Refixia (nonacog beta pegol, or N9-GP) is a replacement therapy candidate developed by the healthcare company Novo Nordisk. It is for the prevention and treatment of bleeding in people with hemophilia B.
Novo Nordisk expects a decision shortly by the U.S. Food and Drug Administration (FDA) on Refixia for the treatment for people with hemophilia B. The European Medicines Agency (EMA) is also expected to make a decision on the therapy.
Blood clots are formed through a complex process that involves platelets (a type of blood cell) and several enzymes known as coagulation factors.
People with hemophilia have alterations in the portions of their genetic material that carry the information to form coagulation factor VIII, in the case of hemophilia A, and coagulation factor IX in the case of hemophilia B. This leads to a decreased amount of these enzymes and compromises the coagulation process.
How does Refixia work?
Refixia is a modified form of coagulation factor IX that has an extended activity period. The structure of Refixia allows it to remain longer in the body without being detected and inhibited by naturally existing antibodies against factor IX.
Once bleeding starts, Refixia is capable of acting like factor IX and successfully contributes to the formation of a blood clot to stop the bleeding.
Studies indicate that Refixia may be used by people with hemophilia B as a form of prevention against bleeding, as well as an “on-demand” treatment to stop bleeding.
Studies with Refixia
Refixia has been tested in four Phase 3 trials in previously treated patients with severe or moderate hemophilia B with a factor IX activity below 2 percent. Participants were blinded to the dose and randomized to either receive 10 IU/kg or 40 IU/kg of the drug once-weekly.
Out of the four trials, two evaluated the safety and effectiveness of Refixia in adults (NCT01333111) and in children age 12 and younger (NCT01467427). The second study is still ongoing. The other two evaluated Refixia’s safety and efficacy after long-term exposure (NCT01395810) and during surgical procedures (NCT01386528).
In all the trials and treatments, Refixia was successful in the treatment of 93 percent of bleeds. For adolescents and adults receiving 40 IU/kg of the drug once a week, 99 percent of bleeds were treated using a single dose of the drug.
Patients treated with 40 IU/kg once weekly had a low annualized bleeding rate in adults (mean 2.51) and children (mean 1.44), while patients treated with 10 IU/kg once weekly had an annualized mean bleeding rate of 4.56. These patients were 1.9 times more likely to have a bleed and 2.7 times more likely to have a spontaneous bleed than patients treated with the higher dose.
In addition, bleeds into the joint were resolved in patients on the higher dose of Refixia (90 percent of the 20 target joints) within 12 months, and the treatment positively impacted health-related quality of life.
The hemostatic effect of Refixia during surgery was confirmed with a 100 percent success rate in 13 major surgeries, including nine major orthopedic procedures in patients ages 15 to 56.
Refixia’s effectiveness and safety are currently being tested in an open-label, single-arm, non-controlled Phase 3 trial for the prevention and treatment of bleeding episodes in previously untreated patients with hemophilia B, presenting a factor IX activity below 2 percent (NCT02141074). This trial is still recruiting participants.
Finally, participants are also being recruited for a Phase 1 clinical trial to compare the pharmacokinetics of Refixa to Alprolix (a standard replacement therapy drug) in patients with hemophilia B (NCT03075670).
Other details about Refixia
Refixia is awaiting approval by the U.S. Food and Drug Administration (FDA) to treat hemophilia B patients in the U.S.
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