Early Treg suppression by a listeriolysin-O-expressing E. coli vaccine in heterologous prime-boost vaccination against cancer

► Heterologous vaccination against cancer is more immunogenic than homologous. ► Early regulatory T cell suppression is the key to enhanced antigen-specific CTL. ► Heterologous vaccination improves the efficacy of Treg-modulating E. coli vaccine. ► Heterologous vaccination against cancer in the therapeutic setting is feasible.