This past week saw the approval of two new therapies, representing significant scientific breakthroughs in the field of cell-based gene therapy to treat patients with sickle cell disease (SCD), a rare condition historically associated with few viable treatment options.

SCD encompasses a group of inherited blood disorders associated with an abnormality in the hemoglobin protein, which normally helps carry oxygen throughout the body via red blood cells. This causes red blood cells, normally disc shaped and flexible enough to travel smoothly in the body, to become rigid and misshapen to resemble a “C” or sickle. The resulting symptoms include anemia, swelling of the extremities (hand and feet), frequent infections, vision problems, stroke, and very severe pain in the chest, abdomen, and joints.

Another major impact on patients is severe pain and organ damage called vaso-occlusive events (VOEs) or vaso-occlusive crises (VOCs) – an accumulation of these events can result in physical disabilities and even death. The majority of SCD cases in the U.S. are found in people who are of African Ancestry or identify themselves as Black.

On December 8th the U.S. Food and Drug Administration (FDA) approved Casgevy™ (Vertex Pharmaceuticals Inc.) and Lyfgenia™ (Bluebird Bio Inc.) both innovative cell-based gene therapies. According to a new FDA release, these products are developed from the patients’ own blood stem cells, which are removed and genetically modified, then transplanted back as a one-time, single-dose infusion.

Casgevy, which is now indicated for the treatment of SCD patients 12 years of age and older with recurrent VOCs, is the first FDA-approved therapy developed with a type of genome editing technology known as CRISPR/Cas9. Lyfgenia, which is approved for the treatment of patients 12 years of age and older with SCD and a history of VOEs, employs a lentiviral vector to deliver the modified genetic material. 

“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 Nicole Verdun, MD, 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.”

“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,” added Peter Marks, MD, PhD, 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.”

Read the full FDA news release to learn more about these therapies, including their specific mechanisms of action and the successful clinical trials that led to their approvals.

Source: FDA release dated December 8, 2023