Zanidatamab-hrii

What Zanidatamab-hrii is used for

Quoted from the “Indications and Usage” section of the FDA-approved label.

ZIIHERA is a bispecific HER2-directed antibody indicated for: Gastroesophageal Adenocarcinoma (GEA) • in combination with fluoropyrimidine- and platinum-containing chemotherapy, and tislelizumab-jsgr, as first-line treatment of adult patients with HER2-positive (IHC 3+ or IHC 2+/ISH+) unresectable locally advanced or metastatic gastric, gastroesophageal junction, or esophageal adenocarcinoma, as detected by an …

— FDA label: Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026. Read the full label on DailyMed →

Label quoted: the one for the most common form (injection, powder, lyophilized, for solution, intravenous), Ziihera, Jazz Pharmaceuticals, Inc.; it covers 1 product in the FDA NDC Directory. The side effects, interactions, dosage and pregnancy quotes below come from this same label.

This page is not medical advice. Talk to your doctor or pharmacist before you start, stop or change any medicine.

Boxed warning

A boxed warning (“black box”) is the FDA’s strongest warning on a drug label, for serious or life-threatening risks.

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Zanidatamab-hrii boxed warning: what the label says

Quoted from the boxed warning of the FDA-approved label.

WARNING: DIARRHEA AND EMBRYO-FETAL TOXICITY ZIIHERA, in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr, can cause severe diarrhea, including life threatening and fatal cases. Use antidiarrheal prophylaxis during the first cycle when ZIIHERA is given in combination with these drugs. Manage with antidiarrheals and supportive measures as clinically indicated.

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Interrupt, reduce the dose or discontinue ZIIHERA based on severity [see Dosage and Administration (2.4), Warnings and Precautions (5.1), Use in Specific Populations (8.5)]. Embryo-Fetal Toxicity: Exposure to ZIIHERA during pregnancy can cause embryo-fetal harm. Advise patients of the risk and need for effective contraception [see Warnings and Precautions (5.2), Use in Specific Populations (8.1, 8.3)]. WARNING: DIARRHEA and EMBRYO‑FETAL TOXICITY See full prescribing information for complete boxed warning.

• ZIIHERA, in combination with fluoropyrimidine- and platinum-containing chemotherapy with or without tislelizumab-jsgr can cause severe diarrhea, including life threatening, and fatal cases. Use antidiarrheal prophylaxis during the first cycle when ZIIHERA is given in combination with these drugs. Manage with antidiarrheals and supportive measures as clinically indicated. Interrupt, reduce the dose or discontinue ZIIHERA based on severity. (2.4, 5.1, 8.5)
• Exposure to ZIIHERA during pregnancy can cause embryo-fetal harm. Advise patients of the risk and need for effective contraception. (5.2)

— FDA label: Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026. Read the full label on DailyMed →

Zanidatamab-hrii side effects

Quoted from the “Adverse Reactions” section of the FDA-approved label. Tell your doctor about any side effect that worries you.

The following clinically significant adverse reactions are described in greater detail in other sections of the labeling:

• Diarrhea [see Warnings and Precautions (5.1)]
• Embryo-Fetal Toxicity [see Warnings and Precautions (5.2)]
• Left Ventricular Dysfunction [see Warnings and Precautions (5.3)]
• Infusion-Related Reactions [see Warnings and Precautions (5.4)]
• Most common adverse reactions (≥ 20%) with ZIIHERA in combination with chemotherapy and tislelizumab-jsgr were diarrhea, nausea, decreased appetite, vomiting, hypokalemia, fatigue, rash, peripheral neuropathy, and IRR.

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(6.1)

• Most common adverse reactions (≥ 20%) with ZIIHERA in combination with chemotherapy were diarrhea, nausea, vomiting, decreased appetite, fatigue, hypokalemia, peripheral neuropathy, IRR, and rash. (6.1)
• Most common adverse reactions (≥ 20%) with ZIIHERA as a single agent were diarrhea, IRR, abdominal pain, and fatigue. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Jazz Pharmaceuticals, Inc. at 1‑800‑520‑5568 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. Gastroesophageal Adenocarcinoma (GEA) The pooled safety population of ZIIHERA described in WARNINGS AND PRECAUTIONS, reflects exposure to ZIIHERA in combination with chemotherapy, with or without tislelizumab-jsgr, in 725 patients with GEA from four open-label studies, including HERIZON-GEA-01 (N=605), ZWI-ZW25-201 (N=46), ZWI-ZW25-101 (N=41), and BGB-A317-ZW25-101 (N=33) at doses of 1,800 mg every 3 weeks (< 70 kg), 2,400 mg every 3 weeks (≥ 70 kg), 1,200 mg every 2 weeks (< 70 kg), 1,600 mg every 2 weeks (≥ 70 kg), or other doses. Among the 330 patients who received ZIIHERA in combination with chemotherapy and tislelizumab-jsgr for GEA, 64% were exposed for 6 months or longer, and 41% were exposed for 1 year or more. Among the 395 patients who received ZIIHERA in combination with chemotherapy for GEA, 57% were exposed for 6 months or longer, and 34% were exposed for 1 year or more. Biliary Tract Cancer (BTC) The pooled safety population of ZIIHERA administered 20 mg/kg intravenously as a single agent, described in WARNINGS AND PRECAUTIONS reflects exposure in 233 patients in two single-arm, open-label studies (ZWI-ZW25-101 and HERIZON-BTC-01): 109 patients with biliary tract cancer, and 124 patients with other cancers. Among 233 patients who received ZIIHERA as a single agent, 39% were exposed for 6 months or longer, and 17% were exposed for greater than one year. Gastroesophageal Adenocarcinoma (GEA) (HERIZON-GEA-01) The safety of ZIIHERA administered in combination with chemotherapy, with or without tislelizumab-jsgr for the treatment of GEA was evaluated in 901 patients [see Clinical Studies (14.1)]. Patients received ZIIHERA by IV infusion every 3 weeks at 1,800 mg (< 70 kg body weight) or 2,400 mg (≥ 70 kg), with or without tislelizumab-jsgr and an investigator choice of a fluoropyrimidine- and platinum-based chemotherapy (CAPOX or FP) or trastuzumab with CAPOX or FP [see Clinical Studies (14.1)]. Treatment in each arm continued until disease progression or unacceptable toxicity.

— FDA label: Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026. This is part of the section. Read the full label on DailyMed →

Zanidatamab-hrii dosage

Quoted from the “Dosage and Administration” section of the FDA-approved label. Your own dose is the one your doctor prescribes: do not change it on your own.

• Premedicate all patients to reduce the risk of infusion-related reactions (IRRs). (2.2)
• Administer loperamide during the first cycle to patients receiving ZIIHERA in combination with fluoropyrimidine- and platinum-containing chemotherapy for diarrhea prophylaxis.

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(2.2) Gastroesophageal Adenocarcinoma (GEA):

• Patients weighing less than 70 kg: ZIIHERA 1,800 mg intravenously every 3 weeks or 1,200 mg every 2 weeks infusion in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr. (2.3)
• Patients weighing 70 kg or greater: ZIIHERA 2,400 mg intravenously every 3 weeks or 1,600 mg every 2 weeks in combination with fluoropyrimidine- and platinum-containing chemotherapy, with or without tislelizumab-jsgr. (2.3) Biliary Tract Cancer: ZIIHERA 20 mg/kg intravenously every 2 weeks. (2.3) 2.1 Patient Selection HER2-Positive Gastroesophageal Adenocarcinoma (GEA) Select patients for treatment of unresectable locally advanced or metastatic GEA based on HER2-positive status (IHC 3+ or IHC 2+/ISH+), as detected by FDA-authorized tests [see Clinical Studies (14.1)]. Information on FDA-authorized tests for HER2 protein expression and gene amplification in gastric, gastroesophageal junction, or esophageal adenocarcinoma is available at: http://www.fda.gov/CompanionDiagnostics. Biliary Tract Cancer (BTC) Select patients for treatment of unresectable or metastatic biliary tract cancer based on HER2-positive (IHC 3+) tumor specimens, as detected by an FDA-authorized test [see Clinical Studies (14.2)]. Information on FDA-authorized tests for HER2 protein expression in biliary tract cancers is available at: http://www.fda.gov/CompanionDiagnostics. 2.2 Premedications and Important Administration Information Premedicate all patients 30 to 60 minutes prior to each dose of ZIIHERA to reduce the risk of infusion-related reactions [see Warnings and Precautions (5.4)]:
• Administer acetaminophen, an antihistamine (such as diphenhydramine) and a corticosteroid (such as hydrocortisone). ZIIHERA in combination with fluoropyrimidine- and platinum-containing chemotherapy with or without tislelizumab-jsgr Antidiarrheal prophylaxis:
• Administer loperamide 4 mg twice daily beginning on Day 1 and continue for at least 7 days during the first cycle of treatment.
• If patients experience Grade 1 or higher diarrhea during the first cycle, continue prophylaxis with loperamide 4 mg twice daily for at least the first 7 days of each subsequent cycle [see Warnings and Precautions (5.1)]. Fluorouracil-containing regimens:
• When ZIIHERA is administered in combination with fluorouracil-containing regimens, administer fluorouracil as an intravenous infusion. Do NOT administer fluorouracil as an intravenous bolus due to the potential increase in diarrhea [see Warnings and Precautions (5.1)].

— FDA label: Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026. This is part of the section. Read the full label on DailyMed →

Zanidatamab-hrii in pregnancy

Quoted from the pregnancy part of the FDA-approved label. Ask your doctor before you take any medicine while pregnant or planning a pregnancy.

Risk Summary Based on mechanism of action, ZIIHERA can cause fetal harm when administered to a pregnant woman. There are no human or animal data on the use of ZIIHERA in pregnancy. In literature reports, use of a HER2-directed antibody during pregnancy resulted in cases of oligohydramnios and oligohydramnios sequence manifesting as pulmonary hypoplasia, skeletal abnormalities, and neonatal death.

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Use of ZIIHERA is not recommended during pregnancy (see CLINICAL CONSIDERATIONS). Advise patients of potential risks to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, background risks of major birth defects and miscarriage in clinically recognized pregnancies are 2 to 4% and 15 to 20%, respectively. Clinical Considerations Fetal/Neonatal Adverse Reactions Monitor women who received ZIIHERA during pregnancy or within 4 months prior to conception for oligohydramnios. If oligohydramnios occurs, perform fetal testing that is appropriate for gestational age and consistent with local standard of care.

— FDA label: Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026. Read the full label on DailyMed →

Forms and how it is given

Companies that list this medicine

Labelers in the FDA NDC Directory: the company named on the package (maker or distributor), with the number of prescription products.

• Jazz Pharmaceuticals, Inc.1 product

FDA approval history

• BLA: Biologics License Application: how a biologic medicine (made from living cells) is approved.

Shortage status

The FDA drug shortage list does not show these products.

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Recalls

No recall linked to these products (by their NDC code) appears in the FDA enforcement reports.

Official identifiers

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Sources

1. FDA-approved label on DailyMed (National Library of Medicine) — Ziihera, Jazz Pharmaceuticals, Inc., effective August 24, 2026; via openFDA, FDA data exported October 30, 2026, retrieved October 31, 2026
2. NDC Directory (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026
3. Drugs@FDA (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026
4. Drug recall enforcement reports (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 27, 2026, retrieved October 31, 2026
5. Drug shortages (openFDA) — U.S. Food and Drug Administration (FDA), FDA data exported October 30, 2026, retrieved October 31, 2026

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