CRISPR vs. Leber's Amaurosis: Continued
CRISPR/Cas therapy helped two patients with retinal dystrophy to see the light
Anastasia Kuznetsova-Fantoni, N+1
CRISPR/Cas technology has helped two out of five patients in the treatment of congenital retinal dystrophy — people have become better able to distinguish light sources and navigate in space. The results of clinical trials of genomic editing were published on the company Editas Medicine, which controls the study, on its website. She plans to start clinical trials on children soon.
The CRISPR/Cas genomic editing method is a promising way to treat genetic diseases. Such a system makes it possible to make breaks in a certain place in the genome using the Cas9 protein in combination with the guide RNA. So you can either inactivate a broken gene, or embed a new sequence in the gap. Despite all the advantages of the method, until recently it was used only on cells and was not administered to live patients. In order to test the CRISPR/Cas tool in humans for the first time, it took years of preclinical research.
In 2020, CRISPR/Cas technology was first used in vivo: on patients with a genetic disease that made the photoreceptors of their eyes defective, so that people could only distinguish objects in front of them and saw them very dim. We have already talked about this — in March 2020, the American company Editas Medicine began clinical trials of an experimental drug that edited the defective CEP290 gene with the help of "molecular scissors" in patients with Leber type 10 amaurosis. In clinical studies, 18 patients were divided into three groups depending on the dosage of the drug, and with the help of an adeno-associated virus, a CRISPR/Cas construct was delivered to them in one eye. The second eye was going to be treated later if the procedure was successful.
15 months after the operation, scientists from Editas Medicine published preliminary results of clinical trials for two experimental groups: a low dosage (1.1×10 12 viral genomes per milliliter) and an average dosage of the drug (6×10 11 viral genomes per milliliter). All participants underwent the operation well, and none of them showed serious side effects after it.
In two participants who received a low dosage of the drug, the treatment did not affect vision in any way, but in two of the three patients to whom the drug was delivered to the eye in a higher dosage, vision improved. By the third month after the procedure, they began to see light sources better, and therefore it became easier for them to move independently. One of the patients even began to distinguish the letter "E", which is at the very top of the vision check table. Doctors do not know exactly why this particular patient achieved the greatest success after treatment, but they will continue to monitor her and other test participants to understand why the operation helped some people and not others.
The next stage of studying the drug will be studies on children. In June, they were approved by the medical regulator after analyzing data from clinical trials on adults.
Recently, CRISPR/Cas technology was introduced intravenously to sick people for the first time, and at the end of the year its trials for the treatment of HIV infection in humans will begin.
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