On Friday, the Food and Drug Administration approved the first gene editing therapy ever to be used in humans, for sickle cell disease, a debilitating blood disorder caused by a single mutated gene.
The agency also approved a second treatment using conventional gene therapy for sickle cell that does not use gene editing.
For the 100,000 Americans with the disease, most of them Black, the approvals offer hope for finally living without an affliction that causes excruciating pain, organ damage and strokes.
While patients, their families and their doctors welcome the F.D.A.’s approvals, getting either therapy will be difficult, and expensive.
“It is practically a miracle that this is even possible,” said Dr. Stephan Grupp, chief of the cellular therapy and transplant section at Children’s Hospital of Philadelphia. Dr. Grupp, who consults for Vertex, said his medical center was hoping to begin treating sickle cell patients next year.
But, he added, “I am very realistic about how hard this is.”
The obstacles to treatment are myriad: an extremely limited number of medical centers authorized to provide it; the requirement that each patient’s cells be edited or have a gene added individually; procedures that are so onerous that not everyone can tolerate them; and a multimillion-dollar price tag and potential insurance obstacles.
As a result, sickle cell experts said, only a small fraction of patients in the United States are expected to receive the new treatment (to say nothing of the millions of sickle cell patients overseas, particularly in Africa, for whom it may be completely out of reach for now).
The F.DA. estimates that about 20,000 patients — who are 12 and older and have had episodes of debilitating pain — will be eligible for the therapies.
The gene editing treatment, called Exa-cel and using the brand name Casgevy, was jointly developed by Vertex Pharmaceuticals of Boston and CRISPR Therapeutics of Switzerland. It uses CRISPR, the Nobel Prize-winning gene editing tool, to snip patients’ DNA. For a small number of subjects in clinical trials, it corrected the effects of the mutation, which results in red blood cells that are shaped like sickles or crescents that become caught in blood vessels, blocking them.
Casgevy is the first treatment to be approved that uses CRISPR. Patients will also need expensive, intensive medical care and a long hospitalization.
offers hope
