Courtesy of Oliver Chu familyThe first child in history has successfully been treated with a new genetic therapy for an ultra-rare developmental defect called Hunter syndrome.
Several years in the making, Oliver Chu became the first in the world to receive the stem cell-based treatment in February, and 3 months later seemed to be a normal child again, meeting important milestones and playing without supervision.
Royal Manchester Children’s Hospital, which oversaw the trial of Oliver and 4 other patients, says that children with severe Hunter syndrome cannot properly break down complex sugar molecules and have widespread symptoms including rapid and progressive learning and memory problems, heart and lung dysfunction, hyperactivity and behavioral problems, bone and joint malformations and hearing impairment.
They cannot break down the sugars because their genetic code was formed with a defect: the gene that codes for the production of an enzyme called iduronate-2-sulfatase (IDS) doesn’t work properly.
Professor Brian Pigger, professor of cell and gene therapy at the University of Manchester, developed a method of replacing the faulty gene with a functioning copy, called autologous hematopoietic stem cell (HSC) gene therapy.
In December, Oliver Chu, from California, arrived at Royal Manchester for the first stage of the procedure. The 3-year-old had his blood cycled in a machine to extract the hematopoietic stem cells he produces naturally. These were then sent off to a laboratory at Great Ormond Street Hospital in London, where a functioning copy of the defective gene is inserted into a virus and placed inside the stem cells.
In February, mother Jingru cradled Oliver in his hospital bed as he received an injection of 125 million modified cells twice in the space of 2 hours. It was a momentous day that the young boy was completely oblivious to.
After a few days, Oliver flew back to California to reunite with his older brother Skyler, who also has the disease, and his father Ricky.
Hunter syndrome affects almost exclusively boys, and then only 1 in 100,000 live births. A major challenge in the disease that can often be fatal is that treatment methods can’t cross the blood-brain barrier, as the major manifestation of the inability to break down sugars occurs in the brain.
One commercially available drug called Elaprase can slow the effects, but can’t cross the blood brain barrier. It costs as much as a house for a year’s prescription. Another treatment has been to give regular infusions of the missing enzyme, just like a diabetic would take infusions of insulin.
In May of this year, BBC reports that Oliver’s development has become remarkably normal. He’s talking all the time, and been able to stop the enzyme infusions. He runs around like any other 3-year-old, utilizing a newly-exploded vocabulary, and demonstrates genuine inquisitiveness.
“Every time we talk about it I want to cry because it’s just so amazing,” his mother Jingru told the BBC.
“We can see he’s improving, he’s learning, he’s got new words and new skills and he’s moving around much more easily,” said Professor Simon Jones, who ran the trial that saw Oliver and four other boys receive the gene therapy. “We need to be careful and not get carried away in the excitement of all this, but things are as good as they could be at this point in time.”
Unfortunately for Skyler, who also has Hunter syndrome, he’s too old to receive his younger brother’s treatment. The 5-year-old receives infusions like Oliver used to, it allows him to regain some physical development normalcy, but the infusions can’t cross the blood-brain barrier.The treatment window in the trial was 3 months to 1 year of age. It was originally believed that Oliver was too old, but a battery of tests concluded there was still a window where the therapy might reverse the genetic defect in the brain as well as the body. Ricky is hopeful the treatment will prove successful, prompting further innovation into how it might help treat older children like Skyler. Boy with Rare Genetic Disorder Amazes Doctors After World-First Gene Therapy
