The results from the first human trials for a gene therapy to treat patients with haemophilia A have just been published, and they are truly remarkable. The treatment has essentially cured almost all the participants, suggesting a transformative change is on the horizon in how this previously incurable genetic disease is treated.

2017 has been a landmark year in the field of gene therapy. In August the FDA approved the first gene therapy for public use in the United States, while other treatments race through various stages of clinical trials, targeting everything from blindness to multiple sclerosis.

This latest gene therapy innovation focuses on a devastating hereditary genetic condition called haemophilia A, which leaves sufferers unable to produce a protein essential to blood clotting that puts them at risk of uncontrollable bleeding. The new treatment involves a single infusion of a gene therapy drug engineered to replace the missing gene responsible for production of the blood-clotting protein.

"We have seen mind-blowing results which have far exceeded our expectations," says one of the researchers on the trial, John Pasi. "When we started out we thought it would be a huge achievement to show a five percent improvement, so to actually be seeing normal or near normal factor levels with dramatic reduction in bleeding is quite simply amazing."

This phase 1–2 dose-escalation study took 13 patients with severe haemophilia A and found the treatment successfully improved levels of the blood-clotting protein in all patients. Most exciting was the follow-up study 19 months later that found 11 of the patients displayed normal or near normal levels of the protein. All 13 patients were able to discontinue any prior regular treatments for their disease following this experimental therapy.

One of the participants in the trial, Jake Omer, is now effectively cured of his disease. He previously had to inject himself three times a week with supplements of the blood-clotting protein in order to prevent extreme bleeding. Now, following the gene therapy treatment, his overall health and quality of life has been transformed.

"The first time I noticed a difference was about four months after the treatment when I dropped a weight in the gym, bashing my elbow really badly," explains Omer. "I started to panic thinking this is going to be really bad, but after icing it that night I woke up and it looked normal. That was the moment I saw proof and knew that the gene therapy had worked."

The treatment still needs to be expanded to wider trials for further confirmation of its safety and efficacy, and it is also unknown how long the therapy will remain effective and whether continued treatment is needed to maintain the effects.

Cost is another significant concern after another recently approved gene therapy came with a price tag of half a million dollars per dose. These new treatments are undeniably expensive to develop and produce, although in this particular case current treatments for haemophilia A can easily cost in excess of US$100,000 a year, so perhaps a single curative dose of a more expensive drug isn't entirely unreasonable.

We are currently at the vanguard of a revolution in medicine with gene therapy research accelerating into public use at an unprecedented rate. This trial marks another important milestone in a field of medicine that is incredibly exciting and provides hope for treating a wide variety of conditions.

"We really now have the potential to transform care for people with haemophilia using a single treatment for people who at the moment must inject themselves as often as every other day," says Pasi. "It is so exciting."

The study was published in the New England Journal of Medicine.

Source: Queen Mary University of London