stated that zanidatamab addresses an unmet clinical need in a patient population with limited therapeutic options after disease progression. As with all authorised medicines, the MHRA will continue to monitor the safety and effectiveness of the therapy in routine clinical use.
