(ANTIMEDIA) — On Monday morning, the FDA announced the approval of a novel gene therapy for a rare inherited disease that affects vision in children and adults. This is a historic moment as it is the first time the FDA has approved a directly administered gene therapy for a specific gene mutation.
“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,” read the department’s press release.
Luxturna (voretigene neparvovec-rzyl) targets the RPE65 gene mutation associated with inherited retinal dystrophy. People who have a biallelic mutation, meaning mutation in both maternal and paternal copies of the RPE65 gene, aren’t able to produce an enzyme in the retina that converts light into an electrical signal transmitted to the brain, which leads to progressive vision loss, and ultimately blindness.
The gene therapy works by utilizing an existing virus as a vehicle to deliver a normal copy of the gene directly to the retina. This technique, called adeno-associated virus vector-based genome therapy, has gained traction as one of the most reliable forms of genome therapy. Still, there are some risks involved with using viral vectors, including the possibility of the virus targeting the wrong cells and causing other diseases, such as cancer.
Luxturna reports few adverse reactions (incidence ≥ 5%) in their official product insert, but they admittedly have yet to study the potential carcinogenesis effects of the therapy. In addition, the Phase 3 clinical trial of Luxturna was relatively small. It included 31 enrolled subjects, just 21 of whom actually received the treatment — barely above the minimum of subjects typically required for a Phase 1 trial, per official FDA guidelines.
Aside from the safety concerns of genome therapy, there are also numerous ethical concerns whenever genome editing is considered. As explained by the National Human Genome Research Institute, “…researchers and bioethicists are concerned that any genome editing, even for therapeutic uses, will start us on a slippery slope to using it for non-therapeutic and enhancement purposes, which many view as controversial.”
There is also the concern of the financial accessibility of the gene treatment. As NPR reported in October, analysts have speculated that the cost for each patient would be hundreds of thousands of dollars…for each eye. This means a cost of up to $1 million per patient, a price tag that begs a lot of questions about how the insurance industry will respond in terms of coverage and premiums in this previously uncharted territory of expensive gene therapy development.
Regardless of the causes for concern, the gene therapy industry is moving forward with no indication of stopping soon.
Spark Therapeutics of Philadelphia, the company behind Luxturna, is already in the early clinical stages of developing viral vector genome therapies for liver diseases and neurodegenerative diseases. The FDA is also moving forward with plans for further investment in genome therapy development in 2018, according to the same press release:
“Next year, we’ll begin issuing a suite of disease-specific guidance documents on the development of specific gene therapy products to lay out modern and more efficient parameters — including new clinical measures — for the evaluation and review of gene therapy for different high-priority diseases where the platform is being targeted.”
Whatever the case may be for the future of genome therapy, one thing is certain: this is just the beginning.