A Game-Changing Era in Sickle-Cell Disease
Last week, I was amazed to realize that Sickle-cell disease (SCD) is mostly a sub-Saharan African problem. This week, I was delighted to see some cheering news about the disease.
But first, some background: A normal red blood cell in the body has a round shape. However, in sickle cell disease, the cells become like crescent moons. That’s where the ‘sickle’ comes from. Round red blood cells can move easily through the blood vessels, but sickle-shaped cells interconnect and can result in blood clots.
Because they are sickled, they get stuck inside blood vessels, restricting blood flow and causing what are known as pain crises. These blood clots can cause extreme pain in the back, chest, hands, and feet. The disrupted blood flow can also cause damage to bones, muscles, and organs. People with sickle cell disease often feel weak, tired, and look pale. The whites of the eyes and skin often have a yellowish tint.
In medical parlance, SCD is an autosomal recessive genetic disorder of red blood cells, meaning among other things that it is transferable from parent carriers (AS father and AS mother) to their offspring.
It is often the case that environmental factors play a role in these painful attacks. Common triggers include cold temperatures, dehydration, excessive amounts of exercise, and tobacco smoke. Some refuse to get on airplanes because high altitudes trigger attacks for them. The majority of children with the most severe form of the disease die before the age of 5, usually from an infection or severe blood loss.
Seeing that every year, about 300,000 newly diagnosed SCD children are born worldwide, the World Health Organization and the United Nations have designated SCD as a global public health problem.
Sub-Saharan Africa (SSA) unfortunately contributes about 75% of the number. Even in the United States, the ~100,000 Americans affected are mostly of African descent. In countries such as Cameroon, the Republic of Congo, Gabon, Ghana, and Nigeria, the prevalence of the sickle cell trait is between 20% to 30%, while in some parts of Uganda, it is as high as 45%. Because Nigeria is my constituency, I was sad to find out that we account for 100,000–150,000 newborns living with SCD annually.
But some cheering news came on Friday when it was announced that approval was given to a particularly intriguing treatment for the disease. Using the novel CRISPR gene-editing system, cells were harvested from a patient’s bone marrow, edited in a lab using CRISPR, and then the modified cells were inserted back into the patient’s body.
This new one-time therapy is called Casgevy. The treatment is also aimed at extending the lifespan of sickle-cell patients, who have an average life expectancy 20+ years shorter than the general public.
For now, Casgevy is outside the price range of most people who need it, as it costs a whopping $2.2 million per patient. But then, drugs are usually expensive when they first come out. For instance, in 2000, the cost for first-line treatment was over $10,000 per patient per year, and nearly two decades later in 2018, the cost has decreased to as low as $75 per patient per year. The trajectory for almost all drugs you can afford now, including Paracetamol, is the same.
Someone in the comments raised the point that my analogy, which draws a comparison between drugs for long-term effects and addressing pricing challenges, may not be entirely fitting for this situation. His argument is that the solution in this case lies in technology rather than a drug. To that, I say that if the past 30 years has taught us anything, it is that technology tends to become more affordable at a quicker rate than drugs. For instance, in 2001, you needed $95 million to sequence your DNA. Today, it costs only $450.
However, more importantly for me is that the CRISPR gene-editing system makes one pay attention. Because it uses the patient’s cells, CRISPR has the potential to treat or cure a wide range of genetic diseases — especially those where the patient would otherwise need a specific donor.
It’s also the technology behind the recent pig-to-human heart transplants and the first-ever genetically modified human babies.
Outside of medicine, other real-world applications of CRISPR include creating drought-resistant crops and high-energy biofuel that’s 100% renewable, as well as eliminating disease-carrying mosquitoes.
Science just continues to blow the mind.
