Idelvion for Hemophilia B Now Available in Large 3500 IU Vial Size, CSL Behring Announces

Idelvion (albutrepenonacog alfa), a hemophilia B treatment approved for up to 14-day dosing, is now available in a large, 3500 IU vial size (3500 IU), CSL Behring announced.

Vials for the treatment are now available in five sizes – 250 IU, 500 IU, 1000 IU, 2000 IU and 3500 IU.   

“This enhancement to our Idelvion family of products represents our focus on patients and our commitment to help hemophilia patients lead full lives,” Bob Lojewski, senior vice president and general manager of North America Commercial Operations at CSL Behring, the treatment’s developer, said in a news release.

Idelvion is available as a freeze-dried powder in single-use vials containing a specific factor IX potency expressed in international units (IU). The powder needs to be mixed with sterile water for injection (a process known as reconstitution) before it can be injected into a vein. 

While previous sizes met the needs of most patients, some require higher doses, meaning they need to reconstitute several smaller vials of the therapy. The larger size will be more convenient for these patients or their caregivers.

Idelvion is approved for use in children and adults with hemophilia B (factor IX deficiency) needing on-demand control of bleeding episodes, to manage bleeding before surgery, and to prevent or reduce the frequency of bleeding episodes. 

It is a long-acting recombinant fusion protein that links coagulation factor IX with albumin, a natural protein known for its long half-life. Idelvion links recombinant albumin to recombinant factor IX (rFIX). The protein remains in the bloodstream until activated; when a bleed occurs, the linker in Idelvion is separated, activating the rFIX. This strategy keeps factor IX in the body longer.

A Phase 2/3 open-label, multicenter, safety and efficacy trial of Idelvion in 63 patients with hemophilia B (NCT01496274) found the therapy can achieve a zero median annual spontaneous bleeding rate, and can be safely used for up to 14-day dosing in patients ages 12 and older.

Clinical evidence shows that seven-day dosing of Idelvion increases factor IX levels to 21% at steady state. A 5% rise in factor IX levels was also observed with a single dose of the therapy over 14 days.

Researchers also reported at a scientific congress in 2017 very high rates of compliance with Idelvion as a prophylaxis (preventive) treatment among children under age 12 using it once every seven days, and in adolescents and adults using the therapy once every seven, 10, or 14 days.