The US Food and Drug Administration on Friday approved the country’s first gene-editing therapy, Casgevy, for use in patients with sickle cell disease.
The approval it comes about a decade after the discovery of CRISPR technology for editing human DNA, which represents a major scientific advance. But reaching the tens of thousands of people who could benefit from the treatment could be difficult, given the potential hurdles — including the cost, at $2.2 million per patient — of administering the complex treatment.
Casgevy, developed jointly by Vertex Pharmaceuticals and CRISPR Therapeutics, uses Nobel Prize-winning CRISPR technology to edit a person’s genes to treat disease. The treatment was approved by UK regulators last month.
Vertex shares fell 1% on Friday, while CRISPR shares fell 8%.
Sickle cell, an inherited blood disorder, causes red blood cells to become misshapen crescents that stick inside blood vessels, restricting blood flow and causing what are known as pain attacks. About 100,000 Americans are estimated to have the disease.
This microscope photo provided on Oct. 25, 2023 by the Centers for Disease Control and Prevention shows crescent-shaped red blood cells from a patient with sickle cell disease in 1972. Britain’s drug regulator has approved the world’s first gene therapy treatment for sickle cell disease , in a move that could bring relief to thousands of people with the crippling disease in the UK
Dr. F. Gilbert/CDC via AP, File
Casgevy uses CRISPR to make an edit to a person’s DNA that activates fetal hemoglobin, a protein that normally turns off shortly after birth, to help red blood cells maintain their healthy crescent shape. In clinical trials, Casgevy eliminated pain attacks in most patients.
The FDA has approved the treatment for people 12 years of age and older.
“Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need, and we are excited to advance the field, especially for people whose lives have been severely disrupted by the disease,” said Dr. Nicole Verdun , director of the Office of Therapeutic Products within the FDA’s Center for Biologics Evaluation and Research, in a statement.
“Gene therapy holds the promise of providing more targeted and effective treatments, especially for people with rare diseases where current treatment options are limited,” added Verdun.
While the treatment itself is only administered once, the entire process takes months. Blood stem cells are extracted and isolated before being sent to Vertex’s laboratory, where they are genetically modified. Once ready, patients receive chemotherapy for a few days to clear out old cells and make room for new ones. After the new cells are injected, recipients spend weeks in the hospital recovering.
Vertex will take the lead in marketing the drug, and an estimated 16,000 people with severe cases of sickle cell disease will be eligible.
Even among people who could benefit most, analysts worry that few will clamor for a treatment that takes months to complete, carries the risk of infertility and can be prohibitive. Vertex said in a regulatory filing Friday that it will charge $2.2 million per patient for the treatment.
“We believe the price of the drug reflects the value it brings, and the value it brings is a one-time treatment for a potentially lifetime cure,” Vertex CEO Dr. Reshma Kewalramani in an interview with CNBC.
Vertex is seeing “unanimous enthusiasm” from payers, patients and doctors because people with sickle cell disease have been marginalized, Kewalramani said, and the field hasn’t seen much innovation.
Because the procedure is so complex, it will be limited to certain health facilities such as academic medical centers. Nine healthcare facilities are ready to begin administering Casgevy, Vertex said in a release, with more facilities to be added in the coming weeks.
The FDA also approved on Friday a separate gene therapy from Bluebird Bio, called Lyfgenia, works differently than Casgevy, but is administered similarly and is also intended to eliminate pain attacks. This treatment is also approved for the treatment of sickle cell disease in people 12 years of age and older.
Bluebird will charge $3.1 million per patient for Lyfgenia. Shares of that company, which has a market value of just about $300 million, fell 40% on Friday.
Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, estimated during a call with reporters Friday that the two treatments approved Friday will have nearly 20,000 patients eligible for treatment.
But the FDA included a black box warning — the strongest safety warning label — on Bluebird Bio’s Lyfgenia, noting that in rare cases the treatment can cause certain blood cancers.
The FDA added this warning after two patients received Lyfgenia a clinical trial died of a form of leukemia, Verden told reporters Friday.
The agency said it is not yet clear whether Lyfgenia itself or another part of the treatment process, such as chemotherapy, caused the cancer.
But Marks said the FDA wants patients to be aware of all the potential side effects of the entire treatment process: “It’s about the totality of the treatment that’s been given,” he told reporters.
Vertex didn’t see similar cases of blood cancers in its clinical trial, which is why it didn’t get a black box warning on its label, Verden noted.
Both Bluebird Bio and Vertex will follow patients receiving the treatments for 15 years as part of a post-approval study. The FDA has encouraged companies to specifically monitor for malignancy, or the presence of cancer cells that can spread to other parts of the body.