The present invention relates to compositions, systems, kits, and methods for generating and using ALDH1 antigen-pulsed dendritic cells (DCs). In certain embodiments, initial DCs are pulsed in vitro with a composition comprising ALDH1A1 and/or ALDH1A3 immunogenic peptide(s) to generate ALDH1 antigen-pulsed DCs, wherein the composition is free of tumor cells, cell lysates, and full-length ALDH1 proteins. In some embodiments, the ALDH1 antigen-pulsed DCs are administered to a subject in order to at least partially treat cancer (e.g., to kill at least some cancer stem cells in the subject).