What is the real role of CD40 in cancer immunotherapy?

The CD40–CD40 ligand (CD40L) system is of pivotal importance in the immune response via interactions between T cells and antigen-presenting cells. Recent reports have demonstrated that CD40 triggering improves tumour immunogenicity. Nonetheless, as discussed here, the implications of the CD40–CD40L system in host–tumour interactions are pleiotropic and should be evaluated carefully before targeting CD40 for antitumour strategies.