Gastrin releasing peptide compounds

A compound of the general formula:

• M-N—O—P-G
• wherein
• M is a metal chelator of formula 8:
• optionally complexed with a radionuclide, wherein
• R1 is hydrogen, C1-C20 alkyl optionally substituted with one or more carboxy groups, C3-C10 cycloalkyl, C4-C20 cycloalkylalkyl, aryl, arylalkyl or the two R1 groups, taken together, form a straight or cyclic C2-C10 alkylene group or an ortho-disubstituted arylene;
• R2 is hydrogen, carboxy, or an optionally substituted group selected from C1-C20 alkyl, C3-C10 cycloalkyl, C4-C20 cycloalkylalkyl, aryl, arylalkyl, a group bearing an acidic moiety, and a group bearing an amino moiety, each of which may be further optionally substituted with functional groups selected from carboxy and amino groups which allow conjugation with a suitable molecule able to interact with physiological systems via an amide bond;
• R3, R4 and R5, which are the same or different, are hydrogen, carboxy, or an optionally substituted group selected from C1-C20 alkyl, C3-C10 cycloalkyl, C4-C20 cycloalkylalkyl, aryl, arylalkyl, a group bearing an acidic moiety and a group bearing an amino moiety, each of which may be further optionally substituted with functional groups selected from carboxy and amino groups which allow conjugation with a suitable molecule able to interact with physiological systems via and amide bond;
• and
• FG, are the same or different, are carboxy, —PO3H2 or —RP(O)OH groups, wherein R is hydrogen, or an optionally substituted group selected from C1-C20 alkyl, C3-C10 cycloalkyl, C4-C20 cycloalkylalkyl, aryl, arylalkyl, a group bearing an acidic moiety and a group bearing an amino moiety, each of which may be further optionally substituted with functional groups selected from carboxy and amino groups which allow conjugation with a suitable molecule able to interact with physiological systems via an amide bond;
• wherein for the general formula only:
• N is absent, an alpha amino acid, a non-alpha amino acid with a cyclic group or other linking group;
• O is an alpha amino acid or a non-alpha amino acid with a cyclic group;
• P is absent, an alpha amino acid, a non-alpha amino acid with a cyclic group, or other linking group;
• and
• G is a GRP receptor targeting peptide,
• wherein at least one of N, O or P is a non-alpha amino acid with a cyclic group.