Bifunctional chelating agents based on the 1,4-diazepine scaffold (DAZA) for non-invasive molecular imaging

Abstract

A compound for radio metal complexation includes a chelator and one or more biological targeting vectors TV conjugated to said chelator, wherein the chelator has structure (A) or (B) or (C), ##STR00001##
based on 1,4-diazepine with groups R.sub.1, R.sub.2, R.sub.3, R.sub.4, X.sub.1, X.sub.2, X.sub.3. The compound is particularly suited for complexation of radio-isotopic metals, such as .sup.66Ga(III), .sup.67Ga(III) and .sup.68Ga(III).

Claims

1. A compound C for radio metal complexation comprising a chelator and one or more biological targeting vectors TV conjugated to said chelator, wherein the chelator has structure (C) based on 1,4-diazepine with groups R.sub.1, R.sub.2, R.sub.3, R.sub.4, X.sub.1, X.sub.2, X.sub.3; ##STR00029## X.sub.1 and X.sub.2 are OH; X.sub.3 is OH; R.sub.1, R.sub.2 are CH.sub.2CO; R.sub.3 is CH.sub.2CO; R.sub.4 is CH.sub.3, CH(CH.sub.3).sub.2, CH(CH.sub.3).sub.3, (C.sub.6H.sub.5), (C.sub.5H.sub.4N), (C.sub.4H.sub.5NHO) or (C.sub.(5-k)H.sub.(5-k)N.sub.k); wherein (C.sub.6H.sub.5) designates a phenyl ring; (C.sub.(5-k)H.sub.(5-k)N.sub.k) with k=1, 2, 3 or 4 designates a pyrrole, imidazole, triazole or tetrazole residue; (C.sub.4H.sub.5NHO) designates a pyrrolidone residue; (C.sub.5H.sub.4N) designates pyridine residue; and the one or more targeting vectors TV are conjugated at R.sub.4, via optional linker/spacer groups LS, whereby one or more hydrogen atoms of R.sub.4 are substituted and the one or more targeting vectors TV independently of one another are selected from the group comprising amino acid residues; residues of amino acid derivatives; residues of peptides; residues of Octreotide; residues of proteins; residues of micro proteins; antibodies; recombinant antibodies; antibody fragments; bisphosphonates; sugars; glucose; fructose; sucrose; glutamine; glucosamine; lipids; nucleotides; nucleosides; DNA-components; hypoxia tracers; liposomes; polymers and nanoparticles.

2. A compound C for radio metal complexation comprising a chelator and one or more biological targeting vectors TV conjugated to said chelator, wherein the chelator has structure (B); ##STR00030## R.sub.1, R.sub.2 are CH.sub.2CO; R.sub.3 is CHCO, CHPOH, CHPOOH, CH(C.sub.6H.sub.4), CH(C.sub.5H.sub.4), CH(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH(C.sub.4H.sub.5O), CH(C.sub.5H.sub.3N)CO, CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH(C.sub.5H.sub.3N)(PH)O or CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O; R.sub.4 is CH.sub.3; and the one or more targeting vectors TV independently of one another are conjugated at R.sub.1, R.sub.2, R.sub.3 and/or at the CH.sub.2-residues of the 1,4-diazepine ring via optional linker/spacer groups LS, whereby one or more hydrogen atoms of R.sub.1, R.sub.2, R.sub.3 and/or of the CH.sub.2-residues of the 1,4-diazepine ring are substituted.

3. A compound C according to claim 1, wherein the steric bulk value (A-value) of R.sub.4 is greater/equal 7.2 kJ/mol.

4. A compound C according to claim 1, wherein the number of atomic bonds along a shortest path between the exocyclic nitrogen N.sub.x and the O-atom of group X.sub.3 is 3, 4 or 6.

5. A compound C according to claim 1, wherein the residues of amino acid derivatives are selected from L-tyrosine, L-serine, L-lysine and Alpha-methyl-L-tyrosine; the residues of peptides are selected from bombesins and melanocortins; the antibodies are selected from huKS (humanized antibody for EpCAM respectively KSA) and hu14.18 (humanized antibody for disialoganglioside GD2); the hypoxia tracers are selected from 2-nitroimidazole; azomycine (2-nitroimidazole-arabinoside); erythronitroimidazole; ethyltyrosine; and 2-(2-nitro-(1)H-imidazole-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5).

6. A compound C according to claim 1, wherein one or more targeting vectors TV are conjugated at R.sub.4 via linker/spacer groups LS.

7. A compound C according to claim 6, wherein the linker/spacer groups LS independently of one another are residues of molecules selected from the group comprising linear, branched or heterosubstituted, saturated and unsaturated aromatic hydrocarbons of all oxidation states; linear, branched or heterosubstituted alkyls, alkylenes, alkylidenes, aryls, polyethers, polypeptides or sugars.

8. A compound C according to claim 1, wherein said compound (C) is complexed with .sup.68Ga(III) and the chelator consists of a 1,4-diazepine derivative.

9. A compound C according to claim 1, wherein the steric bulk of R.sub.4 is larger than N.sub.x.

10. A compound C according to claim 1, wherein R.sub.4 and N.sub.x have an A-value ratio of greater than 8:1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows embodiments of the inventive compound C according to general structures (A.1) to (A.4), (B.1) to (B.4) and (C.1) to (C.4) with a targeting vector TV attached at either of groups R.sub.1, R.sub.2, R.sub.3, R.sub.4 or at the methyl residue at the exocyclic nitrogen atom N.sub.x;

(2) FIGS. 2 through 5 show embodiments of the chelator of the inventive compound C according to structures (1.1) to (1.2), (2.1) to (2.4), (3.1) to (3.6), (4.1) to (4.2), (5.1) to (5.4), (6.1) to (6.2), (7.1) to (7.4), (8.1) to (8.2), (9.1) to (9.2), (10.1) to (10.2) and (11.1) to (11.2) with various groups R.sub.3 and X.sub.3;

(3) FIGS. 6 through 8 show sections of embodiments of the chelator of the inventive compound C according to structures (20.1) to (20.2), (21.1) to (21.4), (22.1) to (22.6), (23.1) to (23.2), (24.1) to (24.4), (25.1) to (25.2), (26.1) to (26.4), (27.1) to (27.2) with various groups R1, X1 and R2, X2; and

(4) FIGS. 9 and 10 schematically show a first and second apparatus, respectively, for preparing a radio-labelled complex consisting of the inventive compound C and a therewith ligated radio-isotopic metal.

DETAILED DESCRIPTION OF THE INVENTION

(5) The invention pertains to a compound C for radio metal complexation comprising a chelator and one or more biological targeting vectors TV conjugated to said chelator, wherein the chelator has structure (A) or (B) or (C) based on 1,4-diazepine with groups R.sub.1, R.sub.2, R.sub.3, R.sub.4, X.sub.1X.sub.2, X.sub.3;

(6) ##STR00011## X.sub.1 and X.sub.2 independently of one another are vacant, OH, SH, N or NH; X.sub.3 is OH, SH, N or NH; R.sub.1, R.sub.2 independently of one another are H, CH.sub.2CO, CH.sub.2POH, CH.sub.2POOH, CH.sub.2(C.sub.6H.sub.4), CH.sub.2(C.sub.5H.sub.4), CH.sub.2(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH.sub.2(C.sub.4H.sub.5O), CH(CH.sub.3)CO, CH(CH.sub.3)POH, CH(CH.sub.3)POOH, CH(CH.sub.3)(C.sub.6H.sub.4), CH(CH.sub.3)(C.sub.5H.sub.4), CH(CH.sub.3)(C.sub.(4-m)H.sub.(3-m)N.sub.m) or CH(CH.sub.3)(C.sub.4H.sub.5O); R.sub.3 is CH.sub.2CO, CH.sub.2POH, CH.sub.2POOH, CH.sub.2(C.sub.6H.sub.4), CH.sub.2(C.sub.5H.sub.4), CH.sub.2(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH.sub.2(C.sub.4H.sub.5O), CHCO, CHPOH, CHPOOH, CH(C.sub.6H.sub.4), CH(C.sub.5H.sub.4), CH(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH(C.sub.4H.sub.5O), CH.sub.2(C.sub.5H.sub.3N)CO, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH(C.sub.5H.sub.3N)CO, CH(C.sub.(4-p))H.sub.(3-p)N.sub.p)CO, CH.sub.2(C.sub.5H.sub.3N)(PH)O, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O, CH(C.sub.5H.sub.3N)(PH)O or CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O; R.sub.4 is CH.sub.3, CH(CH.sub.3).sub.2, C(CH.sub.3).sub.3, (C.sub.6H.sub.5), (C.sub.5H.sub.4N), (C.sub.4H.sub.5NHO) or (C.sub.(5-k)H.sub.(5-k)N.sub.k); wherein (C.sub.6H.sub.5) and (C.sub.6H.sub.4) designate a phenyl and phenylene ring, respectively; (C.sub.5H.sub.4) designates a cyclic residue, which is complemented by X.sub.1N, X.sub.2N, X.sub.3N, independently of one another, to give a pyridine residue; (C.sub.(4-m)H.sub.(3-m)N.sub.m) designates a cylic residue with m=0, 1, 2 or 3; which is complemented by X.sub.1NH, X.sub.2NH, X.sub.3NH, independently of one another, to give a pyrrole, imidazole, triazole or tetrazole residue; (C.sub.(5-k)H.sub.(5-k)N.sub.k) with k=1, 2, 3 or 4 designates a pyrrole, imidazole, triazole or tetrazole residue; (C.sub.4H.sub.5O) designates a cyclic residue, which is complemented by X.sub.1NH, X.sub.2NH, X.sub.3NH, independently of one another, to give a pyrrolidone residue; (C.sub.4H.sub.5NHO) designates a pyrrolidone residue; (C.sub.5H.sub.3N) and (C.sub.5H.sub.4N) designate pyridine residues; (C.sub.(4-p)H.sub.(3-p)N.sub.p) with p=1, 2 or 3 designates a pyrrole, imidazole or triazole residue;
and the one or more targeting vectors TV independently of one another are conjugated at R.sub.1, R.sub.2, R.sub.3, R.sub.4, at a methyl residue at the exocyclic nitrogen atom N.sub.x and/or at the CH.sub.2-residues of the 1,4-diazepine ring via optional linker/spacer groups LS, whereby one or more hydrogen atoms of R.sub.1, R.sub.2, R.sub.3, R.sub.4, of the methyl residue at the exocyclic nitrogen atom N.sub.x and/or of the CH.sub.2-residues of the 1,4-diazepine ring are substituted.

(7) In structure (A), (B) and (C) groups X.sub.1, X.sub.2, X.sub.3 designate OH, SH, N or NH residues, which in conjunction with the two endocyclic nitrogen residues N.sub.e of the 7-membered 1,4-diazepine ring and the third exocyclic nitrogen residue N.sub.x residue ligate or bind a radio-isotopic metal. Groups X.sub.1, X.sub.2, X.sub.3 and the two endocyclic nitrogen residues N.sub.e and the exoclyclic nitrogen residue N.sub.x provide for hexadentate ligation of the radio-isotopic metal, preferably selected from .sup.66Ga(III), .sup.67Ga(III) and .sup.68Ga(III).

(8) Advantageous embodiments of the inventive compound C are characterized in that: the chelator has structure (B); R.sub.3 is CHCO, CHPOH, CHPOOH, CH(C.sub.6H.sub.4), CH(C.sub.5H.sub.4), CH(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH(C.sub.4H.sub.5O), CH(C.sub.5H.sub.3N)CO, CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH(C.sub.5H.sub.3N)(PH)O or CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O; R.sub.4 is CH.sub.3; and the one or more targeting vectors TV independently of one another are conjugated at R.sub.1, R.sub.2, R.sub.3 and/or at the CH.sub.2-residues of the 1,4-diazepine ring via optional linker/spacer groups LS, whereby one or more hydrogen atoms of R.sub.1, R.sub.2, R.sub.3 and/or of the CH.sub.2-residues of the 1,4-diazepine ring are substituted; the chelator has structure (A) or (B) or (C); R.sub.3 is CH.sub.2CO, CH.sub.2POH, CH.sub.2POOH, CH.sub.2(C.sub.6H.sub.4), CH.sub.2(C.sub.5H.sub.4), CH.sub.2(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH.sub.2(C.sub.4H.sub.5O), CHCO, CHPOH, CHPOOH, CH(C.sub.6H.sub.4), CH(C.sub.5H.sub.4), CH(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH(C.sub.4H.sub.5O), CH.sub.2(C.sub.5H.sub.3N)CO, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH(C.sub.5H.sub.3N)CO, CH(C.sub.(4-p))H.sub.(3-p)N.sub.p)CO, CH.sub.2(C.sub.5H.sub.3N)(PH)O, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O, CH(C.sub.5H.sub.3N)(PH)O or CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O; R.sub.4 is CH(CH.sub.3).sub.2, C(CH.sub.3).sub.3, (C.sub.6H.sub.5), (C.sub.5H.sub.4N), (C.sub.4H.sub.5NHO) or (C.sub.(5-k)H.sub.(5-k)N.sub.k); R.sub.1 or R.sub.2 is H; R.sub.2 or R.sub.1, respectively, is CH.sub.2CO, CH.sub.2POH, CH.sub.2POOH, CH.sub.2(C.sub.6H.sub.4), CH.sub.2(C.sub.5H.sub.4), CH.sub.2(C.sub.(4-m)H.sub.(3-m)N.sub.m), CH.sub.2(C.sub.4H.sub.5O), CH(CH.sub.3)CO, CH(CH.sub.3)POH, CH(CH.sub.3)POOH, CH(CH.sub.3)(C.sub.6H.sub.4), CH(CH.sub.3)(C.sub.5H.sub.4), CH(CH.sub.3)(C.sub.(4-m)H.sub.(3-m)N.sub.m) or CH(CH.sub.3)(C.sub.4H.sub.5O); R.sub.3 is CH.sub.2(C.sub.5H.sub.3N)CO, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH(C.sub.5H.sub.3N)CO, CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)CO, CH.sub.2(C.sub.5H.sub.3N)(PH)O, CH.sub.2(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O, CH(C.sub.5H.sub.3N)(PH)O or CH(C.sub.(4-p)H.sub.(3-p)N.sub.p)(PH)O; and X.sub.3 is OH; the steric bulk value (A-value) of R.sub.4 is greater/equal 7.2 kJ/mol, greater/equal 8.8 kJ/mol or greater/equal 12.6 kJ/mol; the number of atomic bonds along the shortest path between the exocyclic nitrogen N.sub.x and the N-, O- or S-atom of group X.sub.3 is 3, 4 or 6; the one or more targeting vectors TV independently of one another are selected from the group comprising amino acid residues; residues of amino acid derivatives, such as L-tyrosine, L-serine, L-lysine and Alpha-methyl-L-tyrosine; residues of peptides, such as bombesins and melanocortins; residues of Octreotide; residues of proteins; residues of micro proteins; antibodies, such as huKS (humanized antibody for EpCAM respectively KSA) and hu14.18 (humanized antibody for disialoganglioside GD2); recombinant antibodies; antibody fragments; bisphosphonates; sugars; glucose; fructose; sucrose; glutamine; glucosamine; lipids; nucleotides; nucleosides; DNA-components; hypoxia tracers, such as 2-nitroimidazole; azomycine (2-nitroimidazole-arabinoside); erythronitroimidazole; ethyltyrosine; 2-(2-nitro-(1)H-imidazole-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)-acetamide (EF5); liposomes; polymers and nanoparticles; the one or more targeting vectors TV independently of one another are conjugated at R.sub.1, R.sub.2, R.sub.3 or R.sub.4 via optional linker/spacer groups LS; one or more targeting vectors TV are conjugated at R.sub.4 via optional linker/spacer groups LS; and/or the linker/spacer groups LS independently of one another are residues of molecules selected from the group comprising linear, branched or hetero substituted, saturated and unsaturated aromatic hydrocarbons of all oxidation states; linear, branched or hetero substituted alkyls, alkylenes, alkylidenes, aryls, polyethers, polypeptides or sugars.

(9) Inventors, based on extensive experimentation, have surprisingly found, that compounds according to the above specified structures (A), (B) and (C) afford highly efficient, fast and stable complexation of metals, such as Ga(III). The reasons for the favorable complexation efficacy of the inventive compound C are not yet fully understood. It is believed, that the inventive combination of groups R.sub.1, R.sub.2, R.sub.3, R.sub.4 fulfill stereochemical conditions which promote complexation of metals, such as Ga(III). In particular, the inventive compounds seem to share the feature that the steric bulk (or so called A-value) of R.sub.4 is appreciably larger than that of the exocylic nitrogen N.sub.x. Furthermore, it appears important to select groups R.sub.1, R.sub.2, R.sub.3 in such manner, that their total steric bulk, i.e. the sum of the A-values of R.sub.1, R.sub.2, R.sub.3 does not exceed a certain limit. In addition, inventors have found that there exists an upper limit for the sum of the A-values of R.sub.4 and N.sub.x which is enforced by predominantly steric restrictions. From the experiments conducted by the inventors it is concluded, that R.sub.4 and N.sub.x must be chosen in such manner, that the sum of the A-values of R.sub.4 and N.sub.x is less than 26 kJ mol, less than 25 kJ mol, less than 24 kJ/mol, less than 23 kJ/mol, less than 22 kJ/mol, less than 21 kJ/mol, less than 20 kJ/mol, less than 19 kJ/mol, less than 18 kJ/mol, less than 17 kJ/mol, less than 16 kJ/mol, less than 15 kJ/mol, less than 14 kJ/mol, less than 13 kJ/mol, less than 12 kJ/mol or less than 11 kJ/mol.

(10) Furthermore, R.sub.4 and N.sub.x are preferably chosen in such manner that the ratio of the A-value of R.sub.4 over the A-value of N.sub.x is greater than 8:1, greater than 7:1, greater than 6:1, greater than 5:1, greater than 4:1, greater than 3:1, greater than 2:1 or greater than 1.6:1.

(11) The A-values recited in this invention for R.sub.1, R.sub.2, R.sub.3, and N.sub.x refer to energy measurements of a monosubstituted cyclohexane ring according to Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994); P. Mller, PAC 66 (5): 1077-1184. Exemplary A-values are presented in Table 1.

(12) TABLE-US-00001 TABLE 1 A-Value Sub- A-Value Sub- A-Value Substituent [kJ/mol] stituent [kJ/mol] stituent [kJ/mol] D 0.03 CH.sub.2Br 7.49 OSi(CH.sub.3).sub.3 3.10 F 0.63 CH(CH.sub.3).sub.2 9.00 OH 3.64 Cl 1.80 c-C.sub.6H.sub.11 9.00 OCH.sub.3 2.51 Br 1.59 C(CH.sub.3).sub.3 >16.74 OCD.sub.3 2.34 I 1.80 Ph 12.55 OCH.sub.2CH.sub.3 3.77 CN 0.71 C.sub.2H 5.65 O-Ac 2.51 NC 0.88 CO.sub.2.sup. 8.03 O-TFA 2.85 NCO 2.13 CO.sub.2CH.sub.3 5.31 OCHO 1.13 NCS 1.17 CO.sub.2Et 5.02 O-Ts 2.09 NCNR 4.18 CO.sup.tPr 4.02 ONO.sub.2 2.47 CH.sub.3 7.11 COCl 5.23 NH.sub.2 6.69 CF.sub.3 8.79 COCH.sub.3 4.90 NHCH.sub.3 4.18 CH.sub.2CH.sub.3 7.32 SH 3.77 N(CH.sub.3).sub.3 8.79 CHCH.sub.2 5.65 SMe 2.93 NH.sub.3.sup. 7.95 CCH 1.72 SPh 3.35 NO.sub.2 4.60 CH.sub.2.sup.tBu 8.37 S.sup. 5.44 HgBr ~0.00 CH.sub.2OTs 7.32 SOPh 7.95 HgCl 1.26 SO.sub.2Ph 10.46 Si(CH.sub.3).sub.3 10.46

(13) Substituents on a cyclohexane ring prefer to reside in the equatorial position rather than the axial position. Thus, in the case when there is more than one substituent present, the substituent with the largest A-value is more likely to take up the less hindered equatorial orientation whilst the other is predisposed to an axial orientation. The A-value of a particular substituent is defined as the difference in Gibbs free energy (G) between the higher energy conformation (axial substitution) and the lower energy conformation (equatorial substitution) of the substituent conjugated to cyclohexane and can be determined from reaction equilibrium constants.

(14) Inventors further found it advantageous, to conjugate the one or more targeting vectors TV at R.sub.1, R.sub.2, R.sub.3 or R.sub.4, rather than at the four CH.sub.2-residues of the 1,4-diazepine ring and/or the exocyclic nitrogen N.sub.x directly, thus reducing total steric bulk proximal the three endo- and exocyclic nitrogen residues N.sub.e, N.sub.e and N.sub.x. Large steric bulk proximal to the nitrogen residues N.sub.e, N.sub.e and N.sub.x adversely affects the complexation efficacy of the chelating moiety.

(15) Inventors further found it advantageous, to conjugate the one or more targeting vectors TV at R.sub.4, rather than at R.sub.1, R.sub.2, R.sub.3, thus minimizing interference with the ligating function of groups R.sub.1X.sub.1, R.sub.2X.sub.2 and R.sub.3X.sub.3.

(16) The invention further pertains to a method for preparation of radiolabeled biological markers comprising the steps of (a) providing a solution S containing the compound C as specified above; (b) providing a radioactive metal R, such as .sup.68Ga(III), adsorbed on a ion exchanger; and (c) ligating the radioactive metal R with the compound C to form a complex RC of the radioactive metal R and the compound C in a solution F.

(17) Advantageous embodiments of the inventive method are characterized in that: in step (c) the radioactive metal R is eluted from the ion exchanger using the solution S; in step (c) the radioactive metal R is eluted from the ion exchanger with a solvent E to obtain a solution RE, containing the radioactive metal R, and the solution RE is admixed with the solution S to obtain the solution F with the complex RC; in step (c) prior to elution of the radioactive metal R, the ion exchanger is purged with one or more solvents to remove impurities; the ion exchanger is a cation exchanger; the ion exchanger comprises sulfonated poly(styrene-co-divinylbenzene) resin as active component, wherein the poly(styrene-co-divinylbenzene) resin contains divinylbenzene in an amount of 2 to 20 mol-% based on 100 mol-% of styrene and divinylbenzene monomer units; subsequent to step (c) the solution F is filtered and/or neutralized; step (c) is completed within 6 s to 5 min, within 6 s to 3 min, within 6 s to 2 min or preferably within 6 s to 1 min; step (c) is conducted at a temperature from 10 to 60 C., from 10 to 40 C. or preferably from 10 to 30 C.; and/or in step (b) a radionuclide generator is employed, wherein the radionuclide generator comprises a parent radionuclide, such as .sup.68Ge, and a daughter radionuclide, such as .sup.68Ga, which are adsorbed on a chromatographic column, and the daughter radionuclide is eluted from the chromatographic column prior to adsorption onto the ion exchanger.

(18) The invention is further described with reference to FIG. 1-10, wherein

(19) FIG. 1 shows embodiments of the inventive compound C according to general structures (A.1) to (A.4), (B.1) to (B.4) and (C.1) to (C.4) with a targeting vector TV attached at either of groups R.sub.1, R.sub.2, R.sub.3, R.sub.4 or at the methyl residue at the exocyclic nitrogen atom N.sub.x;

(20) FIG. 2-5 show embodiments of the chelator of the inventive compound C according to structures (1.1) to (1.2), (2.1) to (2.4), (3.1) to (3.6), (4.1) to (4.2), (5.1) to (5.4), (6.1) to (6.2), (7.1) to (7.4), (8.1) to (8.2), (9.1) to (9.2), (10.1) to (10.2) and (11.1) to (11.2) with various groups R.sub.3 and X.sub.3;

(21) FIG. 6-8 show sections of embodiments of the chelator of the inventive compound C according to structures (20.1) to (20.2), (21.1) to (21.4), (22.1) to (22.6), (23.1) to (23.2), (24.1) to (24.4), (25.1) to (25.2), (26.1) to (26.4), (27.1) to (27.2) with various groups R.sub.1, X.sub.1 and R.sub.2, X.sub.2; and

(22) FIG. 9-10 schematically show a first and second apparatus, respectively, for preparing a radio-labelled complex consisting of the inventive compound C and a therewith ligated radio-isotopic metal.

(23) As indicated in FIG. 1, according to structures (A.1) to (A.4) and (B.1) to (B.4), targeting vectors TV are conjugated to the chelator via optional linker/spacer groups LS at either of groups R.sub.1, R.sub.2, R.sub.3 and/or R.sub.4.

(24) The invention further encompasses compounds C, wherein two or more targeting vectors TV, which are equal or different are conjugated at two or more of groups R.sub.1, R.sub.2, R.sub.3, R.sub.4 and/or the CH.sub.2-residues of the 1,4-diazepine via optionally two or more linker/spacer groups LS, which are equal or different.

(25) FIG. 2-5 show various embodiments of ligating group R.sub.3X.sub.3. The chemical structure of R.sub.3X.sub.3, or the basic group, of which R.sub.3X.sub.3 constitutes a residue, are recited in Table 2:

(26) TABLE-US-00002 TABLE 2 Structure [R.sub.3]X.sub.3 or [R.sub.3X.sub.3] basic group (1.1), (1.2) [CH.sub.2/CHCO]OH (2.1), (2.2) [CH.sub.2/CHPHO]OH (2.3), (2.4) [CH.sub.2/CHPHO.sub.2]OH (3.1), (3.2), (3.3), (3.4) [CH.sub.2/CH-phenylene]OH/SH (3.5), (3.6) [CH.sub.2/CH-pyridine] (4.1), (4.2) [CH.sub.2/CH-pyrrole] (5.1), (5.2), (5.3), (5.4) [CH.sub.2/CH-pyrrolidone] (6.1), (6.2) [CH.sub.2/CH-imidazole] (7.1), (7.2), (7.3), (7.4) [CH.sub.2/CH-triazole] (8.1), (8.2) [CH.sub.2/CH-tetrazole] (9.1), (9.2) [CH.sub.2/CH-pyridine-CO]OH (10.1), (10.2) [CH.sub.2/CH-pyrrole-CO]OH (11.1), (11.2) [CH.sub.2/CH-imidazole-CO]OH (12.1), (12.2) [CH.sub.2/CH-pyridine-(PH)O]OH (13.1), (13.2) [CH.sub.2/CH-pyrrole-(PH)O]OH

(27) In Table 2, the term CH.sub.2/CH designates either CH.sub.2 or CH and the term OH/SH refers to either OH or SH.

(28) Structures (9.1), (9.2), (10.1), (10.2), (11.1), (11.2), (12.1), (12.2), (13.1), (13.2) pertain to specific embodiments, wherein R.sub.3X.sub.3 provides bidentate ligating function and one of R.sub.1X.sub.1 and R.sub.2X.sub.2 is substituted by hydrogen or employed as attachment site for a targeting vector TV, optionally conjugated via linker/spacer group LS.

(29) FIG. 6-8 show various embodiments of ligating groups R.sub.1X.sub.1 and R.sub.2X.sub.2. The chemical structure of R.sub.1X.sub.1 and R.sub.1X.sub.1, or the basic group, of which R.sub.1X.sub.1 and R.sub.2X.sub.2 constitute a residue, are recited in Table 3:

(30) TABLE-US-00003 TABLE 3 Structure [R.sub.1/2]X.sub.1/2 or [R.sub.1/2X.sub.1/2] basic group (20.1), (20.2) [CH.sub.2/CH.sub.3CO]OH (21.1), (21.2) [CH.sub.2/CH.sub.3PHO]OH (21.3), (21.4) [CH.sub.2/CH.sub.3PHO.sub.2]OH (22.1), (22.2), (22.3), (22.4) [CH.sub.2/CH.sub.3-phenylene]OH/SH (22.5), (22.6) [CH.sub.2/CH.sub.3-pyridine] (23.1), (23.2) [CH.sub.2/CH.sub.3-pyrrole] (24.1), (24.2), (24.3), (24.4) [CH.sub.2/CH.sub.3-pyrrolidone] (25.1), (25.2) [CH.sub.2/CH.sub.3-imidazole] (26.1), (26.2), (26.3), (26.4) [CH.sub.2/CH.sub.3-triazole] (27.1), (27.2) [CH.sub.2/CH.sub.3-tetrazole]

(31) Groups R.sub.1X.sub.1 and R.sub.2X.sub.2 are selected independently of one another from the structures, recited in Table 3, FIG. 6-8 or in the claims. In Table 3, the term CH.sub.2/CH.sub.3 designates either CH.sub.3 or CH.sub.3 and the term OH/SH refers to either OH or SH.

(32) FIG. 9 schematically shows a first apparatus 1 for preparation of a complex consisting of the inventive compound C and a radio-isotopic metal, preferably selected from .sup.66Ga, .sup.67Ga and .sup.68Ga. Apparatus 1 comprises a radionuclide generator 10 with a chromatographic column 12, whereon a radiometallic parent nuclide, such as .sup.68Ge, and its corresponding daughter nuclide R are adsorbed, and an eluant supply device 11 for elution of daughter nuclide R from chromatographic column 12 with a suitable solvent. The various components of apparatus 1 are connected via fluid conduits, which in FIG. 9 are collectively designated by reference sign 9. The exit or outlet of chromatographic column 12 is connected via a fluid conduit and a first multiport valve 13 to the inlet of a ion exchanger 14. The ion exchanger 14 preferably comprises sulfonated poly(styrene-co-divinylbenzene) resin as active component, wherein the poly(styrene-co-divinylbenzene) resin contains divinylbenzene in an amount of 2 to 20 mol-% based on 100 mol-% of styrene and divinylbenzene monomer units. The daughter nuclide R eluted from chromatographic column 12 is adsorbed onto ion exchanger 14 and concomitantly eluted parent nuclide is practically completely passed into a waste vessel 16 via a second multiport valve 15.

(33) Apparatus 1 preferably comprises further eluant supply devices 21, 22, 23, which are connected to the inlet of ion exchanger 14 via fluid conduits and the first multiport valve 13. Supply devices 21, 22, 23 are employed to purge ion exchanger 14, i.e. the thereon adsorbed daughter nuclide R from impurities, such as residual parent nuclide, Fe.sup.III, Zn.sup.II and Ti.sup.IV, originating from the radionuclide generator 10. The one or more purging eluates respectively solvents exiting the ion exchanger 14 are also passed into waste vessel 16 via the second multiport valve 15.

(34) A further eluant supply device 30, connected to the inlet of ion exchanger 14 via a fluid conduit and the first multiport valve 13, is employed for elution of the purified daughter nuclide R from the ion exchanger 14 via the second multiport valve 15 into a process vessel 17. Process vessel 17 is preferably equipped with an electric heater 17A. A supply device 40 is used to feed a solution, which contains the inventive compound C, into process vessel 17 and thereby initiate complexation of the daughter nuclide R with the compound C. Upon completion of the complexation reaction the solution, containing the radiolabelled compound C, i.e. the complex comprising compound C and the thereto ligated daughter nuclide R, is passed through an optional filter 18 into a product vessel 19, where it may be optionally neutralized with a solution, that is provided from a supply device 50.

(35) FIG. 10 shows a second apparatus 2 for preparation of a complex consisting of the inventive compound C and a radio-isotopic metal, preferably selected from .sup.66Ga, .sup.67Ga and .sup.68Ga. In FIG. 10, reference signs equal to those of FIG. 9 designate components providing the same functionality. The second apparatus 2 differs from apparatus 1 in that a solution, containing the inventive compound C is fed from an eluant supply device 43 in order to elute the daughter nuclide R from ion exchanger 14 via multiport valve 15 and an optional filter 18 into product vessel 19. The high complexation efficacy of the inventive compound C and the stability of the corresponding complex formed by ligation with radio-isotopic metals, such as .sup.68Ga, afford a simplified process wherein elution and complexation of daughter nuclide R are carried out fully or partially simultaneously.

EXAMPLE 1

(36) Compounds of the general formula

(37) ##STR00012##
such as

(38) ##STR00013## ##STR00014##

(39) Optionally deprotected, complexed with a gallium isotope and/or attached to a targeting vector.

EXAMPLE 2

(40) A method for the synthesis of a compound in EXAMPLE 1

(41) ##STR00015##

EXAMPLE 3

(42) Compounds of the general formula

(43) ##STR00016##
such as

(44) ##STR00017##

(45) Optionally deprotected, complexed with a gallium isotope and/or attached to a targeting vector.

EXAMPLE 4

(46) A method for the synthesis of compounds in Example 3

(47) ##STR00018##
or alternatively

(48) ##STR00019##

(49) Leads to structures like:

(50) ##STR00020##

EXAMPLE 5

(51) Compounds of the general formula

(52) ##STR00021##

(53) For example:

(54) ##STR00022##

(55) Optionally deprotected, complexed with a gallium isotope and/or attached to a targeting vector.

EXAMPLE 6

(56) A method for the synthesis of compounds in Example 5

(57) ##STR00023##

(58) Leads to A.1 type structures

(59) ##STR00024##

EXAMPLE 7

(60) Compounds of the general formula

(61) ##STR00025##
such as

(62) ##STR00026##

(63) Optionally deprotected, complexed with a gallium isotope and/or attached to a targeting vector.

EXAMPLE 8

(64) A method for the synthesis of compounds in Example 7

(65) ##STR00027##

(66) Leads to structures like

(67) ##STR00028##

EXAMPLE 9

(68) General labelling procedure applied to radio-label precursors:

(69) A .sup.68Ge/.sup.68Ga generator was eluted and post processed using the method described by Zhernosekov et al. 400 L of the .sup.68Ga eluate was added to 1 mL of an appropriately prepared buffer solution containing 10 nmol of the chelator. The buffer was selected from either acetate or HEPES depending on the requirements. Buffers were selected according to the pH required for radio-labelling. pH 4-6:0.2 M acetate buffer pH 6-7:1.0 M HEPES buffer

(70) The reaction progress was monitored by a radio/TLC method using either instant TLC or MERCK silica TLC plates, and eluted using an appropriate mobile phase selected from 0.5 M sodium citrate (pH 4) or 25% EtOH saline (5%) solution. 1 L of the radio-labelling solution was spotted on the TLC plate at 1, 3, 5 and 10 min intervals following addition of the .sup.68Ga, and the plate eluted. This allowed the relative amounts of complexed and free 68Ga to be determined. The experiments were performed in triplicate over the pH range 4-7 at room temperature (298 K), 323 and 368 K.

(71) For the ligands shown tested radio-labelling was nearly quantitative and achieved within 10 minutes at room temperature over pH range 4-7. In the pH range 4-6 radio-labelling was >90% after 1 minute, and proceeded to completion within 5 minutes. Subsequent stability studies, indicated that the radio-labelled complexes formed (over the entire pH range tested) were stable and in the presence of apo-transferrin, DTPA, new born calf serum and iron(III) under physiological conditions (pH 7.4 and 310.4 K) for at least 2 hours. As such, they are suitable for in vivo application.