“This leukemia was so aggressive that such a response is almost a miracle,” said Professor Paul Veys, director of the marrow transplant unit bone of Great Ormond Street Hospital (GOSH) in London, where Richards was treated Layla.

The baby carrier was diagnosed acute lymphoblastic leukemia, the most common form of childhood leukemia at the age of 14 weeks only.

The baby was treated with chemotherapy and bone marrow transplant, but the cancer had reappeared and doctors had told parents to consider palliative and end of life.

Doctors then proposed to the family an experimental treatment being developed, which sees the doctors change the white blood cells from a healthy donor blood cells so that they can overcome the resistant leukemia drug.

“The doctors explained that even if we could try the treatment, there was no guarantee it would work, but we asked for this to be the case,” said the father of Layla, Ashleigh Richards, 30.

Layla received a small injection of genetically modified cells called UCART19 cells and a few weeks later, the specialists announced to parents that the treatment had worked.

The Doctors stressed that this potentially promising experimental technique had been used only once and the results were to be reproduced.

“We only used this treatment on a small, very strong girl, and we must be careful in saying it will be an appropriate treatment option for all children, “said Waseem Qasim, cell therapy professor and physician specializing in genetics and immunology from the GOSH hospital.

“But this milestone in the use of new genetic technologies and the effects for that child were staggering,” he added. “If this is repeated, it could mean a great step forward in the treatment of leukemia and other cancers.”