In June this year, Layla Richards, a one-year-old girl who had been diagnosed with an aggressive form leukaemia at 14 weeks old received a novel treatment at Great Ormond Street Hospital (GOSH) in London. The treatment, based on genome editing, had only hitherto been tested in the laboratory with mice.
Genome editing techniques have been gaining great importance in the current biomedical panorama in recent years. The technique involves modifying or removing specific sequences of cellular DNA to achieve a determined effect. The technique used in this case is known as TALENs (transcription activator-like effector nucleases), which consists of the binding of a DNA cleavage protein domain, i.e. a protein structure that cuts the DNA, to another DNA binding domain to target the desired sequence of the genome.
Given the severity of Layla’s leukaemia, the chemotherapy that she first underwent was ineffective. The novel possibility of genetically modifying the patient’s T-cells (immunological cells) so that they attack the cancer cells cannot be used either in cases as serious as Layla’s, as the patient does not have enough healthy T-cells. As a last resort, the doctors tried a bone marrow transplant to restore her damaged blood cells, but seven weeks after the transplant, the cancer reappeared. After this, the doctors informed the family that there were no more options and that only palliative care remained.
However, Layla’s parents did not want to accept palliative care, and asked that they try any treatment, even if it was experimental. The doctors at GOSH therefore contacted Waseem Qasim, an immunologist at University College London, who was working on an experimental treatment that could be applicable.
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