the invention concerns a method for identifying peptide compounds derived from hsp70 , having at least one mutation relative to the hsp70 natural sequence , said compounds bringing about a response t specific of tumours , and the peptide compounds obtainable by said method . the invention also concerns the use of said peptide compounds for performing repeated immunization in a subject so as to interrupt immune tolerance for the corresponding natural peptide . said peptide compounds are useful for preparing a medicine designed in particular for treating cancer optionally in combination with any agent provoking tumour cell stress .