An experimental gene-editing treatment for sickle cell disease is edging closer to FDA approval following discussions among FDA advisors on Tuesday.
Prospects for Approval
Although the committee did not vote on the efficacy or safety of the treatment, many panelists expressed a belief that its benefits outweigh potential risks. The FDA is expected to make a decision by December 8, and following this week’s meeting, approval appears likely.
CRISPR Gene Editing
The treatment involves the use of CRISPR, a gene-editing technology that can precisely modify DNA. If approved, it would mark the first FDA-approved CRISPR treatment.
A Promising Future
John Tisdale, a member of the advisory committee and a researcher of sickle cell disease, noted the significance of the potential approval, saying, “We are finally at a spot where we can envision broadly available cures for sickle cell disease.”
Sickle Cell Disease Overview
Sickle cell disease is a group of inherited blood cell disorders affecting hemoglobin, the protein responsible for carrying oxygen. In individuals with this condition, abnormal hemoglobin forms cause red blood cells to become crescent-shaped instead of round. These misshapen cells can obstruct blood vessels, leading to pain, infections, strokes, and other health issues. On average, people with sickle cell disease have a life expectancy of 42 to 47 years.
Prevalence and Current Treatments
More than 100,000 people in the U.S. and 20 million worldwide have sickle cell disease. Currently, the only cure is a bone marrow transplant, but other treatments can alleviate symptoms and increase life expectancy. The condition predominantly affects Americans of African ancestry or those who identify as Black and also impacts people from Hispanic, Southern European, Middle Eastern, or South Asian backgrounds.
The Exa-Cell Treatment
The proposed treatment, known as exa-cell, utilizes CRISPR to modify cells, enabling them to produce a form of hemoglobin that restores normal red blood cell function. The process involves extracting cells from the patient’s bone marrow, editing a gene, and reintroducing the cells into the patient.
Positive Results
In an ongoing study, 29 out of 30 patients who received the treatment did not experience severe pain crises for a year following the procedure. Prior to the treatment, these patients had encountered over four such crises annually on average.
Discussion on Safety and Future Research
The FDA advisors discussed the possibility of “off-target” edits, where the technology could inadvertently modify other parts of DNA. While no such incidents occurred during the clinical trial, some panelists argued that additional research would be beneficial.
Monetary and Healthcare Costs
The treatment is intensive, involving blood transfusions, chemotherapy, and an extended hospital stay, with estimated costs of up to $2 million per patient. Vertex Pharmaceuticals, one of the developers, has received indications from Medicaid and private insurers regarding potential coverage. However, younger children with the condition and patients who have already suffered extensive damage may not be eligible for the treatment.