The present invention relates to antibodies and immunogenic peptides specific to misfolded prion protein (PrP e g PrPSc) and uses thereof. The immunogenic peptides comprise the amino acid sequence tyrosine-methionine-leucine (YML). The antibodies or peptides can be used for treating or preventing a disease or disorder associated with misfolded PrP including cancer. In particular a IgM monoclonal antibody designated 1A1 was generated using a peptide consisting of the sequence GGYMLGS (i e SEQ ID NO 8) which corresponds to residues 126-132 of human PrP 1A1 recognizes misfolded PrP but not normal PrP.