FDA Approves First Two Sickle Cell Gene Therapies

The Food and Drug Administration on Friday approved two gene therapies to treat patients with sickle cell disease, a serious genetic blood disorder most common in African-American people in the U.S.

• The new treatments, one developed by Vertex Pharmaceuticals (VRTX) and Crispr Therapeutics (CRSP)  and the other by bluebird bio (BLUE)  are the first two gene therapies available in the U.S. for sickle cell, which the FDA says affects 100,000 people in the U.S.
• Bluebird said it would price Lyfgenia at $3.1 million. Vertex, in a securities filing, said it would price Casgevy at $2.2 million.

Both Casgevy and Lyfgenia are made with a patient’s own blood stem cells, which must be removed and then modified. Casgevy edits the DNA of the patient’s stem cells, which are then returned to the patient, where they improve the body’s production of a particular form of hemoglobin. Lyfgenia modifies the stem cells using a viral vector approach. For both treatments, the process for patients is intensive and requires lengthy hospital stays and chemotherapy.

By midafternoon, shares of bluebird had dropped 33.9%. Nasdaq halted trading because of volatility four times between 1:30 p.m. and 1:55 p.m.

The FDA’s label for bluebird’s drug included a warning that some patients who received the treatment had developed blood cancer. The label for the Vertex and Crispr drug included no such warning.

In a related financial setback, bluebird said Friday that the FDA hadn’t awarded the company a priority review voucher along with the approval of its gene therapy. Those vouchers entitle a company to speedier regulatory review of a drug, and are awarded by the agency along with certain approvals. Bluebird had already agreed to sell any priority review voucher it received along with the gene therapy approval to Novartis for $103 million; that sale won’t happen now.

The Vertex and Crispr gene therapy, which will be marketed under the name Casgevy, is also the first FDA-approved drug that uses a cutting-edge genome editing technology called Crispr/Cas9. That technology, described as “genetic scissors,” won a Nobel Prize in Chemistry in 2020 but had been out of reach for the patients it could benefit.

U.K. regulators approved Casgevy in mid-November. The approval of the bluebird bio gene therapy, Lyfgenia, came as a surprise; an FDA decision on the treatment wasn’t expected until Dec. 20.