MARGENZA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MARGENZA (MARGENZA).
Margetuximab is an Fc-engineered monoclonal antibody that targets the extracellular domain of human epidermal growth factor receptor 2 (HER2). It binds to HER2 on tumor cells and mediates antibody-dependent cellular cytotoxicity (ADCC) via enhanced affinity for activating Fcγ receptors (FcγRIIIa) and reduced affinity for inhibitory FcγRIIb, thereby augmenting immune effector cell activation.
| Metabolism | Margetuximab is a monoclonal antibody; it is degraded into small peptides and amino acids via general protein catabolism. No specific metabolic enzymes or pathways are involved. |
| Excretion | Primarily cleared via proteolytic degradation; renal excretion of intact drug is negligible (<1%). No significant biliary or fecal elimination reported. |
| Half-life | Terminal half-life approximately 17-23 days (mean ~20 days) following intravenous administration, supporting a 3-week dosing interval for sustained receptor occupancy. |
| Protein binding | ~99% bound to plasma proteins, primarily to albumin and immunoglobulin G (as a monoclonal antibody). |
| Volume of Distribution | Volume of distribution approximately 3.0-4.0 L (0.04-0.06 L/kg). Low Vd indicates limited extravascular distribution, consistent with large antibody molecule primarily confined to plasma and interstitial space. |
| Bioavailability | Bioavailability is 100% by intravenous route as it is administered as an IV infusion; not available for oral or other routes. |
| Onset of Action | Onset of clinical effect is typically observed within 2-4 weeks after first dose, based on radiographic response in clinical trials; maximum effect may require multiple cycles (~6-12 weeks). |
| Duration of Action | Duration of action extends throughout the dosing interval (3 weeks) with sustained HER2 receptor blockade; clinical effect persists for several weeks after treatment cessation due to long half-life. |
15 mg/kg intravenously over 60 minutes every 3 weeks until disease progression or unacceptable toxicity.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment recommended for mild to moderate renal impairment (CrCl ≥30 mL/min). Not studied in severe renal impairment (CrCl <30 mL/min) or end-stage renal disease. |
| Liver impairment | No dose adjustment recommended for mild hepatic impairment (total bilirubin ≤ ULN and AST > ULN, or total bilirubin >1-1.5× ULN with any AST). Not studied in moderate (total bilirubin >1.5-3× ULN with any AST) or severe (total bilirubin >3× ULN with any AST) hepatic impairment. |
| Pediatric use | Safety and effectiveness in pediatric patients have not been established. |
| Geriatric use | No specific dose adjustment recommended. Of the 292 patients treated with MARGENZA in the SOPHIA trial, 45% were aged 65 years or older, 11% were 75 or older. No overall differences in efficacy or safety observed between elderly and younger patients. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MARGENZA (MARGENZA).
| Breastfeeding | There are no data on the presence of margetuximab in human milk, its effects on the breastfed infant, or its effects on milk production. Maternal IgG is present in human milk, but the amount of margetuximab transferred is expected to be low due to its large molecular size. However, because of the potential for serious adverse reactions in nursing infants, women should discontinue breastfeeding during treatment and for at least 4 months after the last dose. M/P ratio is not available. |
| Teratogenic Risk | MARGENZA (margetuximab-cmkb) is an IgG1 monoclonal antibody. Based on its mechanism of action (HER2/neu receptor blockade) and findings from animal studies with other HER2-targeted agents, it is expected to cause fetal harm or death when administered to a pregnant woman. Human IgG molecules cross the placenta, with increasing transfer as pregnancy progresses, reaching peak levels during the third trimester. There are no adequate and well-controlled studies in pregnant women. First trimester exposure may have lower risk, but second and third trimester exposure is associated with oligohydramnios, fetal renal dysfunction, and fetal loss. |
■ FDA Black Box Warning
No black box warning exists for MARGENZA.
| Serious Effects |
["None known."]
| Precautions | ["Cardiotoxicity: Left ventricular ejection fraction (LVEF) decline; assess LVEF prior to and during treatment. Discontinue for symptomatic heart failure or persistent decline.","Infusion-related reactions: Monitor during infusion; reduce rate or discontinue for severe reactions.","Embryo-fetal toxicity: Can cause fetal harm; advise females of reproductive potential of the risk and use effective contraception.","Pulmonary toxicity: Interstitial lung disease and pneumonitis; monitor for signs/symptoms and permanently discontinue if confirmed.","Neutropenia and febrile neutropenia: May occur; monitor blood counts.","Hypokalemia and hypomagnesemia: Monitor electrolytes and replace as needed."] |
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| Fetal Monitoring | Monitor pregnancy status in women of reproductive potential. If MARGENZA is used during pregnancy or if the patient becomes pregnant while receiving the drug, apprise the patient of the potential hazard to the fetus. Perform serial ultrasound examinations to assess for oligohydramnios and fetal renal function if exposure occurs during the second or third trimester. Consider pregnancy testing prior to initiation in women of childbearing potential. |
| Fertility Effects | MARGENZA may impair fertility in females based on findings from animal studies with anti-HER2 antibodies, which have shown effects on female reproductive organs, including ovarian failure and decreased fertility. No data are available on male fertility. The potential for fertility impairment in humans is unknown. |