Gene therapy is now a reality. At least in the United States. Today, the U.S. Food and Drug Administration (FDA) approved the gene therapy Luxturna (voretigene neparvovec-rzyl) to treat patients with a rare form of blindness – biallelic RPE65 mutation-associated retinal dystrophy.

In a news release, FDA Commissioner Scott Gottlieb, M.D. said, “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.”

Dr Gottlieb added, “The culmination of decades of research has resulted in three gene therapy approvals this year for patients with serious and rare diseases. I believe gene therapy will become a mainstay in treating, and maybe curing, many of our most devastating and intractable illnesses.”

The approval was largely based on an open-label, phase 3 clinical trial published earlier this year in the journal, LancetIn that study, 20 patients were given the gene therapy and after 1 year, mean bilateral multi-luminance mobility testing (MLMT) change score was 1.8 (1.1) light levels in the gene therapy group compared to a change in the MLMT score of 0.2 (= 1.0) in the control group (n=9; P = .0013).  Three-year follow-up data confirmed that the gene therapy-treated patients were able to maintain their level of visual improvement.

The most common adverse reactions from treatment with Luxturna included eye redness (conjunctival hyperemia), cataract, increased intraocular pressure and retinal tear.

The developers of the therapy, Spark Therapeutics, also received a Rare Pediatric Disease Priority Review Voucher from the FDA. That voucher is given to any drug approved for a rare pediatric condition and the voucher can be used to give a future drug a ‘priority review’ by the FDA (i.e., the drug would be reviewed in 6 months instead of 10 months by the FDA). The voucher can also be sold and many smaller biotech companies sell their vouchers for sums in access of $160 million.

Inherited retinal dystrophies associated with RPE65 gene mutations often show early symptoms such as night blindness (nyctalopia) and involuntary back-and-forth eye movements (nystagmus). The disease is progressive condition and most will eventually become totally blind. Until today, there were no treatments available for these patients.

At present, it is not known what the cost will be for this therapy nor when it will be available in Canada.