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Patient with genetic form of childhood blindness regained and maintained vision for more than a year after receiving a single injection of experimental RNA therapy directly into the eye, according to a new study published in the journal Nature medicine.
While impressive, it’s important to encourage cautious optimism about this development – for there is no magic cure-all for blindness.
One-shot improved central vision for a blind child
Treatment was designed for people pre-diagnosed with Leber’s congenital amaurosis (LCA) – which is an eye disorder that typically affects the retina – who also have a CEP290 mutation, a gene commonly associated with patients with the disease. . People with this type of stroke usually suffer from severe visual impairment from early childhood.
“Our results set a new standard for the biological improvements possible with antisense oligonucleotide therapy in stroke caused by CEP290 mutations,” said ophthalmology research professor Artur V. Cideciyan, also co-lead author of the new study. , according to a MedicalXpress report. “Importantly, we are establishing a comparator for gene editing therapies currently underway for the same disease, which will allow the relative merits of two different interventions to be compared.”
Researchers at the Scheie Eye Institute at the Perelman School of Medicine at the University of Pennsylvania performed the clinical trial and found that the treatment resulted in substantial changes in the fovea – the crucial locus of human central vision. Penn Medicine led the international effort, along with Samuel G. Jacobson, who is also a professor of ophthalmology.
During the study, participants received an intraocular injection of an antisense oligonucleotide called sepofarsen. It is a short RNA molecule that increases CEP290 protein levels in photoreceptors in an eye, improving retinal function and daylight perception.
The improvement in visual acuity remained for more than 15 months
In a 2019 study of Nature medicine, Jacobson, Cideciyan and others discovered how repeated injections of sepofarsene once every three months resulted in increased visual capacity in 10 patients. The eleventh patient – whose treatment was explained in the new article in the same journal, received only one injection and then examined over a 15-month period. Prior to treatment, the patient suffered from reduced visual acuity, small visual fields and lack of night vision. But after the shot, scientists decided not to add quarterly maintenance doses – as it could cause cataracts.
After the single injection of sepofarsen, scientists noticed more drastic improvements, substantially supporting a biological effect of the treatment. A critical finding in more than a dozen measurements of visual function and retinal structure was that biological improvement was slow to take. The researchers recorded an improvement in vision after one month, but the patient’s vision peaked after two months.
More importantly, some improvements in visual acuity remained for more than 15 months after the single injection. This was unexpected, but it has implications for the future treatment of other ciliopathies – the general category of diseases linked to genetic mutations encoding dysfunctional proteins, which in turn cause cilia to function abnormally, a sensory organelle that overtakes cells.
“This work represents a truly exciting direction for antisense RNA therapy,” said Jacobson, in the MedicalXpress report. “It’s been 30 years since there have been any new drugs using antisense RNA oligonucleotides, although everyone has realized that these treatments hold great promise. The unexpected stability of the ciliary transition zone observed in the patient also prompts reconsideration of sepofarsen dosing regimens. like other therapies targeted to the eyelash. “
A major step towards new techniques to help restore vision
Researchers believe that one of the reasons the antisense oligonucleotide can improve vision is that the tiny RNA molecules are small enough to squeeze inside the cell nucleus, but stay long enough to have a substantial effect.
“There is now, at least in the eye area, a series of clinical trials using antisense oligonucleotides for different genetic defects brought about by the success of the ACV work associated with CEP290 by Drs Cideciyan and Jacobson,” said President of Ophthalmology Joan O-Brien of the Perelman School of Medicine and Director of the Scheie Eye Institute.
Obviously, this is not a panacea for blindness. But it still represents a pretty big step towards developing new techniques to drastically improve poor visual acuity in literal eyes of people genetically predisposed to eye disease.
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