Gene editing breakthrough in treating baby's leukaemia

"Baby girl is first in the world to be treated with 'designer immune cells'," The Guardian reports.

Pioneering work carried out at Great Ormond Street Hospital made use of a new technique known as genome editing.

The girl, one-year-old Layla Richards, developed acute lymphoblastic leukaemia (ALL) when she was five months old.

ALL is cancer of the white blood cells and although it is generally rare, it is one of the most common childhood cancers, affecting around 1 in 2,000 children.

The outlook for ALL is usually good, with around 85% of children achieving a complete cure. However, this was not the case with Layla, as she failed to respond to conventional treatments. The staff treating Layla at Great Ormond Street Hospital sought permission to try a new technique, previously only used in mice, called genome editing.

What is genome editing?

Genome editing uses a range of molecular techniques to make changes to the genome (the complete set of DNA) of individual organisms.

Genome editing can:

• modify genetic information to create new characteristics
• remove regions from genomes, such as those that can cause genetic diseases
• add genes from other organisms to specific locations within a genome

The editing process modifies the actual nucleotides – the "letters" of DNA (A, T, C, G) – of genetic code.

In Layla's case, proteins known as Transcription Activator-Like Effector Nucleases (TALENs), were used as a kind of "molecular scissors" to modify the DNA inside a batch of donated T-cells (an immune cell).

The T-cells were modified to seek out and destroy the abnormal leukaemia cells, while also becoming resistant to the chemotherapy drugs Layla was taking.

Layla responded well to the treatment and is now back home with her family.

Researchers were keen to stress that it is too soon to say if Layla has been completely cured of the cancer, and there could still be long-term complications. 

However, this should be regarded as truly pioneering work that could lead to a new generation of treatments for a range of conditions.