What Is Alhemo?
Alhemo is a monoclonal antibody designed to target and inhibit tissue factor pathway inhibitor (TFPI), a natural anticoagulant protein that limits thrombin generation. By blocking TFPI, Alhemo enhances the body’s ability to generate thrombin and form stable blood clots — which is essential for controlling bleeding in people with hemophilia A or B.
Unlike traditional factor replacement therapies, which require intravenous infusions, Alhemo is administered subcutaneously using prefilled pen devices. The dosing regimen is once daily, offering increased convenience and potentially better adherence, especially for younger or needle-averse patients.
Clinical Trial Evidence: EXPLORER8 Study
The FDA’s approval is based on data from the Phase 3 EXPLORER8 trial, which included 156 male patients aged 12 years and older with hemophilia A or B without inhibitors. Participants were randomized in a 1:2 ratio to either receive:
On-demand therapy with clotting factor concentrates, or
Daily prophylaxis with concizumab (Alhemo)
Key findings include:
Hemophilia B subgroup:
Alhemo reduced the annualized bleeding rate (ABR) by 79% compared to the control group.ABR for Alhemo: 3.1 (median: 1.6)
ABR for control: 14.8 (median: 14.9)
Hemophilia A subgroup:
ABR was reduced by 86%.ABR for Alhemo: 2.7 (median: 2.9)
ABR for control: 19.3 (median: 19.6)
These results demonstrate that Alhemo offers strong protection against both spontaneous and traumatic bleeds.
Safety Profile
Alhemo was generally well tolerated across trial populations. The most frequently reported side effects were:
Injection site reactions
Headaches
Each occurred in approximately 7% of participants. No new safety signals emerged, and there was no indication that Alhemo induces development of inhibitors to clotting factors.
The treatment is not approved for:
Patients under 12 years of age
Those undergoing immune tolerance induction therapy
Monitoring for hypersensitivity and thrombotic events is still advised, as with other therapies that modulate coagulation pathways.
What Makes Alhemo Different?
Alhemo offers a convenient, non-factor-based treatment option for both types of hemophilia (A and B), even in the absence of inhibitors. Its daily subcutaneous administration via a prefilled pen makes it a practical choice for many patients compared to intravenous factor infusions, which can be more invasive and logistically challenging.
This approval also marks the first time a single treatment has been approved in both hemophilia A and B without inhibitors using a non-factor, TFPI-targeted approach.
