Sickle cell anemia doc. of America for FDA approval of gene therapies

On December 8, 2023, the Food and Drug Administration (FDA) approved two cell-based gene therapies for sickle cell disease (SCD), Casgevy by CRISPR/Vertex and Lyfgenia by Bluebird bio.

This is the first treatment of its kind available to individuals with SCD in the United States. The SCDAA welcomes the approval of these potentially curative therapies, which represent a significant advance in the treatment of sickle cell disease; however, there are legitimate concerns about availability and potential adverse effects.

Dr. Lewis Hsu, chief medical officer of the Sickle Cell Association of America Inc. said: We at the Sickle Cell Association of America Inc. we celebrate that today, December 8th, the FDA approved two gene therapies for sickle cell disease. This double milestone has been a long time coming, and sickle cell disease now joins other genetic diseases with gene therapy treatments. Sickle cell disease was called “the first molecular disease” about 70 years ago, and a gene therapy treatment was predicted for sickle cell disease in the 1950s, when DNA was first described.

These two gene therapies represent a major step forward for research and treatment of sickle cell disease. The results of clinical trials are very impressive. Selected patients had major pain (two or more hospitalizations for vaso-occlusive crisis pain per year for two years). The data show that almost all patients were free of hospitalizations for vaso-occlusive crises for at least nine consecutive months after gene therapy. The patients’ quality of life also improved in every way: physically, emotionally, socially and functionally with both gene therapies.

Regina Hartfield, president and CEO of the Sickle Cell Association of America Inc. she said gene therapy is an exciting and potentially curative addition to the treatments available for sickle cell disease fighters. This is a historic milestone, but not everyone may be eligible for gene therapy. We must continue to research to ensure that there is a solution for every member of our community.

Is gene therapy a cure for sickle cell disease?

Sickle Cell Association of America Inc. recognizes gene therapy as a “potentially curative” therapy. The treatment is so new that more data are needed to understand its impact and patient prognosis. Moreover, the word “treat” suggests a simple solution that does not reflect the reality of these therapies. Even after treatment is completed, the FDA recommends 15 years of monitoring patients for health problems.

What is the treatment?

The patient journey will be similar for both Casgevy and Lyfgenia. Gene therapy is given during a single infusion; however, there are steps patients must take to prepare for treatment. First, the patient’s care team collects stem cells, which are progenitors of red blood cells, from their body. Then these cells will be treated in the laboratory. The patient will undergo chemotherapy to remove the original abnormal stem cells from the bone marrow. After this process is complete, the treated stem cells are injected back into the patient through an intravenous process such as a transfusion (not surgery). The whole procedure takes about a year. It is similar to an autologous bone marrow transplant because there is no need to find a stem cell donor.

What is the difference between these two therapies?

These two gene therapy strategies are scientifically different. Casgevy is gene editing, the first of its kind, and Lyfgenia uses gene addition. Both gene therapy strategies have roughly the same patient journey and potential challenges: access, cost, infertility, unknown potential for organ damage, and unknown long-term effects.

How effective is it?

Gene therapy provides a significant reduction in acute episodes of sickle cell pain within several years of administration. More years of follow-up will be needed to see if it also reduces organ damage from sickle cell disease, and if the stem cells they were treated with continue to produce non-sickle red blood cells for the rest of a person’s life, or if the stem cells die within a certain number of years. Currently, treatment requires chemotherapy, which means there are also concerns about complications associated with chemotherapy, such as infertility or secondary cancer.

When will it be possible to use gene therapy?

Gene therapy is likely to be available in early 2024.

Who is eligible?

We are awaiting details, but probably for use by individuals aged 12 and over.

Where is gene therapy administered?

Individuals with SCD can receive gene therapy in existing sickle cell bone marrow facilities, which can present accessibility issues for patients. SCDAA encourages gene therapy centers to partner with sickle cell centers, such as the National Alliance of Sickle Cell Centers, so that there is expertise in monitoring sickle cell organ damage.

How much will it cost? Will insurance cover gene therapy?

Gene therapy treatments are produced using expensive, highly technical processes. The estimated cost of treatment is $2 million and more. However, the high price should be worth it, as the savings over a lifetime of care can outweigh the one-time cost of gene therapy. High-cost FDA-approved drugs come with insurance barriers and rules that are not evidence-based.

What do these approvals mean for people living with sickle cell disease?

These approvals are expected to be life-changing for many and usher in a new age of sickle cell disease treatment. Until now, the only way to cure sickle cell disease has been a bone marrow transplant, which is not a widely available option because it requires a suitable bone marrow donor. Gene therapy does not require a donor; thus, it has the potential to become a more widely available treatment.

What does this mean for the treatment of sickle cell disease in the future?

Casgevy and Lyfgenia are the first gene therapies approved by the FDA for sickle cell disease. They open the door for other gene therapies to gain approval and help advance research into other potentially curative treatments. At the same time, there are concerns that these approvals will create increased competition for health care resources, which could make access to other forms of treatment beyond gene therapy more difficult. Many people will not be eligible for gene therapy. In order to provide the highest quality of care to these individuals, we must continue to research different treatment options beyond gene therapy.

What are the implications for the medical community as a whole?

More broadly, Casgevy is the first FDA-approved CRISPR gene-editing therapy for a genetic disease. This could have far-reaching implications for individuals with other conditions such as cystic fibrosis, Tay-Sachs disease, and others.

Where can I find more information?

Research specifically on Casgeva and Lyfgenia continues; however, there is a wide range of information on gene therapy for sickle cell disease that relates to clinical trials.

Sickle Cell Association, Inc. advocates for people affected by sickle cell disease and empowers community organizations to maximize quality of life and raise public awareness while advancing the search for a universal cure.

The association and more than 50 member organizations support sickle cell research, public and professional health education, and patient and community services. (

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