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Health and Medicine

New Gene Therapy Successfully Sends Six Patients With Rare Blood Disorder Into Remission

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Rachel Baxter

Copy Editor & Staff Writer

clockJan 29 2020, 12:59 UTC

Left: White blood cells (red) from one of the X-CGD clinical trial participants prior to gene therapy. Right: After gene therapy, white blood cells from the same patient show the presence of the chemicals (blue) needed to attack and destroy bacteria and fungus. UCLA Broad Stem Cell Research Center/Nature Medicine

Six patients with a rare blood disease are now in remission thanks to a new gene therapy. The condition, known as X-CGD, weakens the immune system leaving the body vulnerable to a range of nasty infections and shortens a person’s lifespan. It is normally treated using bone marrow transplants, but matching donors to patients can be tricky and time-consuming and the procedure comes with risks.

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A team led by UCLA recently treated nine people with the disease and six successfully went into remission, allowing them to stop other treatments. All six patients are doing well and haven’t suffered any adverse effects.

X-CGD is a form of chronic granulomatous disease (CGD). People with CGD have an inherited mutation in one of five genes involved in helping their immune system attack invading microbes with a burst of chemicals. This means that CGD sufferers have weaker immune systems than healthy people, so they have a greater risk of getting infections. These infections can be life-threatening, particularly if they affect the bones or cause abscesses in vital organs.

X-CGD is the most common type of CGD and only affects males. It is caused by a mutation in a gene on the X-chromosome. Current treatments are limited to targeting the actual infections with antibiotics as well as bone marrow transplants. Bone marrow contains stem cells that develop into white blood cells, so bone barrow from a healthy donor can provide a CGD patient with healthy white blood cells that can help their body to fend off disease.

However, bone marrow transplants are far from ideal. The patient has to be matched to a specific donor, and the body can reject the implanted bone marrow. That means that following a transplant, the patient needs to take anti-rejection drugs for at least six months.

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For their new treatment, researchers removed blood cell-forming stem cells from the patients themselves and genetically modified them so that they no longer carried the unwanted mutation. Then, the edited stem cells were returned to their bodies, ready to produce healthy new infection-fighting white blood cells.

This is the first time this treatment has been used to try to correct X-CGD. The researchers followed up with the nine patients but sadly, two passed away within three months of the treatment. It’s important to note that their deaths were not a result of the treatment but of rather severe infections that they had been suffering from for a long time. The remaining seven were followed for 12 to 36 months – all remain free from infections related to their condition, and six have been able to stop taking preventative antibiotics entirely. The results are reported in Nature Medicine.

“None of the patients had complications that you might normally see from donor cells and the results were as good as you’d get from a donor transplant – or better,” said Dr Donald Kohn, a member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA and a senior author of the paper.

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What’s more, four new patients have also been treated since the initial research was conducted. None experienced any adverse reactions and all remain infection-free. Now, the team plans to conduct a bigger clinical trial to further test the safety and efficacy of their new treatment, with the hopes that it may one day become available to the masses.


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