Bluebird Bio Says Lentiviral Vector Not the Cause Of Blood Cancer Reported In Sickle Cell Study

Based on multiple independent analyses, Bluebird bio Inc (NASDAQ: BLUE) has announced that it is very unlikely that Suspected Unexpected Serious Adverse Reaction of acute myeloid leukemia was related to the BB305 lentiviral vector of LentiGlobin gene therapy.

• LentiGlobin is in Phase 1/2 (HGB-206) study for sickle cell disease. The trial was put on clinical hold following reports that two participants in the study developed blood cancers.
• As reported in February, laboratory analyses showed that this patient had significant chromosomal abnormalities and mutations in genes typically associated with the development of AML.
• Preliminary findings suggested that the BB305 LVV vector was present in the AML blast cells, but sufficient information was not there.
• Analyses have confirmed that vector insertion in the AML cells from this patient took place in the VAMP4 gene, which has no known role in the development of AML or any cellular process related to cancer.
• Additional analysis showed no disruption to normal VAMP4 gene regulation or gene expression in and around the site of vector insertion.
• Given this, the company has initiated engagement with regulators to begin the process of resuming clinical studies for sickle cell disease and β-thalassemia.
• The company will hold a conference call to discuss this update today at 8:00 a.m. ET. 
• Price Action: BLUE shares increased 11.4% at $33.47 in premarket trading on the last check Wednesday.