What Alhemo Means for Patients With Hemophilia A and B Without Inhibitors

The recent FDA approval of Alhemo (concizumab-mtci) in the U.S. for those 12 years and older with hemophilia A or B without inhibitors could reshape treatment for many living with these rare bleeding disorders.

The approval, announced July 31, expands the drug’s indication beyond its earlier approval in December 2024 for patients with inhibitors, offering a once-daily subcutaneous injection in place of traditional intravenous (IV) infusions.

For those with hemophilia, prophylaxis—a preventive therapy to reduce the frequency of bleeding episodes—has long required IV administration of missing clotting factors. While it’s effective, IV therapy can be challenging for patients and caregivers because of the need to access the veins of patients, infusion time and the skills required to perform the procedure.

The FDA's approval of Alhemo (concizumab-mtci) revolutionizes hemophilia treatment, offering a simpler, subcutaneous injection for better bleed control and patient independence.

This new approval suggests that many patients without inhibitors now have access to a simpler delivery method: a prefilled pen for injection under the skin.

Alhemo works by targeting and blocking tissue factor pathway inhibitor (TFPI), a protein that limits blood clotting. In hemophilia, those affected are missing clotting factors VIII or IX, making it difficult for blood to form clots. By blocking TFPI, Alhemo helps the body create more thrombin, which improves clotting even if the person has inhibitors.

Alhemo comes in prefilled, premixed pens in three strengths: 60 mg/1.5 mL, 150 mg/1.5 mL and 300 mg/3 mL. The dosing starts with a loading phase (1 mg per kilogram of body weight daily) followed by a maintenance phase (0.2 mg per kilogram daily), adjusted based on blood levels measured at week four of treatment.

With roughly 800,000 people worldwide living with hemophilia, even slight improvements in treatment can make a significant impact on daily life. This expanded approval of Alhemo represents not just another drug on the market, but a shift toward more patient-friendly, less invasive prophylaxis.

The approval is based on results from the phase 3 explorer8 trial, which evaluated Alhemo in patients 12 years and older with hemophilia A or B without inhibitors. In the trial, participants either did or did not receive a prophylaxis—using clotting factor replacement only after a bleed occurred—or took Alhemo daily.

Findings revealed that patients with hemophilia B who received Alhemo prophylaxis saw a 79% reduction in annualized bleeding rate (ABR) compared to those without prophylaxis.

For those with hemophilia A, the reduction was even greater at 86%. The average ABR for hemophilia B patients on Alhemo was 3.1 compared to 14.8 for those without prophylaxis. For hemophilia A patients, the averages were 2.7 and 19.3, respectively.

In the trial, the most common side effects in at least 5% of patients were injection site reactions (7%) and headache (7%). Serious but less common risks included blood clots, which may be more likely when high doses of clotting factor products or bypassing agents are used.

Allison P. Wheeler, M.D., scientific director at the Washington Center for Bleeding Disorders, highlighted the importance of maintaining control over bleeding.

“For people living with hemophilia, it is important to continually monitor and discuss bleed control with their healthcare professional,” she said. “With today’s approval of Alhemo for hemophilia A or B without inhibitors, more people living with these rare blood disorders now have a daily prophylaxis option that may help decrease their bleeding rates.”

Subcutaneous delivery could also lower barriers to adherence.

Many people with hemophilia need lifelong prophylaxis, and switching from IV infusions to a daily injection could be especially meaningful for teenagers, adults with poor venous access or patients managing their condition without consistent caregiver support, according to the World Federation of Hemophilia.

Adherence to prophylaxis is one of the biggest factors in preventing joint damage and other long-term complications of the disease.

For patients without inhibitors—particularly those who have struggled with the burden of IV therapy—the availability of a subcutaneous, once-daily pen may open the door to better bleed control, greater independence, and improved quality of life. While the initial announcement is now over a week old, its implications are just beginning to reach the community it aims to serve.