We found that the levels of cytokines, including IL-2, IFN-γ and TNF-α, were very low in tumours treated with AXL-CAR T cell monotherapy (Fig. 6b), suggesting that mono-CAR T cells were hypofunctional and/or that the absolute number of AXL-CAR T cells responding to the tumour cells was low. This evidence concerns the gene IL2 and neoplasm.