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Bluebird Bio’s Gene Therapy for Blood Disease Wins European Approval

Xconomy Boston — 

Bluebird Bio has won regulatory approval for its first gene therapy, a treatment for the rare blood disease beta thalassemia.

Cambridge, MA-based Bluebird said Monday that the European Commission’s regulatory nod for its therapy, Zynteglo, is a conditional approval, meaning the decision was made with less data than typically required for new drugs. Such approvals are reserved for treatments addressing serious or life-threatening diseases, and Bluebird will be required to submit additional data as a part of an annual renewal process. The regulatory decision comes two months after a European Commission advisory committee recommended approval.

Shares of Bluebird (NASDAQ: BLUE) rose 3.2 percent in mid-day trading.

Beta thalassemia is caused by a defect in the gene that codes for hemoglobin, the protein in red blood cells that carries oxygen. The disease’s severity depends on the amount of hemoglobin a patient’s body is able to produce. The lack of oxygen-rich blood throughout the body can lead patients to feel fatigue, shortness of breath, and headaches. In the most serious cases, patients require lifelong blood transfusions every two to four weeks. These transfusions can lead to a dangerous buildup of iron in organs that requires chelation therapy to remove it. Bone marrow transplants offer another treatment option, but not all patients qualify and, for those who do, the procedure comes with its own risks.

The European approval for Zynteglo is for patients 12 and older who depend on blood transfusions to treat the disorder and can’t find a donor for a stem cell transplant. Zynteglo involves removing blood stem cells from a patient’s body, then taking those cells to a lab where a virus is used to insert a functional copy of the beta globin gene. Before the stem cells are reintroduced to the body, the patient is treated with chemotherapy to prepare the bone marrow for the modified cells.

Infusion of the modified stem cells is meant to give patients the ability to produce enough hemoglobin to reduce or even eliminate the need for blood transfusions. Bluebird expects the effects of its one-time treatment will be lifelong.

In Phase 1/2 clinical trials, Bluebird reported that 11 of 14 patients treated were able to stop transfusion treatments, and maintained “transfusion independence” until the cutoff of the study, which was as long as 56 months. In a Phase 3 test that is still ongoing, Bluebird reported that four out of five patients achieved transfusion independence.

Non-serious side effects attributed to the gene therapy in clinical testing included hot flush, difficulty breathing, abdominal pain, pain in the extremities, and non-cardiac chest pain. One case of thrombocytopenia, a deficiency of platelets, was considered as being possibly related to treatment with Zynteglo.

Conditional approval in Europe is for one year, but Bluebird can renew it annually as long as the additional data submitted continue to show that the treatment’s benefits outweigh the risks. Once Bluebird has compiled enough data, it can seek to convert the conditional approval to standard marketing authorization.

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