margetuximab (Rx)

Brand and Other Names:Margenza, margetuximab-cmkb
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Dosing & Uses


Dosage Forms & Strengths

injection, solution concentrate

  • 250mg/10mL (25mg/mL) single-dose vial

Breast Cancer

Indicated in combination with chemotherapy for metastatic human epidermal growth factor receptor 2-positive (HER2+) breast cancer in patients who have received ≥2 anti-HER2 regimens, at least 1 of which was for metastatic disease

15 mg/kg IV q3weeks

Continue until disease progression or unacceptable toxicity

Refer to prescribing information for each therapeutic agent administered in combination therapy for dosing information

Dosage Modifications

Left ventricular dysfunction

  • Withhold dosing for ≥4 weeks
    • ≥16% absolute decrease in left ventricular ejection fraction (LVEF) from pretreatment levels
    • LVEF below institutional limits of normal (or 50% if no limits are available) and ≥10% absolute decrease in LVEF from pretreatment values
    • May resume if, within 8 weeks, LVEF returns to normal limits and absolute decrease from base line ≤15%
  • Permanently discontinue
    • LVEF decline persists for >8 weeks, or
    • Dosing interrupted on >3 occasions for LVEF decline

Infusion-related reactions

  • Mild or moderate: Decrease infusion rate
  • Dyspnea or clinically significant hypotension: Interrupt infusion
  • Severe or life-threatening IRRs: Permanently discontinue

Renal impairment

  • Mild-to-moderate (CrCl 30-89 mL/min): No dose adjustment needed
  • Severe (CrCl 15-29 mL/min), end-stage renal disease with or without hemodialysis) Unknown

Hepatic impairment

  • Mild (total bilirubin [TB] ULN, or TB 1-1.5 ULN and any AST): No dose adjustment needed
  • Moderate-to-severe (TB >1.5 ULN and any AST): Unknown

Dosing Considerations

Assess LVEF before initiating and regularly during treatment

Verify pregnancy status before initiating in females of reproductive potential

Safety and efficacy not established

There was a higher incidence of Grade ≥3 adverse reactions observed in patients aged ≥65 years (56%) compared with younger patients (47%), including those associated with potential cardiotoxicity (35% vs 18%)



Interaction Checker

and margetuximab

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            Adverse Effects


            All Grades

            • Increased creatinine (68%)
            • Fatigue/asthenia (57%)
            • Decreased hemoglobin (52%)
            • Decreased leukocytes (40%)
            • Decreased neutrophils (34%)
            • Nausea (33%)
            • Increased activated partial thromboplastin time (aPTT) (32%)
            • Increased ALT (32%)
            • Decreased lymphocytes (31%)
            • Increased lipase (30%)
            • Diarrhea (25%)
            • Increased INR (24%)
            • Increased AST (23%)
            • Vomiting (21%)
            • Increased alkaline phosphatase (21%)
            • Pyrexia (19%)
            • Constipation (19%)
            • Headache (19%)
            • Alopecia (18%)
            • Abdominal pain (17%)
            • Peripheral neuropathy (16%)
            • Cough (14%)
            • Decreased appetite (14%)
            • Arthralgia/myalgia (14%)
            • Palmoplantar erythrodysesthesia (13%)
            • Dyspnea (13%)
            • Infusion-related reaction (13%)
            • Extremity pain (11%)


            All Grades

            • Dizziness (10%)
            • Stomatitis (10%)
            • Decreased weight (6%)
            • Dysgeusia (6%)
            • Rash (6%)
            • Insomnia (6%)
            • Hypertension (5%)
            • Syncope (1.5%)

            Grade 3 or 4

            • Decreased neutrophils (9%)
            • Fatigue (7%)
            • Increased lipase (6%)
            • Decreased leukocytes (5%)
            • Decreased lymphocytes (4.4%)
            • Increased aPTT (3.4%)
            • Decreased hemoglobin (3.2%)
            • Diarrhea (2.3%)
            • Increased ALT (2%)
            • Increased AST (2%)
            • Abdominal pain (1.5%)
            • Infusion-related reaction (1.5%)
            • Increased INR (1.2%)
            • Nausea (1.1%)
            • Peripheral neuropathy (1.1%)
            • Dyspnea (1.1%)


            Grade 3 or 4

            • Vomiting (0.8%)
            • Constipation (0.8%)
            • Extremity pain (0.8%)
            • Pyrexia (0.4%)
            • Cough (0.4%)
            • Decreased appetite (0.4%)
            • Arthralgia/myalgia (0.4%)
            • Increased creatinine (0.4%)


            Black Box Warnings

            Left ventricular dysfunction

            • May lead to reductions in LVEF
            • Evaluate cardiac function before and during treatment
            • Discontinue treatment for confirmed clinically significant decrease in left ventricular function

            Embryofetal toxicity

            • Exposure during pregnancy can cause embryofetal harm
            • Advise patients of risk and use for effective contraception




            May cause fetal harm when administered to pregnant females

            Left ventricular dysfunction

            • Left ventricular dysfunction may occur
            • Not studied in patients with pretreatment LVEF <50%, history of myocardial infarction or unstable angina within 6 months, or congestive heart failure NYHA class II-IV
            • Conduct thorough cardiac assessment (eg, history, physical examination, determination of LVEF by ECG or multiple gated acquisition (MUGA) scan
            • Measure baseline LVEF within 4 weeks before initiation; then every 3 months during and upon completion
            • Repeat LVEF at 4-week intervals if therapy withheld for significant left ventricular dysfunction

            Infusion-related reactions

            • Infusion-related reactions (IRRs) reported
            • Symptoms may include fever, chills, arthralgia, cough, dizziness, fatigue, nausea, vomiting, headache, diaphoresis, tachycardia, hypotension, pruritus, rash, urticaria, and dyspnea
            • Monitor for IRRs during administration and as clinically indicated after completing infusion
            • Have medications and emergency equipment available to immediately to treat IRRs

            Drug interaction overview

            • Anthracyclines
              • Avoid anthracycline-based therapy for up to 4 months after discontinuing margetuximab
              • Patients treated with anthracyclines <4 months after discontinuing therapy may be at increased risk of cardiac dysfunction
              • Interaction has not been studied with margetuximab
              • Clinical data from other HER2-directed antibodies warrant consideration
              • If use is unavoidable, closely monitor cardiac function


            Pregnancy & Lactation


            Based on findings in animals and mechanism of action, fetal harm may occur when administered to pregnant females

            No data available on use in pregnant females to inform of the drug-associated risks

            In postmarketing 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

            Verify pregnancy status of females of reproductive potential before initiation

            Animal data

            • IV administration to pregnant cynomolgus monkeys once every 3 weeks, starting at gestational day 20 until delivery, resulted in oligohydramnios and delayed infant kidney development
            • Animal exposures were ≥3x the human exposures at the recommended dose, based on peak plasma levels
            • Advise patients of potential risks to a fetus

            Fetal/neonatal adverse reactions

            • Monitor treated females during pregnancy or within 4 months before conception for oligohydramnios
            • If oligohydramnios occurs, perform fetal testing appropriate for gestational age and consistent with community standards of care


            • Females of reproductive potential: Use effective contraception during treatment and for 4 months following final dose


            No information available on drug presence in human milk, effects on breastfed child, or effects on milk production

            Published data suggest human IgG is present in human milk but does not enter neonatal or infant circulation in substantial amounts

            Consider drug washout period of 4 months when weighing the risks versus benefits

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.



            Mechanism of Action

            Human epidermal growth factor receptor 2 (HER2)/neu receptor antagonist; chimeric Fc-engineered IgG1 kappa monoclonal antibody that targets HER2-expressing tumors

            Binds to extracellular domain of HER2 protein; upon binding to HER2-expressing tumor cells, the drug inhibits tumor cell proliferation, reduces shedding of the HER2 extracellular domain, and mediates antibody-dependent cellular cytotoxicity


            Peak plasma concentration (steady-state): 466 mcg/mL

            AUC (steady-state): 4120 mcg⋅day/mL

            Steady-steady is reached at 2 months

            No clinically significant differences were observed when infusion time was reduced from 120 to 30 minutes


            Vd (steady-state): 5.47 L


            Expected to be metabolized into small peptides by catabolic pathways


            Half-life: 19.2 days

            Clearance: 0.22 L/days

            4 months after discontinuation, concentrations decrease to ~3% of steady-state trough serum concentration



            IV Incompatibilities


            IV Compatibilities

            0.9% NaCl

            IV Preparation

            Inspect visually for particulate matter and discoloration; solution is clear to slightly opalescent, colorless to pale yellow or pale brown; some visible, translucent, inherent proteinaceous particles may be present

            Swirl the vial(s) gently; do not shake vial(s)

            Calculate required volume (rounded to nearest 0.1 mL)

            Transfer calculated dose into 100- to 250-mL 0.9% NaCl IV bag (ie, polyvinyl chloride, polyolefins [polyethylene, polypropylene], polyamide or polyolefins only, or copolymer of olefins) may be used

            Final concentration of diluted soltuion: 0.5-7.2 mg/mL

            Gently invert IV bag to mix diluted solution; do NOT shake

            Discard any unused portion left in vial(s)

            Do not mix with other drugs

            IV Administration

            Administer through IV line containing sterile, nonpyrogenic, low-protein-binding polyethersulfone 0.2-micron in-line or add-on filter

            Do NOT give IV push or bolus

            On days when administered with chemotherapy, administer margetuximab immediately after chemotherapy completion

            Do not coadminister other drugs through same infusion line

            Infusion rate

            • Initial dose: Administer over 2 hr
            • Subsequent doses: Administer over at least 30 minutes

            Missed dose

            • Administer scheduled dose as soon as possible
            • Adjust schedule to maintain 3-week interval between doses


            Does not contain a preservative

            Unopened vials

            • Refrigerate at 2-8ºC (36-46ºF) in original carton to protect from light
            • Do not freeze
            • Do not shake

            Diluted IV solution

            • Room temperature: Up to 4 hr
            • Refrigerated: 2-8ºC (36-46ºF) up to 24 hr
            • If refrigerated, allow the diluted solution to come to room temperature prior to administration
            • Do not freeze




            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
            Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
            ST Step Therapy
            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
            OR Other Restrictions
            Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.