Trastuzumab

What it is and how it works

Mechanism of Action The HER2 (or c-erbB2) proto-oncogene encodes a transmembrane receptor protein of 185 kDa, which is structurally related to the epidermal growth factor receptor. Trastuzumab products have been shown, in both in vitro assays and in animals, to inhibit the proliferation of human tumor cells that overexpress HER2. Trastuzumab products are mediators of antibody-dependent cellular cytotoxicity (ADCC). In vitro , trastuzumab product-mediated ADCC has been shown to be preferentially exerted on HER2 overexpressing cancer cells compared with cancer cells that do not overexpress HER2.

Mechanism class: HER2/Neu/cerbB2 Antagonists

Indications

is a HER2/neu receptor antagonist indicated in adults for: • The treatment of HER2-overexpressing breast cancer. ( 1.1 , 1.2 ) • The treatment of HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma. Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product. ( 1 , 2.2 ) Adjuvant Breast Cancer TRAZIMERA is indicated in adults for adjuvant treatment of HER2-overexpressing node positive or node negative (ER/PR negative or with one high risk feature ) breast cancer • as part of a treatment regimen consisting of doxorubicin, cyclophosphamide, and either paclitaxel or docetaxel • as part of a treatment regimen with docetaxel and carboplatin • as a single agent following multi-modality anthracycline based therapy. Select patients for therapy based on an FDA-approved companion diagnostic for a trastuzumab product .

Dosage and administration (summary)

For intravenous (IV) infusion only. Do not administer as an intravenous push or bolus. TRAZIMERA has different dosage and administration instructions than subcutaneous trastuzumab products. Do not substitute TRAZIMERA (trastuzumab-qyyp) for or with ado-trastuzumab emtansine or fam-trastuzumab deruxtecan. Perform HER2 testing using FDA-approved tests by laboratories with demonstrated proficiency. ( 1 , 2.2 ) Adjuvant Treatment of HER2-Overexpressing Breast Cancer Administer at either: • Initial dose of 4 mg/kg over 90 minutes intravenous infusion, then 2 mg/kg over 30 minutes intravenous infusion weekly for 12 weeks (with paclitaxel or docetaxel) or 18 weeks (with docetaxel and carboplatin).

Contraindications

None. • None.

Warnings and precautions

• Exacerbation of Chemotherapy-Induced Neutropenia. ( 5.5 , 6.1 ) Cardiomyopathy Trastuzumab products can cause left ventricular cardiac dysfunction, arrhythmias, hypertension, disabling cardiac failure, cardiomyopathy, and cardiac death . Trastuzumab products can also cause asymptomatic decline in left ventricular ejection fraction (LVEF). There is a 4 to 6 fold increase in the incidence of symptomatic myocardial dysfunction among patients receiving trastuzumab products as a single agent or in combination therapy compared with those not receiving trastuzumab products.

Pregnancy

Pregnancy Risk Summary Trastuzumab products can cause fetal harm when administered to a pregnant woman. In post-marketing reports and published literature, use of trastuzumab products during pregnancy resulted in cases of oligohydramnios and of oligohydramnios sequence, manifesting as pulmonary hypoplasia, skeletal abnormalities, and neonatal death…

Storage and supply

420 mg Multiple-dose vial TRAZIMERA (trastuzumab-qyyp) for injection 420 mg/vial is supplied in a multiple-dose vial as a sterile, white lyophilized powder. Each carton contains one multiple-dose vial of TRAZIMERA and one vial (20 mL) of Bacteriostatic Water for Injection (BWFI) containing 1.1% benzyl alcohol as a preservative. NDC 0069-0305-01.

Source: Trastuzumab-Qyyp (Trazimera) — US FDA prescribing information, 2026-04-10, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.