The United Kingdom (UK) medical regulators have granted approval for a gene therapy designed to cure two blood disorders: sickle cell disease and beta thalassemia. This innovative treatment marks the first instance of licencing utilising the gene-editing tool CRISPR, for which the Nobel Prize was awarded in 2020 to its discoverers.
Sickle cell disease and beta-thalassemia are both inherited blood conditions stemming from errors in the gene for haemoglobin. Individuals with sickle cell disease produce abnormally shaped red blood cells, leading to complications such as reduced lifespan, blood vessel blockages, pain, and life-threatening infections. On the other hand, individuals with beta thalassemia face insufficient production of haemoglobin, necessitating frequent blood transfusions.
The gene-editing process involves extracting bone marrow stem cells from the patient’s blood. In a laboratory setting, the CRISPR tool makes precise cuts in the DNA of these cells, effectively disabling the faulty gene. The modified cells are then reintroduced into the patient’s body, enabling the production of functional haemoglobin.
Trials have shown promising results, with 28 out of 29 sickle cell patients experiencing freedom from severe pain and 39 of 42 beta-thalassemia patients no longer requiring blood transfusions for at least a year. The potential for a permanent solution is a significant advancement. Ongoing trials are being conducted in the UK, US, France, Germany, and Italy.
Sickle cell disease affects around 15,000 people in the UK, predominantly those with African or Caribbean family backgrounds, with nearly 300 babies born with the condition each year. Thalassemia impacts over 1,000 individuals in the UK, primarily those of Mediterranean, Southeast Asian, and Middle Eastern descent.
Julian Beach, interim executive director of healthcare quality and access at the Medicines and Healthcare Products Regulatory Agency (MHRA), emphasised the gravity of these conditions, stating, “Both sickle cell disease and beta-thalassemia are painful, life-long conditions that in some cases can be fatal.” He highlighted that, until now, a bone marrow transplant was the sole permanent treatment option, carrying the risk of rejection due to the need for a closely matched donor.
The MHRA has now authorized a “first-of-its-kind” gene-editing treatment named Casgevy, found in trials to restore healthy hemoglobin production for the majority of participants with sickle-cell disease and transfusion-dependent beta thalassemia, alleviating disease symptoms.