|Title:||Technetium-99m labeled peptides for imaging|
|Abstract:||The invention relates to radiolabeled imaging of a mammalian body. The invention in particular provides for reagents labeled with technetium-99m for such imaging. The invention provides peptides which bind Tc-99m and which can be targeted to specific sites within a mammalian body.|
|Inventor(s):||Dean; Richard T. (Bedford, NH), McBride; William (Manchester, NH), Buttram; Scott (Derry, NH)|
|Assignee:||Diatech, Inc. (Londonderry, NH)|
1. A composition comprising a peptide reagent for preparing an imaging agent for imaging target sites within a mammalian body, wherein the peptide reagent is comprised of a
peptide of between 4 and 100 amino acid residues that is covalently attached to a non-Tc-99m complexing Tc-99m complexing moiety comprising a single thiol group, and a stannous ion.
2. A kit for preparing a radiopharmaceutical preparation, said kit comprising a sealed vial containing a predetermined quantity of a peptide reagent according to claim 1 and a sufficient amount of reducing agent to label said compound with Tc-99m.
3. A method for radiolabeling a peptide reagent to prepare an imaging agent for imaging target sites within a mammalian body, wherein the reagent is comprised of a peptide of between 4 and 100 amino acid residues that is covalently attached to a non-Tc-99m complexed Tc-99m complexing moiety comprising a single thiol group, the method comprising reacting the peptide reagent with Tc-99m in the presence of a reducing agent.
4. The method of claim 3, wherein the reducing agent is selected from the group of a dithionite ion, a stannous ion, or a solid-phase reducing agent.
5. The method of claim 3 wherein the peptide reagent is reacted with Tc-99m by contacting the peptide with Tc-99m in a reduced form.
6. The method of claim 3 wherein the peptide reagent and the reducing agent are packaged in a vial and reacted with .sup.99m TcO.sub.4 -.
7. The method of claim 6 wherein the reducing agent is stannous ion.
8. The method of claim 3 wherein the Tc-99m complexing moiety comprises a single thiol-containing moiety having the formula:
A is H, HOOC, H.sub.2 NOC, --NHOC or --OOC;
B is H, SH, --NHR.sup.3 or --NH--;
X is H, SH, --NHR.sup.3 or --NH--;
R.sup.1, R.sup.2 and R.sup.3 are independently H or lower straight or branched chain or cyclic alkyl;
n is 0, 1 or 2; and
where B is --NHR.sup.3 or --NH--, X is SH, and n is 1 or 2;
where X is --NHR.sup.3 or --NH--, B is SH, and n is 1 or 2;
where B is H, A is HOOC, H2NOC, --NHOC, --OOC, X is SH, and n is 0 or 1;
where A is H, then where B is SH, X is --NHR.sup.3 or --NH-- and where X is SH, B is --NHR.sup.3 or --NH--;
where X is H, A is HOOC, H.sub.2 NOC, --NHOC, --OOC and B is SH;
where B is SH and X is SH, n is not 0;
and wherein the thiol is in the reduced form and the moiety is covalently linked to the peptide.
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