The US drug authority FDA has expanded the approval of the gene therapy Casgevy (exagamglogene autotemcel) to children aged two years and older with sickle cell disease or transfusion-dependent ?-thalassemia. This means the CRISPR-based therapy is now available for very young patients for the first time. Previously, Casgevy was approved for ages twelve and older.
Background
Sickle cell disease and transfusion-dependent ?-thalassemia are serious genetic blood disorders that can lead to severe complications even in early childhood. Many affected individuals suffer from recurrent painful crises or rely on regular blood transfusions. Previous treatments alleviate symptoms but do not cure the diseases.
Mechanism of action of Casgevy
Casgevy is a one-time autologous stem cell therapy. In this process, the patient's own blood stem cells are collected, genetically modified using CRISPR/Cas9 technology, and then re-transplanted. The modification leads to increased production of fetal hemoglobin, which mitigates the pathological effects of sickle cell disease and thalassemia.
Basis for approval
The expansion of approval to children aged two and older was based on an extrapolation of clinical data, as direct studies in this age group were limited. In a small cohort of children aged 5 to under 12 years, positive effects were observed regarding the reduction of severe vaso-occlusive crises and transfusion independence.
Significance for patients
With the new approval, affected children can be treated significantly earlier. This can reduce the risk of long-term organ damage. The FDA emphasizes that the therapy represents an important additional treatment option for these life-threatening diseases.
Safety and side effects
The most common side effects include mucositis, febrile neutropenia, and loss of appetite. As with other gene therapy procedures involving myeloablative conditioning, there are risks such as graft failure or delayed platelet engraftment. The FDA also points out the theoretical risk of off-target effects of gene editing.
Outlook
The approval expansion is considered an important step for gene therapy in pediatric patients with rare blood disorders. Further long-term data will show how sustainable the effect of the one-time treatment is in very young children.
FAQ
For which diseases is Casgevy now approved?
For sickle cell disease with recurrent vaso-occlusive crises and for transfusion-dependent ?-thalassemia in patients aged two years and older.
How does the therapy work?
The patient's own blood stem cells are edited using CRISPR/Cas9 to increase the production of fetal hemoglobin and then re-transplanted.
Why is approval for young children significant?
Early treatment can prevent long-term organ damage and improve the quality of life for affected children.
What are the risks?
In addition to typical side effects of stem cell transplantation, there is a theoretical risk of off-target effects from gene editing.
Who manufactures the preparation?
Vertex Pharmaceuticals in collaboration with CRISPR Therapeutics.
