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First gene therapies to treat sickle cell disease get FDA approval

Donovan J. Thomas, The Atlanta Journal-Constitution on

Published in News & Features

The Food and Drug Administration approved two gene therapies for the treatment of sickle cell disease Friday, including a CRISPR gene-editing therapy to treat the disease, the first treatment approved in the U.S. using CRISPR technology.

Casgevy and Lyfgenia, the gene therapy treatments, will be available for patients 12 and older for treatment of the disease that affects 100,000 people in the United States, a majority of whom are Black.

“Sickle cell disease is a rare, debilitating and life-threatening blood disorder with significant unmet need, and 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,” said Dr. Nicole Verdun, director of the Office of Therapeutic Products within the FDA’s Center for Biologics Evaluation and Research.

“Gene therapy holds the promise of delivering more targeted and effective treatments, especially for individuals with rare diseases where the current treatment options are limited.”

Casgevy, developed by Vertex Pharmaceuticals Inc., uses a typed of gene therapy called CRISPR gene editing, which corrects a patient’s cells with genetic errors.

CRISPR is an abbreviation for a family of gene sequences, and the new technology allows doctors to edit a patient’s genes to eliminate a faulty genetic code that causes sickle cell.

Lyfgenia, a product of Bluebird Bio Inc., uses a deactivated virus called a lentiviral vector as a gene delivery vehicle to insert a hemoglobin that is produced through gene therapy into blood stem cells. This then reduces the cells’ chances of sickling, which promotes better blood flow.

Both treatments require doctors to take bone marrow and stem cells out and treat it in a laboratory setting before returning it to the patients. The procedure requires a month-long stay in the hospital, but could replace blood transfusions and other older treatment options.


Sickle cell is a disease caused by one wrong amino acid in hemoglobin that causes normally round red blood cells to be shaped like a sickle, meaning they clump and clot as a result.

Severe pain riddles the lives of those living with sickle cell, often leading to many emergency room or hospital visits, sometimes multiple times a year, to manage crises. Many are unable to work, exercise or do other things to lead a normal life.

In addition to blood transfusions, traditional treatments for sickle cells have involved stem cell or bone marrow transplants, which carry risks and may not work. According to the American Society of Hematology, the median life expectancy for people with the disease is 42 to 47 years, compared to 76 years overall in the United States.

“These approvals represent an important medical advance with the use of innovative cell-based gene therapies to target potentially devastating diseases and improve public health,” said Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research.

“Today’s actions follow rigorous evaluations of the scientific and clinical data needed to support approval, reflecting the FDA’s commitment to facilitating development of safe and effective treatments for conditions with severe impacts on human health.”


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