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HealthUnited States of America

US approves CRISPR gene-editing to treat sickle cell disease

December 8, 2023

The treatment uses the revolutionary gene-editing tool CRISPR to permanently change DNA in the patient's blood cells. Sickle cell disease is a life-threatening illness that medical science has struggled to address.

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This electron microscope image provided by the National Institutes of Health in 2016 shows a blood cell altered by sickle cell disease
A genetic mutation causes cells to become sickle or crescent-shaped, which can block blood flowImage: NCATS/AP/picture alliance

The United States Food and Drug Administration (FDA) Friday approved a landmark gene-editing treatment for sickle cell disease.

The US drug regulator "approved two milestone treatments, Casgevy and Lyfgenia, representing the first cell-based gene therapies for the treatment of sickle cell disease," it said in a statement.

As DW reported last month, Exa-cel, using the brand name Casgevz, is based on CRISPR, a Nobel Prize-winning gene editing tool, used to snip patients' DNA.

Casgevy was also approved by Britain's Medicines and Healthcare Products Regulatory Agency last month.

What is sickle cell disease?

"Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need," the FDA's Dr. Nicole Verdun said in a statement announcing the approvals.

"We are excited to advance the field especially for individuals whose lives have been severely disrupted by the disease."

In the US, an estimated 100,000 people have the disease, and globally, it affects more than 7.7 million people, primarily people of African or Caribbean descent.

Sickle cell patients have elongated blood cells resembling sickles rather than normal blood cells' typical donut shape. These misshaped cells can get stuck in the blood vessels and block the oxygen supply, causing patients to experience excruciating pain, strokes, and organ damage.

How does the Casgevy gene editing tool work?

The new medication, Casgevy, targets the problematic gene in a patient's bone marrow stem cells. It results in the production of properly functioning hemoglobin, the protein in red blood cells that carries oxygen, in the body.

Patients first receive a course of chemotherapy before doctors take stem cells from the patient's bone marrow, and then those cells are treated with the medication in a lab, which, using the CRISPR gene editing tool, essentially cuts out the sections of DNA that cause the sickle shape.

The treated stem cells are reintroduced into the body.

Infografik Die Gen-Schere CRISPR/Cas9 EN

Gene therapy treatments can cost millions of dollars and experts have raised concerns that they could remain out of reach for the people who would benefit most.

The other treatment approved by the FDA, Lyfgenia, utilizes a harmless virus to insert a gene into patients' stem cells.

Before Casgevy and Lyfgenia were approved treatments included medications and blood transfusions.

The only permanent solution was a bone marrow transplant, which must come from a closely matched donor without the disease and brings a risk of rejection.

lo/sms (AP, AFP, Reuters)