Game-changer – CRISPR-Cas9 Gene Therapy Approved for Sickle Cell Disease and Beta Thalassemia | 13 December 2023 | UPSC Daily Editorial Analysis

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What's the article about?

  • It talks new gene therapy based treatment for the Sickle Cell and Beta Thalassemia diseases.


  • GS3: Science and Technology- Developments and their Applications and Effects in Everyday Life; Awareness in the fields of Bio-technology and issues relating to Intellectual Property Rights


  • A groundbreaking moment in medicine has arrived, with the U.S. Food and Drug Administration (FDA) approving two gene therapies, Casgevy and Lyfgenia, for the treatment of sickle cell disease in patients over 12 years old.
  • This follows closely on the heels of the UK's approval of Casgevy for both sickle cell disease and beta thalassemia just weeks earlier.
  • These landmark decisions signify the dawn of a new era in treating these debilitating blood disorders, offering a potential cure where bone marrow transplantation was previously the only option.

Sickle Cell and Beta Thalassemia diseases

  • Sickle cell disease and beta-thalassemia are both inherited blood disorders that affect the red blood cells. They are caused by mutations in genes that control the production of hemoglobin, the protein that carries oxygen in red blood cells.
  • Sickle cell disease is caused by a mutation in the beta-globin gene that changes the amino acid sequence of hemoglobin. This change causes the hemoglobin molecules to become sticky and clump together, forming sickle-shaped red blood cells. Sickle-shaped cells are less flexible than normal red blood cells and can get stuck in small blood vessels, blocking blood flow and causing pain, tissue damage, and other complications.

  • Beta-thalassemia is caused by mutations in the beta-globin gene that reduce the amount of beta-globin protein produced. This results in a shortage of hemoglobin, which leads to anemia (a lack of red blood cells or hemoglobin). Beta-thalassemia can range in severity from mild to life-threatening.


  • CRISPR-Cas9: A Gene-Editing Revolution
    • Both Casgevy and Lyfgenia utilize the revolutionary CRISPR-Cas9 gene-editing tool. Here's how they work:
    • Lyfgenia: This therapy employs a disabled lentivirus to introduce a functional beta-globin gene into blood stem cells, essentially mimicking the healthy version.
    • Casgevy: This therapy takes a different approach. It uses CRISPR-Cas9 to disable the BCL11A gene within blood stem cells. This gene normally shuts down fetal hemoglobin production after birth. By disabling it, Casgevy allows the continued production of fetal hemoglobin, which lacks the mutations causing sickle cell disease and beta thalassemia.
  • Promising Results in Clinical Trials:
    • Clinical trials for both therapies have shown encouraging results:
    • Casgevy:
      • 28 out of 29 sickle cell disease patients experienced freedom from the debilitating effects of the disease for a year.
      • 39 out of 42 beta thalassemia patients did not require blood transfusions for one year, and the remaining three patients saw their transfusion needs reduced by over 70%.
    • Lyfgenia:
      • 30 out of 32 sickle cell disease patients did not experience severe blocked blood flow, a hallmark symptom of the disease, six to 18 months after treatment.
      • 28 out of 32 patients did not experience any blocked blood flow events altogether.
  • Hope beyond Bone Marrow Transplantation:
    • These therapies offer several advantages over traditional bone marrow transplantation, the existing cure for these diseases:
    • No reliance on matching donors: Both Lyfgenia and Casgevy utilize the patient's own blood cells, eliminating the need for a compatible bone marrow donor, often a challenging and limiting factor.
    • Potentially larger pool of treatable patients: This approach opens the door to treating a wider range of patients who may not have suitable bone marrow donors.
  • Challenges and the Road Ahead:
    • Cost: Both therapies are expected to be exorbitantly expensive, potentially limiting access for many patients.
    • Infrastructure: Only specialized hospitals equipped for blood stem cell extraction and genetic editing will be able to offer these treatments.
    • Long-term safety and efficacy: Clinical trials have involved a small number of patients and a limited follow-up period. Continued monitoring of real-world data is crucial to ensure long-term safety and efficacy. The potential for unintended genetic modifications and their consequences necessitates careful vigilance.

Way Forward:

  • While challenges exist, the approval of these CRISPR-Cas9 gene therapies marks a significant step forward in the fight against sickle cell disease and beta thalassemia. With continued research and development, these groundbreaking treatments offer the hope of a future where a cure, not just management, is within reach for millions of individuals suffering from these debilitating disorders.
  • This is just the beginning of a new era in gene therapy, and its potential to revolutionize the treatment of various diseases is immense. As research progresses and these therapies become more accessible, we can look forward to a future where genetic disorders are no longer insurmountable obstacles, but challenges met and overcome with the power of science.

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