World-first gene therapy for inherited blood disorders approved in UK

The regulator has authorised the treatment for patients aged 12 and over (Peter Byrne/PA)
The regulator has authorised the treatment for patients aged 12 and over (Peter Byrne/PA) The regulator has authorised the treatment for patients aged 12 and over (Peter Byrne/PA)

The UK’s medicines regulator has authorised a world-first gene therapy as a potential cure for two inherited blood disorders.

The treatment, Casgevy, for sickle cell disease and beta thalassemia, is the first to be licensed using the gene-editing tool known as Crispr, for which its inventors were awarded the Nobel prize in 2020.

The Medicines and Healthcare products Regulatory Agency (MHRA) said the treatment was for patients aged 12 and over “after a rigorous assessment of its safety, quality and effectiveness”.

Both sickle cell disease and beta thalassemia are genetic conditions caused by errors in the genes for haemoglobin, which is used by red blood cells to carry oxygen around the body.

Sickle cell disease is particularly common in people with an African or Caribbean family background, while beta thalassemia mainly affects people of Mediterranean, south Asian, south-east Asian and Middle Eastern origin.

Symptoms of sickle cell disease can include very severe pain, serious and life-threatening infections, and anaemia.

People with beta thalassemia can have severe anaemia. Patients often need a blood transfusion every three to five weeks, alongside regular injections and medicines.

Casgevy is designed to work by editing the faulty gene in a patient’s bone marrow stem cells so that the body produces functioning haemoglobin.

For this to work, stem cells are taken out of bone marrow, edited in the lab and then infused back into the patient, with the potential to cure people.

The MHRA said clinical trials had found Casgevy restored healthy haemoglobin production in the majority of people.

In the clinical trial for sickle-cell disease, 28 out of 29 patients in an analysis (97%) were free of severe pain for at least 12 months after treatment.

In the clinical trial for beta thalassemia, 39 out of 42 patients analysed (93%) did not need a red blood cell transfusion for at least 12 months after treatment.

The remaining three had more than a 70% reduction in the need for red cell transfusions.

Julian Beach, interim executive director of healthcare quality and access at the MHRA, said both conditions “are painful, life-long conditions that in some cases can be fatal”.

He added: “To date, a bone marrow transplant – which must come from a closely matched donor and carries a risk of rejection – has been the only permanent treatment option.”

John James, chief executive of the Sickle Cell Society, said: “Sickle cell disorder is an incredibly debilitating condition, causing significant pain for the people who live with it and potentially leading to early mortality.

“There are limited medicines currently available to patients, so I welcome today’s news that a new treatment has been judged safe and effective, which has the potential to significantly improve the quality of life for so many.”

The treatment has not yet been examined for more widespread use on the NHS.

Reshma Kewalramani, president of Vertex, which launched the drug together with Crispr Therapeutics, said: “Today is a historic day in science and medicine: this authorisation of Casgevy in Great Britain is the first regulatory authorisation of a Crispr-based therapy in the world.”