Shares of Bluebird Bio (BLUE 1.27%) were plunging 22.3% as of 10:41 a.m. ET on Monday. The big drop came after the company announced that the Food and Drug Administration (FDA) placed its clinical testing of lovo-cel in treating sickle cell disease on partial clinical hold. This partial clinical hold applies only to patients under age 18.
The FDA's decision is connected with Bluebird's ongoing investigation related to one adolescent patient who experienced persistent non-transfusion-dependent anemia after being treated with lovo-cel. Bluebird said that the patient is "clinically well" and added that there has been "no evidence of malignancy or clonal predominance."
It's not surprising for a biotech stock to sink on news of an FDA clinical hold. In this case, though, Bluebird seems to expect that the partial clinical hold will only be temporary. Bluebird's chief medical officer, Richard Colvin, said that the company is working with the FDA to "understand and address their concerns."
Bluebird isn't sure at this point how this partial clinical hold might impact its timing for the filing for FDA approval of lovo-cel. The company has previously stated that it hoped to file a Biologics License Application for the gene therapy in the first quarter of 2023.
Bluebird expects to receive written questions from the FDA early next year about the partial clinical hold for lovo-cel. The company plans to respond to those questions as quickly as possible in hopes of having the partial hold lifted. In the meantime, Bluebird continues to enroll and dose patients ages 18 and older in its clinical studies evaluating lovo-cel.