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Innovative CRISPR treatment for sickle cell disease deemed safe enough for patients

November 1, 2023

Yesterday, FDA's Cellular, Tissue and Gene Therapies Advisory Committee affirmed the safety of Vertex Pharmaceuticals and CRISPR Therapeutics' exagamglogene autotemcel (exa-cel) for severe sickle cell disease (SCD) that permanently changes the DNA in a patient's blood cells.

The FDA now has until Dec. 8 to decide whether to approve this CRISPR treatment for use in patients 12 and older with SCD and recurrent vaso-occlusive crises (VOCs).

Some key takeaways from yesterday's meeting:

• Until now, the only cure for SCD, a serious, rare, debilitating, and life-shortening hemoglobinopathy with no broadly available curative options, has been a bone-marrow transplant.
• SCD affects approximately 100,000 people in the US; approximately 90% of people with SCD are of African descent.
• Severe SCD, as defined by recurrent VOCs, is even more rare, estimated at 20,000 people in the US.
• exa-cel was jointly developed by Vertex Pharmaceuticals of Boston and CRISPR Therapeutics of Switzerland.
• exa-cel is a one-time, single dose cellular product consisting of autologous CD34+ human hematopoietic stem and progenitor cells (hHSPCs) modified by CRISPR/Cas9-mediated gene editing that was developed to treat patients 12 years and older with severe SCD.
• Vertex said that 44 people received the treatment in its study. Among the 30 participants with at least 18 months of follow-up, 29 were free of pain crises for at least a year and all 30 avoided hospitalization for pain crises.
• exa-cel treatment is expected to be be extremely expensive, potentially in the millions of dollars per patient.

A second gene therapy for sickle cell disease that the FDA is expected to consider on December 20 is made by Bluebird Bio of Smerville, Mass. It's intended to work by making functional copies of a modified gene that helps red blood cells produce non-misshapen hemoglobin.

Sources:

Vertex. (2023, October 31). Sponsor Briefing Document. FDA's Cellular, Tissue and Gene Therapies Advisory Committee. Exagamglogene Autotemcel (EXA-CEL) for the Treatment of Sickle Cell Disease in Patients 12 Years and Older with Recurrent Vaso-Occlusive Crises. BLA 125787. https://www.fda.gov/media/173415/download

Kolata, G. (2023, October 31). The New York Times. Panel Says That Innovative Sickle Cell Cure is Safe Enough for Patients. https://www.nytimes.com/2023/10/31/health/sickle-cell-fda-cure-crispr.html