(Reuters) – Bluebird’s blood disorder treatment demonstrates “clinically significant” benefit in patients. Staff reviewers from the U.S. Food and Drug Administration stated in briefing papers published Tuesday.

This company applied to approve beti-cel, a gene therapy that is used for treatment of Beta-thalassemia patients who are dependent on blood transfusions.

The FDA staff stated that the FDA has confirmed the efficacy of beticel in treating these patients using data provided by the applicant.

Additionally, the authors published documentation for bluebird’s alternative gene therapy, called elicel. This is for patients under 18 years old to treat a rare neurologic disorder, cerebral adrenoleukodystrophy.

According to agency reviewers, it is not clear if eli-cel’s effectiveness is comparable to stem cell transplants. These are the current only treatments available for patients with CALD.

An FDA panel will be discussing approvals of eli/cel and of beti-cel this week.

It is the first meeting since 2017 of the Cellular, Tissue and Gene Therapies Advisory Committee. This event marks a significant moment in the field. After recommending approval of Spark Therapeutics Luxturna’s gene therapy, which was the first to be approved in America, the panel then recommended that Luxturna be approved.