FDA approves first gene-editing treatment for Sickle Cell

Opening a new era of treatments for genetic conditions, the U.S. Food and Drug Administration (FDA) has approved two gene-based treatments for sickle cell disease, marking a significant development in the treatment of this inherited blood disorder. The approved therapies are Casgevy and Lyfgenia, with Casgevy being the first therapy to use the gene-editing technique CRISPR to potentially cure sickle cell disease.

Sickle cell is a debilitating and life-shortening inherited red blood cell disorder that disproportionately affects African Americans. The approvals are considered significant milestones in treating a disease that has long been neglected in medical research. 

Dr. Nicole Verdun, director of the FDA’s Office of Therapeutic Products within its Center for Biologics Evaluation and Research said, “Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need. We are excited to advance the field especially for individuals whose lives have been severely disrupted by the disease by approving two cell-based gene therapies today.”

Casgevy is the CRISPR-based treatment, made by Vertex Pharmaceuticals and Crispr Therapeutics; Lyfgenia, made by bluebird bio, uses an older gene therapy approach. Both were cleared for people 12 and older with histories of vaso-occlusive crises, painful events caused by the disease. There are about 100,000 people in the U.S. affected by sickle cell disease, and these gene-based treatments offer potential cures. 

Casgevy involves the use of the CRISPR gene-editing technique to modify cells taken from a patient’s bone marrow. The edited cells are then infused back into the patient, producing a form of hemoglobin known as fetal hemoglobin. This aims to restore normal function to red blood cells, alleviating symptoms of sickle cell disease. Designed as a one-time treatment, Casgevy has shown promising results in resolving severe pain crises for at least 18 months in a significant percentage of patients. The hope is that it provides a long-lasting solution for patients with sickle cell disease.

Lyfgenia (Non-CRISPR Gene Therapy was developed by bluebird bio and utilizes a more conventional form of gene therapy. It relies on a virus to deliver a gene into cells to treat sickle cell disease.

While these advancements are promising, questions remain about the accessibility and affordability of these treatments, particularly given their high costs. Casgevy is priced at $2.2 million for a one-time treatment, while Lyfgenia is priced at $3.1 million. The high costs have raised questions about accessibility, and experts have encouraged pricing that enables broader access.

Signifying a new era in the treatment of genetic conditions, the FDA approvals are hailed as milestones for treating sickle cell disease and for the rapidly advancing field of gene editing to target and more effectively treat rare diseases with limited treatment options.

Mayo Clinic bioethicist Megan Allyse said, “To have sickle cell suddenly be the focus of this dramatic new approach to therapy development is, on the one hand, great, because hopefully it will undo some of that history of neglect and really give the sickle cell community the attention that is always needed.” However, she questioned access to the cutting-edge treatment, which carries a price of more than $2 million. According to the US Centers for Disease Control and Prevention, sickle cell impacts an estimated 1 of every 365 Black babies born, and has long been considered neglected by the pharmaceutical industry.

About 20,000 people in the US are thought to have a severe enough form of the disease to potentially qualify for a treatment like this.