An estimated 100,000 people in the United States suffer from sickle cell anemia, most of whom are of African descent. Sickle cell anemia shortens life, damages organs and bones, and causes episodes of stabbing pain that can send patients to the emergency room repeatedly or lead to long hospital stays.

A report from the Institute for Clinical and Economic Review said that for people who do not have sickle cell anemia, “it is difficult to understand the physical, emotional and mental harm it causes them.” People with the disease, that is The report continued, “not only described severe fatigue, anxiety and depression, but sometimes extreme hopelessness.”

One patient, Mariah Jacqueline Scott, 32, who lives in Highland Park, New Jersey, has had two hip and shoulder replacements, a splenectomy, a gallbladder removal and a tonsillectomy due to the disease. She spent the year after her daughter’s birth in hospital, where she was treated for extreme pain caused by blocked blood vessels. She had her second shoulder replacement after her shoulder collapsed while holding her baby.

The only cure so far has been a bone marrow transplant, which requires finding a donor, intensive chemotherapy and taking immunosuppressants. But gene editing offers an alternative. Vertex and CRISPR Therapeutics, the makers of the treatment considered by the FDA committee on Tuesday, said that in clinical trials, symptoms of the disease disappeared after patients received the treatment. So far the patients appear to be cured. The technique activates a gene that can produce normally functioning blood cells.

Ms Scott said she knew gene editing was arduous but she seriously considered undergoing the treatment when it became available.

Vertex’s therapy begins with doctors taking stem cells from the blood and sending them for treatment. Next comes intensive chemotherapy to completely cleanse the bone marrow before the treated cells are injected. Patients then have to spend at least a month in the hospital while the treated cells repopulate the bone marrow.

Since each patient’s cells must be treated individually, the question arises as to how quickly companies can ramp up production.

“The production is very complicated,” said Dr. Stephan Grupp, head of cell therapy and transplantation at Children’s Hospital of Philadelphia, who consults for Vertex.

The treatment will be extremely expensive, potentially in the millions of dollars per patient, and the companies won’t initially say how many patients they expect to be able to treat.

Gene editing can also cause personal distress for patients and their families. A hospital with the expertise to treat and care for patients may be far from home. And patients have to stay there for a long period of time.

If the advisory committee recommends the Vertex treatment, the FDA will decide on approval on December 8.

On December 20, the FDA will decide on another application from 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 therapies.

While these therapies could ease the suffering of sickle cell patients in the United States and other wealthy countries, there is an even greater need for them in some developing countries, such as Nigeria. However, it will be difficult to export them to developing countries because the treatments are extremely expensive and can only be carried out in hospitals where doctors have expertise in a range of advanced techniques.

One company, Beam, is testing a way to edit genes that requires just a single infusion in a doctor’s office. Vertex has what it calls an “ambitious” method that would enable gene editing in a pill.

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