Boy With Rare Condition Amazes Doctors After World-First Gene Therapy

A three-year-old boy has astounded doctors with his progress after becoming the first person in the world with his devastating disease to receive a ground-breaking gene therapy.

Oliver Chu has a rare, inherited condition called Hunter syndrome - or MPSII - which causes progressive damage to the body and brain.

In the most severe cases, patients with the disease usually die before the age of 20. The effects are sometimes described as a type of childhood dementia.

Due to a faulty gene, before the treatment Oliver was unable to produce an enzyme crucial for keeping cells healthy.

In a world first, medical staff in Manchester have tried to halt the disease by altering Oliver's cells using gene therapy.

Prof Simon Jones, who is co-leading the trial tells the BBC: "I've been waiting 20 years to see a boy like Ollie doing as well as he is, and it's just so exciting."

Until now, the only medicine available for Hunter syndrome was Elaprase, which costs around £300,000 per patient, per year and can slow the physical effects of the disease. The drug is unable to cross the blood-brain barrier and so does not help with cognitive symptoms.

But today, Oliver is being hooked up to a machine and having some of his cells removed - the first crucial step in trying to halt his genetic disorder in this one-off treatment.

"His blood is being passed through a fancy machine that is collecting a specific type of cell called stem cells which will be sent to a lab to be modified and then given back to him," Dr Claire Horgan, consultant paediatric haematologist explains.

Oliver's cells are tweaked

Oliver's cells are carefully packaged and sent to a laboratory at Great Ormond Street Hospital (GOSH) in London.

In Hunter syndrome, a genetic error means that cells are missing the instructions for making an enzyme, iduronate-2-sulfatase (IDS), essential for breaking down large sugar molecules which over time accumulate in tissues and organs.

Scientists insert the missing IDS gene into a virus, which has its genetic material removed so that it can't cause disease.

A similar method has been used in other gene therapies, such as the treatment for another rare inherited condition, MLD.

Dr Karen Buckland, from the Cell and Gene Therapy Service at GOSH and UCL senior research fellow, explains: "We use the machinery from the virus to insert a working copy of the faulty gene into each of the stem cells.

"When those go back to Oliver, they should repopulate his bone marrow and start to produce new white blood cells and each of these will hopefully start to produce the missing protein [enzyme] in his body."

There still remains the issue of how to get enough of the missing enzyme into the brain.

To overcome this, the inserted gene is modified so that the enzyme it produces crosses the blood-brain barrier more efficiently.

- Author: Fergus Walsh - Medical editor, BBC

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