Early Gene Therapy Results in Wiskott-Aldrich Syndrome Are Promising; Self-Inactivating Lentivirus Used for Gene Delivery; Four Treated Boys Show Improvement

On December 6, 2015, promising preliminary outcomes were reported for the first four children enrolled in a U.S. gene therapy trial for Wiskott-Aldrich syndrome (WAS), a rare, X-linked recessive, life-threatening blood and immune disorder. These new results were presented at the 57th Annual Meeting of the American Society of Hematology (http://www.hematology.org/Annual-Meeting/) (abstract #260: https://ash.confex.com/ash/2015/webprogram/Paper80692.html), which is taking place in Orlando, Florida (December 5-8). All four boys are alive and have improved between 9 and 24 months following treatment, according to study principal investigator Sung-Yun Pai (photo), M.D., a pediatric hematologist/oncologist at Dana-Farber/Boston Children's Cancer and Blood Disorders Center. Since undergoing treatment, none of the four boys has experienced bleeding events or severe WAS-related infections. In addition, all four boys have experienced improvements in immunologic symptoms and variable improvements in platelet count. The two patients who had required medication to stimulate platelet production prior to undergoing gene therapy are no longer on those medicines. It is too early, however, to draw conclusions about long-term outcomes. The study protocol calls for the children to be monitored for 15 years in order to assess the treatment's safety and efficacy. WAS is caused by mutations that lead to the loss or dysfunction of the WAS gene, which is found on the X chromosome. The condition, which occurs only in boys, affects the development and function of T-cells and platelets, leaving patients vulnerable to bleeding, eczema, and infections. The only curative treatment is a hematopoietic (blood-forming) stem cell transplant from a compatible donor. However, it is often difficult to identify an appropriate match.
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