Sanofi and Sobi Report Positive Results for Altuviiio in Kids with Severe Hemophilia A

Rare Daily Staff

Sanofi and Sobi reported pivotal data from their phase 3 XTEND-Kids study of their therapy Altuviiio as a once-weekly prophylaxis for the rare bleeding disorder hemophilia A in children 12 and younger.

The companies presented results from the study of children with a severe form of the condition in a late-breaking session at the Annual Meeting of the International Society on Thrombosis and Haemostasis (ISTH) in Montreal, Canada. Altuviiio met the primary endpoint with no inhibitor development to factor VIII detected, and key secondary endpoints including annualized bleeding rate and maintenance of factor VIII activity were above pre-specified levels.

Hemophilia A is a rare, lifelong condition in which the ability of a person’s blood to clot properly is impaired, leading to excessive bleeds and spontaneous bleeds into joints that can result in joint damage and chronic pain, and potentially impact quality of life. The severity of hemophilia is determined by the level of clotting factor activity in a person’s blood, and there is a negative correlation between risk of bleeding and factor activity levels.

Altuviiio is a first-in-class, high-sustained factor VIII replacement therapy approved in February 2023 by the U.S. Food and Drug Administration for routine prophylaxis and on-demand treatment to control of bleeding episodes, as well as surgical management for adults and children with hemophilia A.

The U.S. Food and Drug Administration granted Breakthrough Therapy designation to Altuviiio in May 2022, Fast Track designation in February 2021, and Orphan Drug designation in 2017. The European Commission granted Orphan Drug designation in June 2019, and the European Medicines Agency accepted the Marketing Authorization Application in May 2023.

In the pediatric population, clearance of administered factor concentrates in the blood is greater than in adults, often meaning injections are needed 2 to 4 times per week using standard or extended half-life factor VIII products. These data confirm that a once-weekly 50 IU/kg dose of Altuviiio provides highly effective bleed protection in both children and adults and can be used across clinical scenarios.

The phase 3 XTEND-Kids study was an open-label, non-randomized interventional study of the safety, efficacy, and pharmacokinetics of once-weekly Altuviiio in previously treated patients younger than 12 years of age with severe hemophilia A. Patients received once-weekly Altuviiio prophylaxis for 52 weeks.

Development of factor VIII inhibitors was not detected. The median annualized bleeding rate was 0.00 and the mean rate was 0.89. Some 64 percent of patients had zero bleeding episodes, 82 percent had zero joint bleeds, and 88 percent of patients had zero spontaneous bleeds.

In this study, Altuviiio was well-tolerated and demonstrated a safety profile similar to the XTEND-1 trial, confirming safety and efficacy in both adults and children. No serious allergic reactions, anaphylaxis, or embolic or thrombotic events were reported. The most common treatment-emergent adverse events (more than 10 percent) were SARS-CoV-2 test positive, upper respiratory tract infection, and fever. No adverse events led to treatment discontinuation.

“In an effort to reduce their risk of bleeding episodes, many children living with hemophilia A are currently limited in their ability to fully participate in daily activities. This burden is compounded by the challenge of administering prophylactic treatments intravenously multiple times a week,” said Karin Knobe, therapeutic area head of rare diseases and rare blood disorders for Sanofi. “Today’s XTEND-Kids results reinforce the ability of Altuviiio to provide effective bleed protection with once weekly dosing and reinforce our commitment to developing new treatment options designed to redefine the standard of care for people living with rare blood disorders.”