A revolution could come from gene editing.
Modern gene editing technologies are now capable of inducing selective modifications of parts of the DNA of cells. The most recent developments in this field have in fact made it possible to potentially edit almost all genes in the human body with the aim of activating, deactivating or rewriting genes identified as the cause of certain diseases. This opportunity creates enormous potential for treating diseases that were previously untreatable, even with conventional gene therapy.
In this field, the American start-up Editas Medicine (Cambridge, Massachusetts) is developing a gene editing programme that could be ready in 2017, marking an extraordinary step forward in biotechnology.
The specific aim of this project is to identify a treatment route for a rare form of blindness, caused by a genetic defect: Leber congenital amaurosis (ACL).
ACL is a rare form of retinopathy, characterised by severe low vision or blindness, either already present at birth or beginning in the first six months of life. Children with the condition present with chaotic, erratic eye movements and pupils that are poorly responsive to light. ACL accounts for 10-18% of cases of congenital blindness in children; its incidence is 2-3 children per 100,000 births.
The genetic cause of ACL has been identified as a mutation in an intron of the CEP290 gene. In most cases, ACL is transmitted in an autosomal recessive manner. This means that the presence of the altered gene in both parents, who are otherwise healthy, results in a 25% chance of having a child with the disease.
To halt the course of this serious eye disease, Editas Medicine plans to use CRISPR/CAS technology, which was developed about three years ago and is rapidly spreading in biotechnology laboratories. The CRISPR (acronym for Clustered, Regularly Interspaced Short Palindromic Repeats)/Cas9 (acronym for CRISPR Associated Protein 9) system uses a protein-RNA complex formed by an enzyme, known as Cas9, linked to a guide RNA molecule and designed to recognise a particular DNA sequence.
The CRISPR treatment for ACL involves administering a suitable inoculum directly under the retina to eliminate the defective genetic component and replace it with the healthy one. In more detail, Editas scientists designed guide RNA molecules (gRNA), combined them with the Cas9 protein from the Staphylococcus aureus and used a single adenovirus-associated vector (AAV) to perform CEP290 mutation correction in fibroblasts from primary patients.
In order to effectively treat Leber's genetic Amaurosis, the procedure developed by Editas requires that approximately 1,000 characters in the DNA of the CEP290 gene be effectively deleted.
Previous laboratory experiments have shown that the gene thus treated should work properly. However, further tests on laboratory animals are planned before starting human clinical trials.
In order to find the necessary funds to finance this project, at the very beginning of 2016 Editas, founded as a start-up with the backing (among others) of Bill Gates and Google Ventures, launched an IPO, i.e. a public offering of its securities to the value of USD 100 million.
If the financial deal goes through, Editas plans to use USD 20 million of the proceeds to fund ACL research, whose clinical trials are expected to start in 2017, while it will allocate around USD 22 million to a partnership with Juno Therapeutics focused on the potential of gene editing in the fight against cancer (see news on Fortune).
Dr. Carmelo Chines
Direttore responsabile
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