St. Jude Develops Gene Therapy for Severe Combined Immunodeficiency

Researchers at St. Jude Children’s Research Hospital have developed a new gene therapy that creates fully-functioning immune systems in babies diagnosed with severe combined immunodeficiency (SCID), commonly referred to as the “Bubble Boy” disease.

This extremely rare condition is the effect of a genetic mutation and impacts 1 in every 50,000 to 100,000 live births, with patients almost always being male. Patients with SCID are unable to produce T-cells, B-cells and natural killer cells that protect the body from viruses and bacteria.

Per St. Jude, symptoms commonly include recurrent, persistent infections, rashes, diarrhea, fever, ear infections, and pneumonia. Children are also unable to gain weight or grow at a normal pace due to their weak immune system. Most children will die by age 2 if they are not treated effectively.

Historically, treatment involved a bone marrow transplantation with a fully matched sibling, yet efficacy was low due to 80% of patients having no sibling match. In these situations, surgery would further complications and create zero benefits in patients.

With the goal of improving patient outcome, St. Jude has created a therapy that utilizes a re-engineered virus carrying a normal copy of the gene to replace the mutated one. Safety features were also included by St. Jude scientists to ensure that the virus does not activate cancer-causing genes nearby.

The treatment involves the patient's bone marrow being removed, allowing blood-producing stem cells to incubate with the re-engineered virus carrying the normal gene. A chemotherapy drug is introduced to deter the activation of cancer mutations in genes before the stem cells from the bone marrow are returned to the patient. Following this treatment, patients could potentially produce the three types of immune cells.

"What we're finding is the gene therapy is working very well. The patients ... are having their immune systems restored," stated Dr. Brian Sorrentino, a member of St. Jude's department of hematology in the USA Today. Sorrentino led the study alongside colleague Dr. Ewelina Mamcarz

6 of the 7 patients in the trial have developed immune systems within 4 months of treatment without unexpected complications. These patients are now being monitored at St. Jude and a second children’s hospital in San Francisco to confirm the long-term benefits of treatment. The findings from this clinical study insinuate that a permanent cure for SCID may be closer than was originally thought.

John G. Boyle, president and CEO of the Maryland-based Immune Deficiency Foundation, stated that his group is "optimistic that this recent clinical trial offers further evidence and hope that gene therapy may be a practical treatment option for patients with SCID in the future."

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