On the 9th of December, 2023, there was a major breakthrough in global health as the Food and Drug Administration (FDA) approved a powerful therapy for sickle cell disease, an inherited disease of the blood known to affect over 20 million people globally. This novel treatment is called Casgevy, developed by Vertex Pharmaceuticals and CRISPR Therapeutics.
What do we know about sickle cell disease?
Sickle cell disease is a group of inherited blood disorders in which the body produces abnormally-shaped red blood cells that look like crescent moons or sickles. Sickle cells have a shorter-than-normal life span and their premature destruction leads to shortage of red blood cells, a condition known as anaemia.
Unlike normal red cells which are pliant, sickle cells are rigid and sticky. They may clump together and stick to the walls of blood vessels, causing obstruction in small vessels and subsequent reduced oxygen supply to various organs. This happens repeatedly and manifests as periodic episodes of pain, called crisis. Crises can last hours to days, and may result in damage to organs like the eyes, kidneys, lungs, bones, and brain.
Sickle cell disease is a lifelong illness and until yesterday, its only cure was bone marrow transplantation. It involves replacing diseased stem cells in the bone marrow with healthy cells from an eligible donor, usually a relative. This procedure is complex and finding a suitable donor can be difficult.
The New Cure: What it entails
Casgevy works by making changes to one’s genetic makeup so that their stem cells will no longer produce sickled cells. Although, it is meant to be a one-time treatment, there are a number of steps that are that are involved. These steps are carried out over some months before the patient gets the modified stem cells. It begins with a series of blood transfusion and then extraction of the patient’s bone marrow, after which they are edited in the laboratory.
The “bad” stem cells that remain in the patient are cleared by chemotherapy. Then, the modified stem cells are infused into the patient. The cells are allowed to grow and the patient recovers over a few months.
Although Casgevy has been shown to be effective, its potential long term effects and complications are still unknown. This is largely because it is still new. It is also very expensive costing about $2.2 million and only available in the United States at the moment.
A word from HealthFacts to you
The advent of genetic engineering technology promises a bright future for clinical medicine. However, a lot of these technologies are expensive and mostly limited to high income countries. Hence, efforts in low-and-middle income countries such as Nigeria must be towards disease prevention and control.
Suggested Reading: See the “Do nots” in sickle cell disease!