Details for Patent: 5,807,538
✉ Email this page to a colleague
| Title: | Technetium-99m labeled peptides for imaging inflammation |
| Abstract: | This invention relates to radiolabeled peptides and methods for producing such peptides. Specifically, the invention relates to technetium-99m (Tc-99m) labeled leukocyte-binding peptides, methods and kits for making such peptides, and methods for using such peptides to image sites of infection and inflammation in a mammalian body. |
| Inventor(s): | Dean; Richard T. (Bedford, NH), Lees; Robert S. (Brookline, MA), Buttram; Scott (Derry, NH) |
| Assignee: | Diatide, Inc. (Londonderry, NH) |
| Filing Date: | Jun 07, 1995 |
| Application Number: | 08/484,774 |
| Claims: | 1. A complex formed by reacting a reagent comprising a leukocyte-binding chemotactic peptide covalently linked to a radiolabel-binding moiety selected from the group consisting of: wherein Cp is a protected cysteine and (aa) is any primary .alpha.- or .beta.-amino acid; a radiolabel-binding moiety comprising a single thiol-containing moiety having a formula wherein A is H, HOOC, H.sub.2 NOC, or NHOC; B is H, SH, or NHR", where R" is H, lower alkyl, or --C.dbd.O; X is SH or NHR", where R" is H, lower alkyl or --C.dbd.O; R and R' are independently H or lower alkyl; n is 0, 1, or 2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, X is SH and n is 0 or 1; and wherein the thiol moiety is in the reduced form; and a radiolabel-binding moiety of formula ##STR3## wherein each R is independently H, lower alkyl having one to six carbon atoms, phenyl, or phenyl substituted with lower alkyl or lower alkoxy, and wherein each n is independently one or 2, with technetium-99m in the presence of a reducing agent, wherein the complex is capable of accumulating at a site of inflammation in a mammalian body. 2. The complex of claim 1, wherein the reducing agent is selected from the group consisting of a dithionite ion, a stannous ion, a solid-phase reducing agent, and a ferrous ion. 3. The complex of claim 1, formed by ligand exchange of a prereduced technetium-99m complex. 4. A method for preparing an imaging agent for detecting infection or inflammation in a mammalian body comprising the steps of a) providing a reagent comprising a leukocyte-binding chemotactic peptide covalently linked to a radiolabel-binding moiety selected from the group consisting of wherein Cp is a protected cysteine and (aa) is any primary .alpha.- or .beta.-amino acid; a radiolabel-binding moiety comprising a single thiol-containing moiety having a formula wherein A is H, HOOC, H.sub.2 NOC, or NHOC; B is H, SH, or NHR", where R" is H, lower alkyl, or --C.dbd.O; X is SH or NHR", where R" is H, lower alkyl or --C.dbd.O; R and R' are independently H or lower alkyl; n is 0, 1, or 2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, X is SH and n is 0 or 1; and wherein the thiol moiety is in the reduced form; and a radiolabel-binding moiety of formula ##STR4## wherein each R is independently H, lower alkyl having one to six carbon atoms, phenyl, or phenyl substituted with lower alkyl or lower alkoxy, and wherein each n is independently one or 2, and b) reacting the reagent with technetium-99m in the presence of a reducing agent. 5. The method of claim 4, wherein the reducing agent is selected from the group consisting of a dithionite ion, a stannous ion, a ferrous ion, and a solid-phase reducing agent. 6. A method for preparing an imaging agent for detecting infection or inflammation in a mammalian body comprising the steps of a) providing a reagent comprising a leukocyte-binding chemotactic peptide covalently linked to a radiolabel-binding moiety selected from the group consisting of wherein Cp is a protected cysteine and (aa) is any primary .alpha.- or .beta.-amino acid; a radiolabel-binding moiety comprising a single thiol-containing moiety having a formula wherein A is H, HOOC, H.sub.2 NOC, or NHOC; B is H, SH, or NHR", where R" is H, lower alkyl, or --C.dbd.O; X is SH or NHR", where R" is H, lower alkyl or --C.dbd.O; R and R' are independently H or lower alkyl; n is 0, 1, or 2; and where B is NHR", X is SH and n is 1 or 2; where X is NHR", B is SH and n is 1 or 2; where B is H, X is SH and n is 0 or 1; and wherein the thiol moiety is in the reduced form; and a radiolabel-binding moiety of formula ##STR5## wherein each R is independently H, lower alkyl having one to six carbon atoms, phenyl, or phenyl substituted with lower alkyl or lower alkoxy, and wherein each n is independently one or 2, and b) labeling the reagent with technetium-99m by ligand exchange of a prereduced technetium-99m complex. 7. A complex formed by reacting technetium-99m with a reagent comprising a leukocyte-binding chemotactic peptide covalently linked to a radiolabel-binding moiety, wherein the technetium-99m complexed radiolabel-binding moiety has a net charge of -1, and wherein the complex is capable of accumulating at a site of inflammation in a mammalian body. 8. The complex of claim 7, formed by reacting the reagent with technetium-99m in the presence of a reducing agent. 9. The complex of claim 8, wherein the reducing agent is selected from the group consisting of a dithionite ion, a stannous ion, a solid-phase reducing agent, and a ferrous ion. 10. The complex of claim 7 formed by reacting the reagent with technetium-99m by ligand exchange of a prereduced technetium-99m complex. 11. A method for preparing an imaging agent for detecting infection or inflammation in a mammalian body comprising the steps of a) providing a reagent comprising a leukocyte-binding chemotactic peptide covalently linked to a radiolabel-binding moiety capable of forming a complex with technetium-99m having a net charge of -1; and b) labeling the reagent with technetium-99m by ligand exchange of a prereduced technetium-99m complex. 12. A complex formed by reacting technetium-99m with a reagent comprising a chemotactic peptide which binds to leukocytes covalently linked to a radiolabel-binding moiety, wherein the technetium-99m and the radiolabel-binding moiety form a neutral complex, and wherein the complex is capable of accumulating at a site of inflammation in a mammalian body. |
