Chimeric antigen receptors (CARs) are antibody fragments linked to activation molecules, that recognise molecules specifically present on the surface of cancer cells. These CAR complexes are genetically engineered into the immune cell (T cell or NK cell) genome and expressed on their surface. When the antibody fragment engages with the cancer cell, the activation molecules signal the immune cell to kill the cancer cell or endometriosis tissues by releasing toxic granules or cytokines that cause cell death. They keep killing target cells until exhausted. We also knock out genes in our immune cells that can inhibit their killing function in the tumour microenvironment.