Bluebird’s gene therapy promises thalassaemia cure

Patients with the rare genetic blood disorder beta thalassaemia have been spared the need for routine blood transfusions after receiving a new gene therapy.

So far, four patients in the phase I/II study – developed by US biotech Bluebird Bio – have responded to the treatment, which aims to correct the main genetic defect in beta thalassaemia.

Beta thalassaemia is caused by a single gene defect that impairs the ability of red blood cells to product haemoglobin, the body’s oxygen-carrying molecule, and is found in around 40,000 new births every year.

Patients with the most severe form of inherited disorder, beta thalassaemia major, develop life-threatening anaemia from the age of around four to six months and have to undergo monthly blood transfusions as well as additional treatment to prevent complications, such as chelation drugs to remove excess iron from the body.

In some cases a stem cell transplant can cure the disease, although this procedure is not suitable for every patient and carries significant risks of its own, so is generally only offered to children with matched sibling donors, who account for around a quarter of all beta thalassaemia cases.

In the gene therapy study, patients had haematopoietic stem cells collected from their bone marrow, which were then transfected with an engineered lentivirus carrying a functional copy of the gene coding for beta-globin, which is defective in thalassaemia. The cells were then infused back into the patient in the hope they would ‘seed’ the bone marrow and produce functional red blood cells.

According to results of the Northstar study presented at the American Society of Haematology (ASH) meeting this week, the four patients treated with the therapy – called LentiGlobin BB305 – have not needed any blood transfusions for up to 12 months.

The results “demonstrate the potential for a one-time gene therapy treatment to transform the lives of patients with beta-thalassemia major,” said lead investigator Alexis Thompson of Northwestern University Feinberg School of Medicine in the US.

Bluebird expects to complete enrolment in Northstar and a second trial called HGB-205 – which also includes a patient with sickle cell disease – during the course of 2015. The company said it is now preparing to work out a possible route to approval of LentiGlobin BB305 with “medical experts, patient communities and regulatory authorities.”

Shares in the company rocketed to around $85 from around $50 on the news of the study, and also helped drag up other gene therapy players, including Sangamo which is developing a gene therapy for thalassaemia and sickle cell disease in collaboration with Biogen Idec.

The positive data adds to the sense that momentum is starting to build in the gene therapy field after decades of research and disappointment.

The first gene therapy approved in Europe – UniQure’s Glybera (alipogene tiparvovec) for lipoprotein lipase deficiency – is now nearing launch, although it is not due to reach the US market until 2018.

Meanwhile, in the US, Spark Therapeutics recently became the first company to get breakthrough status from the US Food and Drug Administration for a gene therapy. Looking outside Western markets, a gene therapy for head and neck cancer – Shenzhen SiBiono Gene Technologies’ Gendicine – has been on the market since 2004.

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