Gene editing surgery performed at Great Ormond Street Hospital in London has “cured” a two-year-old girl named Layla Richards from a life-threatening cancer. The pioneering surgery was carried out when Layla was just 11 months old, although it will take years before she will be confirmed to be completely cancer-free.

“When doctors mentioned the new gene-editing treatment, there was no doubt for us that it was something we wanted to try. Layla was very sick and we had run out of other options,” said Lisa Richards, Layla’s mother.

Standard treatments failed to work

Layla was three months old when she was diagnosed with acute lymphoblastic leukaemia, detected by vast numbers of immature immune cells in the blood, released by cancerous stem cells from the bone marrow.

At first, Layla was put on standard chemotherapy treatments followed by a bone marrow transplant. Sujith Samarasinghe, a leukaemia specialist at the hospital and one of Layla’s doctors said that the treatment is usually successful, but for children as young as Layla, success rates drop to only 25%.

Within two months, Layla’s condition relapsed and her parents, Lisa and Ashleigh were given the news that nothing more could be done.

During this time, the doctors contacted Waseem Qasim from University College London, a professor in cell and gene therapy who had been developing a groundbreaking treatment for cancer.

Modified donor T cells a silver lining

Prior to Layla’s surgery in July 2015, this gene therapy treatment had only ever been tested on mice in laboratories.

“It was scary to think the treatment had never been used in a human before,” said Layla’s father, Ashleigh Richards, “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.”

Gene therapy involves removing immune cells from a patient’s body for the purpose of genetically engineering them to attack cancerous cells before placing them back into the body. This is in the ideal case, however in Layla’s case, she did not have enough T cells to modify because she was too sick.

Qasim and his team have been modifying donor’s healthy T cells via gene editing so they could be given to hundreds of patients, much like an off-the-shelf treatment. This was the counter measure and the silver lining that Layla’s case needed.

“Molecular scissors” an important tool

Gene editing is revolutionary as such that it allows for some elements of the DNA to be cut away with “molecular scissors”, unlike conventional gene therapy where only adding genes to the DNA was allowed.

The T cells underwent four genetic changes; two of which were to make the cells universal, allowing them to be used in any patient without the risk of being rejected, while the other two were adding signature receptors to seek out and attack the cancer cells. These gene-edited donor T cells were inserted into Layla and worked within weeks.

Qasim’s molecular scissors are known as TALEN proteins, which is an older method, is now being replaced by the new CRISPR method as it is easier and cheaper to create gene-editing tools. Similarly, CRISPR has been used to fight cancer battles on behalf of those who are on the losing end, as in the case of using CRSPR gene-edited T-cells in a patient with lung cancer.

18 months since the surgery, Layla’s condition is in remission. Qasim and his team’s work shows promise and has paved the way for more successful treatments for cancers, as well as other diseases such as inherited cystic fibrosis. MIMS

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