The particular failed study that gave a completely different treatment for blindness

In textbooks, science is simple. You get a concept, put it into practice and then accept or avoid it depending on what your experiments show. In the real world, though, things are infrequently that simple. Sometimes failed studies have advantages in conditions that scientists would not think of. That’s what happened now with cure for blindness.

As a recent papers in Science Translational Medicine indicates, according to Included, a group of researchers led by Ike Yu-Wai-Man, an ophthalmologist at Cambridge University, investigated a promising new gene therapy for a hereditary form of loss of sight.

Officially, their study was a inability because the experiment did not show the particular researchers hoped for. But it was, alternatively, an impressive success, because 29 in the 37 participants reported great advancements for them.

What good is this finding?

The disease in question is innate Leber optic neuropathy. A faulty gene in a patient’s mitochondria – the small structures that supply a cell’s energy – causes retinal cell death. This leads to a sudden and rapid loss of vision, with many sufferers becoming blind within a year. It affects between one in 30,000 and one in 50,000 people. Men in their 20s and 30s are particularly susceptible to this condition. The treatment for blindness is limited and not particularly effective.

Because most cases are caused by a mutation in a single gene, this condition is a good candidate for gene therapy, a form of genetic engineering that aims to replace the defective gene with a functional one. With this in mind, Dr. YuinstructionsWai-Man and colleagues loaded a modified virus with a corrected copy of the gene and injected it into the eyes of their patients.

Many viruses can insert their genes into the DNA of their hosts. This is usually a bad thing because the cells produce more copies of the virus. In this case, the hope was that the infection would be a good thing. The virus could not reproduce. But he was able to replace the damaged gene with a working copy.

A condition that can cause blindness will be treated

Most medical studies use a control group, against which the effectiveness of treatment can be measured. Here, the researchers controlled the experiment by injecting only one of the eyes of each patient – chosen at random – with the virus. The other eye received a fake injection, inside which a syringe was just pressed against the eyes. The use of two eyes on the same patient ensures perfect control: their genetic structure is identical.

The surprise came a few months after the study. The researchers hoped to see a big improvement in treated eyes compared to untreated ones. This did not happen and, for this reason, the study failed. In contrast, more than three-quarters of their patients saw substantial improvements in both eyes.

The treatment is awaiting approval next year

Obviously, it was weird. After all, only one eye had received the treatment. Subsequent studies on monkeys confirmed what the researchers had suspected. It seems the fact that the virus had found a way to travel from one eye to another, probably through the optic nerve. Tissue and fluid samples from monkeys receiving the same treatment as human patients showed viral DNA in both eyes, not just one.

Although it has had a happy outcome in this case, the prospect of a gene therapy virus traveling to places it is not intended to go could worry regulators.

Fortunately, the researchers found no trace in the virus elsewhere in the particular monkeys’ bodies. And, although the study was technically a failure, its practical success means that an effective treatment for this condition can finally be at hand. GenSight Biologics, the company that developed the treatment, has already sent its results to the European healthcare regulator. He hopes to get acceptance by the end regarding 2021.


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