A new treatment that uses genetic manipulation to tailor genes and create modified immune cells programmed to seek out and destroy drug-resistant leukemia has been used in a hospital in the UK
A three-month-old baby girl diagnosed with an aggressive form of bone marrow cancer called acute lymphoblastic leukemia, given a cycle of chemotherapy, a bone marrow transplant, became a part of a clinical trial all before her first birthday- but cancer relapsed! As doctors knew the success rate for such aggressive form of this disease at this age is not more than 25%, doctors lost all hope and was preparing for her to perish. But doctors wanted to try one last option as they have heard about Dr. Waseem Qasim of University College London, who was working on a specific mode of gene therapy to treat cancer.
The therapy involved creating a modified immune cell with an ability to attack cancerous bone marrow cell and destroy them. This programs the T-cells to seek out and kill any cells with a protein called CD19 on their surface – which is found on the cells that cause acute lymphoblastic leukemia. This genetically modified T-cell was created by tools of “molecular scissor” called Transcription activator-like effector nucleases (TALENs) to modify a gene in CAR19 cells and converting it to Universal CAR19 (UCART19) cell line, those are meant to attack cancerous cells. In this course, the major problem remains with the recognition of those engineered cells as foreign by the host immune system. In leukemia patients, this is not a problem because they are given drugs that destroy their immune system. Except, one of these immunosuppressant drugs – an antibody – also destroys donor T-cells. So they also disabled a second gene in the donor T-cells, which made them invisible to the antibody.
The treatment consisted of 1ml of UCART19 cells delivered intravenously line in around 10 minutes. After the cells had been delivered, the patient spent in isolation to protect her from infections while her immune system was extremely weak. After patient showed up with signs of the immune response in the form of rashes etc, doctors became sure that the treatment is working and the patient is ready for another round of bone marrow transplant to replace her blood cells. Though much clinical evidence for the effectiveness of this therapy was not ready in the hand of researchers at that moment, but keeping in mind the pain and suffering of the baby they decided to try this therapy and it worked like wonder. She survived through the aggression of the disease and showed no symptom of relapse even after3 months of treatment. To the much hope of the baby’s family, when bags of chemo did not work, an ml of injection did the trick. Though it is too early to declare her to be cancer free but this success to counter the aggression of disease is monumental
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.
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