The present invention pertains to novel immunogenic peptide sequences that can be used as vaccines in the treatment of cancer diseases such as brain cancers and specifically glioma. The cancer vaccines of the invention are designed based on the K27M mutated variant of the human Histone 3. Provided are further fusion proteins comprising the sequences of the cancer vaccines, nucleic acids encoding such vaccines, such as RNA vaccines, and vectors and host cells comprising these sequences. Furthermore the invention pertains to T cells and T cell receptors binding the cancer vaccines of the invention, preferably when presented by the human Major Histocompatibility Complex (MHC). The peptide immunogens of the invention elicit a HLA restricted immune response and therefore are of use in the treatment of cancer diseases, in particular glioma. Further aspects of the invention pertain to pharmaceutical compositions as well as diagnostic methods based on the immunogenic capacity of the disclosed peptides.