Version July 2025
Dosage guidance:
Safety: Verify that patient is not pregnant prior to initiating marstacimab (in patients who could become pregnant).
Clinical considerations:
Breakthrough bleeding episodes: Clotting factor concentrates (factor VIII concentrates for hemophilia A and factor IX concentrates for hemophilia B) may be utilized at the lowest possible effective dose for management of breakthrough bleeds in patients receiving marstacimab. Do not use additional marstacimab doses to treat breakthrough bleeds.
Management of perioperative patients: For major surgery, discontinue marstacimab and initiate management with clotting factor concentrate and manage the risk of venous thrombosis (which can be elevated in the perioperative period) per local standard of care. When resuming marstacimab, consider overall clinical status, including postsurgical thromboembolic risk factors, the use of other hemostatic products, and other concomitant medications. In clinical studies, patients have undergone minor surgical procedures without discontinuing marstacimab prophylaxis.
Hemophilia A, prophylaxis: Note: When converting from prophylactic factor replacement therapy to marstacimab, discontinue treatment with clotting factor VIII concentrates prior to marstacimab initiation. Marstacimab may be initiated at any time after discontinuing the clotting factor concentrates.
Loading dose: SUBQ: 300 mg single loading dose (as two 150 mg injections).
Maintenance dose (begin 1 week after the loading dose): SUBQ: 150 mg once weekly (on the same day each week at any time of the day).
Dosage adjustment: Patients ≥50 kg: SUBQ: If control of bleeding events is determined to be inadequate, consider an increase to 300 mg once weekly.
Hemophilia B, prophylaxis: Note: When converting from prophylactic factor replacement therapy to marstacimab, discontinue treatment with clotting factor IX concentrates prior to marstacimab initiation. Marstacimab may be initiated at any time after discontinuing the clotting factor concentrates.
Loading dose: SUBQ: 300 mg single loading dose (as two 150 mg injections).
Maintenance dose (begin 1 week after the loading dose): SUBQ: 150 mg once weekly (on the same day each week at any time of the day).
Dosage adjustment: Patients ≥50 kg: SUBQ: If control of bleeding events is determined to be inadequate, consider an increase to 300 mg once weekly.
Missed doses:
150 mg maintenance dose missed: If a dose is missed, administer as soon as possible before the day of the next scheduled dose, and then resume the usual 150 mg once-weekly dosing schedule (same schedule as prior to the missed dose or new schedule based on date of administration of missed dose). If more than 13 days have passed since the last dose was administered, administer a loading dose of 300 mg followed by a resumption of 150 mg maintenance dose once weekly thereafter.
300 mg maintenance dose missed: If one or more doses are missed, administer a dose as soon as possible, and then resume the usual 300 mg once-weekly dosing schedule (same schedule as prior to the missed dose or new schedule based on date of administration of missed dose).
eGFR ≥60 mL/minute/1.73 m2: There are no dosage adjustments provided in the manufacturer’s labeling; there were no clinically significant differences in marstacimab pharmacokinetics in patients with mild impairment.
eGFR ≤59 mL/minute/1.73 m2: There are no dosage adjustments provided in the manufacturer’s labeling (effects are unknown).
Mild impairment (total bilirubin >1 to ≤1.5 times ULN): There are no dosage adjustments provided in the manufacturer’s labeling; there were no clinically significant differences in marstacimab pharmacokinetics in patients with mild impairment.
Moderate or severe impairment (Child-Turcotte-Pugh class B, C): There are no dosage adjustments provided in the manufacturer’s labeling (effects are unknown).
Hypersensitivity, severe: Discontinue marstacimab and manage as clinically appropriate.
Thromboembolic events: Interrupt marstacimab prophylaxis if thromboembolism occurs; manage as clinically indicated.
Refer to adult dosing.
(For additional information see "Marstacimab: Pediatric drug information")
Hemophilia A, prophylaxis:
Children ≥12 years and Adolescents:
<50 kg:
Loading dose: SUBQ: 300 mg once (two 150 mg injections), then initiate maintenance dose in 1 week.
Maintenance dose (initiate 1 week after loading dose): SUBQ: 150 mg once weekly, administer on the same day each week at any time of day. Do not administer additional doses for breakthrough bleeding.
≥50 kg:
Loading dose: SUBQ: 300 mg once (two 150 mg injections), then initiate maintenance dose in 1 week.
Maintenance dose (initiate 1 week after loading dose): SUBQ: 150 mg once weekly, administer on the same day each week at any time of day; may increase dose to 300 mg for inadequate control of bleeding events. Do not administer additional doses for breakthrough bleeding.
Hemophilia B, prophylaxis:
Children ≥12 years and Adolescents:
<50 kg:
Loading dose: SUBQ: 300 mg once (two 150 mg injections), then initiate maintenance dose in 1 week.
Maintenance dose (initiate 1 week after loading dose): SUBQ: 150 mg once weekly, administer on the same day each week at any time of day. Do not administer additional doses for breakthrough bleeding.
≥50 kg:
Loading dose: SUBQ: 300 mg once (two 150 mg injections), then initiate maintenance dose in 1 week.
Maintenance dose (initiate 1 week after loading dose): SUBQ: 150 mg once weekly, administer on the same day each week at any time of day; may increase dose to 300 mg for inadequate control of bleeding events. Do not administer additional doses for breakthrough bleeding.
Changing from prophylactic factor replacement therapy (factor VIII or factor IX concentrates) to marstacimab : Discontinue clotting factor concentrates then initiate marstacimab at any time.
Note: No data exist for changing from non-factor-based hemophilia medicinal products to marstacimab.
Management of perioperative patients: For major surgery, discontinue marstacimab and initiate management with clotting factor concentrate and manage the risk of venous thrombosis (which can be elevated in the perioperative period) per local standard of care. When resuming marstacimab, consider overall clinical status, including postsurgical thromboembolic risk factors, the use of other hemostatic products, and other concomitant medications. In clinical studies, patients have undergone minor surgical procedures without discontinuing marstacimab prophylaxis.
Children ≥12 years and Adolescents:
Mild impairment (eGFR 60 to 89 mL/kg/1.73 m2): There are no dosage adjustments provided in the manufacturer's labeling; there were no clinically significant differences in marstacimab pharmacokinetics in patients with mild impairment.
Moderate to severe impairment (≤59 mL/kg/1.73 m2): There are no dosage adjustments in the manufacturer's labeling (effects are unknown).
Children ≥12 years and Adolescents:
Mild impairment: There are no dosage adjustments provided in the manufacturer's labeling; there were no clinically significant differences in marstacimab pharmacokinetics in patients with mild impairment.
Moderate to severe impairment: There are no dosage adjustments in the manufacturer's labeling (effects are unknown).
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Adverse reactions reported in adolescents and adults.
>10%: Immunologic: Antibody development (20%; neutralizing: 26%)
1% to 10%:
Dermatologic: Pruritus (3%)
Local: Injection-site reaction (9%)
Nervous system: Headache (7%)
<1%: Cardiovascular: Peripheral edema
There are no contraindications listed in the manufacturer's labeling.
Concerns related to adverse effects:
• Hypersensitivity: Marstacimab may cause hypersensitivity reactions (including, although not limited to, urticaria and pruritus). If hypersensitivity occurs, the manufacturer recommends to discontinue marstacimab and manage as clinically appropriate.
• Thromboembolic events: Marstacimab is a tissue factor pathway inhibitor (TFPI) antagonist and may increase the risk of thromboembolic complications. Marstacimab has not been studied in patients with a history of previous thromboembolic events. If factor VIII or factor IX products are indicated in a patient receiving marstacimab prophylaxis, use the minimum effective factor VIII or factor IX dose. If thromboembolism occurs, the manufacturer recommends to interrupt marstacimab prophylaxis and manage as clinically indicated.
Dosage form specific issues:
• Polysorbate 80: Some dosage forms may contain polysorbate 80 (also known as Tweens). Hypersensitivity reactions, usually a delayed reaction, have been reported following exposure to pharmaceutical products containing polysorbate 80 in certain individuals (Ref). Thrombocytopenia, ascites, pulmonary deterioration, and kidney and hepatic failure have been reported in premature neonates after receiving parenteral products containing polysorbate 80 (Ref). See manufacturer's labeling.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Solution Auto-injector, Subcutaneous [preservative free]:
Hympavzi: Marstacimab-hncq 150 mg/mL (1 mL) [latex free; contains edetate (edta) disodium, polysorbate 80]
No
Solution Auto-injector (Hympavzi Subcutaneous)
150 mg/mL (per mL): $18,360.00
Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.
SUBQ: For SUBQ administration only. Administer on the same day each week; however, may administer at any time of the day on that day. If more than 1 injection is required to deliver a complete dose, administer each injection at a different injection site.
Administer SUBQ in the abdomen or thigh; other injection sites are acceptable if required. Administration in the upper arm (prefilled syringe only) or buttocks (prefilled pen only) should be performed by a caregiver or health care professional only. Rotate injection site with each new injection. Do not administer into bony areas or areas where the skin is bruised, red, tender, or hard, or areas where there are scars or stretch marks. Do not inject into a vein.
During treatment with marstacimab, other SUBQ medicines should preferably be injected at different anatomical sites (away from the site of the marstacimab injection).
Note : Properly trained patients may self-inject or caregivers may administer marstacimab using prefilled syringes or pens.
Parenteral: For SUBQ administration only. Administer by SUBQ injection into the abdomen at least 2 inches away from navel or thigh; health care professionals or caregivers may also administer into the upper arm (use prefilled syringe only) or the buttocks (use prefilled pen only) for some patients. Do not inject into bony areas or skin that is tender, bruised, hard, red, or has scars or stretch marks. Administer on the same day each week at any time of day. If the dose requires more than one injection, ensure each injection is at least 1 inch from the prior injection site; rotate body areas for subsequent doses.
Prefilled pen: Determine the number of prefilled pen(s) needed for dose. Remove prefilled pen(s) required for the dose from the refrigerator and allow to warm at room temperature for 15 to 30 minutes away from sunlight prior to use; do not use a warming source (eg, microwave, hot water); inspect visually for particulate matter and discoloration; do not use if solution is cloudy, dark yellow, or contains flakes or particles. Do not shake pens. Place clear base flat and firmly against skin at a 90-degree angle. Press and hold the injection button and listen for 2 loud clicks (dose is almost complete after the second click); leave needle in injection site for a slow count of 5 and until the yellow marker completely fills the window, then remove from skin; refer to manufacturer's labeling for additional information. Do not rub injection site. Pens are for single use; discard immediately after use.
Prefilled syringes: Determine the number of prefilled syringe(s) needed for dose. Remove prefilled syringe(s) required for the dose from the refrigerator and allow to warm at room temperature for 15 to 30 minutes away from sunlight prior to use; do not use a warming source (eg, microwave, hot water); inspect visually for particulate matter and discoloration; do not use if solution is cloudy, dark yellow, or contains flakes or particles. Do not shake syringes. Gently pinch skin at injection site, insert needle at a 45-degree angle; slowly and steadily push plunger rod until it completely stops and the barrel is empty; leave needle in injection site for a slow count of 5 and then remove from skin; refer to manufacturer's labeling for additional information. Do not rub injection site. Syringes are for single use; discard immediately after use.
Missed doses:
Maintenance dose of 150 mg:
≤13 days since last dose: Administer missed dose as soon as possible before the day of the next dose, then resume the usual weekly dosing schedule (same schedule as prior to missed dose or new schedule based on day missed dose administered).
>13 days since last dose: Administer a loading dose of 300 mg and then resume the weekly dosing schedule (same schedule as prior to missed dose or new schedule based on day missed dose administered).
Maintenance dose of 300 mg: If one or more missed doses, administer a dose as soon as possible, then resume the usual weekly dosing schedule (same schedule as prior to missed dose or new schedule based on day missed dose administered).
Hemophilia A, prophylaxis: Routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and pediatric patients ≥12 years of age with hemophilia A (congenital factor VIII deficiency) without factor VIII inhibitors.
Hemophilia B, prophylaxis: Routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adults and pediatric patients ≥12 years of age with hemophilia B (congenital factor IX deficiency) without factor IX inhibitors.
None known.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.
Efgartigimod Alfa: May decrease therapeutic effects of Fc Receptor-Binding Agents. Risk C: Monitor
Nipocalimab: May decrease therapeutic effects of Fc Receptor-Binding Agents. Risk C: Monitor
Rozanolixizumab: May decrease therapeutic effects of Fc Receptor-Binding Agents. Risk C: Monitor
Verify pregnancy status prior to initiating treatment in patients who could become pregnant.
Patients who could become pregnant should use effective contraception during therapy and for 2 months after the last marstacimab dose.
Female animal reproduction studies have not been conducted. Based on the mechanism of action, in utero exposure to marstacimab may cause fetal harm.
Marstacimab is a humanized monoclonal antibody (IgG1). Human IgG crosses the placenta. Fetal exposure is dependent upon the IgG subclass, maternal serum concentrations, placental integrity, newborn birth weight, and GA, generally increasing as pregnancy progresses. The lowest exposure would be expected during the period of organogenesis and the highest during the third trimester (Ref).
It is not known if marstacimab is present in breast milk.
Marstacimab is a humanized monoclonal antibody (IgG1). Human IgG is present in breast milk.
According to the manufacturer, the decision to breastfeed should consider the risk of infant exposure, the benefits of breastfeeding to the infant, and the benefits of treatment to the mother.
Verify pregnancy status prior to treatment initiation (in patients who could become pregnant). Monitor for signs/symptoms of hypersensitivity and/or thromboembolic events.
Antidrug antibodies: Antidrug antibodies against marstacimab, including neutralizing antibodies, have been reported. The clinical significance of marstacimab antidrug antibodies is unknown. Patients should be monitored for loss of efficacy during marstacimab treatment as a potential sign of the development of clinically significant neutralizing antibodies.
Classification of hemophilia; normal is defined as 100% factor VIII or IX (Ref):
Severe: Factor level <1% of normal.
Moderate: Factor level 1% to 5% of normal.
Mild: Factor level >5% to <40% of normal.
Marstacimab is a human monoclonal IgG1 antibody directed against tissue factor pathway inhibitor (TFPI) by targeting the Kunitz-type domain 2 of TFPI to neutralize TFPI-mediated inactivation of activated factor X protease functions and enhance coagulation (Ref). TFPI blocks early phases of coagulation by inhibiting activated factor VII (FVIIa) and activated factor X (FXa) (Ref).
Distribution: Vdss: 8.6 L.
Metabolism: Expected to be metabolized into small peptides and amino acids via catabolic pathways (in the same manner as endogenous IgG).
Bioavailability: SUBQ: ~71%.
Half-life elimination: ~7 to 10 days.
Time to peak: SUBQ: 23 to 59 hours.
Body weight: Body weight was a significant covariate impacting the pharmacokinetics of marstacimab; exposures over the body weight range of 35 to 120 kg show a trend for increase in exposure with decrease in body weight.
