Montréal, May 21st, 2025 – A historic milestone has just been reached at CHU Sainte-Justine. This spring, a patient with chronic granulomatous disease (CGD) received a next-generation gene therapy known as “prime editing.” At 18 years old, the young man becomes the first person ever to undergo this groundbreaking treatment, which has the potential to transform the management of rare genetic diseases.
Developed by a U.S.-based company, this innovative technology enabled the direct correction of a genetic mutation in the patient’s hematopoietic stem cells. This mutation is responsible for CGD, a condition that weakens the immune system and leaves individuals vulnerable to potentially life-threatening bacterial and fungal infections, as well as difficult-to-treat inflammatory diseases.
The success, announced Monday via press release, is part of an international clinical trial in which CHU Sainte-Justine participated under the leadership of Dr. Élie Haddad, pediatric immunologist and professor in the Department of Pediatrics at Université de Montréal. This major breakthrough was made possible thanks to the combined expertise of several teams at CHU Sainte-Justine and Centre de recherche Azrieli du CHU Sainte-Justine, including the Centre de cancérologie Charles-Bruneau.
A precision approach: correcting the mutation at its source
Unlike traditional approaches that insert a functional gene to compensate for a defective one, prime editing works at the source: it literally corrects the mutation in stem cells to replace a faulty immune system with a corrected, functional one. After the patient’s hematopoietic stem cells were collected and selected, they were sent to the United States for gene editing in a laboratory. The corrected cells were then reinfused into the patient following preparatory chemotherapy.
“This final phase of the treatment was carried out just a few weeks ago, and already, more than half of the patient’s white blood cells are corrected. He is now back home and doing well. We are very optimistic!” said Dr. Haddad.
“The implications of this clinical trial are significant,” he continued. “For people living with CGD, it represents the hope of a fast, safe, and curative treatment. But beyond this disease, this revolutionary therapy could transform the treatment of many rare genetic disorders and is a perfect example of precision medicine. A therapeutic revolution is underway—and the first patient to benefit from it received the treatment right here at CHU Sainte-Justine!”
International recognition for CHU Sainte-Justine
To conduct this trial, the U.S. company called on the most renowned research centers in the United States and Canada. CHU Sainte-Justine stood out as the very first center selected.
Despite this success, the clinical trial was suspended by the company because of financial constraints. Unfortunately, therefore, no additional patients will be able to access the treatment for now. Nevertheless, with this world first, CHU Sainte-Justine reaffirms its leadership in the treatment of rare diseases and in precision health. “Our clinical research teams are world-class,” concluded Dr. Haddad, emphasizing the importance of continued investment in cutting-edge academic research to offer new hope to individuals living with rare diseases.
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