Bluebird bio's blood disorder therapy effective - FDA staff

Signage is seen outside of the Food and Drug Administration (FDA) headquarters in White Oak, Maryland, U.S., August 29, 2020. REUTERS/Andrew Kelly

June 7 (Reuters) - Bluebird bio's (BLUE.O) blood disorder treatment demonstrates "clinically meaningful" benefit in patients, staff reviewers at the U.S. Food and Drug Administration said in briefing documents published on Tuesday.

The company has applied for approval of beti-cel as a one-time gene therapy for the treatment of Beta-thalassemia patients dependent on blood transfusions.

Data provided supports the effectiveness of beti-cel in these patients, the staff said, sending the company's shares up 12% to $3.34. Through Monday's close, the stock has slumped about 70% this year following regulatory setbacks.

The reviewers also published documents for bluebird's other gene therapy, eli-cel, for treating a rare neurological disease called cerebral adrenoleukodystrophy in patients below 18 years, raising safety concerns.

It is unclear whether the treatment's benefit outweighs the significant and unknown long-term risk of myelodysplastic syndrome (MDS), the reviewers wrote. The agency put the program on clinical hold last year after three trial patients developed MDS, a type of cancer.

There was a causal relationship between the treatment and two of the cases, the reviewers said on Tuesday, adding longer follow-up will uncover additional cases.

In response, bluebird said totality of the data made a clear case for eli-cel's efficacy.

A panel of FDA's outside experts is scheduled to discuss approval of the treatments later this week.

It will mark a defining moment for gene therapy for it would be the first time the Cellular, Tissue, and Gene Therapies Advisory Committee has met since 2017. The panel had then recommended approval of the first U.S. gene therapy - Spark Therapeutics' Luxturna.

The meeting's outcome is also seen as critical for bluebird after the company in March flagged "going concern" doubts.

"The company is in a very precarious financial position now, given cash runway...(the decision) is not only big for the gene therapy space, but pivotal for the company as well," William Blair analyst Raju Prasad told Reuters.

Reporting by Mrinalika Roy in Bengaluru; Editing by Sriraj Kalluvila

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