The FDA just approved the first gene therapy for an inherited disease

AP

In this Oct. 4, 2017 photo, Dr. Albert Maguire checks the eyes of Misa Kaabali, 8, at the Children's Hospital of Philadelphia. Misa was 4 years old when he received his gene therapy treatment.

• The US Food and Drug Administration just approved the first gene therapy for an inherited disease.
• The treatment, called Luxturna, is for Leber congenital amaurosis, a hereditary form of blindness.
• It's a one-time treatment is injected into the retina of the eye.

The US Food and Drug Administration just approved a cutting-edge gene therapy.

The treatment, called Luxturna and made by Spark Therapeutics, treats Leber congenital amaurosis, a hereditary form of blindness. It's been tested in people with the condition who specifically have a faulty RPE65 gene.

"Today's approval marks another first in the field of gene therapy - both in how the therapy works and in expanding the use of gene therapy beyond the treatment of cancer to the treatment of vision loss - and this milestone reinforces the potential of this breakthrough approach in treating a wide-range of challenging diseases," FDA Commissioner Scott Gottlieb said in a statement. So far, the FDA has approved two other gene therapies to treat forms of blood cancer.

Here's what you need to know about the drug:

• Leber congenital amaurosis is caused by a gene defect doesn't lead the retina to make a key protein.
• The one-time treatment is injected into the retina of the eye. From there, a virus carrying the corrected gene can get to work replacing the faulty gene and start producing the protein.
• Within a month, the benefits of the treatment start to appear.
• In a phase 3 trial of 20 patients injected with the gene therapy and 10 in the control group, 13 were able to navigate a mobility maze used to gauge vision at the lowest light level a year after treatment. No one in the control group was able to pass through the maze at this light level, leading investigators to conclude that the therapy improved visibility, light sensitivity, and the visual field participants had.
• The treatment, if approved, likely won't be cheap. The first gene therapy the FDA approved costs $475,000, while some gene therapies approved in Europe carry $1 million price tags.