By Stephanie Ma
Scientists for the first time have performed gene editing inside a human body, in a daring effort to permanently tackle an incurable disease by artificially rewriting a patient’s DNA.
The experiment was administered last Monday in California on 44-year-old Brian Madeux, who has been diagnosed with Hunter Syndrome – a rare genetic condition caused by a deficient enzyme that prevents the breakdown of long sugary molecules called mucopolysaccharides. With the imminent result being an accumulation of molecules inside the body patients of the metabolic disease could eventually face the threats of heart problems, breathing trouble, as well as brain and organ damage if the problem is left unaddressed.
“It’s kind of humbling” to be the first to test this, said the Arizona Native to Time Magazine. “I’m willing to take that risk. Hopefully, it will help me and other people.”
With the utilisation of a gene-editing tool called Zinc Finger Nucleases, Madeux has been intravenously injected with billions of copies of a corrective gene, as well as a genetic tool in a three-part therapy that includes a new gene and two zinc finger proteins. In each part, DNA instructions are inserted into a virus that has been previously modified to facilitate their transformation into cells.
Under this process these cells will travel to the liver, where they employ DNA instructions to produce zinc fingers and prepare the corrective gene. The zinc fingers would then cut the DNA in a precise spot, allowing the new gene to slip in, and finally directing it to create the enzyme patients ridden with Hunter Syndrome lacks.
“We cut your DNA, open it up, insert a gene, stitch it back up. Invisible mending,” said Dr Sandy Macrae, president of Sangamo Therapeutics, the California company testing the therapy for two metabolic diseases and haemophilia. “It becomes part of your DNA and is there for the rest of your life.” However, this may also indicate that there is no possible way of erasing any error genetic tinkering might bring about.
Suggestions concerning the effectiveness of the technique will be available in 4 weeks, while test results will be released within three months. If deemed successful, the groundbreaking technology would make a giant leap forward in the fledging front of gene therapy.
Dr David R. Liu, from Harvard University, said the trial signified a revolutionary era in a recent interview with The Telegraph. “The Hunter syndrome trial, led by a pioneering company, is another reminder that we have entered an era of genome editing,” he said.
“I’m hopeful that the approach might provide both therapeutic benefits for the patient, as well as valuable insights that inform the development of future editing therapeutics.” But Dr Robin Lovell-Badge, from the Francis Crick Institute, said getting the treatment to work on more complex conditions would be a challenge.
For the time being, gene editing therapy can merely be used to treat a handful of diseases. Whilst some test results indicate that the effectiveness of the therapy could not be maintained in the long-term, others suggest that an uncontrolled insertion of a new gene in the body might have unforeseen effects on other genes and potentially lead to new problems such as cancer.
“When you stick a chunk of DNA in randomly, sometimes it works well, sometimes it does nothing and sometimes it causes harm,” said Hank Greely, a Stanford University bioethicist. “The advantage with gene editing is you can put the gene in where you want it.”
“You’re really toying with Mother Nature” and the risks can’t be fully known, but the studies should move forward because these are incurable diseases, said Dr Eric Topol, an independent expert from the Scripps Translational Science Institute located in San Diego.
“Protections are in place to help ensure safety, and animal tests were very encouraging”, commented Dr Howard Kaufman, a Boston scientist on the National Institutes of Health panel that approved the studies. “Gene tinkering’s promise is too great to be disregarded,” he said, “So far there’s been no evidence that this is going to be dangerous. Now is not the time to get scared.”
Despite the myriad of safety concerns and risks raised, Madeaux remains positive about his treatment. “I’m nervous and excited,” he said. “I’ve been waiting for this my whole life: something that can potentially cure me.”