Scientists now have a better approach in treating severe combined immunodeficiency using gene therapy that allows patients to fully recover without medical side effects.
SCID is a rare and potentially deadly condition caused by several types of impairment in the immune system. It affects fewer than 100 newborns a year in the United States.
Individuals who have this disease have complete loss of immune functions, making them highly susceptible to infections.
Today, children and parents whose lives were affected by SCID find hope of a potential cure through a groundbreaking technique in gene therapy.
Down The Memory Lane Of SCID Treatments
A bone marrow transplant is the standard treatment for SCID. The patient typically has to undergo cycles of monthly infusions of antibodies called immunoglobulins.
A successful transplant does not mean cure since only a part of the child's immune system is restored. Finding an exact match presents a major challenge even when the donor is from the immediate family.
In 1990, Drs. William French Anderson and Michael Blaese from the National Heart, Lung, and Blood Institute and the National Cancer Institute first initiated gene therapy for SCID.
The process involved removing the defected blood cells from the patient, injecting a new gene in aid of a virus, and then putting the modified cells back into the body. Doctors expected that the new cells would eventually build up the child's immune system.
All of the 20 children who underwent the gene therapy recovered, but five of them eventually developed leukemia. Scientists were faced with the dilemma of how to modify the defected SCID cells without triggering cancer.
Modern Gene Therapy
In a study recently published in The New England Journal of Medicine, researchers at St. Jude Children's Research Hospital reported that they have developed a way that would allow successful gene therapy without the risk of leukemia.
The team cured 10 infants born with SCID-X1, a specific type of SCID that requires matched bone marrow tissues from a sibling donor. The researchers reengineered the human immunodeficiency virus so that it would cause neither HIV/AIDS nor cancer.
All of the children responded well to the experimental treatment and have received vaccinations to further strengthen their immune systems.
"These patients are toddlers now, who are responding to vaccinations and have immune systems to make all immune cells they need for protection from infections as they explore the world and live normal lives. This is a first for patients with SCID-X1," said co-author Dr. Ewelina Mamcarz of the St. Jude Department of Bone Marrow Transplantation and Cellular Therapy.
Patients who had infections prior to the gene therapy recovered completely. Developmental milestones were noted as normal. None of them developed leukemia or any life-threatening condition as side effects.
Tribute To The Bubble Boy
The term "Bubble Boy" disease was colloquially given to refer to a patient with SCID. It was coined in the 1970s when a documentary featured David Vetter who practically lived in isolation inside plastic bubbles to protect him from infections.
Shortly after the young Vetter had received an incompatible bone marrow transplant, he succumbed to death in 1984 at age 12. The bone marrow samples from his sister contained a dormant virus that caused hundreds of tumors.
Vetter's death provided a wealth of scientific material to study SCID with the hope of developing potent treatments. It was also through his autopsy that doctors confirmed a virus can cause cancer.
