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Hemophilia A FAQ
Frequently Asked Questions About Advances in the Management of Hemophilia A

Released: January 30, 2020

Expiration: January 28, 2021

Michael Callaghan
Michael Callaghan, MD
Stacy E. Croteau
Stacy E. Croteau, MD, MMS
Cindy A. Leissinger
Cindy A. Leissinger, MD
Guy Young
Guy Young, MD
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This ClinicalThought features 2 key questions asked by participants during a CME-certified symposium at the 2019 ASH annual meeting in Orlando, Florida, which focused on advancements in therapies for hemophilia A and the potential for a more personalized approach for patients.

Should pharmacokinetic (PK) testing with every available extended half-life factor VIII be done to determine which one might be best for the patient?
Many patients with hemophilia A are comfortable and well protected with their current prophylactic IV factor replacement infusion regimen. However, some patients may want to try an alternative approach. Our panel of experts recommends using a PK modeling tool such as WAPPS-HEMO to select the best initial regimen for patients.

Current ISTH guidance recommends limited sampling within optimal time windows post infusion, specifically between 4 and 8 hours, 16 and 20 hours, 40 and 60 hours, and, if possible, 60 and 84 hours—to estimate an individual’s PK profile based on population PK modelling.

Sampling windows, rather than specific time points, allow flexibility and convenience for the patient. When patients see their PK data in graphic form, showing their overall change factor activity between factor infusions helps them to better understand the importance of timing their infusions and changing bleeding risk.

If you try a product and have a favorable PK profile that allows for reasonable dosing and frequency that meets the patient’s needs, it is not obligatory to continue trialing other factor concentrates at that time. When a product with an extended half-life doesn’t show a clinically meaningful extension in the patient, than a different product can be tested.

Is emicizumab the best option for every patient with hemophilia A, including previously untreated patients (PUPs)?
Hemophilia treatment is now increasingly personalized, and we are fortunate to have many treatment options, including the factor VIIIa mimetic emicizumab. Our experts agree, however, that emicizumab is not for everyone and suggest the use of a shared decision-making model that allows patients to be guided through the clinical trial data and clinical experience with each treatment option.

Many patients have been switched to emicizumab, but other patients infusing factor VIII concentrates for prophylaxis are doing very well and not having any bleeding episodes may want to continue their current regimen—and that is a very reasonable decision.

Current data show that emicizumab provides good prophylaxis in patients with severe hemophilia overall, but what about a younger patient who is an aggressive athlete with competitive aspirations? Would this therapy provide adequate protection in the short term for this patient’s aggressive sports activity and in the longer term for overall musculoskeletal health? We do not have the data right now to support emicizumab as a good choice for such a patient—we hope to learn more with more experience.

Because a protocol that applies to all PUPs does not exist at this time, our experts agree that they would treat PUPs with emicizumab, with the caveat that this choice is after a shared decision-making process that considers the family’s wishes with respect to emicizumab and factor VIII exposure.

Our faculty members also agree that factor VIII exposure in childhood to induce primary tolerance despite prophylaxis with emicizumab may be beneficial in reducing inhibitor development; however, whether this is necessary and how to achieve this is not well understood at this time. Enrolling PUPs in studies of the impact of exposure would help us understand how to effectively induce primary tolerance.

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What challenges do you encounter when switching patients with hemophilia A from factor replacement therapy to a new therapy? Please answer the polling question on your screen and share your thoughts in the comments box below.

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