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New approval in gene therapy for the treatment of beta-thalassemia

On 28 March, the Committee on Human Medicinal Products (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending a marketing authorization for the medicinal product Zynteglo, intended for patients suffering from β-Thalassemia-dependent Transfusions (TDT).

Transfusion-dependent β-thalassemia (with a minimum of 8 transfusion sessions / year) is a severe genetic disorder caused by a mutation that hampers their ability to produce hemoglobin, a protein in red blood cells that is essential for the transport of oxygen through the body. Patients with TDT are diagnosed at an early age, and require lifelong blood transfusions, in order to maintain a sufficient level of hemoglobin. However, this treatment causes long-term multi-organ damage. Currently, the only curative treatment is haematopoietic stem cell (HSC) transplantation, as long as there is a familial compatible donor. The goal of gene therapy, and particularly Zynteglo treatment, is to restore a sufficient level of hemoglobin in TDT patients, to enable them to overcome the lifelong chronic transfusions. The active substance of Zynteglo is HSC collected from the TDT patient, to which a gene encoding a modified and functional beta-globin has been added, with the potential to increase the total hemoglobin level, and thus eliminate the dependence on chronic transfusions. This gene is transferred to HSC via a Lentiviral (LV) vector, called “LentiGlobin”. This vector has been developed in a first time, at Harvard University in Boston and CEA Fontenay-aux-Roses, and in a second time by the Bluebird Bio company. Once modified, the cells are reinjected to the patient after a myeloablative treatment.

Since 2013, clinical studies have been conducted in collaboration with Pr. Marina Cavazzana of the Necker Hospital, who is actively working on gene therapy in the treatment of β-thalassemia since its collaboration with the founder of the Bluebird Bio company, Pr Philippe Leboulch, in 2002. The recent clinical studies, including 4 patients managed at the Necker Enfants-Malades Hospital in Paris, revealed the safety and the efficacy of Zynteglo treatment in TDT patients, for whom no compatible donor for transplantation is available. More than 3 years after treatment, 14 of 22 treated patients achieved transfusion independence, while the others have significantly reduced the number and the volume of transfusion.

Designated as an “orphan drug” since 2013, Zynteglo was reviewed under an accelerated assessment timeline by the EMA, as Zynteglo is an advanced therapy medicinal product. The Final approval for marketing authorization depends on the European Commission, but if it follows the EMA’s recommendation, Zynteglo will be the first gene therapy treatment to obtain a European marketing authorization for this indication (the first european marketing authorization approved for a gene therapy treatment was Strimvelis, in 2016, indicated in severe combined immunodeficiency due to adenosine deaminase deficiency). This marketing authorization could therefore change the management of TDT patients and improve their quality of life.

Aurélie Laubier, PhD, project manager DIM Thérapie Génique