Stories about: gene therapy

Sickle cell gene therapy to boost fetal hemoglobin: A 70-year timeline of discovery

sickled cells occluding a blood vessel
Sickled cells occluding a blood vessel. (Image: Elena Hartley)

Boston Children’s Hospital is now enrolling patients age 3 to 35 in a clinical trial of gene therapy for sickle cell disease. Based on technology developed its own labs, it differs from other gene therapy approaches by having a two-pronged action. It represses production of the mutated beta hemoglobin that causes red blood cells to form the stiff “sickle” shapes that block up blood vessels. It also increases production of the fetal form of hemoglobin, which people normally stop making after birth.

Fetal hemoglobin doesn’t sickle and works fine for oxygen transport. The gene therapy being tested now restores fetal hemoglobin production by turning “off” a silencing gene called BCH11A.

BCL11A represses fetal hemoglobin and also activates beta hemoglobin, which is affected by the sickle-cell mutation,” David Williams, MD, the trial’s principal investigator, told Vector last year. Williams is also president of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. “So when you knock BCL11A down, you simultaneously increase fetal hemoglobin and repress sickling hemoglobin, which is why we think this is the best approach to gene therapy in this disease.”

The therapy is the product of multiple discoveries, the first dating back 70 years. Click selected images below to enlarge.

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2017 pediatric biomedical advances at Boston Children’s Hospital: Our top 10 picks

New tools and technologies fueled biomedicine to great heights in 2017. Here are just a few of our top picks. All are great examples of research informing better care for children (and adults).

1. Gene therapy arrives

(Katherine C. Cohen)

In 2017, gene therapy solidly shed the stigma of Jesse Gelsinger’s 1999 death with the development of safer protocols and delivery vectors. Though each disease must navigate its own technical and regulatory path to gene therapy, the number of clinical trials is mounting worldwide, with seven gene therapy trials now recruiting at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. In August, the first gene therapy won FDA approval: CAR T-cell therapy for pediatric acute lymphoblastic leukemia.

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Routing gene therapy directly into the brain

Image of mouse brain that received a transplantation of hematopoietic stem cells. The image shows the transplanted cells (green) rapidly engrafted and gave rise to new cells (also green) that have widely distributed throughout the entire brain. 
Image of a mouse brain that received a direct transplantation of hematopoietic stem cells. The image reveals the transplanted cells (green) rapidly engrafted and gave rise to new cells (also green) that have widely distributed throughout the entire brain.

A therapeutic technique to transplant blood-forming (hematopoietic) stem cells directly into the brain could herald a revolution in our approach to treating central nervous system diseases and neurodegenerative disorders.

The technique, which could be used to transplant donor-matched hematopoietic stem cells (HSCs) or a patient’s own genetically-engineered HSCs into the brain, was reported in Science Advances today by researchers from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and the San Raffaele Telethon Institute for Gene Therapy.

In their study, the team tested the technique in a mouse model to treat lysosomal storage disorders, a group of severe metabolic disorders that affect the central nervous system.

The team’s findings are groundbreaking because, until now, it was thought that HSCs — from a healthy, matched donor or a patient’s own genetically-corrected cells — needed to be transplanted indirectly

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Gene therapy halts progression of cerebral adrenoleukodystrophy in clinical trial

David Williams, MD, the principal investigator of the clinical trial, discusses gene therapy and its impact on children with adrenoleukodystrophy

Adrenoleukodystrophy — depicted in the 1992 movie “Lorenzo’s Oil” — is a genetic disease that most severely affects boys. Caused by a defective gene on the X chromosome, it triggers a build-up of fatty acids that damage the protective myelin sheaths of the brain’s neurons, leading to cognitive and motor impairment. The most devastating form of the disease is cerebral adrenoleukodystrophy (CALD), marked by loss of myelin and brain inflammation. Without treatment, CALD ultimately leads to a vegetative state, typically claiming boys’ lives within 10 years of diagnosis.

But now, a breakthrough treatment is offering hope to families affected by adrenoleukodystrophy. A gene therapy treatment effectively stabilized CALD’s progression in 88 percent of patients, according to clinical trial results reported in the New England Journal of Medicine. The study was led by researchers from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and Massachusetts General Hospital.

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New hope for X-linked myotubular myopathy as gene therapy clinical trial begins

gene therapy myotubular myopathy

Boys born with X-linked myotubular myopathy (XLMTM) face a grim prognosis. Extreme muscle weakness leaves many ventilator-dependent from birth, and most infants need feeding tubes. About half pass away before 18 months of age.

Last week, the biotechnology company Audentes Therapeutics announced the dosing of the first patient in a gene-therapy clinical trial — 21 years after the MTM1 gene was first cloned.

Hopes are high. Gene therapy has already shown striking benefits in dogs with XLMTM in studies co-authored by Alan Beggs, PhD, director of the Manton Center for Orphan Disease Research at Boston Children’s Hospital, and colleagues at Généthon and the University of Washington. In the most recent study, 10-week-old Labrador retrievers already showing signs of the disease showed improvements in breathing, limb strength and walking gait after a single dose of the gene therapy vector.

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Landmark moment for science as the FDA approves a gene therapy for the first time

Leukemia blast cells, which could now be destroyed using a first-of-its-kind, FDA-approved gene therapy called CAR-T cell therapy
Leukemia blast cells.

Today, the Food and Drug Administration approved a gene therapy known as CAR T-cell therapy that genetically modifies a patient’s own cells to help them combat pediatric acute lymphoblastic leukemia (ALL), the most common childhood cancer. It is the first gene therapy to be approved by the FDA.

“This represents the progression of the field of gene therapy, which has been developing over the last 30 years,” says gene therapy pioneer David A. Williams, MD, who is chief scientific officer of Boston Children’s Hospital and president of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. “It’s a realization of what we envisioned to be molecular medicine when this research started. The vision — that we could alter cells in a way to cure disease — is now coming true.”

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Gene therapy: The promise, the reality, the future

gene therapy
(Graphs courtesy Alexandra Biffi, Dana-Farber/Boston Children’s Cancer and Blood Disorders Center)

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.

A recent panel at Boston Children’s Hospital, hosted by the hospital’s Technology and Innovation Development Office (TIDO), explored where gene therapy is and where it’s going. Here were the key takeaways:

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With no time to lose, parents drive CMT4J gene therapy forward

CMT4J
Talia Duff’s disorder, CMT4J, is a rare form of Charcot-Marie-Tooth. It has been modeled in mice that will soon undergo a test of gene therapy, largely through her parents’ behind-the-scenes work.

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.”

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A gene therapy advance for muscle-wasting myotubular myopathy

X-linked myotubular myopathy XLMTM gene therapy
Nibs, a carrier of MTM whose descendants provided the basis for the gene therapy study. (Read more of her story.)

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.

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Gene therapy restores whisper-fine hearing, balance in Usher syndrome mice

gene therapy for deafness
Sensory hair cells contain tiny cilia that get wiggled by incoming sound waves, sparking a signal to the brain that ultimately translates to hearing. Gene therapy restored this tidy “V” formation. (Credit: Gwenaelle Géléoc and Artur Indzkykulian)

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.

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