The present invention relates to cancer immunotherapy, in particular to sequence variants of tumor-related antigenic epitope sequences. Namely, the present invention provides a method for identification of microbiota sequence variants of tumor-related antigenic epitope sequences. Such microbiota sequence variants are useful for the preparation of anticancer medicaments, since they differ from self-antigens and, thus, they may elicit a strong immune response. Accordingly, medicaments comprising microbiota sequence variants, methods of preparing such medicaments and uses of such medicaments are provided.
