Stones on the Path to Healing: Skysona and the Cancer Risk

The recent findings on the side effects of Skysona, the gene therapy from bluebird bio, bring a serious issue to the forefront. Seven children participating in clinical trials for Skysona developed a form of blood cancer. According to a study just published in the New England Journal of Medicine, hematological cancers occurred in seven out of 67 patients under 18 years old who participated in a Phase II and Phase III study on Skysona. These patients received the one-time autologous hematopoietic stem cell therapy as treatment for early cerebral adrenoleukodystrophy (CALD), a rare and deadly neurodegenerative disease. Researchers at Boston Children's Hospital analyzed blood and bone marrow samples and found in studies ALD-102 and ALD-104, as well as in an ongoing follow-up study LTF-304, seven cases where cancer developed. Six cases were diagnosed with myelodysplastic syndrome (MDS), and one child with acute myeloid leukemia (AML). The cases examined support FDA findings that the Skysona lentiviral vector may integrate into a proto-oncogene. In a statement issued by bluebird bio, the company emphasized that the well-being of CALD patients is the top priority. They aim to provide the treating physicians with the latest safety information to enable informed treatment decisions. While some patients are already cancer-free again, concerns about the safety of the therapy persist. Errors in vector integration could lead to cancerous tumors, explained Jasminemay Barcelon, Senior Analyst at GlobalData. The approach of potentially causing dangerous changes in the genome remains a challenge in gene therapies using lentiviruses. Skysona is the only approved gene therapy for the treatment of CALD in the USA and the EU. Despite its efficacy, hurdles are now emerging in the company's development. Recently, bluebird bio announced plans to cut 25% of its workforce to reduce costs.