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Bispecific Antibody Therapy

Bispecific Antibody Therapy

Bispecific antibodies are proteins that can bind to two different molecules. In the case of bleeding disorders, that can be helpful because clots only form when each of the proteins in the blood work together, and some need to bind together to do their job. There is only one approved bleeding disorder treatment product that is a bispecific antibody, and it is for hemophilia A. It is important to work with your health care provider to determine which treatment is best for you.

This therapy, known as emicizumab (brand name Hemlibra®), can be used to help prevent bleeding in individuals with hemophilia A (with and without inhibitors) by working as a bridge between two factors. It mimics, or imitates, the way factor VIII (8) works. It brings together factor IX (9) and factor X (10), which allows the blood to clot. 

Preventing Versus Treating Bleeds 

Emicizumab 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. It is important to keep enough emicizumab available for routine bleed prevention and enough factor replacement therapy for bleeds. Work with your health care provider to determine what is the right amount to keep available for both. Work with your health care provider if you are having a major procedure or surgery, so there is a plan in place if factor or other products are needed.

If you have an inhibitor to your factor replacement therapy, then you will need to work closely with your health care provider for steps to take if you have a bleed. 

About the Treatment 

Emicizumab is given by an injection into the skin, 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.

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 you 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 inject every week, every two weeks or every 4 weeks. 

Emicizumab causes some 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. 

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. 

It is also important to work closely with your health care provider to understand the impact on inhibitor and other lab testing if needed, and if you need to stop using emicizumab. 

You can find more information in the MASAC treatment recommendation on emicizumab.

Learn more about FDA-approved products for the treatment of bleeding disorders.