UK Approves World’s First Gene Therapy for SCD, Transfusion-Dependent Beta-Thalassemia

The United Kingdom’s Medicines and Health Care Products Regulatory Agency (MHRA) approved the world’s first gene therapy to treat sickle cell disease (SCD) and transfusion-dependent beta-thalassemia (TDT) on Thursday. The new treatment is approved to treat patients ages 12 and older.

The first approved therapy to employ CRISPR gene editing technology, exagamglogene autotemcel (Casgevy, Vertex) is designed to work by editing the faulty gene in a patient’s bone marrow stem cells so that the body produces functioning hemoglobin.

MHRA based its approval on results from two clinical trials of 45 patients with SCD and 54 patients with TDT; 29 SCD patients and 42 TDT patients had been in the trial long enough for primary efficacy interim analysis. Among eligible SCD patients, 28 (97%) were free of severe pain crises for at least 12 months after treatment. Of 42 eligible TDT patients, 39 (93%) did not require RBC transfusions for 12 months following treatment. The remaining three experienced a 70% reduction in the need for RBC transfusions. Side effects mirrored those of autologous stem cell transplants: nausea, fatigue, fever and increased infection risks.

The trials are ongoing, and MHRA and Vertex continue to monitor safety.