Genetic engineering saved a person from leukemia for the first time
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Genetically modified cells helped save a terminally ill child from leukemia for the first time. This is reported by New Scientist (Gene editing saves girl dying from leukaemia in world first).
At the age of three months, Leila was diagnosed with acute lymphoblastic leukemia, a malignant disease in which cancer stem cells of the bone marrow release immature lymphoid cells into the blood in huge quantities. The girl was immediately treated with standard procedures (chemotherapy and bone marrow transplantation), but at her age, this therapy is successful only in a quarter of cases, and Leila was unlucky.
Despite the presence of cancer cells after chemotherapy sessions, doctors decided to transplant bone marrow, hoping that the immune cells in the donor organ would defeat leukemia – but this did not happen either. Two months later, Leila's condition worsened again, then the doctors turned to Waseem Qasim from University College London, who is developing genetic ways to fight cancer.
In general terms, therapy consists in taking immune cells from the patient's body, genetically modifying them to fight cancer cells and returning them back. Sometimes the CAR19 receptor gene is added there, which causes cytotoxic T lymphocytes (T cells) to search for and kill cells with CD19 protein on the surface - they cause acute lymphoblastic leukemia.
However, Layla was too small and sick to provide such T cells. Therefore, Kasim had to use the material obtained from another healthy donor and modified so as to treat hundreds of patients. In order for these cells not to perceive all the cells in the recipient's body as foreign and not attack them, gene editing with the help of "molecular scissors" – TALEN proteins was required.
Kasim cut out two genes: one responsible for the receptor that recognizes the recipient's cells as foreign, and another gene, the absence of which made the donor T-cells invisible to the antibodies that Leila took (as a drug that suppresses her own immune system).
At that moment, the modified UCART19 T cells were tested only on mice, but since the girl was dying, her parents decided to take a chance. Despite the possibility of incorrect operation of molecular scissors (sometimes they cut out the wrong genes, and the donor cells themselves turn into cancer cells), the treatment was successful: T-cells successfully overcame lymphoblasts.
Three months later, Leila had a bone marrow transplant again: healthy immune cells recognized UCART19 cells as foreign and destroyed them. Thus, now there are no genetically modified cells left in the girl's body.
It's too early to talk about Leila's complete recovery, but she is alive and well. Full-fledged clinical trials of UCART19, which may prove that the successful results of the London girl were not accidental, will begin in 2016.
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06.11.2015