A therapy that would once have been considered a feat of science fiction has reversed aggressive and incurable blood cancers in some patients, doctors report.

The treatment involves precisely editing the DNA in white blood cells to transform them into a cancer-fighting "living drug".

The first girl to be treated, whose story we reported in 2022, is still free of the disease and now plans to become a cancer scientist.

Now eight more children and two adults with T-cell acute lymphoblastic leukaemia have been treated, with almost two thirds (64%) of patients in remission.

T-cells are supposed to be the body's guardians - seeking out and destroying threats - but in this form of leukaemia, they grow out of control.

For those on the trial, chemotherapy and bone marrow transplants had failed. Apart from the experimental medicine, the only option left was to make their death more comfortable.

"I really did think that I was going to die and I wouldn't be able to grow up and do all the things that every child deserves to be able to do," says 16-year-old Alyssa Tapley from Leicester.

She was the first person in the world to have the treatment at Great Ormond Street Hospital and is now enjoying life.

The revolutionary treatment three years ago involved wiping out her old immune system and growing a new one. She spent four months in hospital and couldn't see her brother in case he brought in an infection.

But now her cancer is undetectable and she needs only annual check-ups. Alyssa is doing her A-levels, the Duke of Edinburgh Award, eyeing up driving lessons and planning her future.

"I'm looking into doing an apprenticeship in biomedical science, and hopefully one day I'll go into blood cancer research as well," she said.

Girl with long brown hair and wearing glasses stairs down a microscope in a biology class.

The team at University College London (UCL) and Great Ormond Street Hospital used a technology called base editing.

Bases are the language of life. The four types of base in DNA - adenine (A), cytosine (C), guanine (G) and thymine (T) - are the building blocks of our genetic code. Just as letters in the alphabet spell out words that carry meaning, the billions of bases in our DNA spell out the instruction manual for our body.