As a parent or caregiver of an infant, toddler, or early school aged child, making sure their bleeding disorders treatment is able to protect them through all these stages is top of mind. You may have questions about the different types of treatment options for your child. This section has answers to common questions about bispecific antibody therapy. There is only one bleeding disorder bispecific antibody therapy product, called emicizumab (brand name Hemlibra®). This section can also help you develop your own set of questions to then ask your child’s health care provider to find the best treatment option.
Emicizumab is a treatment for people with hemophilia A, with or without inhibitors. It helps prevent bleeding from happening in the first place (prophylaxis or “prophy”). However, it can’t be used to treat bleeds if your child has one. To treat a bleed, you would use your child’s prescribed clotting factor replacement therapy.
When there is an injury, the body works to form a clot- using a complicated process called the clotting cascade. As part of the clotting cascade, different proteins called factors, are activated in a series of steps, with one factor often activating another factor. Factor VIII (8) and factor IX (9) combine with each other and when combined together, are able to activate factor X (10) during the clotting cascade. When a person has hemophilia A, they are missing factor VIII (8). This means that there is nothing to combine with factor IX (9) so that factor X (10) can be activated. Without factor X (10) being activated, it will be much more difficult for your child’s body to form a strong blood clot.
Emicizumab uses a lab made bispecific antibody to mimic, or imitate, the way factor VIII (8) works in the body. It can bind to both factor IX (9) and factor X (10). This allows the clotting cascade to continue and your blood to form a clot.
Emicizumab is given using a needle inserted under the skin to deliver medicine in the body. This is called a subcutaneous injection or sometimes just “sub Q” for short. This differs from many other treatments for hemophilia A in which the medicine is injected directly into a person’s vein, called an infusion. If you want more information on how to give a sub Q injection, please go to Injection Basics.
This treatment starts with weekly injections for the first 4 weeks. This is the loading dose phase to build up the medicine in your child’s blood so that they have the right amount to get to a steady level. After that, you can work with your child’s health care provider to figure out if your child should have an injection every week, every two weeks, or every 4 weeks.2
Your child’s dose of emicizumab is determined based on their weight. Please check with your child’s health care provider to see which dose is right for them.
Emicizumab can be used by:
- people who have hemophilia A, with and without inhibitors
- all ages, infants through adults
- any severity level2
Some of the benefits of using emicizumab include:
- No presentation of peaks and throughs leading to more stable protection
- FVIII inhibitors have no effect on how well the medication works
- Fewer bleeds including:
- Fewer bleeds that occur without an injury (called spontaneous bleeds)
- Fewer joint bleeds
- Only need to inject treatment weekly, every other week or every 4 weeks, depending on your child's treatment plan
Some of the limitations of using emicizumab include:
- Emicizumab causes some inhibitor and other lab tests to be inaccurate. So, make sure that all of your child’s different types of health care providers know that they are taking emicizumab before having lab tests done.
- There are some important things to think about if your child has an inhibitor to their factor replacement therapy. There are possible side effects with other medications used to treat inhibitors. Your child may need to stop their treatment before starting on emicizumab.
- Your child may have a breakthrough bleed, despite taking emicizumab. In this case, your child will need to be treated with a factor replacement product. Talk to your child’s health care provider to have a plan in place.
Risks with using emicizumab:
This treatment product has a Box Warning from the FDA. This warning is used to draw attention to the serious or life-threatening side effects or risks. You can find the warning on the box or in the product insert.1 It is important to speak with your health care provider about this box warning and what it would mean if your child will use this treatment product.
Other names for emicizumab are as follows:
- Hemlibra®
You may also hear other terms used for this therapy, including “mimetic”, “non-factor replacement”, or even “factor substitute”. Mimetic medicines work by mimicking something that normally naturally takes place in the body. Non-factor replacement therapies are a category for any bleeding disorder treatment that isn’t factor replacement therapy. Factor substitute may be used because this medicine substitutes the bispecific antibody for where the factor protein would have been.
If you want more information about using bispecific antibody therapy for treatment of bleeding disorders, please go to NBDF’s MASAC Recommendation on the Use and Management of Emicizumab.
If you want more information about all FDA-approved products for the treatment of bleeding disorders, please go to Products Licensed in the U.S. to Treat Bleeding Disorders
- Genentech. (2021, December). Hemlibra Prescribing Information. https://www.gene.com/download/pdf/hemlibra_prescribing.pdf
- NBDF’s Medical and Scientific Advisory Council (MASAC). (2022). MASAC Document 268 - Recommendation on the Use and Management of Emicizumab-kxwh (Hemlibra®) for Hemophilia A with and without Inhibitors (MASAC 268). National Hemophilia Foundation. https://www.hemophilia.org/healthcare-professionals/guidelines-on-care/masac-documents/masac-document-268-recommendation-on-the-use-and-management-of-emicizumab-kxwh-hemlibrar-for-hemophilia-a-with-and-without-inhibitors