NZ 602824 Disclosed is a composition for delivering a therapeutic or diagnostic agent to a disease site in a mammal comprising a therapeutically or diagnostically effective amount of a pharmaceutical composition comprising the therapeutic or diagnostic agent coupled to a SPARC-binding-peptide (SBP) and a pharmaceutically acceptable carrier, wherein the SBP comprises SEQ ID NO: 2 as defined in the complete specification. Also disclosed is the use of said composition in the treatment of a tumour.