Recently, Mackensen et al. published their first results from a phase I / IIa study using CLDN6 CAR-T-cells (BNT211, BioNTech SE) with or without a CLDN6-encoding CAR-T cell amplifying RNA vaccine (CARVac) for the treatment of seven pre-treated patients suffering from testicular-, ovarian-, or endometrial cancer, as well as soft-tissue sarcoma (Mackensen et al. 2021). Here, CLDN6 is linked to endometrial cancer.