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Gene editing saves girl dying from leukemia in world first. Total remission in 5 mos, after chemotherapy and bone marrow transplant failed.

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For the first time ever, a person’s life has been saved by gene editing.

One-year-old Layla was dying from leukaemia after all conventional treatments failed. “We didn’t want to give up on our daughter, though, so we asked the doctors to try anything,” her mother Lisa said in a statement released by Great Ormond Street Hospital in London, where Layla (pictured above) was treated.

And they did. Layla’s doctors got permission to use an experimental form of gene therapy using genetically engineered immune cells from a donor. Within a month these cells had killed off all the cancerous cells in her bone marrow.

It is too soon to say she is cured, the team stressed at a press conference in London on 5 November. That will only become clear after a year or two. So far, though, she is doing well and there is no sign of the cancer returning. Other patients are already receiving the same treatment.

Layla was diagnosed with acute lymphoblastic leukaemia when she was just three months old, a disease in which cancerous stem cells in the bone marrow release vast numbers of immature immune cells into the blood. She was immediately taken to Great Ormond Street to start the standard treatment of chemotherapy followed by a bone marrow transplant to restore the immune system.

In older children, this treatment is usually successful, says Sujith Samarasinghe, a leukaemia specialist at the hospital and one of Layla’s doctors. But for children as young as Layla, the cure rates are only 25 per cent.

Layla was one of the unlucky ones. Cancerous cells were still detectable after the chemotherapy. Despite this, it was decided to go ahead with a bone marrow transplant. “We hoped for a graft-versus-leukaemia reaction,” says Paul Veys, head of bone marrow transplants at the hospital. This is where immune cells in the donor bone marrow attack the cancer – but this failed too.


Conventional gene therapy can only be used to add genes to DNA. But with gene editing, specific DNA sequences can be cut with “molecular scissors”, introducing mutations that disable a particular gene. Qasim’s molecular scissors were of a kind known as TALEN proteins.

But there was still another problem to overcome. The recipient’s immune system also recognises non-matched T-cells as foreign and will attack them. In leukaemia patients, this is not a problem because they are given drugs that destroy their immune system. Except, one of these drugs – an antibody – also destroys donor T-cells. So Qasim’s team also disabled a second gene in the donor T-cells, which made them invisible to the antibody.

At the time that Qasim was contacted by Layla’s doctors, his engineered T-cells, called UCART19 cells and developed in collaboration with New York biotech company Cellectis, had only ever been tested in mice. “It was scary to think the treatment had never been used in a human before,” said Layla’s father Ashleigh, “but there was no doubt we wanted to try the treatment. She was sick and in lots of pain, so we had to do something.” And it worked within weeks.

This is only the second time that gene-edited cells have been used in people. The first ever trial involved modifying T-cells in people with HIV to make them more resistant to the virus, although these participants were not in immediate danger of dying.

This did not use CRISPR but it shows we've only scratched the surface for applications of gene editing.

Top Reddit comments:

Doctors got permission to use an experimental form of gene therapy using genetically engineered immune cells from a donor. Within a month these cells had killed off all the cancerous cells in her bone marrow.

People with terminal illnesses are the ones who will lead us into the medical revolution because they are willing to try anything for a cure. It's both depressing and encouraging.

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