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Bluebird bio Can Restart Halted Clinical Trials

By Todd Campbell - Jun 7, 2021 at 5:25PM

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The FDA has lifted the hold on bluebird bio's gene-therapy studies in sickle cell disease and transfusion-dependent β-thalassemia.

The Food and Drug Administration (FDA) has told bluebird bio (BLUE 2.75%) it can resume trials of its experimental gene therapy, LentiGlobin, after it determined the therapy wasn't responsible for a rare case of cancer diagnosed in a trial participant earlier this year.

A woman scientist working in a research laboratory.


Using a lentiviral vector, LentiGlobin inserts a modified gene in patients that allows them to produce enough adult hemoglobin to potentially eliminate or significantly reduce the need for transfusions. 

In February, bluebird bio halted LentiGlobin's sickle cell disease (SCD) and transfusion-dependent beta-thalassemia (β-thalassemia) trials after one patient was diagnosed with acute myeloid leukemia (AML). At the time, the news was particularly concerning given expectations for an FDA filing for approval in SCD as soon as 2022.

In March, management's internal investigation suggested it's unlikely the patient developed AML because of LentiGlobin because the gene therapy's integration site, VAMP4, doesn't have a known association with AML, and there's an absence of "significant gene misregulation attributable to the insertion event."

Apparently, the FDA agrees with those findings. Now that it has the regulatory green light, bluebird bio plans to resume its SCD and β-thalassemia trials as soon as possible. The company didn't specify if the delay will interfere with plans to apply for FDA approval of the therapy in SCD next year, but it did say it's on track to complete its rolling biologics license application with the FDA in transfusion-dependent β-thalassemia by mid-year.

The news may also help the company accelerate commercialization efforts in Europe where LentiGlobin secured a conditional marketing authorization in β-thalassemia in 2020.


Todd Campbell owns shares of bluebird bio. His clients may or may not have a position. The Motley Fool recommends bluebird bio. The Motley Fool has a disclosure policy.

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