World-first gene editing therapy for sickle cell disease

KHP Haematology will be one of the first centres in the UK to deliver a world-first gene editing therapy for patients with sickle cell disease, which has just been approved for use in the NHS.

Exa-cel treatment uses CRISPR gene editing technology to increase the level of fetal haemoglobin in people with sickle cell disease, which has a major effect in reducing the severity of the condition. 

The patient’s own blood stem cells are collected and edited in a laboratory. The edited cells are then infused back into the patient. The gene-edited stem cells go on to produce red blood cells that are far less prone to sickling. As exa-cel involves patients receiving their own edited cells, no donor is needed and they have no risk of their body rejecting them.

King’s College Hospital is one of five centres in England chosen to provide this ground-breaking treatment, which has been based on discoveries made at King’s College London by Dr Stephan Menzel and Prof Swee Lay Thein.

Exa-cel has been approved for use in the NHS from 31 January by the National Institute for Health and Care Excellence (NICE) for older children and adults with a severe form of sickle cell disease. Potentially more than 5,000 people with sickle cell disease may be eligible for this in the UK.

This new treatment could allow some patients to live a normal life with few or no restrictions caused by sickle cell disease.

David Rees, Professor of Paediatric Sickle Cell Disease, King’s College London said,

“It is encouraging that exa-cel has been approved for use to treat patients with sickle cell disease in England. 

The treatment is not curative in the traditional sense of the word, in that the patients still have some features of sickle cell disease, but early studies suggest that successfully treated patients have very few symptoms of the condition, at least in the medium term.

Exa-cel treatment still requires very strong chemotherapy, similar to having a bone marrow transplant, which causes problems with reduced fertility and sometimes more serious complications.

Despite these concerns, the availability of exa-cel is a major advance and offers a really important new treatment option for some patients with sickle cell disease. Excitingly, advances in gene editing are happening very rapidly at the moment and it seems likely that cheaper, safer and more effective forms of gene editing will emerge for sickle cell disease over the coming years, offering the prospect of a curative treatment which is universally applicable, even in low income countries where the majority of patients live.”

Subarna Chakravorty, Consultant Paediatric Haematologist, King’s College Hospital NHS FT said;

“We are enormously fortunate to be the first publicly-funded healthcare system in the world to have exa-cel approved for use in sickle cell patients. The approval came after months of careful assessment of clinical trial data, expert opinion and economic modelling by NICE. 

Trials have demonstrated that exa-cel treatment results in a remarkable improvement in symptoms in the majority of sickle cell patients, leading to marked improvement in their quality of life. Gene editing therapy is not without its risks, including the use of toxic chemotherapy to prepare the patient to receive the edited stem cells. Hence, it is important that patients are made fully aware of the risks and benefits associated with the treatment. We encourage patients to talk to their consultants and specialist nurses to discuss if they qualify for this transformative treatment.”

Find out more about the work of KHP Haematology.