As you age, you may have different goals for your bleeding disorders treatment that change over time. It can be important to learn about all of your options, but you may have questions. 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 health care provider to work together 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 you have one. To treat a bleed, you would use your prescribed clotting factor replacement therapy.
When there is an injury in the body, a blood clot is formed using a complex process called the clotting cascade. As part of the clotting cascade, different proteins called factors, are activated in a series of events, with one factor often activating another factor. Factor VIII (8) and factor IX (9) combine with each other and when combined, 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 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 so blood forms 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 blood so that they have the right amount to get to a steady level. After that, you can work with your health care provider to figure out if you should have an injection every week, every two weeks, or every 4 weeks.2
Your dose of emicizumab is determined based on your weight. Please check with your health care provider to see which dose is right for you.
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 a more stable protection
- FVIII inhibitors have no effect on how well the medication works
- Fewer bleeds including:
- Fewer bleeds that occur in the absence of injury (called spontaneous bleeds)
- Fewer joint bleeds
- Only need to inject treatment weekly, every other week or every 4 weeks, depending on your 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 the different types of health care providers you see know that you are taking emicizumab before having labs done.
- There are some important things to consider if you have an inhibitor to your factor replacement therapy. There are potential side effects with other medications used to treat inhibitors. You may need to stop your treatment before starting on emicizumab.
- You may have a breakthrough bleed, despite taking emicizumab. In this case, you will need to treated with a factor replacement product. Talk to your 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.2 It is important to speak with your health care provider about this box warning and what it would mean for you if you 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 to Treat Bleeding Disorders in the U.S.
- 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 Bleeding Disorders 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