Did you know there are over 20 million sickle cell anemia patients worldwide?
The journey to combat this disease started in 1910. Dr. James B. Herrick, a physician in Chicago, noticed something unusual in a patient with chronic anemia. The red blood cells were shaped like sickles. That's how sickle cell anemia got its name.
According to the Centers for Disease Control and Prevention, around 100,000 Americans are living with sickle cell disease. The disease has sub-Saharan Africa as its epicenter. It also affects areas like the Middle East, India, and Mediterranean countries.
What is Sickle cell anemia?
Sickle cell anemia is a genetic disorder. It stems from a gene mutation that alters the structure of adult hemoglobin.
The result? Red blood cells can't carry oxygen properly, leading to a cascade of problems.
These misshapen cells tend to clog up blood vessels. This causes intense pain and organ damage. The reoccurrence of these events is life-threatening.
Historical Hurdles:
Although one of the oldest genetic disorders, there exists only limited treatment options. They include managing pain and taking hydroxyurea.
The only possible curative treatment includes a stem cell transplant.
Stem cell transplant requires myeloablative chemotherapy to remove the patient's blood cells. Then, the patients receive an infusion of a healthy donors' stem cells.
It seemed like a breakthrough cure was out of reach.
Turning the Tide: approval of Revolutionary Gene-editing therapies
On December 8, 2023, the U.S. Food and Drug Administration approved two new treatments:
Casgevy (by Vertex Pharmaceuticals Inc.)
Lyfgenia (by Bluebird Bio Inc.)
These are the world's first cell-based gene therapies for sickle cell disease. Both treatments are approved for patients 12 years and older.
The Science Behind the Marvel:
Casgevy uses CRISPR/Cas9 technology, gene-editing marvel. They use it to alter patients' blood stem cells. These cells are modified to produce fetal hemoglobin.
Lyfgenia uses a lentiviral vector, a gene delivery vehicle, that modifies patients' stem cells, allowing them to produce normal adult hemoglobin.
What's groundbreaking is that both therapies use the patient's own blood stem cells. This eliminates the chance of rejection. Before treatment, the medical team collects and modifies the patient's stem cells. The patients undergo myeloablative chemotherapy to remove the existing faulty cells. The modified stem cells are then delivered in a one-time single-dose infusion.
The Human Side of the Story:
These treatments, while promising, come with their share of side effects. Some common side effects include mouth sores, febrile neutropenia, low platelets, and low white blood cell counts. Some patients treated with Lyfgenia developed blood cancer. The Lyfgenia treatment comes with a black box warning informing about this risk. Lifelong monitoring is essential to ensure safety. Even so, approval of Casgevy and Lyfgenia is a beacon of hope for those affected by sickle cell anemia.
The Road Ahead
As we celebrate this milestone, we can't ignore the big question. How do we make these treatments accessible and affordable for everyone? Policymakers now must strike a balance between innovation, cost, and public health.
The approval of Casgevy and Lyfgenia is more than just a scientific feat. It's a call to action for a more inclusive and healthier future.
Sources
Assessed and Endorsed by the MedReport Medical Review Board