Sickle Cell breakthrough
- Recently, the UK approved a gene therapy called Casgevy for the cure of sickle cell disease and thalassaemia.
- Casgevy is the first licensed therapy in the world based on the Crispr-Cas9 gene editing technology, awarded a Nobel Prize in 2020.
Sickle Cell Disease and Thalassaemia
- Sickle cell disease causes red blood cells to assume a crescent shape, leading to blocked blood flow and severe symptoms.
- Thalassaemia results in low levels of haemoglobin, causing fatigue, shortness of breath, and irregular heartbeats, requiring lifelong blood transfusions.
How Casgevy Works
- Both the diseases are caused by errors in the gene for haemoglobin, a protein in the red blood cells that carry oxygen to organs and tissues.
- Casgevy edits the faulty gene responsible for sickle cell disease and thalassaemia using the patient's own blood stem cells.
- So far, the only permanent treatment has been a bone marrow transplant, for which a closely matched donor is needed.
- The therapy targets the BCL11A gene, promoting the production of foetal haemoglobin, which does not carry the same abnormalities as adult haemoglobin.
Trial Results
- In trials, Casgevy showed promising results
- A significant reduction in severe pain crises for sickle cell disease patients
- A 70% drop in the need for transfusions in thalassaemia patients
Treatment Process
- Casgevy is a one-time treatment that involves collecting blood stem cells from the bone marrow through apheresis.
- The edited cells are then transplanted back into the patient after undergoing a six-month editing and testing process.
- Side effects from the treatment are similar to those associated with autologous stem cell transplants, including nausea, fatigue, fever and increased risk of infection.
Challenges and Concerns
- The therapy's high cost, estimated to be as much as $2 million per patient, poses a significant challenge.
- Also, absence of local manufacturing facilities means that the harvested blood stem cells have to be sent across countries.
- Pricing is a concern, especially for people in poorer countries where a high proportion of patients with these conditions reside.
Conclusion
- Despite the challenges, the approval of Chevy is seen as a significant breakthrough in gene therapy.
- Ongoing efforts to develop local manufacturing facilities and collaborative research may contribute to overcoming challenges in the future