Although checkpoint inhibition seeks to improve the ability of endogenous T-cells to clear tumours, adoptive transfer can take one of two approaches; ex-vivo expansion of a patients' own tumour-infiltrating lymphocytes (TILs) which are then infused back into the patient [8], or generation of T-cells genetically modified to target the tumour, either through introduction of tumour-specific T-cell receptors (TCRs) or chimeric antigen receptors (CARs) [9,10], which replace the antigen recognition domain of a TCR with the epitope binding moiety of an antibody [11]. The gene discussed is CARS1; the disease is neoplasm.