Two years ago, at the age of 38, Arthur lost his sight. The Paris-based consultant discovered he had a neurodegenerative disease of retinal cells that causes profound and permanent loss of vision. Leber’s hereditary optic neuropathy is a rare genetic disorder. But Arthur had a lucky break. His doctor was able to sign him up for a trial of a new treatment—gene therapy—being developed by GenSight Biologics, also based in Paris. When he enrolled he was patient 15.
Gene therapy is not new. In the 1990s many enthusiastically hailed its potential to treat terribly sick children born with severe genetic disorders that leave them without a working immune system. One of these was called “bubble boy” disease, because sufferers were forced to live inside sterile enclosed spaces to prevent them from catching infections that would be fatal. The basic idea was to fix the genetic fault inside each cell by delivering a correct copy of the DNA—often via a virus. Despite this early promise, the work faltered because of unexpected side-effects, and the death of a young man during a trial.
Since then the safety and efficiency of gene therapy have greatly improved. Doctors at the San Raffaele Telethon Institute for Gene Therapy, in Milan, have shown that gene therapy can offer a long-term cure for ADA-SCID, a rare immune disorder (which is often fatal in the first year of life). Thanks to a deal with a British pharma firm, GlaxoSmithKline, this treatment was put on the market in 2016. Spark Therapeutics, a biotech firm, has hopes of being the first American company to receive approval for a gene-therapy treatment in 2017.
There seems little doubt that a revolution is on the horizon. The number of gene therapies in development has doubled since 2012, according to analysts at Datamonitor Healthcare. Thousands of treatments are in clinical trials, with around 100 in late-stage trials. Although success is by no means guaranteed, the sheer numbers making it through the pipeline suggest a flurry of approvals is coming in the next year or two.
A single shot was all it took for Arthur to start recovering. He recovers a bit more each day. He can now read a little, see colour, cross the road and use a cash machine and a laptop. He is excited about the treatment, even though he does not know how much better it will make him. “It is, of course, the future for me,” he says. And for many others as well.