In the event that hemophilia patients on Hemlibra become infected with COVID-19, the company warns that not all tests will be suitable to monitor the abnormal clotting in blood vessels — a condition called disseminated intravascular coagulation — that sometimes happens with the coronavirus infections.
“Given that the physicians and laboratories treating COVID-19 patients may not be familiar with Hemlibra, we want you to be prepared to share this information in cases where it is relevant,” the company wrote in the notice.
Hemlibra is approved in the U.S. for the routine preventive treatment of adults and children with hemophilia A, with or without inhibitors. These patients lack a functional factor VIII (FVIII), which is essential for blood to clot properly.
Similar to FVIII, Hemlibra works by binding to factors IX and X. This helps blood to clot normally, reducing blood loss and preventing damage to joints and tissues from internal bleeding.
However, due to its mechanism of action, Hemlibra interferes with some laboratory tests measuring blood coagulation, making doctors overestimate Hemlibra’s coagulation potential in certain circumstances.
Notably, these tests are not used just to monitor patients with hemophilia; they also help diagnose and monitor patients with other diseases affecting coagulation. One such case is disseminated intravascular coagulation, a condition that may develop in severe coronavirus infections and that can occur independently of hemophilia.
This means that such tests may not accurately detect COVID-19-associated coagulation problems if a patient is taking Hemlibra.
While this information is known in the hemophilia community, Genentech recognizes that many healthcare professionals treating COVID-19 may not be familiar with Hemlibra and its affect on coagulation tests.
So, the company provided a table with the assays most commonly used to manage people with COVID-19-associated coagulation diseases, with information about whether they are affected by Hemlibra, and possible alternatives.
“[I]f an individual on Hemlibra seeks treatment due to symptoms of COVID-19 infection, we recommend the above table or information is communicated proactively to the treating healthcare provider to ensure they are aware of this information and to remind them to consult the U.S. Prescribing Information,” the company wrote.
Genentech also warned that Hemlibra is stable and remains in the blood for long periods (its half-life, or the time required for its levels to reduce by half, is about 30 days), which should be taken into consideration for the clinical management of patients.
The company also is working to understand whether Hemlibra affects coagulation problems related to COVID-19 infections. Genentech encourages healthcare providers to report all cases of suspected or confirmed infections among those on the therapy through Genentech’s “adverse event reporting line” at 888–835–2555. Details on what to report and other useful resources can be found here.
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