Why it matters: A disease whose toll is hard to imagine.
An estimated 100,000 people in the United States have sickle cell disease, the majority of whom are of African descent. Sickle cell shortens life, injures organs and bones, and causes severe pain that can send patients to the emergency room frequently, or lead to long hospital stays.
A report by the Institute for Clinical and Economic Review Said For people who do not have sickle cell disease, “it is difficult to understand the physical, emotional and mental effects.” People suffering from the disease describe not only intense fatigue, anxiety and depression, but sometimes extreme hopelessness, the report said.
One patient, Maria Jacqueline Scott, 32, who lives in Highland Park, NJ, has had two hip replacements, two shoulder replacements, a splenectomy, a gall bladder removal and a tonsillectomy because of the disease. She spent a year in and out of hospital for treatment of extreme pain caused by blocked blood vessels after the birth of her daughter. Her other shoulder was replaced after her shoulder collapsed while holding her child.
The only treatment is a bone marrow transplant, which requires finding a donor, undergoing intensive chemotherapy, and taking immunosuppressive drugs. But gene editing offers an alternative. Vertex and CRISPR Therapeutics, makers of the treatment being taken up by an FDA committee on Tuesday, said that in clinical trials, patients’ disease symptoms went away after treatment. So far the patients seem to be recovering. This technique activates a gene that can create normally functioning blood cells.
Ms Scott said she knew gene editing was difficult, but she was seriously considering undergoing the treatment when it became available.
Facts to Keep in Mind: Gene therapy comes with its own challenges.
Vertex’s therapy begins when doctors extract stem cells from the blood and send them for treatment. This is followed by intensive chemotherapy to completely clear the bone marrow before the treated cells are injected. After that, patients must spend at least a month in the hospital while the treated cells reactivate the bone marrow.
Since each patient’s cells must be treated individually, there are questions about how fast companies can scale up production.
“Manufacturing is very complex,” said Dr. Stephen Grupp, chief of the cellular therapy and transplant section at the Children’s Hospital of Philadelphia, who consults for Vertex.
The treatment would be extremely expensive, potentially millions of dollars per patient, and the companies would not say how many patients they expect to be able to treat at first.
Gene editing may also impose personal hardship on patients and their families. A hospital with expertise in treating and caring for patients may be far from home. And patients will have to stay there for a long time.
What’s next: More FDA decisions and more drugs.
If the advisory committee recommends the Vertex treatment, the FDA will decide on December 8 whether to approve it.
On December 20, the FDA will decide on another application made by Bluebird Bio for sickle cell gene therapy. Two other companies and an academic center, Boston Children’s Hospital, are testing their own sickle cell gene therapy.
Although these treatments can ease the suffering of sickle cell patients in the United States and other wealthy countries, they are needed even more in some developing countries such as Nigeria. However, it would be difficult to export them to developing countries because the treatments are extremely expensive and can only be administered in hospitals where doctors have expertise in many advanced technologies.
One company, Beam, is testing a way to deliver gene editing that requires nothing more than a single infusion in a doctor’s office. Vertex has an “aspirational” method that would deliver gene editing in a pill.