The most expensive drug in the world: Hemgenix, a $3.5 million treatment for hemophilia B

It is an innovative and effective treatment, but it comes with a stratospheric price tag.

Hemgenix, a gene therapy against hemophilia B that was approved by the US Food and Drug Administration (FDA) in late November and will be marketed by the drugmaker CSL Behring, has just become the most expensive drug in history: $3.5 million.

It is the latest example of how investment by biotech companies in new gene therapies is making it possible to develop drugs for diseases that lacked adequate treatment until now – yet these new compounds will be accessible only to a few.

On the podium of the world’s most expensive medication, Hemgenix now occupies first place, displacing Bluebird Bio’s Skysona, a $3 million drug to treat adrenoleukodystrophy, a type of gene condition that damages the membrane that insulates nerve cells in the brain. Zynteglo, another Bluebird Bio gene therapy for the blood disorder beta-thalassemia, was priced at $2.8 million earlier this year.

What they all have in common is that they are enormously expensive and innovative gene therapies. CSL argues that, despite Hemgenix’s record price, it is a one-time treatment that may end up reducing health care costs because hemophilia B is a chronic disease for which conventional therapy is also very expensive and must be administered indefinitely.

The high price tag will make it difficult for public health systems to finance the therapy. In the United States, it will only be available to billionaires or people with extremely comprehensive health insurance coverage.

On November 22, the FDA announced approval of Hemgenix (etranacogene dezaparvovec), an adeno-associated virus vector-based gene therapy for the treatment of adults with hemophilia B, a less common form of the disease that causes life-threatening hemorrhage and serious, spontaneous bleeding episodes.

Hemgenix will be manufactured in Lexington, Massachusetts, by uniQure NV, which sold the marketing rights to CSL Behring in 2020.

A majority of men

The majority of individuals with hemophilia B who experience symptoms are male. Symptoms may include prolonged or heavy bleeding after an injury, surgery, or dental procedure. Bleeding episodes can also occur spontaneously without a clear cause and, if prolonged, can lead to serious complications such as bleeding into joints, muscles, or internal organs, including the brain.

Hemophilia B affects approximately one in 40,000 people. Around 16,000 individuals in the United States and Europe have it, according to uniQure. Hemophilia B accounts for about 15% of all hemophilia patients.

Hemgenix is a one-time intravenous administration of a gene therapy product. Conventional treatment now usually consists of administering, also intravenously, replacement products for the absent or deficient clotting factor to improve the body's ability to stop bleeding and promote healing.

“Gene therapy for hemophilia has been on the horizon for more than two decades. Despite advancements in the treatment of hemophilia, the prevention and treatment of bleeding episodes can adversely impact individuals’ quality of life,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, in a statement.“[This] approval provides a new treatment option for patients with hemophilia B and represents important progress in the development of innovative therapies for those experiencing a high burden of disease associated with this form of hemophilia.”

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