Breakthrough CRISPR Therapy Casgevy Approved for Inherited Blood Disorders - written by Harsha varthini.B (Managing Editor, Bisjhintus News)

This article highlights the groundbreaking approval of the world's first CRISPR gene-editing therapy, Casgevy, to address inherited blood disorders.

Casgevy, also known as Exa-cel, gained regulatory approval from the U.K. Medicines and Healthcare products Regulatory Agency (MHRA) on November 16, 2023 , for treating sickle-cell disease and transfusion-dependent beta-thalassemia. Subsequently, the U.S. Food and Drug Administration (FDA) granted approval for sickle-cell disease treatment.

While the approval marks a historic moment in gene therapy,  the article underscores lingering concerns regarding Casgevy's affordability and long-term safety.

Key Points:

1. Targeted Conditions:

• Casgevy is approved to treat sickle-cell disease (SCD) and transfusion-dependent beta-thalassemia, both chronic genetic disorders resulting from hemoglobin gene mutations.
• SCD affects over 100,000 people in the U.S., with a higher prevalence in certain populations, such as 1 in 365 Black babies.
• Beta-thalassemia, impacting around 1 in 100,000 people globally, particularly affects individuals of Mediterranean, Asian, African, and Middle Eastern descent.

2. CRISPR Gene-Editing Technique:

• Casgevy utilizes the CRISPR gene-editing technique, developed in 2012, which involves the Cas9 enzyme as "molecular scissors" guided by RNA to cut genes out of DNA.
• It targets the BCL11A gene, responsible for regulating the switch from fetal to adult hemoglobin. Casgevy aims to disable BCL11A, allowing the production of functional fetal hemoglobin.
• The gene-editing process involves extracting blood-making stem cells, editing the BCL11A gene in the lab, and infusing the modified cells back into the patient after eliminating unedited cells with a chemotherapy drug called busulfan.

3.Clinical Efficacy:

• Casgevy demonstrated efficacy in late-stage clinical trials, restoring hemoglobin production and alleviating symptoms.
• Patients with SCD experienced a significant reduction in severe pain crises, with 28 out of 29 patients remaining crisis-free for at least a year post-treatment.
• Similarly, 39 out of 42 beta-thalassemia patients did not require red blood cell transfusions during the same post-treatment period.

4.Safety Concerns:

• Initial trials of Casgevy reported no serious safety concerns, with only transient side effects like fever and fatigue.
• Ongoing monitoring by regulatory bodies and manufacturers, Vertex Pharmaceuticals and CRISPR Therapeutics, aims to assess long-term safety, addressing concerns about potential "off-target" effects.

5.Global Approvals:

• The U.K. approved Casgevy for individuals over 12 with SCD or transfusion-dependent beta-thalassemia in November 2023.
• In December, the FDA granted approval for Casgevy to treat sickle-cell disease in individuals aged 12 and older.
• Further approvals from the European Medicines Agency and the Saudi Food and Drug Authority are under review.

6. Availability and Affordability:

• Casgevy's availability remains unclear, and its global accessibility depends on addressing cost challenges associated with gene therapies.
• Vertex is working with health authorities to establish reimbursement and access for eligible patients in the U.K.

7. Future CRISPR Therapies:

• Other companies, like Intellia Therapeutics, are developing CRISPR therapies for inherited diseases.
• Innovations like "base editing" and "prime editing" aim to enhance CRISPR's precision and effectiveness in treating various diseases.

Conclusion:

The article emphasizes its informational nature and clarifies that it does not provide medical advice. The ongoing developments in CRISPR-based therapies, exemplified by Casgevy, showcase the transformative potential of gene-editing technologies in addressing complex genetic disorders.