CD4 and neoplasm: However, given the diversity of CD4+ T cell functional subtypes (Fig. 1) and the current lack of information regarding potential cross-talk between CAR signalling and CD4+ T cell-intrinsic gene programmes, it is very likely that CD4+ T cell-derived CAR T cells polarised towards non-TH1 phenotypes may also mediate effective anti-tumour immunity in a context-dependent manner.