The FDA has granted accelerated approval to Jazz Pharmaceuticals’ Ziihera (zanidatamab-hrii) for the treatment of adult patients with previously treated, unresectable or metastatic HER2-positive biliary tract cancer (BTC). This regulatory decision marks a significant advancement, providing a chemotherapy-free option for this patient population.
Clinical Efficacy of Ziihera
The approval of Ziihera was based on data from the Phase IIb HERIZON-BTC-01 trial (NCT04466891), which evaluated Ziihera as a monotherapy in patients previously treated for HER2-positive BTC. The trial enrolled patients aged 18 years and older who had received prior treatment with a gemcitabine-containing regimen but had not been previously treated with HER2-targeted therapies.
Data presented at the 2024 ASCO Annual Meeting showed promising results. Among the overall evaluable patient population enrolled in cohort 1 (n = 80), the confirmed objective response rate (cORR) was 41.3%, with a disease control rate of 68.8%. Specifically, the cORR was 51.6% in a subgroup of patients with HER2-positive IHC 3+ disease and 5.6% in patients with IHC 2+ disease. Across a median follow-up of 22 months (range, 16-34), the median duration of response increased to 14.9 months (95% CI, 7.4-not reached).
Survival Benefits
The median overall survival (OS) in the overall population in cohort 1 was 15.5 months (95% CI, 10.4-18.5). The OS was 18.1 months (95% CI, 12.2-23.2) in patients with HER2-positive IHC 3+ disease, and 5.2 months (95% CI, 3.1-10.2) in patients with IHC 2+ disease. The 12-month OS rates were 56.2% in the overall population (95% CI, 44.3%-66.5%), 65.0% in the IHC 3+ subgroup (95% CI, 51.6%-75.6%), and 20.8% in the IHC 2+ subgroup (95% CI, 5.1%-43.7%).
Expert Commentary
"As a clinical investigator and medical oncologist focused on advancing the care of patients with biliary tract and liver cancers, I have experienced firsthand the significant unmet need for effective therapies for patients with these diseases," said James Harding, MD, associate attending, Gastrointestinal Oncology and Early Drug Development Services, at Memorial Sloan Kettering Cancer Center. "Zanidatamab has demonstrated antitumor activity and is now a new option for patients with HER2-positive biliary tract cancer. I look forward to continued and successful drug development for patients with biliary tract cancer."
Addressing Unmet Needs in Biliary Tract Cancer
Biliary tract cancer is a devastating disease with a poor prognosis, characterized by five-year survival rates under 5% in the metastatic setting. The approval of Ziihera addresses a critical unmet need for patients with unresectable or metastatic HER2-positive BTC, who have had limited treatment options and few approved therapies. Ziihera, which previously received Breakthrough Therapy Designation from the FDA for this indication, represents the first and only dual HER2-targeted bispecific antibody and chemotherapy-free treatment for these patients.
