UCLA stem cell researchers use gene therapy to restore immune systems in 'bubble babies'

Public release date: 11-Sep-2012 [ | E-mail | Share ]

Contact: Kim Irwin kirwin@mednet.ucla.edu 310-435-9457 University of California - Los Angeles Health Sciences

UCLA stem cell researchers have found that a gene therapy regimen can safely restore immune systems to children with so-called "Bubble Boy" disease, a life threatening condition that if left untreated can be fatal within one to two years.

In the 11-year study, researchers were able to test two therapy regimens for 10 children with ADA-deficient severe combined immunodeficiency (SCID). During the study, they refined their approach to include a light dose of chemotherapy to help remove many of the blood stem cells in the bone marrow that are not creating an enzyme called adenosine deaminase (ADA), which is critical for the production and survival of healthy white blood cells, said study senior Dr. Donald Kohn, a professor of pediatrics and of microbiology, immunology, and molecular genetics in Life Sciences and a member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA.

The refined gene therapy and chemotherapy regimen proved superior to the other method tested in the study, restoring immune function to three of the six children who received it, Kohn said. Going forward, an even further refined regimen using a different type of virus delivery system will be studied in the next phase of the study, which already has enrolled eight of the 10 patients needed.

The study appears Aug. 30 in the advance online issue of the peer-reviewed journal Blood.

"We were very happy that in the human trials we were able to see a benefit in the patients after we modified the protocol," Kohn said. "Doctors treating ADA-deficient SCID have had too few options for too long, and we hope this will provide them with an efficient and effective treatment for this devastating disease."

Children born with SCID, an inherited immunodeficiency, are generally diagnosed at about six months. They are extremely vulnerable to infectious diseases and don't grow well. Chronic diarrhea, ear infections, recurrent pneumonia and profuse oral candidiasis commonly occur in these children. SCID cases occur in about 1 of 100,000 births

Currently, the only treatment for ADA-deficient SCID calls for injecting the patients twice a week with the necessary enzyme, Kohn said, a life-long process that is very expensive and often doesn't return the immune system to optimal levels. These patients also can undergo bone marrow transplants from matched siblings, but matches can be very rare.

About 15 percent of all SCID patients are ADA-deficient. Kohn and his team used a virus delivery system that he had developed in his lab in the 1990s to restore the gene that produces the missing enzyme necessary for a healthy immune system. To date, about 40 children with SCID have received gene therapy in clinical trials around the world, Kohn said.

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UCLA stem cell researchers use gene therapy to restore immune systems in 'bubble babies'