Jazz Pharmaceuticals has received conditional marketing authorisation from the European Commission (EC) for its new bispecific antibody, Ziihera (zanidatamab), for biliary tract cancer (BTC).

The dual human epidermal growth factor receptor 2 (HER2)-targeted antibody is authorised as a single agent in adults with unresectable locally advanced or metastatic HER2-positive (IHC 3+) BTC.

These individuals had previously received at least one line of systemic therapy.

Zanidatamab is administered intravenously every two weeks, with a recommended dose of 20mg/kg until disease progression or unacceptable toxicity occurs.

The approval of Ziihera extends across European Union (EU) member states along with Norway, Iceland and Liechtenstein.

The EC's decision marks Ziihera as the first conditionally authorised therapy targeting HER2-positive BTC within the EU.

Continuation of this approval depends on further clinical benefits demonstrated in Phase III HERIZON-BTC-302 trial comparing zanidatamab with standard-of-care treatments against standard care alone.

The Phase IIb HERIZON-BTC-01 trial data supported the EC authorisation. This trial involved 87 participants and included patients with previously treated, unresectable, locally advanced or metastatic HER2-positive BTC.

Ziihera showed a confirmed objective response rate (cORR) of 41.3%, including two complete responses after a median follow-up period of almost two years.

Median duration of response reported was 14.9 months while median overall survival was 15 months.

Jazz Pharmaceuticals executive vice-president, global head of research and development, and chief medical officer Robert Iannone stated: “This milestone reinforces our commitment to advancing biomarker-driven therapies that address serious unmet needs and improve patient outcomes.

“We are actively recruiting for our global Phase III trial in first-line HER2-positive BTC and continue to explore zanidatamab's potential in other HER2-expressing tumours."

BTCs, which include cholangiocarcinoma (CCA) and gallbladder cancer (GBC), are an aggressive group of cancers, often diagnosed at an advanced stage when curative surgery is not viable.

In March 2025, Jazz Pharmaceuticals signed an agreement to acquire Chimerix for $935m. This deal will enable Jazz to gain control over dordaviprone.