CTX001 is a therapy that uses a technology called CRISPR-Cas9 to modify a person’s own stem cells. This treatment is designed for people with certain blood disorders, specifically transfusion-dependent thalassemia and severe sickle cell disease. The goal of this therapy is to make changes in the stem cells that can help improve the symptoms of these conditions. In this clinical trial, the focus is on understanding the long-term safety of using CTX001 in patients who have already received this treatment.

Sickle Cell Disease – Sickle Cell Disease is a genetic disorder that affects the shape of red blood cells, causing them to become rigid and sickle-shaped. These abnormally shaped cells can block blood flow, leading to pain and potential organ damage. The disease is characterized by episodes of pain, known as sickle cell crises, and can cause anemia due to the rapid breakdown of the misshapen cells. Over time, individuals may experience complications such as infections, delayed growth, and vision problems. The severity of symptoms can vary widely among individuals. It is a lifelong condition that requires ongoing management.

Transfusion-Dependent Thalassemia – Transfusion-Dependent Thalassemia is a severe form of thalassemia where the body produces an insufficient amount of hemoglobin, leading to anemia. Individuals with this condition require regular blood transfusions to maintain adequate hemoglobin levels. The disease is caused by genetic mutations affecting hemoglobin production, resulting in fatigue, weakness, and pale skin. Over time, frequent transfusions can lead to iron overload, which may affect organs such as the heart and liver. Growth and development may be delayed in children with this condition. It is a chronic condition that necessitates lifelong medical care.