After delays, bluebird's sickle cell gene therapy finally lands at the FDA's desk

After being hit with a partial clinical hold for its gene therapy back in 2021, bluebird bio has finally submitted its lovo-cel application to the FDA. 

The company has submitted its lovotibeglogene autotemcel (lovo-cel) biologics license application in sickle cell disease slightly behind its most recent first-quarter 2023 goal. The gene therapy specialist is seeking a priority review for its prospect, which would enable a six-month review at the FDA.

The application is backed by efficacy results from 36 patients with 32 months of follow-up data and two patients with 18 months follow-up, according to the drugmaker. The filing also includes safety data from 50 patients, including six patients with six or more years of follow-up.  Meanwhile, the company is conducting a long-term safety and efficiency study in patients who were enrolled in the studies.

The filing comes after a 2021 partial hold, when the FDA held testing on the medicine after one case of “persistent, nontransfusion-dependent anemia” in an adolescent patient following treatment with lovo-cel.

That came after the FDA in November 2020 requested “an analytical comparability strategy” from the company that would ensure its final product didn't differ from clinical supplies. The manufacturing-related request caused about a one-year delay.

“We are pleased to have satisfied the agency’s questions about comparability to enable our BLA submission,” bluebird’s CEO Andrew Obenshain said in a statement.

The timing of this submission puts bluebird's prospect essentially neck and neck with Vertex and CRISPR Therapeutics’ sickle cell therapy, which was submitted to the FDA just weeks ago. If it's approved, the therapy, known as exa-cel, would be the first gene editing therapy based on CRISPR technology. Already, regulators in Europe and the U.K. have validated exa-cel filings.

In a Monday note to clients, analysts with William Blair wrote that Vertex and CRISPR’s potential head start won’t be as long as originally expected because of the close timing of the filings. They added that the FDA could hold a joint advisory committee meeting on the two applications.

The analysts anticipate bluebird’s submission will be accepted by the agency in June, setting up a potential approval in the second half of 2023.  

For bluebird, lovo-cel would be the company's third approved gene therapy after last year's approvals for beta thalassemia therapy Zynteglo and cerebral adrenoleukodystrophy drug Skysona.