Weekly infusion reduces bleeding in boys with hemophilia A

Once-weekly preventive treatment with Altuviiio (efanesoctocog alfa) safely reduced bleeding rates while maintaining protective clotting factor levels without triggering neutralizing antibodies in pediatric patients with hemophilia A.

That’s according to a real-world study that reviewed data from 22 boys at the University of Texas Southwestern and Children’s Health in Dallas. The study, “Real-World Clinical Data and Thrombin Generation of Efanesoctocog Alfa Prophylaxis in Pediatric Patients With Haemophilia A,” was published in Haemophilia.

Excessive bleeding is caused in hemophilia A by a lack of clotting factor VIII (FVIII), a protein that helps blood clot. Given as an infusion into the bloodstream, Altuviiio is an approved factor replacement treatment that replaces the missing FVIII, providing sustained protection against bleeds. It was designed to remain active in the body longer than the naturally occurring FVIII.

Although clinical studies have shown that Altuviiio is safe and effective for pediatric patients, real-world data remain limited. Two researchers from the Texas center set out to collect evidence from clinical settings, reviewing the medical records of 22 boys ranging in age from 4 to 17.

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No spontaneous bleeds seen

Fifteen of the 22 (68.3%) had severe hemophilia A, six (27.3%) had moderate hemophilia A, and one (4.5%) had mild hemophilia A with type 1 von Willebrand disease, another inherited bleeding disease. All boys had started or switched to Altuviiio as regular prophylaxis (preventive treatment) to reduce bleeding, and they received it for a median of 15.5 months.

The average annual bleeding rate, a measure of the number of bleeds adjusted to a one-year time window, decreased significantly from 1.05 before treatment to 0.45 after starting Altuviiio. No spontaneous bleeds occurred during treatment. However, six boys (27.3%) experienced a combined eight episodes of bleeding following injuries or physical activities. Five of these patients participated in sports, including soccer, basketball, and football.

The treatment was generally well tolerated. Two patients experienced temporary symptoms after their first infusion, including flushing, feeling warm, nausea, and dizziness. These symptoms disappeared without treatment and did not return. No serious side effects were reported, and no inhibitors (antibodies that can block replacement FVIII, making treatment less effective) were detected.

Blood tests showed an average FVIII trough level of 15 IU/dL seven days after treatment and a peak level of 137 IU/dL shortly after infusion. The trough level represents the lowest amount of FVIII between doses, while the peak level represents the highest amount after treatment. These results indicate that FVIII was maintained within the mild hemophilia range throughout the weekly dosing period.

Patients’ overall ability to form blood clots more than doubled shortly after receiving an infusion, compared with right before their next scheduled dose, as measured by the total thrombin produced over time. Thrombin is an enzyme involved in blood clotting, and increased activity suggests a greater capacity to form blood clots. Ferritin, a protein that stores iron in the body, also increased. Higher levels may indicate greater iron stores, potentially related to fewer bleeds.

Although the study was limited by its small number of patients, single-center design, and relatively short follow-up, it shows that Altuviiio has “an overall favourable profile” in pediatric patients, the researchers wrote. Larger studies with longer follow-up are needed to confirm these findings and examine other measures, such as quality of life, they said.