Gene Therapy Works for 'Bubble Boy' Disease
9 Years Later, 14 Out of 16 Kids With the Rare Disease Leading Normal Lives
How the Children Fared continued...
The 16 children with SCID who got the gene therapy ranged in age from 6 months to 3 years. Four of them had the ADA-deficiency type of SCID. The other kids had the X1 form of SCID. Those are the two most common types of SCID.
For most of the children, gene therapy was a success. But one boy who had the X1 form of SCID developed treatment-related leukemia. The complication was not unexpected, Gaspar says, because four children with the X1 from of SCID in a French study had developed leukemia after getting the gene therapy.
Gaspar says researchers learned from those cases and have modified the treatment in hopes of reducing the risk for patients with the X1 form of the disorder.
Kohn says gene therapy should be considered the treatment of choice for children with ADA-deficient SCID who do not have perfect bone marrow donor matches. It may prove to be a better choice for patients with perfect donor matches, too, he says.
As for the X1 form of the disease, Kohn says it remains to be seen if the new approach to gene delivery works and has less risk of leukemia.
Lessons learned from the SCID trials have spurred studies to find effective gene-based treatments for other blood cell diseases, including sickle cell anemia, Kohn notes.
“The history of gene therapy research can be summarized as, 'Two steps forward and one step back.' We retrench, we learn, and then we move forward again,” he says.
“Twenty years ago, nothing was working," Kohn says. "Ten years ago, these treatments started to work, but with complications. The hope is that the next decade will bring highly effective treatments with few complications.”