What happened

Shares of bluebird bio (BLUE -3.30%) were flying 8.2% higher as of 10:49 a.m. on Wednesday. The gain came after the biotech announced its analyses have determined it's "very unlikely" that a serious adverse reaction observed with its phase 1/2 study of LentiGlobin in treating sickle cell disease was related to the BB305 lentiviral vector (LVV) used to deliver the gene therapy.

So what

Bluebird's findings could be critical in getting its LentiGlobin program back on track. In February, the company temporarily suspended its phase 1/2 and phase 3 studies of the gene therapy in treating sickle cell disease after a patient was diagnosed with acute myeloid leukemia (AML). 

Scientist looking through a microscope

Image source: Getty Images.

The U.S. Food and Drug Administration (FDA) followed up by placing both of those studies on clinical hold. In addition, the agency placed two clinical studies of betibeglogene autotemcel in treating beta-thalassemia on clinical hold because it uses the same lentiviral vector as LentiGlobin. Bluebird temporarily suspended marketing of the gene therapy in Europe, where it's sold under the brand name Zynteglo.

Now what

Bluebird chief scientific officer Philip Gregory said the company has shared its analyses with the FDA. The company thinks the data are compelling enough to support the lifting of the FDA's clinical holds on its studies of LentiGlobin and betibeglogene autotemcel. This could be the best news for the biotech stock in a long time: Bluebird's shares have plunged nearly 50% over the last 12 months.