Bluebird's gene therapy eliminates blood transfusions for some beta-thalassemia patients

Blood transfusions are a life-saving treatment for patients transfusion-dependent beta-thalassemia but they eventually lead to iron overload that can cause multiorgan failure and shorten a patient's life span. (Arek Socha)

Bluebird Bio published interim data from a pair of two-year studies showing that its lentiviral-based gene therapy eliminated or reduced the need for blood transfusions in patients with transfusion-dependent beta-thalassemia. 

The genetic blood disorder is characterized by greatly reduced production, or no production at all, of red blood cells and can lead to severe anemia. Blood transfusions are a life-saving treatment for those with the transfusion-dependent form of beta-thalassemia but they eventually lead to iron overload that can cause multiorgan failure and shorten a patient's life span. 

The trial involved 22 patients who received a one-time treatment of Bluebird's LentiGlobin therapy, which involves LentiGlobinblood stem cells from a patient, inserting a functional human beta-globin gene into them and transplanting them back into the patient's bone marrow. 

The investigators followed patients for at least two years, finding that 15 of the 22 no longer needed transfusions. Most of the remaining seven patients had a more severe form of the disease. They still needed transfusions, but fewer of them, posting a median decrease in transfusion volume of 73%. The findings appeared in the New England Journal of Medicine. 

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“These interim data demonstrate the potential of LentiGlobin gene therapy to address the underlying genetic cause of TDT and increase production of functional red blood cells,” said Dave Davidson, M.D., Bluebird's chief medical officer. 

“Nearly all patients in the two studies with a non-β0/β0genotype achieved freedom from chronic blood transfusions and, importantly, several of these patients reached normal or near-normal total hemoglobin levels and sustained those levels throughout the interim study period. We hope the refined manufacturing process implemented in our ongoing pivotal trials of LentiGlobin will translate into further normalization of total hemoglobin levels across genotypes.” 

Bluebird hit a roadblock in 2015, when it found that the first incarnation of the treatment did not work the same way in all patients. This led it to change the manufacturing process for the therapy—it aimed to increase the number of vector copy numbers (VCN) produced and increase the number of lentiviral vector positive (LVV+) cells in the hope of making responses more consistent. 

“We look forward to our first filing in the European Union (EU) this year and continue to work closely with investigators and regulatory authorities to complete our trials and bring this important treatment option to patients as soon as possible,” Davidson said. 

Bluebird isn't the only biotech taking aim at blood disorders with gene therapy. Vertex Pharmaceuticals inked a $105 million research partnership with CRISPR Therapeutics in 2015 and recently licensed a treatment for beta-thalassemia and sickle cell disease. It is the first CRISPR-based therapy to come out of the deal.