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 and CRISPR Therapeutics and the other by bluebird bio, 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.
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.
On a call for reporters, FDA officials said it wasn't clear whether the cancers observed in patients in the bluebird trial were because of the treatment or because of the chemotherapy regimen patients must undergo when receiving the treatment.
"We will continue to look at both of these," said Dr. Peter Marks, director of the Center for Biologics Evaluation and Research, on the call. "What we can only do at this point is put on the label what we've seen."
In a note out in the afternoon, RBC Capital Markets analyst Luca Issi said he sees an "uphill commercial battle" for bluebird, and that doctors will choose the Vertex and CRISPR treatment because it has no similar warning on its label.
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.
Vertex shares were down 0.7% on midday Friday, while CRISPR shares were down 8.7%.
The drugs could be transformative for patients able to access them. Existing sickle cell treatments are complex and challenging. Both Casgevy and Lyfgenia offer the possibility of a one-time cure, though the process of receiving the treatments is arduous.
Bluebird said it would price Lyfgenia at $3.1 million. Vertex, in a securities filing, said it would price Casgevy at $2.2 million. Gene therapies are often priced in the millions of dollars under the theory that treatment can obviate the need for multiple expensive treatments over the course of a lifetime. A bluebird gene therapy for beta thalassemia called Zynteglo had a list price of $2.8 million as of its launch. The company said last month that 16 patients had begun the process of receiving Zynteglo.
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.
The FDA said it had included a so-called black box warning in its label for Lyfgenia, noting that patients who received Lyfgenia had developed blood cancer and stating that patients who receive Lyfgenia should be monitored for blood cancers.