According to a recent news release, CTX001, a gene-edited therapy for patients with transfusion-dependent beta thalassemia, received Priority Medicines (PRIME) designation from the European Medicines Agency (EMA). The treatment was developed through a partnership and research collaboration between biotechnology company Vertex Pharmaceuticals (“Vertex”) and gene-editing company CRISPR Therapeutics (“CRISPR”).

CTX001

So what is CTX001? This investigational, autologous, ex vivo treatment uses healthy hematopoietic stem cells from the patient’s own body. Ex vivo means the cells are genetically edited outside of the patient’s body. Once modified, these cells begin to produce more fetal hemoglobin (HbF), a type of oxygen-carrying hemoglobin. Once levels of HbF rise in the body, patients are able to be less dependent on transfusions.

CTX001 is also used to treat patients with sickle cell disease (SCD), for which the treatment also received PRIME designation.

Prime Designation

According to the EMA:

PRIME is a scheme launched by the European Medicines Agency (EMA) to enhance support for the development of medicines that target an unmet medical need. Through PRIME, the Agency offers early and proactive support to medicine developers to optimize the generation of robust data on a medicine’s benefits and risks and enable accelerated assessment of medicines applications.

In this case, the designation was granted following data from the Phase 1/2 CLIMB-Thal-111 clinical trial. Altogether, this trial is evaluating the safety, efficacy, and tolerability of CTX001 for patients with transfusion-dependent beta thalassemia. Enrolled patients are between ages 12-35. Overall, 45 patients will enroll. The follow-up period will consist of 2 years following CTX001 infusion. Beyond this trial, CTX001 is also being evaluated in the Phase 1/2 CLIMB-SCD-121 clinical trial. Later, researchers will use CLIMB-131 to evaluate the results from patients who received the treatment in either of the above trials.

Beyond PRIME designation, CTX001 has also received:

• Orphan Drug Designation (within the European Union)
• Orphan Drug, Fast Track, Regenerative Medicine Advanced Therapy, and Rare Pediatric Disease designations (within the United States)

Beta Thalassemia

Hemoglobin beta (HBB) gene mutations cause beta thalassemia, a blood disorder which reduces hemoglobin levels within the body. Normally, hemoglobin is found in red blood cells. It is iron-rich and helps carry oxygen throughout the body. But when your body creates less hemoglobin, less oxygen is carried throughout, causing health issues. Patients with one HBB mutation develop minor beta thalassemia, while those with two defects develop either intermedia or major beta thalassemia. For those with the minor form, symptoms are often mild. However, severity may increase depending on the specific mutations.

Symptoms of beta thalassemia include:

• Anemia (low red blood cell count)
• Fatigue
• Shortness of breath
• General weakness 
• Delayed puberty
• Bone abnormalities
• Feeding difficulties (as infants)
• Enlarged spleen, liver, and heart
• Pale skin (pallor)
• Headaches
• Dizziness
• Blood clots
• Iron overload (excess iron levels) 

Learn more about beta thalassemia.