Hemgenix®, a drug indicated for a type of hemophilia, has become the most expensive drug in the world after being approved by the United States Food and Drug Administration (FDA) on November 22, since each treatment with this product it costs 3.5 million dollars, which is equivalent to around 3.3 million euros. Its price is therefore higher than that of Zolgensma, which is used to treat spinal muscular atrophy and costs $2.1 million per treatment cycle.
The biopharmaceutical company CSL Behring has developed Hemgenix, which is a gene therapy to treat adults with hemophilia B, a genetic disease caused by the patient lacking or insufficient levels of blood clotting factor IX, and this protein is needed to produce blood clots to stop bleeding. Therefore, the symptoms of hemophilia can include bleeding (heavy or prolonged bleeding) after an injury, surgery, or dental procedure. Also, in the most severe cases, bleeding episodes can occur spontaneously without an obvious cause, and prolonged bleeding can lead to serious complications, such as bleeding into joints, muscles, or internal organs, including the brain.
Worldwide there are 400,000 people with hemophilia (3,000 in Spain). This disease mainly affects men and there are different types of hemophilia depending on the affected gene and the most frequent is hemophilia A, which affects one in 10,000 people, while B affects one in 50,000, according to the data handled by the Spanish Federation of Hemophilia (Fedhemo). It is estimated that in Spain there are only 319 patients with haemophilia B –also known as Christmas disease– who could benefit from the new drug, if approved.
A gene therapy to control hemophilia B
The treatment of hemophilia is based on providing the patient with the coagulation factor that is lacking, or whose levels are reduced, through transfusions or injections that are administered regularly. Although these treatments are effective and safe, those affected by this disease have to undergo a lifelong injection schedule, whereas the new gene therapy would be administered once.
“Hemgenix allows people with hemophilia B to produce their own clotting factor IX, and this can reduce the risk of bleeding”
Hemgenix consists of a viral vector that carries a gene for coagulation factor IX. The gene is expressed in the liver to produce the Factor IX protein, to increase Factor IX levels in the blood and therefore limit bleeding episodes. This drug is a one-time gene therapy product that is administered as a single dose by IV infusion.
Its safety and efficacy have been evaluated in two studies involving 57 men between the ages of 18 and 75 with severe or moderately severe haemophilia B. Efficacy was established based on reductions in the annualized bleeding rate (ABR) for these men. In a study with 54 participants, patients experienced increases in factor IX activity levels, a decreased need for routine factor IX replacement prophylaxis, and a 54% reduction in ABR compared to baseline.
“Gene therapy for hemophilia has been on the horizon for more than two decades. Despite advances in hemophilia treatment, bleeding prevention and treatment can negatively impact individuals’ quality of life,” said Peter Marks, director of the Center for Biological Assessment and Research. from the FDA. “The approval of this medicine brings a new treatment option for patients with hemophilia B and represents important progress in the development of innovative therapies for those who experience a high burden of this disease.”
The most frequently observed Hemgenix-associated side effects included elevations in liver enzymes, headache, mild injection-related reactions and flu-like symptoms, tiredness and malaise. “They may also experience spontaneous bleeding, poorer mobility, joint damage, or pain from the disease. Hemgenix allows people with hemophilia B to produce their own clotting factor IX, and this can reduce the risk of bleeding,” the company has reported on its website.
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