European Commission Approves First Gene Therapy for “Bubble Boy Disease”

The European Commission approved the first gene therapy for children with severe combined immunodeficiency due to adenosine deaminase deficiency (ADA-SCID), also known as “bubble boy disease.” The therapy is made up of autologous CD34+ cells transduced to express ADA and is the first ex vivo stem cell gene therapy for patients with ADA-SCID for whom no suitable human leukocyte antigen-matched related stem cell donor is available.

The approval was based on results from a pivotal study of 18 children with ADA-SCID that was recently published in Blood. The survival rate after a median of 6.9 years (range = 2.3-13.4 years) was 100 percent, and intervention-free survival in the evaluable population (n=17) was 82 percent.

All 18 patients reported adverse events (AEs), the most frequent of which were upper respiratory tract infection, gastroenteritis, and rhinitis. Of the 39 serious AEs reported, 62 percent were infections, with the most common being device-related. Patients also experienced neurologic, central nervous system, or hearing impairments that continued post-treatment. The safety findings were noted as similar to those expected in this patient population who received low-dose chemotherapy and who are undergoing immune recovery. A significant reduction in severe infections was documented, with no leukemic events observed to date.

Source: GSK press release, May 27, 2016.