Peptide mixture

A method of stimulating the immune system to treat or prevent cancer associated with RAS protein amino acid substitutions in a human or animal subject, the method comprising administering to the subject a peptide mixture suitable for eliciting an immune response in a human or animal subject for treating or preventing cancer in the subject, wherein the peptide mixture comprises a first, second and at least one further peptide, each corresponding to a fragment of the RAS protein,

• wherein each of the first and second peptides comprises a region of at least 8 amino acids which includes position 13 of the RAS protein,
• each of said regions of the first and second peptides independently has at least 6 amino acid residues, other than at said position 13, which are identical to the corresponding region of the RAS protein,
• each of the first and the second peptides has an amino acid substitution at the amino acid corresponding to said position 13, wherein the amino acid substitution of the first peptide is different from the amino acid substitution of the second peptide,
• the at least one further peptide is selected from the group consisting of a peptide comprising a region of at least 8 amino acids which includes position 12 of the RAS protein, wherein each of said regions of the at least one further peptides independently has at least 6 amino acid residues, other than at said position 12, which are identical to the corresponding region of the RAS protein, and wherein there is an amino acid substitution at the amino acid corresponding to position 12 of the RAS protein, and a peptide comprising a region of a least 8 amino acids which includes position 61 of the RAS protein, wherein each of said regions of the at least one further peptides independently has at least 6 amino acid residues, other than at said position 61, which are identical to the corresponding region of the RAS protein, and wherein there is an amino acid substitution at the amino acid corresponding to position 61 of the RAS protein, and combinations thereof,
• in order to elicit an immune response in the subject to treat or prevent cancer.