United Kingdom and USA have mobilized the medical community as the first countries to approve CRISPR-Cas9 gene therapy. This groundbreaking treatment, called Casgevy, targets two challenging blood diseases: sickle cell anemia and β-thalassemia. This marks a milestone in the journey of gene therapy, ten years after the discovery of CRISPR.
Sickle cell anemia, which causes severe pain crises due to abnormal hemoglobin levels, and β-thalassemia, which requires frequent blood transfusions, affect millions of people globally. The innovative treatment called Casgevy, developed by Vertex Pharmaceuticals and CRISPR Therapeutics, is ready to transform the lives of those suffering from these debilitating diseases.
🏥 Clinical trials are showing promising results. For sickle cell anemia, 28 out of 29 participants observed had significantly reduced pain one year after treatment. Similarly, in β-thalassemia trials, 39 out of 42 individuals did not require any blood transfusions at least one year after receiving Casgevy.
🧑⚕️How does it work? Casgevy uses CRISPR to edit the genes that code for hemoglobin. Blood-producing stem cells are taken, edited using CRISPR-Cas9 to promote fetal hemoglobin production, and then reintroduced into the body. This process alleviates symptoms by increasing the oxygen reaching the cells.
The long-term safety of Casgevy is under close observation. Although side effects such as nausea and fever have been observed in clinical trials so far, no major safety concerns have arisen. However, caution is necessary due to the risk of CRISPR causing unintended genetic changes.
🧑⚖️ Approval of the therapy is expected in the EU, but the main challenge lies in the cost of the treatment. With a high price tag of approximately 2 million dollars per patient, accessibility is a concern, especially in underdeveloped and developing countries.
The approval of Casgevy by the United Kingdom and the USA is a significant step in gene therapy and heralds the dawn of a new era in healthcare. Our duty is to ensure that this therapy and many others like it are accessible to everyone who needs it.

Victoria Gray, one of the 300,000 people born with sickle cell anemia each year, is one of the first participants in ongoing clinical trials in the USA. In early 2019, gene editing was performed on the stem cells collected from her body as part of the clinical trial, and they were returned to her body. Following this treatment, Victoria's body began producing physiologically normal-shaped red blood cells.
🌍 Useful Links:
🔗 For Victoria’s transformation story and more: https://www.science.org/content/article/gene-editing-summit-touts-sickle-cell-success-while-questions-embryo-editing-linger
🔗 Ongoing clinical studies: https://clinicaltrials.gov/search?intr=CTX001
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