World’s first gene-editing therapy for humans approved in UK

Treatment offers relief and possibly a cure for patients with sickle cell disease and one other blood ailment

A therapy for blood disorders has become the first gene-editing treatment to get regulatory approval for use on humans in a breakthrough for the technology, which aims to repair genetic code.

Vertex Pharmaceuticals and Crispr Therapeutics said Britain’s Medicines and Healthcare Products Regulatory Agency (MHRA) approved Casgevy for sickle cell disease and another blood ailment called beta thalassaemia, becoming the first regulator to clear the therapy.

Vertex is the company behind a number of expensive treatments for cystic fibrosis in Ireland.

The treatment will be the first in the world to use Crispr in humans. There are about 2,000 patients eligible for Casgevy in Britain, the companies said. It promises potential relief — and possibly a cure — but US regulators have raised concerns about its safety.


The decision is a big test for a technology that, since its discovery more than a decade ago, has been expected to bring about a revolution in medicine. Two women who developed these “genetic scissors” won the Nobel Prize in chemistry in 2020.

“The move by the MHRA to approve this therapy signals a positive moment in history,” said Helen O’Neill, programme director for reproductive science and women’s health at University College London. “The future of life-changing cures resides in Crispr-based technology.”

In a report published last month, the US Food and Drug Administration’s staff said it wasn’t clear if the companies had enough genetic diversity in their studies to assess the risk that the treatment could make unintended changes to patients’ DNA.

The MHRA conducted a robust review of the available evidence and will continue to closely monitor the treatment, it said.

Casgevy is designed to work by editing the faulty gene in a patient’s bone marrow stem cells. The cells are taken out of the bone marrow, edited in a laboratory and infused back into the patient — after which the results have the potential to be lifelong.

“Gene therapy offers a real chance of cure,” Sara Trompeter, a consultant hematologist at University College London Hospitals, said in a statement to the UK’s Science Media Centre. — Bloomberg