Washington (AFP)

Thirty years after the discovery of the cystic fibrosis gene, a new drug has been approved in the United States for patients at least 12 years of age and offering "impressive" efficacy compared to what has existed to date.

Cystic fibrosis is a rare genetic disease that is inherited and incurable. It secretes abnormally thick and viscous mucus, which obstructs the respiratory tract and the digestive system. The patients are out of breath with the slightest effort.

Children have the disease when they inherit two copies of a defective gene from their two healthy carrier parents.

It was once often fatal to children and adolescents, but life expectancy has been progressively longer with treatment, up to more than 40 years for children born recently, according to the American Cystic Fibrosis Foundation ( Cystic Fibrosis Foundation).

The treatments are heavy to clean the lungs every day: respiratory physiotherapy, aerosol sessions, medications ... Many patients suffer from pulmonary infections because of the congestion of the bronchi and must be hospitalized. Lung transplants can extend the life span.

90% of patients should be able to benefit from the new treatment because it targets the most widespread genetic mutation, called F508del. Instead of treating the symptoms as above, it attacks the underlying cause: it repairs the protein that is not doing its job because of the genetic mutation.

The newly licensed drug, manufactured by Vertex Laboratories, is called Trikafta and combines three molecules (elexacaftor-tezacaftor-ivacaftor).

It was approved by the US Drug Agency, the Food and Drug Administration (FDA) on Oct. 21 based on clinical trials published Thursday in the medical journals New England Journal of Medicine and The Lancet.

The results of the trials "document impressive benefits," commented the head of the National Institutes of Health in the United States, Francis Collins, who was part of the team that discovered the responsible gene, CFTR, in 1989.

- No cure -

For a minority of patients, it will even be the first available medicine to treat the underlying causes of the disease.

Trikafta improves the pulmonary function of patients by 10 to 14%, compared to a placebo and an existing treatment, respectively.

"This is a great breakthrough and great news for people with cystic fibrosis," Preston Campbell, president of the Cystic Fibrosis Foundation, said in a statement.

Triple therapy is "a historic moment," said Dr. Raksha Jain of the University of Texas and lead author of the New England Journal of Medicine study.

But, adds Francis Collins in an editorial, "the big day (...) will be one where the more than 70,000 people with cystic fibrosis in the world will no longer need drugs because a permanent cure will exist for everyone."

After the discovery of the gene, the scientists hoped to develop a gene therapy: that is to replace the defective gene with a normal gene.

But this path remains an impasse, and that is why researchers are attacking the dysfunctional protein, making it ... refurbish. The first drug acting on the underlying cause of cystic fibrosis (ivacaftor) was authorized in 2012.

Patients will need to take pills every day for the rest of their lives.

Trikafta trials are underway for children aged 6 to 11 years old.

As for Europe, an application for authorization has just been lodged with the European Medicines Agency.

© 2019 AFP