US-based therapeutics developer bluebird bio has secured positive recommendation from a European Medicines Agency (EMA) panel for the approval of its first gene therapy Zynteglo to treat certain patients with transfusion-dependent β-thalassemia (TDT ).

TDT is a genetic disease characterised by the β-globin gene mutations that cause decreased or absent haemoglobin. Patients need lifelong chronic blood transfusions to maintain their haemoglobin levels. However, transfusions are associated with risk of progressive multi-organ damage.

Zynteglo is intended to treat patients without the β00 genotype, who are eligible for hematopoietic stem cell (HSC) transplantation, in cases where a human leukocyte antigen (HLA)-matched related HSC donor is not available.

The therapy comprises autologous CD34+ cells encoding β A-T87Q-globin gene. It adds the functional copies of a modified form of the gene into the patient’s own HSCs, avoiding the need for donor HSCs.

Patients receiving the β A-T87Q-globin gene should be able to generate a gene therapy- derived-haemoglobin called HbAT87Q at levels that could significantly cut or eliminate the requirement for transfusions following treatment.

The Committee for Medicinal Products for Human Use (CHMP) recommended conditional marketing authorisation of the drug for patients aged 12 years and above.

“The positive CHMP opinion for Zynteglo is a crucial step toward providing what would be the first one-time gene therapy for people living with TDT.”

The drug is bluebird bio’s first gene therapy submitted for regulatory approval. The European Commission will consider CHMP’s opinion while reviewing the application for approval.

bluebird bio chief medical officer David Davidson said: “The goal of treatment with Zynteglo is to enable patients with transfusion-dependent β-thalassemia to produce haemoglobin at sufficient levels to allow lifelong independence from blood transfusions.

“The positive CHMP opinion for Zynteglo is a crucial step toward providing what would be the first one-time gene therapy for people living with TDT.”

CHMP’s recommendation is based on safety, efficacy and durability results from the Phase I/II HGB-205 and HGB-204 (Northstar) clinical trials, as well as data from the ongoing Phase 3 Northstar-2 (HGB-207), Northstar-3 (HGB-212) studies.

The panel also reviewed findings from the ongoing long-term follow-up LTF-303 study.

As of 14 September 2018, the Phase I/II Northstar data demonstrated that 80% of patients without β00 genotype achieved transfusion independence, which was maintained for a median duration of 38 months.

Non-serious Zynteglo-related adverse events (AEs) in the trials were hot flush, dyspnoea, abdominal pain, pain in extremities and non-cardiac chest pain.