Marstacimab is an active pharmaceutical ingredient in the Other Systemic Hemostatics group (B02BX). The information below is compiled per regulator from the product labels on record, with direct links to the original documents.
GBOfficial regulatory label· revised February 20, 2026[1]
Hympavzi is indicated for routine prophylaxis of bleeding episodes in patients 12 years of age and older, weighing at least 35 kg, with: • severe haemophilia A (congenital factor VIII deficiency, FVIII < 1%) without factor VIII inhibitors, or • severe haemophilia B (congenital factor IX deficiency, FIX < 1%) without factor IX inhibitors.
How to take
EUEuropean Union· EMA
1 product
Uses
EUOfficial regulatory label· revised March 19, 2026[2]
Hympavzi is indicated for routine prophylaxis of bleeding episodes in patients 12 years of age and older, weighing at least 35 kg, with: severe haemophilia A (congenital factor VIII deficiency, FVIII < 1%) without factor VIII inhibitors, or severe haemophilia B (congenital factor IX deficiency, FIX < 1%) without factor IX inhibitors.
[1]MHRA (UK) · PLGB000571730 · revised February 20, 2026
[2]European Medicines Agency · EMEA/H/C/006240 · revised March 19, 2026
Information on this page is compiled from public regulatory records. Drugvu is not affiliated with any regulator or pharmaceutical manufacturer. This is not medical advice. Always consult a qualified healthcare professional.
Treatment should be initiated under the supervision of a healthcare professional experienced in the treatment of haemophilia. Treatment should be initiated in a non-bleeding state. Posology The recommended dose for patients 12 years of age and older, weighing at least 35 kg, is an initial loading dose of 300 mg by subcutaneous injection followed thereafter by 150 mg by subcutaneous injection once weekly, at any time of day.
Duration of treatment Hympavzi is intended for long-term prophylactic treatment. Dose adjustments during treatment A dose adjustment to 300 mg subcutaneous injection weekly can be considered in patients weighing ≥ 50 kg when control of bleeding events is judged to be inadequate by the healthcare professional.
The maximum weekly dose of 300 mg should not be exceeded. Guidance on treating breakthrough bleeds Additional doses of Hympavzi should not be used to treat breakthrough bleeding events. For guidance on treatment in the event of breakthrough bleeds, see section
This is not medical advice. Consult a qualified healthcare professional.
Side effects & warnings
GBOfficial regulatory label· Adverse reactions· revised February 20, 2026[1]
Summary of the safety profile The overall safety profile of marstacimab is based on data from clinical studies. 4). 2%). 1). The data from the pivotal Phase 3 study 12-month Active Treatment Phase reflects exposure of 116 male patients with haemophilia A or B without inhibitors to marstacimab administered once weekly.
4%) were adolescents (12 years up to < 18 years). At the time of data cut-off, a total of 87 of the 116 patients completing the 12-month treatment period subsequently enrolled in the OLE study. 5 days (range 28 to 847 days). Table 1 summarises the adverse reactions reported in patients who received marstacimab prophylaxis.
The adverse reactions listed in the table below are presented by system organ class (SOC) and frequency categories, defined using the following convention: very common (≥ 1/10); common (≥ 1/100 to < 1/10), uncommon (≥ 1/1 000 to < 1/100), rare (≥ 1/10 000 to < 1/1 000), very rare (< 1/10 000) or frequency not known (cannot be estimated from the available data).
Within each frequency grouping, adverse reactions are presented in the order of decreasing seriousness. Table 1. Adverse reactions • System organ class • Adverse reaction • Frequency • Nervous system disorders • Headache • Common • Vascular disorders • Hypertension • Thromboembolic events (thrombosis,b) • Common • Uncommon • Skin and subcutaneous tissue disorders • Pruritus • Rasha • Common • Uncommon • General disorders and administrations site conditions • Injection site reactionsa • Very common a.
see ‘Description of selected adverse reactions’ b. ADR reported in the open-label extension study post-data cut-off. 2% of patients treated with marstacimab reported ISRs. The majority of ISRs observed in marstacimab clinical studies were transient and reported as mild to moderate in severity.
No occurrences of injection site reaction led to a dose adjustment or drug discontinuation. ISRs include injection site bruising, injection site erythema, injection site haematoma, injection site induration, injection site oedema, injection site pain, injection site pruritus, and injection site swelling.
9% of patients reported non-serious rash (Grade 1). Paediatric population The paediatric population studied comprises a total of 19 adolescent patients (from 12 to < 18 years of age). The safety profile of marstacimab was overall consistent between adolescents and adults.
Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.
GBOfficial regulatory label· Warnings and precautions· revised February 20, 2026[1]
4. 4). Treatment of acute severe illness should be managed per local standard of care, and continued treatment with Hympavzi in this situation should be weighed against the potential risks involved. Additional monitoring for adverse reactions and the development of thromboembolism may be warranted in these patients when marstacimab is administered.
Hympavzi should be temporarily interrupted if clinical symptoms, imaging, and/or laboratory findings consistent with thrombotic events occur, and managed as clinically indicated. Hympavzi therapy may be resumed once the patient has clinically recovered at the clinical judgement of the healthcare provider (see Missed dose section below).
Missed dose If a dose is missed, administer as soon as possible before the day of the next scheduled dose, and then resume usual weekly dosing schedule. If the missed dose is more than 13 days after the last dose, then a loading dose of 300 mg by subcutaneous injection should be administered followed thereafter by a resumption of 150 mg by subcutaneous injection once weekly.
Switching to Hympavzi Switching from prophylactic factor replacement therapy to Hympavzi: Prior to initiation of Hympavzi, patients should discontinue treatment with clotting factor concentrates (factor VIII or factor IX concentrates).
Patients can initiate Hympavzi at any time after discontinuing clotting factor concentrates.
Switching from non-factor-based haemophilia medicinal products to Hympavzi:
No clinical study data are available to guide converting patients from non-factor-based medicinal products to marstacimab. Although a washout period has not been studied, one approach is to allow an adequate washout period (at least 5 half-lives) of the prior agent based on labelled half-life before initiating treatment with Hympavzi.
Haemostatic support with clotting factor concentrates may be needed during the switch from other non-factor-based haemophilia medicinal products to Hympavzi. 2). Marstacimab has not been studied in patients with moderate or severe hepatic impairment.
2). Marstacimab has not been studied in patients with moderate or severe renal impairment. 2). Paediatric population Hympavzi should not be used in children less than 1 year of age because of potential safety issues. The safety and efficacy of marstacimab in paediatric patients < 12 years of age have not yet been established.
This is not medical advice. Consult a qualified healthcare professional.
Who should not take it
GBOfficial regulatory label· Contraindications· revised February 20, 2026[1]
1.
This is not medical advice. Consult a qualified healthcare professional.
Treatment should be initiated under the supervision of a healthcare professional experienced in the treatment of haemophilia. Treatment should be initiated in a non-bleeding state. 3 Posology The recommended dose for patients 12 years of age and older, weighing at least 35 kg, is an initial loading dose of 300 mg by subcutaneous injection followed thereafter by 150 mg by subcutaneous injection once weekly, at any time of day.
Duration of treatment Hympavzi is intended for long-term prophylactic treatment. Dose adjustments during treatment A dose adjustment to 300 mg subcutaneous injection weekly can be considered in patients weighing ≥ 50 kg when control of bleeding events is judged to be inadequate by the healthcare professional.
The maximum weekly dose of 300 mg should not be exceeded. Guidance on treating breakthrough bleeds Additional doses of Hympavzi should not be used to treat breakthrough bleeding events. For guidance on treatment in the event of breakthrough bleeds, see section
This is not medical advice. Consult a qualified healthcare professional.
Side effects & warnings
EUOfficial regulatory label· Adverse reactions· revised March 19, 2026[2]
Summary of the safety profile The overall safety profile of marstacimab is based on data from clinical studies. 4). 2%). 1). The data from the pivotal Phase 3 study 12-month Active Treatment Phase reflects exposure of 116 male patients with haemophilia A or B without inhibitors to marstacimab administered once weekly.
4%) were adolescents (12 years up to < 18 years). At the time of data cut-off, a total of 87 of the 116 patients completing the 12-month treatment period subsequently enrolled in the OLE study. 5 days (range 28 to 847 days). Table 1 summarises the adverse reactions reported in patients who received marstacimab prophylaxis.
The adverse reactions listed in the table below are presented by system organ class (SOC) and frequency categories, defined using the following convention: very common (≥ 1/10); common (≥ 1/100 to < 1/10), uncommon (≥ 1/1 000 to < 1/100), rare (≥ 1/10 000 to < 1/1 000), very rare (< 1/10 000) or frequency not known (cannot be estimated from the available data).
Within each frequency grouping, adverse reactions are presented in the order of decreasing seriousness. 8 Table 1. Adverse reactions System organ class Adverse reaction Frequency Nervous system disorders Headache Common Vascular disorders Hypertension Thromboembolic events (thrombosisb) Common Uncommon Skin and subcutaneous tissue disorders Pruritus Rasha Common Uncommon General disorders and administrations site conditions Injection site reactionsa Very common a.
see ‘Description of selected adverse reactions’ b. ADR reported in the open-label extension study post-data cut-off. 2% of patients treated with marstacimab reported ISRs. The majority of ISRs observed in marstacimab clinical studies were transient and reported as mild to moderate in severity.
No occurrences of injection site reaction led to a dose adjustment or drug discontinuation. ISRs include injection site bruising, injection site erythema, injection site haematoma, injection site induration, injection site oedema, injection site pain, injection site pruritus, and injection site swelling.
9% of patients reported non-serious rash (Grade 1). Paediatric population The paediatric population studied comprises a total of 19 adolescent patients (from 12 to < 18 years of age). The safety profile of marstacimab was overall consistent between adolescents and adults.
Reporting of suspected adverse reactions Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the national reporting system listed in Appendix V.
EUOfficial regulatory label· Warnings and precautions· revised March 19, 2026[2]
4. 4). Treatment of acute severe illness should be managed per local standard of care, and continued treatment with Hympavzi in this situation should be weighed against the potential risks involved. Additional monitoring for adverse reactions and the development of thromboembolism may be warranted in these patients when marstacimab is administered.
Hympavzi should be temporarily interrupted if clinical symptoms, imaging, and/or laboratory findings consistent with thrombotic events occur, and managed as clinically indicated. Hympavzi therapy may be resumed once the patient has clinically recovered at the clinical judgement of the healthcare provider (see Missed dose section below).
Missed dose If a dose is missed, administer as soon as possible before the day of the next scheduled dose, and then resume usual weekly dosing schedule. If the missed dose is more than 13 days after the last dose, then a loading dose of 300 mg by subcutaneous injection should be administered followed thereafter by a resumption of 150 mg by subcutaneous injection once weekly.
Switching to Hympavzi Switching from prophylactic factor replacement therapy to Hympavzi: Prior to initiation of Hympavzi, patients should discontinue treatment with clotting factor concentrates (factor VIII or factor IX concentrates).
Patients can initiate Hympavzi at any time after discontinuing clotting factor concentrates.
Switching from non-factor-based haemophilia medicinal products to Hympavzi:
No clinical study data are available to guide converting patients from non-factor-based medicinal products to marstacimab. Although a washout period has not been studied, one approach is to allow an adequate washout period (at least 5 half-lives) of the prior agent based on labelled half-life before initiating treatment with Hympavzi.
Haemostatic support with clotting factor concentrates may be needed during the switch from other non-factor-based haemophilia medicinal products to Hympavzi. 2). Marstacimab has not been studied in patients with moderate or severe hepatic impairment.
2). Marstacimab has not been studied in patients with moderate or severe renal impairment. 2). Paediatric population Hympavzi should not be used in children less than 1 year of age because of potential safety issues. The safety and efficacy of marstacimab in paediatric patients < 12 years of age have not yet been established.
This is not medical advice. Consult a qualified healthcare professional.
Who should not take it
EUOfficial regulatory label· Contraindications· revised March 19, 2026[2]
1.
This is not medical advice. Consult a qualified healthcare professional.
The safety and efficacy of marstacimab in adolescents with a body weight < 35 kg have not been established. No data are available. Management in the perioperative setting The safety and efficacy of marstacimab have not been formally evaluated in the surgical setting.
Patients have had minor surgical procedures without discontinuing Hympavzi prophylaxis in clinical studies. For major surgery, it is recommended to discontinue Hympavzi 6 to 12 days prior and initiate management per local standard of care with clotting factor concentrate and measures to manage the risk of venous thrombosis which can be elevated in the perioperative period.
The product information for the clotting factor concentrate should be consulted for dose guidelines in patients with haemophilia undergoing major surgery. Resumption of Hympavzi therapy should take into account the overall clinical status of the patient, including the presence of post-surgical thromboembolic risk factors, use of other haemostatic products and other concomitant medicinal products (see Missed dose section above).
Method of administration Hympavzi is for subcutaneous use only. Hympavzi is intended for use under the guidance of a healthcare professional. After proper training in subcutaneous injection technique, a patient or caregiver may inject with the medicinal product if a healthcare professional determines that it is appropriate.
6). The medicinal product should not be warmed by using a heat source such as hot water or a microwave. The recommended injection sites are the abdomen (at least 5 cm away from the navel) and thigh. Other locations are acceptable if required.
Administration of Hympavzi in the upper arm (pre-filled syringe only) and buttocks (pre-filled pen only) should be performed by a caregiver or healthcare professional only. The medicinal product should not be administered into bony areas or areas where the skin is bruised, red, tender or hard, or areas where there are scars or stretch marks.
For the 300 mg loading dose, each of the two Hympavzi 150 mg injections should be administered at different injection sites. It is recommended to rotate the injection site with each injection. Hympavzi should not be injected into a vein or muscle.
During treatment with Hympavzi, other medicinal products for subcutaneous administration should, preferably, be injected at different anatomical sites. 6 and the ‘Instructions for Use’ provided at the end of the package leaflet. 1. 4 Special warnings and precautions for […]
The safety and efficacy of marstacimab in adolescents with a body weight < 35 kg have not been established. No data are available. Management in the perioperative setting The safety and efficacy of marstacimab have not been formally evaluated in the surgical setting.
Patients have had minor surgical procedures without discontinuing Hympavzi prophylaxis in clinical studies. For major surgery, it is recommended to discontinue Hympavzi 6 to 12 days prior and initiate management per local standard of care with clotting factor concentrate and measures to manage the risk of venous thrombosis which can be elevated in the perioperative period.
The product information for the clotting factor concentrate should be consulted for dose guidelines in patients with haemophilia undergoing major surgery. Resumption of Hympavzi therapy should take into account the overall clinical status of the patient, including the presence of post-surgical thromboembolic risk factors, use of other haemostatic products and other concomitant medicinal products (see Missed dose section above).
Method of administration Hympavzi is for subcutaneous use only. Hympavzi is intended for use under the guidance of a healthcare professional. After proper training in subcutaneous injection technique, a patient or caregiver may inject with the medicinal product if a healthcare professional determines that it is appropriate.
6). The medicinal product should not be warmed by using a heat source such as hot water or a microwave. The recommended injection sites are the abdomen (at least 5 cm away from the navel) and thigh. Other locations are acceptable if required.
Administration of Hympavzi in the upper arm (pre-filled syringe only) and buttocks (pre-filled pen only) should be performed by a caregiver or healthcare professional only. The medicinal product should not be administered into bony areas or areas where the skin is bruised, red, tender or hard, or areas where there are scars or stretch marks.
For the 300 mg loading dose, each of the two Hympavzi 150 mg injections should be administered at different injection sites. 5 It is recommended to rotate the injection site with each injection. Hympavzi should not be injected into a vein or muscle.
During treatment with Hympavzi, other medicinal products for subcutaneous administration should, preferably, be injected at different anatomical sites. 6 and the ‘Instructions for Use’ provided at the end of the package leaflet. 1. 4 Special warnings and precautions […]