Gene editing technique is ‘landmark’ in cancer battle

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  • November 7, 2015


[dropcap]A[/dropcap]n innovative new gene editing technique has been tested for the first time on a baby girl with inoperable leukemia.

Gene therapy works by using ‘molecular scissors’ to remove immune cells from a patient’s body and genetically alter them. And, once placed back in the body, they attack cancerous cells. This usually modifies individual cells — but the team at Great Ormond Street Hospital, who worked with the child, were able to develop an ‘off the shelf’ version of the treatment, modifying cells from a healthy donor.

One-year-old Layla had relapsed acute lymphoblastic leukemia (ALL), a cancer of the white blood cells. ALL prevents white blood cells growing and dividing in a functional way, ignoring the normal signals that stop the body from making too many cells.

They continue to divide and never mature, filling the bone marrow with cells and preventing them from making new blood cells. And because they fail to mature, they are unable to fight infections in the way that normal, healthy white blood cells do. The bone marrow is also unable to make red blood cells or platelets, which are used for delivering oxygen around the body and help wounds heal.

he had previously undergone several rounds of chemotherapy, as well as a bone marrow transplant. These treatments are often successful in older patients, but only cure around 25 percent of babies as young as Layla. So when cancerous cells were still detected after chemotherapy, Layla’s parents decided to undergo the gene therapy.

Normally, if cells from another person were injected into bone marrow, the body would recognise the cells as foreign and attack them. So the team used gene editing to disable the gene in the donor cells that recognises other cells as foreign.

The case is the first time the treatment had been tested on a human subject, and has been described as a “landmark” case.

But doctors stressed the technique was far from failsafe.

“We have to be cautious about claiming that this will be a suitable treatment option for all children,” said professor Waseem Qasim, who was head of the team.

Layla has been cancer-free for several months, and has also been able to undertake a bone marrow transplant, which was successful. But cancer can reoccur months, or even years, after a patient is declared ‘cancer-free’. While the new technique is promising, it is unclear whether or not the case is a one-off, nor how gene editing could be used in the future. The molecular scissors used to undertake the work are also at risk of making cuts in the wrong place, potentially turning further cells cancerous.

“We have only used this treatment on one very strong little girl,” said Qasim. “But, this is a landmark in the use of new gene engineering technology and the effects for this child have been staggering.”

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