The world’s most expensive drug has been registered. For whom is it intended and how much does one dose cost?

The U.S. Food and Drug Administration has approved a drug for those suffering from a rare genetic disease. It is record expensive. One dose of the breakthrough medicine costs millions of dollars.

Frequent and persistent bleeding, bruises appearing on different parts of the body, swelling and joint pain. Such are the symptoms of hemophilia. The blood of people suffering from it clots much more slowly than in healthy people. This means that any break in a blood vessel can turn into a dangerous hemorrhage in them.

Causes of hemophilia

Under one name are three diseases that share a common etiology. The cause of hemophilia A, hemophilia B and hemophilia C is a deficiency of clotting factors. These are proteins that initiate the formation of a clot at the site of damage to a blood vessel. In each case of hemophilia, a different protein is involved — however, it is encoded by only one gene. Therefore, hemophilia is classified as a single-gene disease.

The genes encoding clotting factors are located on the X sex chromosome. Therefore, the vast majority of patients are men, who have only one X chromosome. Women, having two X chromosomes, are most often only carriers of the disease, which they pass on to their offspring.

Hemophilia B, or Christmas disease

In 1952, the Christmas issue of the scientific journal British Medical Journal contained a description of the disease from which five-year-old Stephen Christmas suffered. This is also the name given to hemophilia B, caused by a deficiency of clotting factor IX.

This is a rarer form of the disease. Hemophilia B has 15 percent of all patients. However, in the general population, one person in 40–50,000 develops it. Treatment consists of regular administration of concentrates containing the missing clotting factor. In the past, doctors primarily tried to stop the bleeding. Now therapy is already focused on preventing hemorrhages.

The next step in hemophilia treatment

Early diagnosis and modern drugs — taken regularly — improve both the quality and length of life of patients. However, they do not remove the cause of the disease. This could only be done by gene therapy. That is, providing the body with the correct recipe for the missing protein in the form of DNA.

A drug of this kind has just been registered in the United States. It is Hemgenix, developed by CSL Behring. The preparation uses a viral vector — that is, a specially crafted, benign virus — that carries DNA containing the recipe for clotting factor IX into liver cells. The genetic information is then duplicated, allowing the body to produce more of the missing protein.

What is the effectiveness of a preparation that is administered only once? In a study involving 54 patients, a significant increase in clotting factor IX levels was observed. It was also reported that the number of hemorrhages halved within a year of administering the drug.

Record drug price

The drug, however, is ultra-expensive. A dose of Hemgenix costs $3.5 million. This makes the preparation the world’s most expensive drug. The previous record holder — Zolgensma, a drug for spinal muscular atrophy, or SMA — cost about $2.1 million.

But, crucially, current therapies, which require continuous administration of clotting factors, also generate very high aggregate costs. So if it turns out that a one-time gene therapy using Hemgenix would be able to free a large group of patients from regular medication, the gamble could be worth the candle.

Orphan drugs — what are they?

Hemgenix is one of the so-called orphan drugs. This is the name given to drugs for people suffering from rare diseases, which — without appropriate government incentives — would not be worth developing or producing. In the United States, the Orphan Drug Act was passed in 1983 with the aim of getting pharmaceutical companies to seek cures for the rarest diseases. It allows them to apply for funding, sometimes multi-million dollar, for research into such drugs. The manufacturer can also get a monopoly on its sale.

CLS Behring, like many others, took advantage of the law. In exchange for producing Hemgenix, it received a seven-year monopoly on the sale of the medicine in the United States. The European Medicines Agency, on the other hand, will decide whether the preparation will be approved in European Union countries.

Source: ScienceAlert, CSL Behring, Guardian

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