Vertex Pharmaceuticals’ Casgevy (exagamglogene autotemcel) has continued to show benefits in sickle cell disease (SCD) patients for 5.5 years and in transfusion-dependent beta-thalassemia (TDT) patients for six years.
Across three ongoing Phase III studies, CLIMB-111 (NCT03655678), CLIMB-121 (NCT03745287) and CLIMB-131 (NCT04208529), all 45 SCD patients who received Casgevy achieved 12 consecutive months of freedom from hospital for an average of 36.1 months. In addition, 95.6% were free from vaso-occlusive crises (VOCs) for at least 12 months, with a mean duration of 35 months.
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In patients with TDT, 98.2% of the 55 patients achieved transfusion independence for at least 12 consecutive months with a weighted average haemoglobin of at least 9g/dL. The mean duration of this endpoint was 40.5 months.
The one evaluable patient who did not achieve this endpoint has been transfusion-free for 14.8 months but did achieve the average haemoglobin level required for the full period.
The safety profile continues to be consistent with myeloablative conditioning with busulfan and autologous haematopoietic stem cell transplant.
University of Toronto haematologist Dr Kevin Kuo said: “This longer-term data reinforces Casgevy’s durable clinical benefits for eligible people living with sickle cell disease or transfusion-dependent beta-thalassemia. These results are a reminder of what science can achieve, especially for patients and communities with significant unmet need.”
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By GlobalDataVertex’s Casgevy is the first authorised CRISPR/Cas9 gene-edited therapy. It was approved by the US Food and Drug Administration (FDA) in December 2023. It is also approved in Austria, Bahrain, Denmark, Saudi Arabia, the United Arab Emirates, Northern Ireland, England, Scotland and Wales. While it has received positive recommendations in Canada, it is yet to be approved there due to concerns over cost.
GlobalData analysis shows that Casgevy generated $10m in sales in 2024, with the therapy predicted to reach blockbuster status in 2030.
GlobalData is the parent company of Clinical Trials Arena.
Cell and gene impact not as large as expected
As of early 2025, the FDA had approved more than 30 cell and gene therapy products, including Casgevy. Although cell and gene therapies promised to revolutionise the pharmaceutical industry, the uptake has been lower than predicted due to high costs and manufacturing challenges. This is also partially due to payers not being willing to cover the therapies due to the high upfront costs, uncertain long-term effectiveness, and the potential for short-term budget impact.
Bluebird bio received FDA approval for its SCD gene therapy Lyfgenia (lovotibeglogene autotemcel) in 2023, but the company struggled on the stock market and has since been acquired by global investment funds Carlyle and SK Capital, with a new leadership team. Despite the acquisition, Lyfgenia is still available on the market for SCD patients.
