2012; Chapouly et al. 2015) and CNS leukaemia (Münch et al. 2017). Kinjyo et al. (2019) further showed that the MA cultured with BCP‐ALL cell‐secreted EVs produced VEGF A and promoted BCP‐ALL cell transmigration across endothelial cell monolayers. He further demonstrated engraftment of BCP‐ALL NALM6 leukaemic cells in NSG female mice resulted in compromised BBB integrity, as evidenced by increased Evans Blue dye incorporation in the brains of NALM6‐engrafted mice compared to controls following intravenous dye injection (Kinjyo et al. 2019). This evidence concerns the gene OPN1SW and acute lymphoblastic leukemia.