One-Time Gene Therapy Improves Quality of Life for Patients with Sickle Cell and β-Thalassemia

THURSDAY, Sept. 4, 2025 (HealthDay News) — A single-dose, CRISPR-Cas9 gene-edited cell therapy, exagamglogene autotemcel (exa-cel), has shown significant and sustained improvements in the quality of life for adolescents and adults with severe sickle cell disease (SCD) and transfusion-dependent β-thalassemia (TDT). The findings from two separate studies were published in the journal Blood Advances.

The studies, funded by Vertex Pharmaceuticals, focused on patient-reported outcomes (PROs), which provide crucial insight into the daily lives of patients beyond clinical lab values.

What is Exa-cel?

Sold under the brand name Casgevy, exa-cel is a groundbreaking one-time gene therapy. It is the first therapy of its kind to be approved that uses CRISPR-Cas9 gene-editing technology.

The treatment is customized for each patient using their own blood stem cells. In a lab, these cells are gene-edited to increase the production of fetal hemoglobin (HbF), a type of hemoglobin naturally present during development. By “turning on” the production of HbF, the therapy helps prevent red blood cells from sickling, which is the root cause of the painful and debilitating symptoms of sickle cell disease. For patients with β-thalassemia, this process can reduce or even eliminate the need for regular blood transfusions.

Significant Patient Benefits

In the Phase 3 CLIMB SCD-121 trial, researchers followed 30 adults and 12 adolescents with severe SCD. The results showed that by just six months after the exa-cel infusion, patients reported substantial improvements in their overall health and well-being, including pain, physical function, and emotional state. These benefits were not only clinically meaningful but also sustained for up to 36 months.

A separate study in the same journal looked at 35 adults and 19 adolescents with TDT. This group also showed significant quality of life improvements following treatment with exa-cel. The benefits, including better physical and psychosocial health, were sustained for up to 48 months and exceeded established benchmarks for what is considered a “minimal clinically important difference.”

Dr. Josu de la Fuente of Imperial College Healthcare NHS Trust in London emphasized the value of the findings, noting, “Although exa-cel is a complex and costly treatment, the significant improvements in quality of life shown in these studies make it a worthwhile investment, especially for younger patients, who showed marked improvements.”