Jazz Pharmaceuticals plc (Nasdaq: JAZZ) announced the U.S. Food and Drug Administration (FDA) accelerated approval of Ziihera^® (zanidatamab-hrii) 50mg/mL for injection for intravenous use for the treatment of adults with previously treated, unresectable or metastatic HER2-positive (IHC 3+) biliary tract cancer (BTC), as detected by an FDA-approved test.¹ Ziihera was approved under accelerated approval based on a 52% objective response rate (ORR) and a median duration of response (DOR) of 14.9 months as determined by independent central review (ICR). Continued approval for this indication may be contingent upon verification and description of clinical benefit in a confirmatory trial.¹ The Phase 3 HERIZON-BTC-302 confirmatory trial is ongoing to evaluate zanidatamab in combination with standard-of-care therapy versus standard-of-care therapy alone in the first-line setting for patients with HER2-positive BTC. 

"BTC is a devastating disease with a poor prognosis and five-year survival rates under five percent in the metastatic setting. Patients with unresectable or metastatic HER2-positive BTC have had a high unmet need with limited treatment options and few approved therapies," said Rob Iannone, M.D., M.S.C.E., executive vice president, global head of research and development, and chief medical officer of Jazz Pharmaceuticals. "The approval of Ziihera, which previously received Breakthrough Therapy Designation from the FDA for this indication, is an important advance and offers the first and only dual HER2-targeted bispecific antibody and chemotherapy-free treatment for patients living with BTC. We look forward to advancing research of zanidatamab in BTC and other HER2-expressing solid tumors, with the goal of improving outcomes for more people diagnosed with these difficult-to-treat HER2-positive cancers."

The FDA approval of Ziihera is based on compelling data from the HERIZON-BTC-01 trial, which included the evaluation of zanidatamab as a single agent in previously treated HER2-positive (as determined by Roche Diagnostic's PATHWAY^® anti-HER-2/neu (4B5) Rabbit Monoclonal Primary Antibody companion diagnostic) BTC and is the largest Phase 2b clinical trial to date specifically for this patient population. The trial achieved its primary endpoint of confirmed objective response rate (cORR) by independent central review (ICR) and results were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting 2023, published in The Lancet Oncology, and included in the 2023 Best of ASCO^® program. Longer follow-up data showing improvement upon previously reported DOR were reported at the ASCO Annual Meeting 2024.¹

"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 Dr. James Harding, 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."

"Metastatic biliary tract cancer, BTC, places a significant burden on patients, affecting their quality of life and their emotional and mental well-being, as well as that of their families," said Stacie Lindsey, CEO and founder of the Cholangiocarcinoma Foundation. "The approval of Ziihera offers a promising treatment option. It provides patients and their loved ones the possibility of more time together and an improved quality of life, which is invaluable for the entire BTC community." 

The efficacy of Ziihera was evaluated in 62 patients with HER2-positive (IHC 3+ by central assessment) BTC in Cohort 1 of HERIZON-BTC-01, with major efficacy outcome measures of ORR and DOR as determined by ICR according to RECIST (Response Evaluation Criteria in Solid Tumors) v1.1.¹ The study demonstrated an ORR of 52% [95% confidence interval (CI): 39, 65)] with a Kaplan Meier (KM) estimated median DOR of 14.9 months [95% CI: 7.4-not estimable] by ICR.¹

Boxed Warning for Embryo-fetal toxicity: Exposure to Ziihera during pregnancy can cause embryo-fetal harm. Advise patients of the risk and need for effective contraception.¹

The safety profile for Ziihera has been demonstrated in 80 patients in the HERIZON-BTC-01 trial. Serious adverse reactions occurred in 53% of patients who received Ziihera. The most common adverse reactions in patients who received Ziihera (≥ 20%) were diarrhea, infusion-related reaction, abdominal pain, and fatigue. Serious adverse reactions in > 2% of patients included biliary obstruction (15%), biliary tract infection (8%), sepsis (8%), pneumonia (5%), diarrhea (3.8%), gastric obstruction (3.8%), and fatigue (2.5%). A fatal adverse reaction of hepatic failure occurred in one patient who received Ziihera. Permanent discontinuation due to an adverse reaction occurred in 2.5% of patients who received Ziihera.¹ See additional safety information below and full prescribing information https://pp.jazzpharma.com/pi/ziihera.en.USPI.pdf.

The confirmatory, global, randomized Phase 3 trial HERIZON-BTC-302 (NCT06282575) is ongoing and is evaluating zanidatamab in combination with standard-of-care therapy versus standard-of-care therapy alone in the first-line setting for patients with HER2-positive BTC. Continued approval for Ziihera may be contingent upon verification and description of clinical benefit in this confirmatory trial.

Zanidatamab is also being investigated in a number of additional tumor types, including Phase 3 trials in gastroesophageal adenocarcinomas (GEAs) and metastatic breast cancer (mBC). The HERIZON-GEA-01 trial evaluating the potential of zanidatamab plus chemotherapy with or without tislelizumab as first-line treatment for patients with advanced/metastatic HER2-positive GEAs. The EmpowHER-303 trial is evaluating the potential of zanidatamab in combination with physician's choice chemotherapy for the treatment of HER2-positive mBC for patients who have progressed on, or are intolerant to, previous trastuzumab deruxtecan treatment.