| By Pallab Ghosh |
Science correspondent, BBC News
27 May 2016
From the section Science & Environment
Regulators have given one of the world's largest drug companies approval to sell a new gene therapy.
The treatment is for an illness called ADA-SCID which prevents babies from fighting off everyday infections.
This is the first approval for a genetic therapy granted to a large multinational drug company, GSK.
Commentators say the development marks the beginning of many more genetic medicines from so-called "Big Pharma".
The condition is extremely rare and affects around two dozen babies each year.
Approval of the gene therapy paves the way for the development of treatments for more widespread illnesses such as thalassemia and sickle cell disease.
Hundreds of inherited disorders such as cystic fibrosis, muscular dystrophy and many types of blindness are caused by faulty genes.
The aim of gene therapies is to cure the disease by introducing healthy copies of the gene into the patient.
And the big advantage of the treatment is that it only needs to be given once and it offers a potentially permanent cure.
The idea first emerged with much hype 30 years ago. At the time, large drug companies such as Novartis and Roche were at the forefront of the technology.
Advocates of gene therapy said it would cure everything but, for 20 years, it cured nothing.
The practicalities of introducing the right gene in the right cells and getting them to stick proved more difficult than first thought.
There were huge setbacks for the technology in the early days.
In 1999, an 18-year-old man Jesse Gelsinger died in a clinical trial of a gene therapy to treat a liver disease. The virus used to transfer the gene into his cells triggered his immune system into overdrive which led to multiple organ failure and brain death.
Three years later, children being treated in Paris for a problem with their immune system developed leukaemia because the healthy gene was inserted too close to a cancer-causing gene which consequently became active.
The setbacks saw large drug companies withdraw from research in the field.
Small biotechnology companies and publicly funded research groups persevered and, in time, many of the early difficulties were overcome.
As well as today's approval of GSK's treatment, which the company calls Strimvelis, in 2012 regulators gave the green light to a gene therapy called Glybera for a pancreatic disorder and another last year called T-Vec for skin cancer.
According to Prof Alan Boyd, who is president of the Faculty of Pharmaceutical Medicine and a pioneer in the development of gene therapy, more approvals are likely to be given in the next few years.
"Most of the hard work has been done by small companies. But as some of these products have come closer to market, Big Pharma has come back in," he says.
GSK's Strimvelis marks a starting point for the company to develop its gene therapies. It has research programmes under way for three relatively rare diseases and a programme and another collaboration to use gene therapy to treat cancers.
One of the issues for Big Pharma is how can it make money out of gene therapy. If one treatment cures its customers then is the industry not in danger of putting itself out of business?
GSK's position and those of other drug companies is that it can't afford not to become involved in gene therapy.
If the vision to treat people with one-off treatments that last a long time becomes a reality, any part of the industry that chooses to ignore gene therapy will be in an awful lot of trouble.
So the time is now right for large drug companies companies to become involved in gene therapy again. The question for Big Pharma the how much to charge for a single life-long cure?
Accessible to patients
GSK has not released details of how it will price its new treatment yet but its president of R&D, Patrick Vallance, says that the aim would be to make Strimvelis and any more gene therapies it develops as accessible as possible to as many patients as it can.
"We are absolutely committed to getting the price right," he says. "It's obvious that you can't charge a price that is unaffordable."
No doubt the pricing will work itself out in the long run and as more trials come through, the cost of gene therapy treatments will get less and less.