The ligand CD40LG and its CD40 receptor are some of the most critical molecular pairs of the stimulatory immune checkpoints (Tang et al. 2021). Gallagher et al. found that the activation of the CD40LG/CD40 pathway suppressed the growth of ovarian cancer cells but promoted their apoptosis (Gallagher et al. 2002). Here, CD40 is linked to ovarian cancer.