The U.S. Food and Drug Administration (FDA) has granted approval to Ziihera (zanidatamab), a novel antibody developed by Zymeworks, for the treatment of adult patients with HER2-positive metastatic biliary tract cancer (BTC). This approval marks a significant advancement in the treatment of this rare and aggressive gastrointestinal cancer, which includes cancer of the bile ducts and gallbladder.
Clinical Efficacy
The FDA's decision was based on the results of a Phase 2b clinical trial, which demonstrated a 52% objective response rate (ORR) among patients treated with zanidatamab. The median duration of response (DOR) was 15 months, indicating a sustained benefit for a significant proportion of patients. These findings highlight the potential of zanidatamab to provide meaningful clinical improvements in a patient population with limited treatment options.
Disease Context
Biliary tract cancer is a rare and aggressive cancer, with an incidence of approximately two per 100,000 individuals in Western countries. The metastatic form of the disease is particularly deadly, with a five-year survival rate of less than 5%. Current treatment options are limited, underscoring the urgent need for new and effective therapies.
Rob Iannone, Executive Vice President, Global Head of Research and Development, and Chief Medical Officer at Jazz Pharmaceuticals, emphasized the significance of this approval, noting the unmet need for effective treatments for metastatic BTC.
Zanidatamab Mechanism and Development
Zanidatamab is a HER2-targeted antibody. Jazz Pharmaceuticals secured commercialization rights to Ziihera for use in North America, Europe, and Japan in a deal worth $375 million USD upfront, with additional royalties based on net sales. Ali Tehrani, co-founder and former CEO of Zymeworks, expressed his excitement about the approval, highlighting the long journey from the company's inception to this pivotal achievement.
Zymeworks' Trajectory
Zymeworks faced challenges in 2022, including disappointing results from another drug and a hostile takeover attempt. However, the company has since rebounded, with its stock price recovering significantly. The FDA approval of zanidatamab represents a major milestone for Zymeworks and a promising development for patients with HER2-positive metastatic biliary tract cancer.
