Managing Inhibitors

For those with hemophilia A (factor VIII [8]), emicizumab is an option to prevent bleeding. It is not an option for those with hemophilia B (factor IX [9]). It is given by injection just below the skin's surface (subcutaneously).  

Emicizumab, brand name Hemlibra®, has been shown to greatly reduce the number of bleeds for those who take it.⁴  

Emicizumab was first FDA approved treatment for use in patients with an inhibitor.  

Emicizumab cannot be used to treat bleeds. If you have a bleed, they will need to treat the bleed with clotting factor or a bypassing agent (see sections below). This is important to know for emergencies or to plan for medical procedures.³  

If you are on emicizumab make sure to work closely with your health care provider when using bypassing agents to treat bleeds. This may increase the risk of developing a blood clot.³ 

This product does not treat the inhibitor or get rid of it.   

Emicizumab may affect some lab blood tests, including tests to measure factor activity levels and inhibitor titers. Individuals taking emicizumab must be tested with a Chromogenic assay to get a real inhibitor result.³ To learn more about testing for an inhibitor and inhibitor titers, please visit What is an Inhibitor?.  

For more information on how emicizumab works in the body and other key questions, please visit Bispecific Antibody Therapy.  

People with low-responding inhibitors may be able to treat and prevent bleeds by using larger amounts of clotting factor. Although some factor binds to the inhibitor and becomes inactive, enough is left to help form a clot.¹   

Your health care provider would guide you on when and how to use the higher dose factor if appropriate.  

Bypassing agents treat bleeding in people with low or high amounts of inhibitors. Instead of replacing the missing factor (factor VIII [8] or factor IX [9]), they go around (or bypass) the inhibitor to help the body form a normal clot.   

There are two main types of bypassing agents:   

Activated prothrombin complex concentrate, or aPCC (brand name Feiba®), which are used to prevent and treat bleeds.²   

Recombinant activated factor VIIa (7a) concentrate (brand names SevenFact®, Novoseven®), which are used to treat bleeds.²  

Bypassing agents can be very effective. They also do have some drawbacks.   

It can be hard to judge how well a medication works. Different patients respond differently to the two types of bypassing agents and there is no standard lab test to tell how well a bypassing agent is working to prevent a bleed. There can be some trial and error in finding the right treatment and right dosing.  

Recombinant factor VIIa (7a) requires frequent infusions. aPCCs must be infused very slowly, resulting in long infusions, to avoid potential reactions that may result from infusing too quickly. These may contribute to difficulty accessing veins.  

If you are using bypassing agents, make sure to work closely with your health care provider to make sure your blood is not clotting too much or clotting in the wrong place in the body. Certain medications should not be used with some bypassing agents for this reason.²   

The goal of ITI therapy is to stop the inhibitor reaction from happening.² In a way, it teaches the body to accept clotting factor treatments.   

With ITI therapy, people receive large amounts of clotting factor daily for many weeks or months.   

Often, ITI does get rid of the inhibitor. However, patients may need to continue taking frequent, large amounts of factor for many years to keep the inhibitor from returning. For others, it can reduce the bleeding complications.  

ITI therapy requires specialized medical expertise, is costly, and may take a long time to work. It is important to talk through all these factors with your health care provider to make a plan that works for you.