After successful experimental procedures utilizing gene editing technology, the cure for sickle cell is currently advancing through the FDA’s approval process.
The development offers greater medical security to Black Americans, as sickle cell is mostly prevalent in the demographic by an extremely wide margin. Both sickle cell trait (SCT) and sickle cell disease (SCD) are disproportionately present in Black people.
The treatment, called exa-cell and jointly developed by Boston-based Vertex Pharmaceuticals and CRISPR Therapeutics of Switzerland, is performed by editing genes in bone marrow stem cells. This is a markedly less intensive and less expensive approach to curing the condition, as previously the only known potential cure was a bone marrow transplant (BMT). Gene therapy, however, is currently incredibly expensive, with patients receiving the treatment paying as high as $3.5 million for treatment.
Most common in those with ancestors from sub-Saharan Africa, Spanish-colonized lands in the Western Hemisphere, Saudi Arabia, and Mediterranean countries, the exact number of Americans living with sickle cell is unknown. However, some sources estimate around 100,000 people are living with SCD in the United States, occurring in 1 in every 365 African-American births. SCT, which occurs in children who have inherited a sickle cell gene from one parent, is present in 1 in 13 African-American births. If both parents have SCT, children have a 25% chance of being diagnosed with SCD.
As an inherited red blood cell disorder, SCD causes blood cells to be sickle-shaped and unable to move as easily through blood vessels as round red blood cells typical in those without SCD. Sickle red blood cells die more quickly, which causes a shortage of red blood cells. Additionally, the cells could hinder proper flow through blood vessels, causing pain, infection, inflammation, acute chest syndrome, and stroke.
The condition’s presence in its specific demographics is due to a commonality of malaria outbreaks in associated regions. This leads inhabitants to develop evolutionary traits in response to help protect them from malaria, such as SCT and SCD. An immune system with sickle cell protects against malaria by preventing hypoxia from setting in, killing red blood cells earlier, thereby lessening the burden of the infection on the body.
Previously, the only known cure for sickle cell was a BMT, which is less expensive and ranges from $80,000 to $400,000 in cost before health insurance. However, the procedure does not fully guarantee recovery and presents a greater potential risk for adults. While the demographic is less likely to die from SCD than Hispanic people, sickle cell crisis and blindness are significantly more likely in Black people.
While mortality rates for sickle cell in children have decreased with advances in technology, death in Black adults has remained largely the same due to lack of access to effective treatment for adults. Exa-cell offers potentially higher chances of survival in adults with SCD, but even utilizing tools editing blood cell genes carries potential risks
Blood diseases are generally safer to cure through gene therapy compared to other illnesses, as editing genes within the body can be incredibly dangerous compared to editing blood that is temporarily removed. Despite this, the FDA has expressed concern that the procedure has the potential to introduce genetic mistakes.
The lifetime cost of treating someone with SCD typically sits around $1.6 to $1.7 million, with severe cases costing even more. Despite the current presidential administration instating a $10 billion demonstration project to explore more accessible payment models for gene therapy through Medicare and Medicaid, accessibility to the procedure remains tentative as the treatment advances through the approval process.
While SCT is present in approximately 8% of Black Americans, exa-cell treatments have a potential to cut costs in the most severe cases of SCD, but will remain largely inaccessible to less economically privileged populations for the foreseeable future without major changes to its current pricing model.