The U.S. Food and Drug Administration (FDA) has granted accelerated approval to zanidatamab-hrii (Ziihera, Jazz Pharmaceuticals, Inc.) for the treatment of previously treated, unresectable or metastatic HER2-positive (IHC 3+) biliary tract cancer (BTC). This approval marks a significant advancement for patients with limited treatment options for this aggressive cancer.
The FDA also approved the Ventana PATHWAY anti-HER-2/neu (4B5) Rabbit Monoclonal Primary Antibody as a companion diagnostic device. This test will aid in identifying patients with BTC who are likely to benefit from zanidatamab therapy.
Efficacy Demonstrated in HERIZON-BTC-01 Trial
The approval was based on data from the HERIZON-BTC-01 trial (NCT04466891), an open-label, multicenter, single-arm study. The trial enrolled 62 patients with unresectable or metastatic HER2-positive BTC who had previously received at least one gemcitabine-containing regimen in the advanced disease setting.
The study's primary efficacy outcome measures were objective response rate (ORR) and duration of response (DoR), as determined by independent central review according to RECIST v1.1. Results showed an ORR of 52% (95% CI: 39%, 65%) and a median DoR of 14.9 months (95% CI: 7.4 months, not estimable).
Dosage and Administration
The recommended dose of zanidatamab-hrii is 20 mg/kg, administered as an intravenous infusion once every 2 weeks until disease progression or unacceptable toxicity.
Safety and Warnings
The prescribing information for zanidatamab-hrii includes a boxed warning for embryo-fetal toxicity. The most common adverse reactions reported in at least 20% of patients were diarrhea, infusion-related reactions, abdominal pain, and fatigue.
Regulatory Information
Zanidatamab-hrii received priority review, breakthrough therapy designation, and orphan drug designation from the FDA. These designations are granted to drugs intended to treat serious conditions and offer significant improvement over existing therapies.
Healthcare professionals are encouraged to report any serious adverse events suspected to be associated with zanidatamab-hrii to the FDA's MedWatch Reporting System.
