Severe combined immunodeficiency disorder (SCID) is also known as the immune disorder popularized by the story of David Vetter—the “bubble boy” disease. Children born with this hereditary disease have almost no immune system and as a result are incredibly susceptible to infections. Early results at St. Jude Children’s Research Hospital have been very positive in a new gene therapy that might protect newborns with the disease.
Approximately four months after treatment, five of the seven patients enrolled in the St. Jude clinical trial had immune systems for the first time. The patients no longer require protective isolation. Four patients have started making serum immunoglobulins (antibodies) for the first time. One has stopped monthly immunoglobulin supplementation and recently received his first set of vaccinations.
"These results are an exciting early indication that this gene therapy is well tolerated and effective in infants as young as 2 months old with this devastating inherited immune disorder," said Ewelina Mamcarz, M.D., an assistant member of the St. Jude Department of Bone Marrow Transplantation and Cellular Therapy. She spoke at the press conference and will present the findings Sunday, Dec. 10, at 4:30 p.m.
No serious complications have been reported.
Currently, transplantation with a tissue-matched sibling donor is the standard treatment for XSCID. More than 80 percent of XSCID patients, including the infants in this study, do not have matched sibling donors. These patients must rely on unrelated donors or parent donors, who are partial genetic matches. Such transplants are less likely to fully restore immune function and are associated with potentially severe treatment-related complications.
In response, St. Jude researchers have re-engineered a lentivirus to function as a vector to ferry a normal copy of IL2RG into the patients' hematopoietic stem cells. The vector includes novel features to enhance safety and effectiveness. The features include genetic insulators to block activation of genes adjacent to the IL2RG DNA insertion site. The design aims to ensure gene therapy will not lead to leukemia by inadvertently activating an oncogene in the patient's hematopoietic stem cells.
Just wonderful.