Although HER2 alterations have been reported in up to 20% of biliary tract cancers (BTCs), no HER2-targeted therapies are currently approved for the treatment of BTC. Zymeworks, a clinical-stage biotechnology company, recently announced positive topline data from their pivotal phase 2b HERIZON-BTC-01 trial, which investigated zanidatamab monotherapy in patients with previously treated HER2-amplified and -expressing BTC. Zanidatamab is a biparatopic antibody that simultaneously binds 2 nonoverlapping epitopes of HER2, which allows for multiple mechanisms of action, including dual HER2 signal blockade, increased binding and removal of HER2 protein from the cell surface, and potent effector function, leading to promising antitumor activity.
Topline results from HERIZON-BTC-01 demonstrated an objective response rate of 41.3% in patients with HER2-amplified and -expressing (immunohistochemistry 2+ and 3+) BTC, as assessed by independent central review, and a median duration of response of 12.9 months. No new safety signals were identified with zanidatamab, and the safety profile was consistent with what has been previously reported in monotherapy studies. Neil Josephson, MD, Chief Medical Officer at Zymeworks, was enthusiastic about the results, stating, “These data demonstrate that zanidatamab, as a single agent, improves on the current standard of care for patients in a difficult-to-treat disease who currently have a poor prognosis based on the limited treatment options currently available.”
Zanidatamab as a single agent has the potential to be the first HER2-targeted therapy for patients with BTC, pending receipt of regulatory approvals.
Source: Zymeworks Inc. Zymeworks Announces Positive Topline Data in the Pivotal HERIZON-BTC-01 Trial of Zanidatamab; December 2022. Accessed December 19, 2022. https://ir.zymeworks.com/node/10901/pdf.
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