The U.S. Food and Drug Administration (FDA) approved the use of Refixia for hemophilia B patients, both adults and children at least 12 and older. The treatment also received approval from the European Medicines Agency (EMA) for the treatment of hemophilia B patients in the European Union.
How Refixia works
Hemophilia B is caused by a mutation in the gene carrying instruction for clotting factor IX, which is one of the proteins that help in normal clotting of blood. The mutation results in a deficiency of factor IX protein, which results in a bleeding disorder.
Refixia is a modified form of factor IX that is used as replacement therapy to replenish the deficient protein. Refixia contains a polyethylene glycol (PEG) molecule attached to the portion of factor IX protein that is broken off when the clotting factor is activated. The addition of PEG helps extend the half-life of factor IX. This process is called PEGylation and prevents the premature breakdown of factor IX by using naturally occurring antibodies against it.
The factor IX protein in Refixia is produced in a Chinese hamster ovary cell line before the PEGylation process.
Once the bleeding starts, Refixia is capable of acting like factor IX and successfully contributing to the formation of a blood clot to stop the bleeding.
People with hemophilia B may use Refixia as a form of prevention against bleeding, as well as an “on-demand” treatment to stop bleeding.
Refixia in clinical trials
A Phase 1 clinical trial (NCT00956345) evaluated the safety and pharmacokinetics (movement in the body) of Refixia in non-bleeding hemophilia B male patients ages 18 to 65. The patients received increasing single doses of Refixia (25U per kg, 50U perkKg, and 100U per kg) through a vein. The results showed that Refixia was successful in treating bleeds in a dose-dependent fashion.
A multi-national Phase 3 study (NCT01333111) assessed the safety and effectiveness of Refixia in 74 male patients with hemophilia B, ages 13 to 70. Patients randomly received either a low dose (10 U per kg) or high dose (40 U per kg) of Refixia once weekly for 52 weeks. The results showed that patients treated with 40 U per kg of Refixia once weekly were less likely to have a bleed compared to those treated with a 10 U per kg once weekly.
The long-term safety and efficiency of Refixia treatment were evaluated in a Phase 3 extension study (NCT01395810) and showed that the treatment’s effectiveness was maintained for at least two years.
A Phase 3 study (NCT01467427) tested the safety, effectiveness and pharmacokinetics of Refixia in male children ages 12 and younger with hemophilia B who had received some treatment. Participants were administered a single weekly dose of 40 U per kg of Refixia for 52 weeks, which was successful in treating a significant number of bleeds. For adolescents and adults receiving 40 U per kg of the medication once a week, 99% of bleeds were treated using a single dose. Moreover, bleeds into the joint were resolved in patients on the higher dose of Refixia (80 U per kg) within 12 months, and the treatment positively impacted patients’ health-related quality of life.
Another Phase 3 clinical trial (NCT01386528) tested the ability of Refixia to prevent and treat bleeding when given to hemophilia B patients before and after major surgery. Thirteen male patients, ages 13 to 70, were enrolled in the study. They were given a single intravenous dose of Refixia 80 U per kg four hours before surgery. After the surgery, they received another 40 U per kg of Refixia at the doctor’s discretion. The hemostatic effect (ability to stop bleeding) of Refixia during surgery was confirmed with a 100% success rate in 13 major procedures, including nine major orthopedic surgeries in patients ages 15 to 56.
A Phase 3 study (NCT03075670) conducted in Asia, North America, and Europe evaluated the safety and effectiveness of Refixia in boys with hemophilia B ages 12 and younger.
Similarly, another global Phase 3 study (NCT02141074) is assessing the safety and effectiveness of Refixia in preventing and treating bleeding in boys ages 6 and younger who have hemophilia B. The study aims to enroll 50 participants.
Refixia’s effectiveness and safety also are being investigated in an open-label Phase 3 trial (NCT02141074) for the prevention and treatment of bleeding episodes in previously untreated patients with hemophilia B, presenting a factor IX activity below 2%. This trial is recruiting participants at sites across the world.
Hemophilia News Today is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare providers with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.