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Zanidatamab (Ziihera) is an antibody that grabs HER2 at two different spots, approved for HER2+ bile duct cancer.
Accelerated approval November 2024 for HER2+ biliary tract cancer (HERIZON-BTC-01). HERIZON-GEA-01 phase 3 in first-line HER2+ gastro-oesophageal cancer with chemotherapy ± tislelizumab was positive (2025). Jazz (ex-Asia) and BeOne. Biparatopic binding drives receptor clustering and internalisation, the basis of the ADC zanidatamab zovodotin.
Backbone ribbon from PDB 8FFJ. RCSB PDB 8FFJ. The ribbon widens where the chain is folded into a regular pattern and narrows where it is a loose loop.
Binds ECD2 and ECD4 of HER2 simultaneously; clustering, internalisation, ADCC. Connects to HER2.
1.Two arms bind two different HER2 epitopes (ECD2 and ECD4) on one or neighbouring receptors
Source: www.fda.gov/drugs/resources-information-approved-drugs/oncology-cancer-hematologic-malignancies-approval-notifications. Doses are for orientation; the current label governs.
Given by infusion or injection in a clinic or hospital outpatient department, so it is a Part B drug: Medicare pays 80% after the Part B deductible and the patient owes 20% coinsurance, uncapped in Original Medicare unless a Medigap policy applies. FDA accelerated approval for HER2-positive biliary tract cancer (2024).
Covered under the medical benefit with prior authorisation confirming diagnosis, biomarker status and line of therapy; site-of-care policies may steer infusions away from hospital outpatient departments.
20% Part B coinsurance on a high-cost infusion adds up quickly: Medigap Plan G or N, Medicare Advantage maximum out-of-pocket, Medicaid dual eligibility, or a charity fund are the usual buffers.
Sources: Medicare.gov: Chemotherapy · Medicare.gov: Prescription drugs (outpatient, Part B). Not medical or financial advice; verify with your plan.
Sources: NICE TA1153. Funding decisions are indication-specific and change monthly; verify with NICE and your treating team.
| Date | Deal | Type | Upfront | Total | Source |
|---|---|---|---|---|---|
| 2022-10-19 | Zymeworks to Jazz Pharmaceuticals Zanidatamab, HER2 biparatopic bispecific antibody | Licence | $50m | up to $1.76bn | source |
Compare all products across the US, EU, UK, Japan, China and Australia →
Breakthrough Therapy designation, HER2+ biliary tract cancer source
Treatment of adults with previously treated, unresectable or metastatic HER2-positive (IHC 3+) biliary tract cancer (BTC), as detected by an FDA-approved test
Accelerated approval, previously treated HER2+ (IHC3+) biliary tract cancer (HERIZON-BTC-01) The confirmatory requirement was still open 1.8 years later, when the FDA's table was read. source
First-line HER2+ gastro-oesophageal adenocarcinoma (HERIZON-GEA-01) submission source
First-line HER2-positive gastric, gastro-oesophageal junction or oesophageal adenocarcinoma with tislelizumab and fluoropyrimidine-platinum chemotherapy source
| Region | Year | Indication |
|---|---|---|
| US | 2024 | HER2+ (IHC 3+) unresectable/metastatic biliary tract cancer, previously treated · Ziihera label (openFDA); 53% of HERIZON-BTC-01 patients had gallbladder cancer: https://api.fda.gov/drug/label.json?search=openfda.brand_name:%22ZIIHERA%22 |
| EU | 2025 | HER2+ biliary tract after ≥1 line; 27 Jun 2025 (conditional) · Conditional marketing authorisation |
| UK | 2026 | HER2-positive (IHC 3+) unresectable locally advanced or metastatic biliary tract cancer after at least one line of systemic treatment; MHRA 19 February 2026, NICE TA1153 published 7 May 2026 with a commercial arrangement · https://www.nice.org.uk/guidance/ta1153 |
| Adverse event |
|---|
| Diarrhoea |
| Infusion-related reactions |
| Abdominal pain |
| Fatigue |
| Nausea |
| Left ventricular dysfunction |
Events listed without rates were not read from a primary source; see the label. Blank cells mean the figure was not sourced, not that it is zero.
| Country | Reimbursement | List price | Assistance |
|---|---|---|---|
| United States | Medicare Part B (physician-administered); commercial plans per formulary | not disclosed | - |
List prices are manufacturer or Medicare figures where publicly disclosed; net prices after rebates are usually lower. Reimbursement changes; check the payer.
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A direct check of the HERIZON-BTC-01 testing algorithm in routine pathology: IHC 3+ can stand alone, 2+ needs ISH, and the low-level amplification in weakly stained tumours is the group where HER2 drugs are least likely to help.
The cleanest split of HER2 alterations in gallbladder cancer into amplification and mutation, which matters because IHC and ISH only see the amplified tumours. It also shows the high-incidence Chilean population has not been sequenced at scale.
One cancer page on OnCo cites this paper by its DOI; this record gives the citation a page of its own so a reader can follow it without leaving OnCo. Read the abstract above alongside the citing page listed under Related; the record was created automatically from the Europe PMC entry and its figures have not been checked by hand.
Query for this drug: (TITLE:"Zanidatamab" OR ABSTRACT:"Zanidatamab" OR TITLE:"Ziihera" OR ABSTRACT:"Ziihera") AND (cancer OR tumor OR tumour OR oncology OR carcinoma OR lymphoma OR leukemia OR leukaemia OR myeloma OR sarcoma OR melanoma OR glioma). Results are unfiltered search hits about Zanidatamab, not a curated reading list.
Shares Clinical and genomic characterization of ERBB2-altered gallbladder cancer: exploring differences between an American and a Chilean cohort, HER2 status in extrahepatic cholangiocarcinoma and gallbladder carcinoma: concordance between immunohistochemistry and chromogenic in situ hybridization in 140 cases, Zanidatamab for HER2-amplified, unresectable, locally advanced or metastatic biliary tract cancer (HERIZON-BTC-01): a multicentre, single-arm, phase 2b study, HER2 testing in biliary tract cancer (IHC, ISH and NGS).
Shares HER2 status in extrahepatic cholangiocarcinoma and gallbladder carcinoma: concordance between immunohistochemistry and chromogenic in situ hybridization in 140 cases, Zanidatamab for HER2-amplified, unresectable, locally advanced or metastatic biliary tract cancer (HERIZON-BTC-01): a multicentre, single-arm, phase 2b study, HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 IHC 3+ (HER2-positive by immunohistochemistry).
Shares HER2 status in extrahepatic cholangiocarcinoma and gallbladder carcinoma: concordance between immunohistochemistry and chromogenic in situ hybridization in 140 cases, Reflex HER2 testing of every advanced gallbladder and extrahepatic biliary cancer, HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 IHC 3+ (HER2-positive by immunohistochemistry).
Shares HER2 and genomic testing for biliary cancer on the NHS, HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 IHC 3+ (HER2-positive by immunohistochemistry), HER2.
Shares Reflex HER2 testing of every advanced gallbladder and extrahepatic biliary cancer, Extrahepatic cholangiocarcinoma (perihilar and distal), Gallbladder cancer roadmap: from a chance finding at gallstone surgery to a disease with its own trials, Biliary tract cancer (all types).
Shares Gallbladder adenocarcinoma, Extrahepatic cholangiocarcinoma (perihilar and distal), Intrahepatic cholangiocarcinoma, Gallbladder cancer roadmap: from a chance finding at gallstone surgery to a disease with its own trials.
Shares Extrahepatic cholangiocarcinoma (perihilar and distal), Intrahepatic cholangiocarcinoma, Bispecific antibodies, Biliary tract cancer (all types).
Shares Clinical and genomic characterization of ERBB2-altered gallbladder cancer: exploring differences between an American and a Chilean cohort, HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 IHC 3+ (HER2-positive by immunohistochemistry), HER2.