Vertex Pharmaceuticals and CRISPR Therapeutics ask FDA to approve sickle cell treatment after successful clinical trial

New Strategies Show Promising Evidence for Sickle Cell Treatment 

Illustration depicting sickling of red blood cells, which are typically disc-shaped but become crescent- or sickle-shaped as a result of sickle cell disease.

An estimated 1,000 babies are born every day worldwide with sickle cell. The disease affects an estimated 100,000 people in the U.S., many of whom are African American, along with an estimated 20 million people worldwide.

The condition, which can cause a lifetime of pain, health complications and expenses, affects one in 365 Black babies born in the U.S. and one in 16,300 Hispanic babies.  The pain comes from episodes, known as sickle cell crises that occur when the flow of blood is blocked to an area because the sickled cells have become stuck in the blood vessel. 

Normally, red blood cells are disc-shaped and flexible enough to move easily through the blood vessels. In sickle cell disease, red blood cells become crescent- or “sickle”-shaped due to a genetic mutation and can easily clump and block blood vessels.

How often someone with sickle cell disease gets episodes of pain varies a lot. Some people may have one every week, while others may have less than 1 a year.

New Treatments

Despite the development of new medical therapies, sickle cell disease remains an incurable condition for most affected individuals. 

It wasn’t until 1984 that bone marrow transplants from siblings or matched donors were approved as a cure for sickle cell.  But other curative therapies are now on the horizon. 

The University of Chicago Medicine Comer Children’s Hospital was one of three sites to enroll patients in the clinical trial, which tested to treat sickle cell disease. 

A clinical trial that tested stem cell gene therapy has shown good results.  Researchers used CRISPR-Cas9 to edit specific genes in stem cells — the building blocks of blood cells — taken from each patient. The edits increased the cells’ production of fetal hemoglobin (HbF), a protein that can replace unhealthy, sickled hemoglobin in the blood and protect against the complications of sickle cell disease. The patients then received their own edited cells as therapeutic infusions.

National Public Radio has followed Victoria Gray, one of the trial participants who Almost four years ago, was the first patient with sickle cell disease to get the experimental treatment.   Today, all of Gray’s symptoms are gone.  

“The life that I once felt like I was only existing in, I am now thriving in, said Gray  

Vertex Pharmaceuticals and CRISPR Therapeutics, the companies that sponsored the study that Gray volunteered for, say they have now treated 31 sickle cell patients and all 31 were free of symptoms, even though all had been previously diagnosed with severe cases.

Based on those results, the companies are asking the Food and Drug Administration to approve the treatment for severe sickle cell. 

Still, some medical professionals warn there are still important questions about this treatment and other gene-editing therapies in the pipeline, including how long the benefits will last.

Also, the sickle cell treatment is expected to be very expensive — possibly costing millions of dollars. That raises questions about whether it will be available to the patients who need it the most, especially less affluent people in the U.S. and in countries where sickle cell is most common, such as those in sub-Saharan Africa.

“I worry that when gene editing comes to market for sickle cell, that the very states in the United States that won’t expand Medicaid or access to insurance, which are some of the very states where prevalence is the highest, will inhibit the affordability and availability of the therapy,” said Melissa Creary of the University of Michigan, who studies policy issues raised by sickle cell.

Still, other professionals say the take-home message is that there are now more potentially curative therapies for sickle cell disease than ever before.  

Sources:  Hopkinsmedicine.org, nhs.uk, uchicaagomedicine.org, and shots health news from NPR