Groundbreaking UK gene therapy offers hope after progress of three-year-old | Medical research
Doctors are cautiously optimistic about a breakthrough gene therapy for children affected by a devastating hereditary disease after seeing positive results in the first boy to receive the treatment.
Three-year-old Oliver Chu from California became the first patient to benefit from the treatment nine months ago as part of a clinical trial led by researchers in Manchester. It’s too early to call the therapy a success, but doctors are encouraged by its progress so far.
“Things look really encouraging at the moment, but Ollie was the first human to receive this therapy and it’s only been nine months,” said Professor Simon Jones, consultant in pediatric hereditary metabolic diseases at the Manchester Center for Genomic Medicine (MCGM) at Saint Mary’s Hospital.
“We have four more boys planned and we will have to prove that the benefits are sustainable,” said Jones, co-leader of the trial.
Oliver was born with a condition called Hunter syndrome. It is caused by a faulty gene that prevents the body from producing a crucial enzyme that breaks down complex sugar molecules. Over time, these molecules build up in organs and tissues, causing a range of symptoms from joint stiffness and hearing loss to heart problems and cognitive decline, resembling dementia. Life expectancy is generally 10 to 20 years.
The only medication approved for children with Hunter syndrome is Elaprase, a weekly infusion that replaces the missing enzyme. The treatment costs around £375,000 per patient and must be followed for life. Although the drug can improve movement and organ problems, it does not reach the brain and therefore cannot prevent cognitive decline.
During a one-time therapy in February, doctors collected stem cells from Oliver’s blood and replaced the faulty gene with a working copy. The corrected stem cells were then injected back into his bloodstream. There, they began producing high levels of the enzyme, which also reached his brain.
Since completing the therapy, Oliver no longer requires weekly Elaprase infusions, an encouraging sign that the treatment is working. The trial is being carried out at the Royal Manchester Children’s Hospital in collaboration with MCGM at Saint Mary’s.
Speaking to the BBC, Oliver’s father Ricky said: “I don’t want to hurt him, but I feel like everything went very, very well.
“Her life is no longer dominated by injections and hospital visits. Her speech, agility and cognitive development have all improved significantly,” he added. “It’s not just a slow, gradual curve as he gets older, it’s accelerated exponentially since the transplant.”
Oliver’s parents hope the therapy can also help his older brother, Skyler, who suffers from the same problem. Therapy cannot repair existing damage to organs and tissues, but tests performed on Skyler show that despite being five years old, he remains largely unchanged.
Hunter syndrome predominantly affects boys, but it is extremely rare, affecting one in 100,000 men born worldwide. The five boys participating in the trial come from the United States, Europe and Australia. None are from the UK because patients are not diagnosed early enough.
“For the majority of patients to be treated with this dose, we would need heel-prick newborn screening, which is now the standard for Hunter syndrome in the United States,” Jones said. The same gene therapy approach is currently being developed to treat other genetic disorders that impair vital enzymes, such as Hurler syndrome and Sanfilippo syndrome.
