Immunotherapy with genetically modified T cells: unintended exposure and potential risks

The amount of research into genetically modified (GM) T cell cancer therapies has been growing in recent years. In such therapies, T cells from the patient are genetically modified outside the body (ex vivo) to enable them to recognise cancer cells so that when they are returned to the patient they will fight the cancer. The environmental risk assessment of gene therapy studies includes consideration of the risks of possible third party exposure to the GMO. GM T cells can be transferred from the patient to third parties via needlestick injuries, donated organs, tissues or blood, across the placenta (to the unborn child), via mother’s milk and via semen (sexual contact). To gain a better understanding of the levels of possible exposure and the potential risks, COGEM commissioned a literature study.

Based on the information in the research report and the scientific literature, COGEM observes that GM T cell therapy can, in specific cases, present a potential risk to third parties. The risk of exposure via needlestick injuries and via semen and donated blood is considered to be negligible. However, exposure to GM T cells via donated tissues, organs or stem cells, across the placenta and via breastfeeding can present a potential risk. The consequences can be serious, but are hard to predict and depend on the type of genetic modification to the T cell. More research is needed before any definitive statements can be made. In addition, a clear understanding is needed of which measures could be required to prevent transfer and where the responsibility for such measures should lie. COGEM observes that the relevant authorities and institutions should be aware of the possible risks and that patients eligible for GM T cell therapy should be informed of the possible risks in combination with pregnancy, breastfeeding and organ, tissue or stem cell donation.