bluebird bio has secured conditional marketing authorisation from the European Commission (EC) for its one-time gene therapy ZYNTEGLO (autologous CD34+ cells encoding βA-T87Q-globin gene) for the treatment of transfusion-dependent β-thalassemia (TDT).
The approval for ZYNTEGLO is for the treatment of TDT in patients 12 years and older who do not have a β0/β0 genotype and for those who are suitable for hematopoietic stem cell (HSC) transplantation but a human leukocyte antigen (HLA)-matched related HSC donor is not available.
Considered to be a severe genetic disease, TDT results from the mutations in the β-globin gene that lead to reduced or absent hemoglobin. For survival, TDT patients need to sustain hemoglobin levels with lifelong chronic blood transfusions, which come with the risk of progressive multi-organ damage owing to unavoidable iron overload.
According to bluebird, ZYNTEGLO addresses the underlying genetic cause of the disease and provides patients without a β0/β0 genotype the potential to become independent from blood transfusions. The gene therapy is said to work by adding functional copies of a modified form of the β-globin gene (βA-T87Q-globin gene) into a patient’s own blood stem cells.
bluebird chief Nick Leschly said: “EC approval of ZYNTEGLO is a milestone that represents the dedication and commitment of clinical investigators, healthcare providers, patients and their families, and our employees, all of whom have helped advance this treatment from concept to an approved therapy
“Our first product approval is a humbling moment for all of us at bluebird, and we look forward to continuing our work with the TDT community and health systems to bring this important treatment to patients.”
The conditional EC approval for the gene therapy was driven by efficacy, safety and durability data from the phase 1/2 HGB-205 study and the completed phase 1/2 Northstar (HGB-204) study among others.
In the HGB-205 study, 75% of patients without a β0/β0 genotype, achieved transfusion independence, following treatment with ZYNTEGLO while sustaining hemoglobin ≥9 g/dL. In the Northstar study, 80% of patients without a β0/β0 genotype achieved transfusion independence following treatment with the gene therapy.
Transfusion independence is defined by the company as the lack of necessity of receiving a transfusion for more than 12 months.