Gene therapy stalled in the early 2000s as adverse effects came to light in European trials (leukemias triggered by the gene delivery vector) and following the 1999 death of U.S. patient Jesse Gelsinger. But after 30 years of development, and with the advent of safer vectors, gene therapy is becoming a clinical reality. It falls into two main categories:
In vivo: Direct injection of the gene therapy vector, carrying the desired gene, into the bloodstream or target organ.
Ex vivo: Removal of a patient’s cells, treating the cells with gene therapy, and reinfusing them back into the patient, as in hematopoietic stem cell transplant and CAR T-cell therapy.
In honor of Rare Disease Day (Feb. 28), we salute “citizen scientists” Jocelyn and John Duff.
When Talia Duff was born, her parents realized life would be different, but still joyful. They were quickly adopted by the Down syndrome parent community and fell in love with Talia and her bright smile.
But when Talia was about four, it was clear she had a true problem. She started losing strength in her arms and legs. When she got sick, which was often, the weakness seemed to accelerate.
Talia was initially diagnosed with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), an autoimmune disease in which the body attacks its own nerve fibers. Treated with IV immunoglobulin infusions to curb the inflammation, she seemed to grow stronger — but only for a time. Adding prednisone, a steroid, seemed to help. But it also caused bone loss, and Talia began having spine fractures.
“We tried a lot of different things, but she never got 100 percent better,” says Regina Laine, NP, who has been following Talia in Boston Children’s Hospital’s Neuromuscular Center the past several years, together with Basil Darras, MD. “That’s when we decided to readdress the possibility that it was genetic.” …
For more than two decades, Alan Beggs, PhD, at Boston Children’s Hospital has explored the genetic causes of congenital myopathies, disorders that weaken children’s muscles, and investigated how the mutations lead to muscle weakness. For one life-threatening disorder, X-linked myotubular myopathy (XLMTM), the work is approaching potential payoff, in the form of a clinical gene therapy trial.
Boys with XLMTM are born so weak that they are dependent on ventilators and feeding tubes to survive. Almost half die before 18 months of age. …
The ear is a part of the body that’s readily accessible to gene therapy: You can inject a gene delivery vector (typically a harmless virus) and it has a good chance of staying put. But will it ferry the corrected gene into the cells of the hearing and/or vestibular organs where it’s most needed?
Back in 2015, a Boston Children’s Hospital/Harvard Medical School team reported using gene therapy to restore rudimentary hearing in mice with genetic deafness. Previously unresponsive mice began jumping when exposed to abrupt loud sounds. But the vector used could get the corrected genes only into the cochlea’s inner hair cells. To really restore significant hearing, the outer hair cells need to be treated too. …
Research going back to the 1980s has shown that sickle cell disease is milder in people whose red blood cells carry a fetal form of hemoglobin. The healthy fetal hemoglobin compensates for the mutated “adult” hemoglobin that makes red blood cells stiffen and assume the classic “sickle” shape.
Normally, fetal hemoglobin production tails off after birth, shut down by a gene called BCL11A. In 2008, researchers Stuart Orkin, MD, and Vijay Sankaran, MD, PhD, at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center showed that suppressing BCL11A could restart fetal hemoglobin production; in 2011, using this approach, they corrected sickle cell disease in mice.
Now, the decades-old discovery is finally nearly ready for human testing — in the form of gene therapy. Today in the Journal of Clinical Investigation, Dana-Farber/Boston Children’s researchers report that a precision-engineered gene therapy vector suppressing BCL11A production overcame a key technical hurdle. …
Sanfilippo syndrome A is a neurodegenerative condition caused by a genetic error in metabolism: because of a missing enzyme, long-chained sugar molecules cannot be broken down. Toxic substrates accumulate in cells, causing a rapid cognitive decline and, later, motor decline. Most affected children die in their teens or earlier.
There is no treatment, and when Karen Aiach’s daughter Ornella was diagnosed with Sanfilippo syndrome A, no companies were even working on the disease.
When Brenden Whittaker of Columbus, Ohio, the first patient treated with gene therapy for chronic granulomatous disease (CGD), showed successful engraftment last winter, the gene therapy team lifted glasses for a celebratory toast. The wine they sipped was no ordinary wine. The 2012 Bordeaux blend came from an award-winning California vineyard owned and operated by Robert Baehner, MD, a pioneering pediatric hematologist with ties to Dana-Farber/Boston Children’s Cancer and Blood Disorders Center.
Decades before, Baehner had done fundamental research in CGD, an inherited immune system disorder that occurs when phagocytes, white blood cells that normally help the body fight infection, cannot kill the germs they ingest and thus cannot protect the body from bacterial and fungal infections.
Children with CGD are often healthy at birth, but develop severe infections in infancy and early childhood from bacteria that would cause mild disease or no illness at all in a healthy child. This was true for Whittaker. Diagnosed with CGD when he was 1, his disease became increasingly severe, forcing him to quit school several years ago. …
When Zhigang He, PhD, started a lab at Boston Children’s Hospital 15 years ago, he hoped to find a way to regenerate nerve fibers in people with spinal cord injury. As a proxy, he studied optic nerve injury, which causes blindness in glaucoma — a condition affecting more than four million Americans — and sometimes in head trauma.
By experimenting with different growth-promoting genes and blocking natural growth inhibitors, he was able to get optic nerve fibers, or axons, to grow to greater and greater lengths in mice. But what about vision? Could the animals see? …