Owing to the successful development of anti-FRβ antibody m909, Low et al. incorporated it in the development of chimeric antigen receptor (CAR) T cell-therapy to treat AML, as approximately 70% of all AML tumours upregulate FRβ.11,61,62 This treatment consists of attaching the single-chain variable fragment (scFv) of a monoclonal antibody (in this case m909) to T cell receptor signalling domains and in doing so, a patient's own T cells can bind to antigen-positive tumours with antibody-like affinity.11 Here, FOLR2 is linked to acute myeloid leukemia.