Jazz Pharmaceuticals' zanidatamab, now branded as Ziihera, has received accelerated approval from the U.S. Food and Drug Administration (FDA) for the treatment of HER2-positive biliary tract cancer (BTC). This approval marks a significant milestone as Ziihera becomes the first and only dual HER2-targeted bispecific antibody approved for this indication in the United States. The drug is intended for adult patients with unresectable or metastatic HER2-positive BTC who have had no prior treatment.
Clinical Efficacy and Trial Data
The FDA's decision was primarily based on data from the HERIZON-BTC-01 clinical trial, a phase 2b study that assessed zanidatamab as a single agent in patients with previously treated HER2-positive BTC. The trial demonstrated a promising 52% objective response rate (ORR) and a median duration of response (DOR) of 14.9 months. These results position Ziihera as a potentially highly effective option for patients facing this aggressive and challenging cancer.
Bispecific Antibodies in Cancer Therapy
Ziihera's approval underscores the growing importance of bispecific antibodies in cancer treatment. These innovative therapies are designed to simultaneously target two different antigens, offering a novel approach to target cancer cells more precisely and effectively. Ziihera, specifically designed to target two epitopes on the HER2 receptor, exemplifies how bispecific antibodies are evolving to address specific needs in cancer therapy, particularly for hard-to-treat cancers like BTC.
Current Treatment Landscape and Unmet Needs
Biliary tract cancer is a rare and aggressive malignancy with a poor prognosis, often diagnosed at advanced stages. While recent advances in first-line treatments, including immuno-oncology agents and targeted therapies like IDH and FGFR2 inhibitors, have shown progress, limited options remain for patients with HER2-positive BTC. The accelerated approval of zanidatamab addresses this unmet need, offering new hope for improved outcomes in this patient population.
Future Development and Market Impact
Ziihera is the 15th bispecific antibody to gain approval, reflecting the increasing prevalence and impact of this therapeutic class in oncology. Bispecific antibodies are projected to play a critical role in managing various cancer types, with sales expected to exceed US$ 40 billion by 2029. Continued approval for Ziihera will depend on the outcome of ongoing confirmatory trials, including the Phase 3 HERIZON-BTC-302 trial, which is evaluating zanidatamab in combination with standard-of-care therapy for first-line treatment of HER2-positive BTC. BeiGene is reportedly responsible for the sales of zanidatamab in Korea and is working on the groundwork for the Ministry of Food and Drug Safety to designate zanidatamab as an orphan drug.
