Bluebird Bio’s Zynteglo Becomes First FDA-Approved Gene Therapy For Beta-Thalassemia

The US FDA has approved Bluebird Bio’s Zynteglo (betibeglogene autotemcel) as the country’s first gene therapy for beta-thalassemia, three years after the treatment received the greenlight in Europe. 

Zynteglo has had a bumpy ride, suffering manufacturing issues and a clinical hold which was only lifted last year. Bluebird has since withdrawn the gene therapy from the European market due to a bumpy rollout and failure to find reimbursement. 

Curing Beta-Thalassemia

Beta-thalassemia is a rare genetic blood disease caused by mutations in the beta-globin, which results in little to no hemoglobin production. Patients with the severe form of this disease, also called transfusion-dependent beta-thalassemia, have to rely on regular red blood cell transfusions for life. 

Zynteglo is a one-time lentiviral vector gene therapy that adds working copies of a modified beta-globin gene into the patient’s hematopoietic stem cells (HSCs) to allow them to produce hemoglobin at normal or near normal levels. 

The US approval is based on results from Bluebird’s Phase 3 studies, where 89% of 41 patients receiving the gene therapy achieved transfusion independence. The patients will be followed up to 4 years, and results have been durable as of the last follow-up.  

An Expensive Therapy

Bluebird’s gene therapy will not be cheap, coming in at $2.8 million, which is well above the $1.7 million tagged on after its European approval. While it is designed as a one-time treatment, the treatment process itself will be conducted over several months. 

The company has said it would reimburse health insurers up to 80% of the cost if Zynteglo fails to produce durable transfusion dependence two years after administration. Bluebird is conducting a long-term follow-up study, LTF-303, to monitor patients who have participated in its clinical studies of lentiviral vector gene therapy through 15 years post-treatment.

Author

Joy Lin

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