| Peptide-based multimeric targeted contrast agents -> Monitor Keywords |
|
|
 
Peptide-based multimeric targeted contrast agentsRelated Patent Categories: Chemistry: Natural Resins Or Derivatives; Peptides Or Proteins; Lignins Or Reaction Products Thereof, Peptides Of 3 To 100 Amino Acid Residues, 8 To 10 Amino Acid Residues In Defined SequencePeptide-based multimeric targeted contrast agents description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070185311, Peptide-based multimeric targeted contrast agents. Brief Patent Description - Full Patent Description - Patent Application Claims
CLAIM OF PRIORITY [0001] This application is a continuation of U.S. application Ser. No. 11/098,665, filed Apr. 4, 2005, which is a continuation of U.S. application Ser. No. 10/209,183, filed Jul. 30, 2002, now abandoned, which claims priority to U.S. Provisional Application Ser. No. 60/308,721, filed Jul. 30, 2001, and is related to co-pending U.S. application Ser. No. 10/209,172, filed Jul. 30, 2002, now U.S. Pat. No. 6,991,775, and to co-pending U.S. application Ser. No. 10/786,791, filed Feb. 25, 2004, all of which are incorporated herein by reference in their entirety. TECHNICAL FIELD [0002] This invention relates to contrast agents for diagnostic imaging, and more particularly to peptide-targeted, multimeric contrast agents, wherein a peptide functions as a targeting group and a point of attachment for one or more chelates at both the amino and carboxy termini of the peptide. BACKGROUND [0003] Diagnostic imaging techniques, such as magnetic resonance imaging (MRI), X-ray, nuclear radiopharmaceutical imaging, ultraviolet-visible-infrared light imaging, and ultrasound, have been used in medical diagnosis for a number of years. Contrast media additionally have been used to improve or increase the resolution of the image or to provide specific diagnostic information. [0004] To be effective, the contrast media must interfere with the wavelength of electromagnetic radiation used in the imaging technique, alter the physical properties of tissue to yield an altered signal, or, as in the case of radiopharmaceuticals, provide the source of radiation itself. MRI and optical methods are unique among imaging modalities in that they yield complex signals that are sensitive to the chemical environment. While the signal from X-ray or radionuclide agents remains the same whether agents are free in plasma, bound to proteins or other targets, or trapped inside bone, certain contrast agents for MRI and optical imaging will have different signal characteristics in differing physiological environments. It is important that the contrast agent be sufficiently sensitive and present at high enough concentration so that signal changes can be observed. [0005] Complexes between gadolinium or other paramagnetic ions and organic ligands are widely used to enhance and improve MRI contrast. Gadolinium complexes increase contrast by increasing the nuclear magnetic relaxation rates of protons found in the water molecules that are accessible to the contrast agents during MRI (Caravan, P., et al., R. B. Chem. Rev. 99, 2293 (1999)). The relaxation rate of the protons in these water molecules increases relative to protons in other water molecules that are not accessible to the contrast agent. This change in relaxation rate leads to improved contrast of the images. In addition, this increase in relaxivity within a specific population of water molecule protons can result in an ability to collect more image data in a given amount of time. This in turn results in an improved signal to noise ratio. [0006] Imaging may also be performed using light, in which case an optical dye is chosen to provide signal. In particular, light in the 600-1300 nm (visible to near-infrared) range passes relatively easily through biological tissues and can be used for imaging purposes. The light that is transmitted through, or scattered by, reflected, or re-emitted (fluorescence), is detected and an image generated. Changes in the absorbance, reflectance, or fluorescence characteristics of a dye, including an increase or decrease in the number of absorbance peaks or a change in their wavelength maxima, may occur upon binding to a biological target, thus providing additional tissue contrast. In some situations, for example the diagnosis of disease close to the body surface, UV or visible light may also be used. [0007] A need persists for contrast agents that can deliver sufficient concentrations of the imaging moiety to the target to improve the sensitivity of the imaging process as well as contrast agents that have a sufficient half-life in vivo. SUMMARY [0008] The invention is based on peptides and peptide-targeted multimeric contrast agents for MR, optical, and radionuclide imaging, wherein a single peptide can function both as a targeting group and a point of attachment for one or more chelates at both the N- and C-termini, either directly or via an optional intervening linker. Surprisingly, contrast agents of the invention maintain binding affinity for biological targets such as fibrin and high relaxivity. Agents of the invention have a sufficient half-life following in vivo administration such that effective imaging studies can be performed. [0009] In one aspect, the invention features purified peptides that include the amino acid sequence: P*-Y*-X.sub.1*-L* (SEQ ID NO:1), wherein P* is a proline or a non-natural derivative thereof, Y* is a tyrosine or a non-natural derivative thereof, X.sub.1* is G or D or a non-natural derivative of G or D; L* is a leucine or a non-natural derivative thereof, and wherein at least one of P*, Y*, X.sub.1*, and L* is a non-natural derivative of the respective amino acid. X.sub.1* can be G or D and L* can be leucine. In some embodiments, P* is proline or 4-hydroxyproline, and Y* is tyrosine or a non-natural derivative of tyrosine substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO.sub.2. Compounds of the invention can include such peptides linked to a thrombolytic agent. [0010] In another aspect, the invention features purified peptides that include the amino acid sequence X.sub.1-X.sub.2-C-P*-Y*-X.sub.3-L-C-X.sub.4-X.sub.5-X.sub.6 (SEQ ID NO:2), wherein: P* is a proline or a non-natural derivative thereof, Y* is a tyrosine or a non-natural derivative thereof, X.sub.1 is selected from the group consisting of W, Y, F, S, Bip, Hx, Dpr, Cy, Gu, Ad, Hfe, 3-Pal, 4-Pal, DopaMe2, nTyr, dW, dF, F(3/4*), and Y(3*), wherein F(3/4*) is a phenylalanine substituted at either the 3 or the 4 position with a moiety selected from the group consisting of CH.sub.3, CF.sub.3, NH.sub.2, CH.sub.2NH.sub.2, CN, F, Cl, Br, I, Et, and OMe, and wherein Y(3*) is a tyrosine substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO.sub.2; X.sub.2 is selected from the group consisting of E, H, dE, S, H(Bzl), 2-Pal, Dpr, and Th; X.sub.3 is selected from the group consisting of G and D; X.sub.4 is selected from the group consisting of H, F, Y, and W; X.sub.5 is selected from the group consisting of I, L, V, N, Bpa, Bal, Hfe, Nle, Tle, Nval, Phg, Cha, Taz, Fua, Th, 4-Pal, and F(3/4*), wherein F(3/4*) is a phenylalanine substituted at either the 3 or the 4 position with a moiety selected from the group consisting of CF.sub.3, Et, iPr, and OMe; X.sub.6 is selected from the group consisting of N, Q, I, L, and V, or X.sub.6 is not present; and wherein at least one of X.sub.1, X.sub.2, X.sub.5, P*, and Y* is a non-natural derivative of an amino acid. For example, P* can be proline or 4-hydroxyproline, and Y* can be tyrosine or a non-natural derivative of tyrosine substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO.sub.2. The purified peptides can be capable of forming a disulfide bond under non-reducing conditions and can have specific binding affinity for fibrin. In some embodiments, the peptides include a disulfide bond. Compounds of the invention can include such peptides linked to a thrombolytic agent. [0011] The invention also features purified peptides having an amino acid sequence selected from the group consisting of W-dE-C-P(4-OH)-Y(3-Cl)-G-L-C-W-I-Q (SEQ ID NO:4), Y-dE-C-P(4-OH)-Y(3-Cl)-G-L-C-Y-I-Q (SEQ ID NO:5), Y-dE-C-P(4-OH)-Y(3-Cl)-G-L-C-W-I-Q (SEQ ID NO:6), W-dE-C-P(4-OH)-Y(3-Cl)-G-L-C-Y-I-Q (SEQ ID NO:7), W-dE-C-P(4-OH)-Y(3-Cl)-D-L-C-W-I-Q (SEQ ID NO:8), Y-dE-C-P(4-OH)-Y(3-Cl)-D-L-C-Y-I-Q (SEQ ID NO:9), Y-dE-C-P(4-OH)-Y(3-Cl)-D-L-C-W-I-Q (SEQ ID NO:10), W-dE-C-P(4-OH)-Y(3-Cl)-D-L-C-Y-I-Q (SEQ ID NO:11), F(4-OMe)-H-C-P(4-OH)-Y(3-Cl)-D-L-C-H-I-L (SEQ ID NO:12), Y-H-C-P(4-OH)-Y(3-Cl)-G-L-C-W-I-Q (SEQ ID NO:13), W-dE-C-P-Y(3-Cl)-G-L-C-W-I-Q (SEQ ID NO:14), W-dE-C-P(4-OH)-Y-G-L-C-W-I-Q (SEQ ID NO:15), and F-H-C-P-(4-OH)-Y(3-Cl)-D-L-C-H-I-L (SEQ ID NO:16). The peptides can be capable of forming a disulfide bond under non-reducing conditions, and in some embodiments, the peptides include a disulfide bond. The peptides can have specific binding affinity for fibrin. Compounds of the invention can include such peptides linked to a thrombolytic agent. [0012] In some embodiments, P* is proline; Y* is tyrosine; X.sub.1 is selected from the group consisting of W, Y, F, S, Bip, Hx, Dpr, Cy, Gu, Ad, Hfe, 3-Pal, 4-Pal, DopaMe2, nTyr, dW, dF, F(3/4*), and Y(3*), wherein F3/4* is a phenylalanine substituted at either the 3 or the 4 position with a moiety selected from the group consisting of CH.sub.3, CF.sub.3, NH.sub.2, CH.sub.2NH.sub.2, CN, F, Cl, Br, I, Et, and OMe, and wherein Y3* is a tyrosine substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO.sub.2; X.sub.2 is selected from the group consisting of dE, H(Bzl), 2-Pal, Dpr, and Th; X.sub.3 is selected from the group consisting of G and D; X.sub.4 is selected from the group consisting of H, F, Y, and W; X.sub.5 is selected from the group consisting of I, L, V, N, Bpa, Bal, Hfe, Nle, Tle, nVal, Phg, Cha, Taz, Fua, Th, 4-Pal, and F(3/4*), wherein F3/4* is a phenylalanine substituted at either the 3 or the 4 position with a moiety selected from the group consisting of CF.sub.3, Et, iPr, and Ome, wherein at least one of X1, X2, or X5 is a non-natural amino acid derivative; and X.sub.6 is selected from the group consisting of N, Q, I, L, and V, or X.sub.6 is not present. Such peptides can be capable of forming a disulfide bond under non-reducing conditions, and in some embodiments, the peptides include a disulfide bond. The peptides can have specific binding affinity for fibrin. [0013] In other embodiments, the invention features purified peptides that include the amino acid sequence: C-P*-Y*-X.sub.1-L-C (SEQ ID NO:3), wherein X.sub.1 is G or D, P* is proline or its non-natural derivative 4-hydroxyproline; and Y* is tyrosine or a non-natural derivative of tyrosine substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO.sub.2; provided that at least one of P* or Y* is a non-natural derivative of the respective amino acid. The purified peptides can be capable of forming a disulfide bond under non-reducing conditions and can have specific binding affinity for fibrin. In some embodiments, the peptides include a disulfide bond. Compounds of the invention can include such peptides linked to a thrombolytic agent. [0014] The invention also features purified peptides that include the amino acid sequence: C-D-Y-Y-G-T-C-X.sub.10 (SEQ ID. NO:17), wherein X.sub.10 is selected from the group consisting of n(decyl)G, n(4-PhBu)G, MeL, Bpa, Bip, Me-Bip, F(4*), F(3-Me), F(3,4-difluoro), Amh, Hfe, Y(3,5-di-iodo), Pff, 1Nal, d1Nal, and MeL, wherein F(4*) is a phenylalanine substituted at the 4 position with a moiety selected from the group consisting of Et, CF.sub.3, I, and iPr. Purified peptides can include the amino acid sequence C-D-Y-Y-G-T-C-X.sub.10-X.sub.11 (SEQ ID. NO:18), wherein X.sub.11 is selected from the group consisting of D, dD, .beta.D, Inp, Nip, Me-D, dC, Cop, and Cmp. For example, a peptide can have the follow amino acid sequences: L-P-C-D-Y-Y-G-T-C-n(Decyl)G-dD (SEQ ID NO:19), L-P-C-D-Y-Y-G-T-C-n(Decyl)G-D (SEQ ID NO:20), L-P-C-D-Y-Y-G-T-C-Bip-D (SEQ ID NO:21), L-P-C-D-Y-Y-G-T-C-Bip-dD (SEQ ID NO:22), L-P-C-D-Y-Y-G-T-C-MeL-Inp (SEQ ID NO:23), L-P-C-D-Y-Y-G-T-C-MeL-Cmp (SEQ ID NO:24), or L-P-C-D-Y-Y-G-T-C-MeBip-D (SEQ ID NO:25). The purified peptides can be capable of forming a disulfide bond under non-reducing conditions and can have specific binding affinity for fibrin. In some embodiments, the peptides include a disulfide bond. Compounds of the invention can include such peptides linked to a thrombolytic agent. [0015] In another aspect, the invention features a method of making an MR imaging agent. The method includes reacting a peptide having an N-terminal amine functional group with a linker-subunit moiety to form a modified peptide having both a C-terminal amine functional group and N-terminal amine functional group; covalently attaching a linker moiety to the C-terminal amine functional group and to the N-terminal amine functional group to form a precursor MR imaging agent; and converting the precursor MR imaging agent to the MR imaging agent. The linker-subunit moiety can be selected from the group consisting of: wherein n is an integer from 1 to 4; m is an integer selected 1 to 12; and R is an aliphatic or aromatic group. The linker moiety can be selected from the group consisting of wherein m is an integer from 1 to 4; n is an integer from 0 to 4; LG is a leaving group; and R' and R'' independently are selected from the group consisting of hydrogen and a chemical protecting group. [0016] The linker moiety also can be selected from the group consisting of: wherein LG is a leaving group; and R.sup.1 and R.sup.2 independently are selected from the group consisting of hydrogen and a chemical protecting group. The LG can be selected from the group consisting of --OH, activated ester, halide, and anhydride. The activated ester can be selected from the group consisting of pentafluorophenol (Pfp), N-hydroxysuccinimide (NHS), N-Hydroxysulfosuccinimide Sodium Salt (NHSS), 2-Thioxothiazolidin-1yl, and hydroxybenzotriazole (OBT). The halide can be selected from the group consisting of F, Cl, Br, and I. The chemical protecting group can be selected from the group consisting of Boc, Fmoc, CBZ, t-butyl, benzyl, and allyl. [0017] Converting the precursor MR imaging agent to the MR imaging agent can include reacting the precursor imaging agent with a precursor chelate moiety to form a covalent bond between the precursor chelate moiety and the linker moiety of the precursor MR imaging agent, the precursor chelate moiety comprising a plurality of carboxylate precursor groups, the carboxylate precursor groups capable of being transformed into carboxylate moieties; transforming a plurality of the carboxylate precursor groups of the bound precursor chelate moiety to a plurality of carboxylate moieties, the carboxylate moieties capable of complexing a paramagnetic metal ion; and complexing a paramagnetic metal ion to the plurality of carboxylate moieties to produce the MR imaging agent. The precursor chelate moiety can be selected from the group consisting of: wherein Y is a synthetic moiety capable of forming a covalent bond with the attached linker moiety, and wherein each X, independently, is an O.sup.- or an O.sup.- precursor so that X, upon conversion to O.sup.-, is capable of forming a carboxylate moiety with its adjacent carbonyl, and R.sup.1 is an uncharged chemical moiety, an aliphatic, alkyl group, or cycloalkyl group, or uncharged substituted versions thereof. The synthetic moiety can be selected from the group consisting of a carboxylic acid, activated ester, acid halide, anhydride, alkyl halide, isocyanate, and isothiocyanate, and wherein the O.sup.- precursor is selected from the group consisting of --OH, --OMe, OEt, OtBu, Obenzyl, and O-allyl. The precursor chelate moiety also can be selected from the group consisting of: wherein LG is a leaving group selected from the group consisting of --OH, activated ester, halide, and anhydride, and wherein each R, independently, is an O.sup.- or an O.sup.- precursor selected from the group consisting of OH, --O-Me, O-Et, O-tBu, O-benzyl, and O-allyl, so that R, upon conversion to O.sup.-, is capable of forming a carboxylate moiety with its adjacent carbonyl. [0018] The precursor chelate moiety also can be selected from the group consisting of: wherein n is an integer from 1 to 4; R is selected from the group consisting of a negative charge and a negative charge precursor capable of being transformed into a negative charge; and X is a chemical leaving group selected from the group consisting of --Cl, --Br, --I, -MsO, -TsO, and -TfO. [0019] the percursor chelate moiety can be selected from the group consisting of: wherein R is selected from the group consisting of a negative charge and a negative charge precursor capable of being transformed into a negative charge; and X is a chemical leaving group selected from the group consisting of --Cl, --Br, --I, -MsO, -TsO, and -TfO. The negative charge precursor is selected from the group consisting of --H, -Me, -Et, -t-Bu, -benzyl, and -allyl. [0020] In some embodiments, the linker moiety can be covalently conjugated to a precursor chelate moiety, the covalent conjugate comprising a plurality of carboxylate precursor groups, the carboxylate precursor groups capable of being transformed into carboxylate moieties. Converting the precursor MRI imaging agent to the MR imaging agent can include transforming a plurality of the covalent conjugate's carboxylate precursor groups into carboxylate moieties, the carboxylate moieties capable of complexing a paramagnetic metal ion; and complexing a paramagnetic metal ion to the plurality of carboxylate moieties to result in the MR imaging agent. The paramagnetic metal ion can be selected from the group consisting of: Gd(III), Fe(III), Mn(II and III), Cr(III), Cu(II), Dy(III), Tb(III and IV), Ho(III), Er(III), Pr(III), Eu(II) and Eu(III). Gd(III) is a particularly useful paramagnetic ion. Continue reading about Peptide-based multimeric targeted contrast agents... Full patent description for Peptide-based multimeric targeted contrast agents Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Peptide-based multimeric targeted contrast agents patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Peptide-based multimeric targeted contrast agents or other areas of interest. ### Previous Patent Application: Thermal- and chemical-resistant acid protection coating material and spin-on thermoplastic adhesive Next Patent Application: Crystals of luxp and complexes thereof Industry Class: Chemistry: natural resins or derivatives; peptides or proteins; lignins or reaction products thereof ### FreshPatents.com Support Thank you for viewing the Peptide-based multimeric targeted contrast agents patent info. IP-related news and info Results in 0.16452 seconds Other interesting Feshpatents.com categories: Tyco , Unilever , Warner-lambert , 3m 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
