Gene therapy for blood disorder ends need for transfusions

Gene therapy for transfusion-dependent thalassemia, an inherited blood disorder, produced positive outcomes in an interim analysis of two international Phase 1/2 clinical trials, according to the results published in New England Journal of Medicine. Out of 22 patients aged 12 - 35 years, 15 patients achieved transfusion-free status, while others needed transfusions less often.

People with thalassemia cannot make enough hemoglobin in their red blood cells, which interferes with oxygen getting to all parts of the body. Those with the most severe type of the disease require red blood cell transfusions every month for survival. Frequent transfusions, however, can cause serious complications due to iron toxicity and viral infections.

"We saw remarkable outcomes using LentiGlobin gene therapy, with most patients no longer needing monthly transfusions," said leading author Alexis Thompson, MD, Head of Hematology and Director of the Comprehensive Thalassemia Program at Ann & Robert H. Lurie Children's Hospital of Chicago, as well as Professor of Pediatrics at Northwestern University Feinberg School of Medicine. "These study results exceeded our expectations with clinical benefit for nearly all patients, and suggest that gene therapy may be an effective treatment for thalassemia in the future."

The studies used the patient's own stem cells that were treated in the lab with a modified virus to replace the gene that is defective in thalassemia. The patient needed to undergo chemotherapy before the new cells could be infused. Patients typically reached peak production of hemoglobin in nine to 12 months after infusion. They were then monitored for 15 - 42 months after receiving the new cells. Treatment-related adverse events were typical of autologous stem cell transplantation. No safety issue could be attributed to gene therapy in either of the studies. Researchers plan to continue follow-up with all patients for 15 years.

"While these gene therapy trials were the largest for thalassemia to date, we need to evaluate effectiveness in a much larger population," said Thompson, who also is the President of the American Society of Hematology (ASH). "Since we saw such positive results, we are now enrolling patients as young as 5 years old on a Phase 3 trial of gene therapy for transfusion-dependent thalassemia."

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Research at Ann & Robert H. Lurie Children's Hospital of Chicago is conducted through the Stanley Manne Children's Research Institute. The Manne Research Institute is focused on improving child health, transforming pediatric medicine and ensuring healthier futures through the relentless pursuit of knowledge. Lurie Children's is ranked as one of the nation's top children's hospitals in the U.S. News & World Report. It is the pediatric training ground for Northwestern University Feinberg School of Medicine. Last year, the hospital served more than 208,000 children from 50 states and 58 countries.

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