PROSTATE SPECIFIC MEMBRANE ANTIGEN (PSMA) LIGANDS
20250360236 · 2025-11-27
Assignee
- Deutsches Krebsforschungszentrum Stiftung des Öffentlichen Rechts (Heidelberg, DE)
- Albert-Ludwigs-Universität Freiburg (Freiburg, DE)
Inventors
Cpc classification
A61K51/0497
HUMAN NECESSITIES
International classification
Abstract
The present invention generally relates to the field of dye labelled, preferably fluorescent dye labelled, radiopharmaceuticals and their use in nuclear medicine as tracers, imaging agents and for the treatment of various disease states of PSMA-expressing cancers, especially prostate cancer, and metastases thereof as well as their use in preoperative PET Imaging and Fluorescence-Guided Surgery of cancers, especially prostate cancer, and metastases thereof.
Claims
1-15. (canceled)
16. A PSMA binding ligand or a pharmaceutically acceptable salt or solvate thereof comprising a PSMA binding motif Q, a chelator residue A, a dye group Z and at least one linker L.sup.BQ comprising at least one amino acid X.sub.1, preferably at least one N-alkylated amino acid, more preferably wherein the amino acid X.sub.1 is N(CH.sub.3)CH.sub.2C(O).
17. The PSMA binding ligand of claim 16 having the structure: ##STR00074## wherein: Q is the PSMA binding motif, A is the chelator residue, Z is the dye group, B is a branching group, L.sup.BQ is a linker connecting Q with B, wherein the linker comprises the at least one amino acid X.sub.1, L.sup.BZ is a linker, wherein n.sub.bz is 0 or 1, and L.sup.BA is a linker, wherein n.sub.ba is 0 or 1.
18. The PSMA binding ligand of claim 17, wherein B has the structure: ##STR00075## wherein: R.sub.5 is an alkyl group, preferably a (CH.sub.2).sub.2-4 group, and Y.sup.B is a functional group linking R.sub.5 to the group -(L.sup.BZ)n.sub.bz-Z or -(L.sup.BA)n.sub.ba-A, wherein Y.sup.B is preferably a group NH or C(O).
19. The PSMA binding ligand of claim 18, having one of the following structures (Ia) or (Ib), preferably the structure (Ia): ##STR00076##
20. The PSMA binding ligand of claim 16 or a pharmaceutically acceptable salt or solvate thereof, wherein A is a chelator residue derived from a chelator selected from the group consisting of 1,4,7,10-tetraazacyclododecane-N,N,N,N-tetraacetic acid (=DOTA), N,N-bis[2-hydroxy-5-(carboxyethyl)benzyl]ethylenediamine-N,N-diacetic acid, 1,4,7-triazacyclononane-1,4,7-triacetic acid (=NOTA), 2-(4,7-bis(carboxymethyl)-1,4,7-triazonan-1-yl)pentanedioic acid, (NODAGA), 2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acid (DOTAGA), 1,4,7-riazacyclononane phosphinic acid (TRAP), 1,4,7-triazacyclononane phosphinic acid (TRAP), 1,4,7-triazacyclononane-1-[methyl(2-carboxyethyl)phosphinic acid]-4,7-bis[methyl(2-hydroxymethyl)phosphinic acid](NOPO), 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1 (15),11,13-triene-3,6,9-triacetic acid (=PCTA), N-{5-[Acetyl(hydroxy)amino]pentyl}-N-[5-({4-[(5-arninopentyl)(hydroxy)amino]-4-oxobutanoyl}amino)pentyl]-N-hydroxysuccinamide (DFO), Diethylenetriaminepentaacetic acid (DTPA), Trans-cyclohexyl-diethylenetriaminepentaacetic acid (CHX-DTPA), 1-oxa-4,7,10-triazacyclododecane-4,7,10-triacetic acid (oxo-Do3A) p-isothiocyanatobenzyl-DTPA (SCN-Bz-DTPA), 1-(p-isothiocyanatobenzyl)-3-methyl-DTPA (1 B3M), 2-(p-isothiocyanatobenzyl)-4-methyl-DTPA (1 M3B) and 1-(2)-methyl-4-isocyanatobenzyl-DTPA (MX-DTPA).
21. The PSMA binding ligand of claim 16 or a pharmaceutically acceptable salt or solvate thereof, wherein A is a chelator residue having the structure: ##STR00077##
22. The PSMA ligand of claim 17, wherein the dye group Z is a fluorescent dye Z comprising, preferably consisting of, the structure: ##STR00078## wherein: X.sup.1z and X.sup.4z are independently selected from the group consisting of N=, N(R.sup.5z)=, and C(R.sup.6z); X.sup.2z and X.sup.3z are independently selected from the group consisting of O, S, Se, N(R.sup.Sz), and C(R.sup.6zR.sup.7z), preferably both are C(CH.sub.3).sub.2; Y.sup.z is a linker connecting the two moieties of (C) and permitting electron delocalization between said moieties, wherein Y.sup.z optionally comprises a group ##STR00079## az and bz are independently selected from the group consisting of 1, 2, and 3; each R.sup.1z and each R.sup.2z is independently selected from the group consisting of (L.sup.z-).sub.cZ.sup.z, (L.sup.z-).sub.cZ.sup.0 and H; and two adjacent R.sup.1z and/or two adjacent R.sup.2z can also form an aromatic ring, which is optionally substituted with one or more (L.sup.z-).sub.cZ.sup.z or (L.sup.z-).sub.cZ.sup.0; R.sup.3z, R.sup.4z, R.sup.5z, R.sup.6z, R.sup.7z, R.sup.9z are independently selected from the group consisting of (L.sup.z-).sub.cZ.sup.z, (L.sup.z-).sub.cZ.sup.0, and H; each c is independently 0 or 1; each L.sup.z is independently T.sup.1, OT.sup.1-, ST.sup.1-, C(O)T.sup.1-, C(O)OT.sup.1-, OC(O)T.sup.1-, C(O)NHT.sup.1-, NHC(O)T.sup.1, or a C.sub.1-10 alkylene group, which is optionally interrupted and/or terminated by one or more of O, S, C(O), C(O)O, OC(O), C(O)NH, NHC(O)O, and T.sup.1; T.sup.1 is phenyl, naphthyl, indenyl, indanyl, tetralinyl, decalinyl, adamantyl, C.sub.3-7 cycloalkyl, 3 to 7 membered heterocyclyl, or 7 to 11 membered heterobicyclyl, wherein T.sup.1 is optionally substituted with one or more substituents selected from the group consisting of halogen, CN, C(O)R.sup.8z, COOR.sup.8z, OR.sup.8z, C(O)N(R.sup.8zR.sup.8az), S(O).sub.2N(R.sup.8zR.sup.8az), S(O)N(R.sup.8zR.sup.8az), S(O).sub.2R.sup.8z, N(R.sup.8z)S(O).sub.2N(R.sup.8azR.sup.8bz), SR.sup.8z, N(R.sup.8zR.sup.8az), NO.sub.2; OC(O)R.sup.8z, N(R.sup.8z)C(O)R.sup.8az, N(R.sup.8z)S(O).sub.2R.sup.8az, N(R.sup.8z)S(O)R.sup.8az, N(R.sup.8z)C(O)N(R.sup.8azR.sup.8bz), N(R.sup.8z)C(O)OR.sup.8az, OC(O)N(R.sup.8zR.sup.8az), oxo (O), where the ring is at least partially saturated, or C.sub.1-6 alkyl, wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen, which are the same or different; each Z.sup.z is independently H, halogen, CN, C(O)R.sup.8z, C(O)OR.sup.8z, C(O)O.sup. OR.sup.8z, C(O)N(R.sup.8zR.sup.8az), S(O).sub.2OR.sup.8z, S(O).sub.2O.sup., S(O).sub.2N(R.sup.8zR.sup.8az), S(O)N(R.sup.8zR.sup.8az), S(O).sub.2R.sup.8z, S(O)R.sup.8z, N(R.sup.z)S(O).sub.2N(R.sup.8azR.sup.8bz), SR.sup.8z, N(R.sup.8zR.sup.8az), NO.sub.2; P(O)(OR.sup.8z).sub.2, P(O)(OR.sup.8z)O.sup., OC(O)R.sup.8z, N(R.sup.8z)C(O)R.sup.8az, N(R.sup.8z)S(O).sub.2R.sup.8az, N(R.sup.8z)S(O)R.sup.8z, N(R.sup.8z)C(O)N(R.sup.8azR.sup.8bz), N(R.sup.8z)C(O)OR.sup.8az, or OC(O)N(R.sup.8zR.sup.8az); R.sup.8z, R.sup.8az, R.sup.8bz are independently selected from the group consisting of H and C.sub.1-6 alkyl, wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen which are the same or different; Z.sup.0 is a chemical bond connecting the dye Z to the group -(L.sup.BZ)n.sub.bz-B, provided that one of R.sup.1z, R.sup.2z, R.sup.3z, R.sup.4z, R.sup.5z, R.sup.6z, R.sup.7z, R.sup.9z is (L.sup.z-).sub.cZ.sup.0 or that Y.sup.z comprises (L-).sub.cZ.sup.0.
23. The PSMA binding ligand of claim 16, wherein the ligand has the structure (IIIa): ##STR00080## wherein: R1 is H or CH.sub.3, preferably H, R2, R3 and R4 are independently of each other, selected from the group consisting ofCO.sub.2H, SO.sub.2H, SO.sub.3H, OSO.sub.3H, PO.sub.2H, PO.sub.3H and OPO.sub.3H.sub.2, Q1 is selected from the group consisting of alkylaryl, arylalkyl, aryl, alkylheteroaryl, heteroarylalkyl and heteroaryl, Q2 is selected from the group consisting of aryl, alkylaryl, arylalkyl, cycloalkyl, heterocycloalkyl, heteroaryl, heteroarylalkyl and alkylheteroaryl, q is an integer of from 0-3, X1 is a methylated amino acid, preferably wherein X1 is N(CH.sub.3)CH.sub.2C(O) and n1 is an integer of from 1 to 25, preferably 5 to 10, more preferably 10, Z is the dye group, L.sup.BZ is a linker, wherein nbz is 0 or 1, and R5 is an alkyl group, preferably a (CH2)2-4 group.
24. A complex comprising: (a) a radionuclide, and (b) the PSMA binding ligand or a pharmaceutically acceptable salt or solvate thereof of claim 16.
25. The complex of claim 24, wherein the radionuclide is selected from the group consisting of .sup.89Zr, .sup.44Sc, .sup.111In, .sup.90Y, .sup.66Ga, .sup.67Ga, .sup.68Ga, .sup.177Lu, .sup.99mTc, .sup.60Cu, .sup.61Cu, .sup.62Cu, .sup.64Cu, .sup.66Cu, .sup.67Cu, .sup.149Tb, .sup.152Tb, .sup.155Tb, .sup.153Sm, .sup.161Tb, .sup.153Gd, .sup.155Gd, .sup.157Gd, .sup.213Bi, .sup.225Ac, .sup.230U, .sup.223Ra, .sup.165Er, .sup.52Fe, .sup.59Fe, and radionuclides of Pb (such as .sup.203Pb and .sup.212Pb, .sup.211Pb, .sup.213Pb, .sup.214Pb, .sup.209Pb, .sup.198Pb, .sup.197Pb), more preferably selected from the group consisting of .sup.90Y, .sup.68Ga, .sup.177Lu, .sup.225Ac, and .sup.213Bi, more preferably the radionuclide is .sup.177Lu or .sup.225Ac.
26. A pharmaceutical composition comprising the PSMA binding ligand or a pharmaceutically acceptable salt or solvate thereof of claim 16.
27. A method for treating and/or preventing PSMA expressing cancer and/or metastases thereof, in particular prostate cancer and/or metastases thereof, comprising administering to a subject in need the complex of claim 24.
28. A method for treating and/or preventing PSMA expressing cancer and/or metastases thereof, in particular prostate cancer and/or metastases thereof, comprising administering to a subject in need the PSMA binding ligand or a pharmaceutically acceptable salt or solvate thereof of claim 16.
29. The method of claim 27, wherein adverse side effects on the kidney are reduced and/or avoided.
30. The method of claim 28, wherein adverse side effects on the kidney are reduced and/or avoided.
31. A method for diagnosing cancer and/or metastases thereof, preferably PSMA-expressing cancer and/or metastases thereof, in particular prostate cancer and/or metastases thereof, comprising using a diagnostic method comprising the complex of claim 24.
Description
FIGURE LEGENDS
[0359]
[0360]
[0361]
[0362]
[0363]
[0364] The following Examples shall merely illustrate the invention. They shall not be construed, whatsoever, to limit the scope of the invention.
EXPERIMENTAL PROCEDURES
[0365] All commercially available chemicals were of analytical grade and used without further purification. .sup.68Ga (half-life 68 min) was obtained from a .sup.68Ge/.sup.68Ga generator (Galliapharm Ge-68/Ga-68 Generator, Eckert&Ziegler) and .sup.177Lu (half-life 6.6 d) was purchased from ITG. The compounds were purified using semipreparative reversed-phase high performance liquid chromatography (RP-HPLC; Chromolith Semi Prep RP-18e, 10010 mm; Merck, Darmstadt, Germany). Compound analysis was performed using analytical RP-HPLC (RP-HPLC; Chromolith RP-18e, 1004.6 mm; Merck, Darmstadt, Germany). Analytical HPLC runs were performed using a linear gradient (5% A (0.1% aqueous TFA) to 100% B (0.1% TFA in CH.sub.3CN)) in 10 min at 2 mL/min. The system Agilent Technologies 1200 Series was equipped with a variable UV and a gamma detector (Ramona*, Elysia). UV absorbance was measured at 220 and 280 nm, respectively. For mass spectrometry a MALDI-MS (Daltonics Microflex, Bruker Daltonics, Bremen, Germany) was used.
Synthesis of Glu-urea-Lys-2-Nal-Chx-Sar.SUB.5.-Lys(DOTA)-Sar.SUB.5.-bAla-sulfoCy5 (BP-1), Glu-urea-Lys-2-Nal-Chx-Sar.SUB.10.-Lys(DOTA)-Sar.SUB.5.-bAla-sulfoCy5 (BP-2) and Glu-urea-Lys-2-Nal-Chx-Sar.SUB.5.-Lys(sulfoCy5)-Sar.SUB.5.-bAla-DOTA (BP-4)
[0366] The synthesis of the pharmacophore Glu-urea-Lys was performed as described previously (1). Briefly, the synthesis started with the formation of the isocyanate of the glutamyl moiety using triphosgene. A resin-immobilized (2-chloro-tritylresin, Merck, Darmstadt) s-allyloxycarbonyl protected lysine was added and reacted for 16 h with gentle agitation. The resin was filtered off and the allyloxy-protecting group was removed by reacting twice with Pd(PPh.sub.3).sub.4 (0.3 eq.) and morpholine (15 eq.) under ambient conditions (1 h, RT).
[0367] Subsequently, the linker between the PSMA pharmacophore and the chelator/dye was introduced by standard Fmoc solid phase protocol. In a first step Fmoc-2-NaIOH and N-Fmoc-tranexamic acid (4 eq. each) with HATU (4 eq.) and DIPEA (10 eq.) were coupled in DMF. Depending on the amino acid sequence, Fmoc-sarcosine was coupled five and ten-times, respectively, followed by Fmoc-Lys(Alloc)-OH with HATU (4 eq.) and DIPEA (10 eq.) in DMF. Subsequently, Fmoc-sarcosine was coupled five-times followed by Boc-beta-Alanine with HATU (4 eq.) and DIPEA (10 eq.) in DMF.
[0368] For the synthesis of BP-1 and BP-2 the allyloxy-protecting group was removed by reacting twice with Pd(PPh.sub.3).sub.4 (0.3 eq.) and morpholine (15 eq.) under ambient conditions (1 h, RT). Bis(tBu)DOTA (bis(tBu)-ester of 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid) (4 eq.) with HATU (4 eq.) and DIPEA (10 eq.) was afterwards coupled in DMF. The precursors were cleaved from the resin for 3 hours at RT using TFA/TIPS/H.sub.2O (95/2.5/2.5, v/v/v) and purified using RP-HPLC using a Chromolith RP-18e column (10010 mm; Merck, Darmstadt, Germany) and identified with mass spectrometry. Finally, sulfoCy5-NHS ester (2.5 mg) was conjugated to the precursors in DMF for 24 h at RT and the final products (BP-1 and BP-2) purified using RP-HPLC using a Chromolith RP-18e column (10010 mm; Merck, Darmstadt, Germany) and identified with mass spectrometry.
[0369] For the synthesis of BP-4, Bis(tBu)DOTA (bis(tBu)-ester of 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid) (4 eq.) with HATU (4 eq.) and DIPEA (10 eq.) were coupled in DMF to Glu-urea-Lys-2-Nal-Chx-Sar.sub.5-Lys(Alloc)-Sar.sub.5-bAla. Afterwards, the allyloxy-protecting group was removed by reacting twice with Pd(PPh.sub.3).sub.4 (0.3 eq.) and morpholine (15 eq.) under ambient conditions (1 h, RT). The precursor was cleaved from the resin for 3 hours at RT using TFA/TIPS/H.sub.2O (95/2.5/2.5, v/v/v) and lyophilized. Finally, sulfoCy5-NHS ester (2.5 mg) was conjugated to the precursor in DMF for 24 h at RT and the final product (BP-4) purified using RP-HPLC using a Chromolith RP-18e column (10010 mm; Merck, Darmstadt, Germany) and identified with mass spectrometry.
.SUP.68.GaLabeling
[0370] The precursor peptide [5 nmol in HEPES buffer (1 M, pH 4, 40 L)] was added to 40 L [.sup.68G]G.sup.3+ eluate (40 MBq) and ascorbic acid (5.68 mM, 0.8 L). The pH was adjusted to 3.8-4.2 using 30% NaOH. The reaction mixture was incubated at 95 C. for 15 minutes. The radiochemical yield (RCY) was determined by RP-HPLC.
.SUP.177.LuLabeling
[0371] The precursor peptide [2 nmol in HEPES buffer (0.1 M, pH 7, 50 L)] was added to 10 L [.sup.177Lu]LuCl.sub.3 (10-30 MBq, 0.04 M HCl) and ascorbic acid (5.68 mM, 0.7 L). The reaction mixture was incubated at 95 C. for 15 minutes. The radiochemical yield (RCY) was determined by RP-HPLC.
Cell Culture
[0372] PSMA.sup.+ LNCaP cells (CRL-1740; ATCC; PSMA-positive) and PC-3 cells (CRL-1435; ATCC; PSMA-negative) were cultured in RPMI medium supplemented with 10% fetal calf serum and 2 mmol/L L-glutamine (all from PAA). Cells were grown at 37 C. in humidified air with 5% CO.sub.2 and were harvested using trypsin-ethylenediaminetetraacetic acid (trypsin-EDTA; 0.25% trypsin, 0.02% EDTA, Invitrogen).
Cell Binding and Internalization
[0373] The competitive cell binding assay and internalization experiments were performed as described previously (2). Briefly, the cells (10.sup.5 per well) were incubated with a 0.8 nM solution of .sup.68Ga-labeled radioligand [Glu-urea-Lys(Ahx)].sub.2-HBED-CC (PSMA-10, precursor ordered from ABX, Radeberg, Germany) in the presence of 12 different concentrations of analyte (0-5000 nM, 100 L/well). After incubation, the mixture was removed and the wells were washed 3 times with PBS using a multiscreen vacuum manifold (Millipore, Billerica, MA). Cell-bound radioactivity was measured using a gamma counter (Perkin Elmer 2480, Wizard, Gamma Counter). The 50% inhibitory concentration (IC50) values were calculated by fitting the data using a nonlinear regression algorithm (GraphPad Software).
[0374] For internalization experiments, 10.sup.5 cells per well were seeded in poly-L-lysine coated 24-well cell culture plates 24 h before incubation. After washing, the cells were incubated with 30 nM of the radiolabeled compound for 45 min at 37 C. Cellular uptake was terminated by washing 3 times with 1 mL of ice-cold PBS. To remove surface-bound radioactivity, cells were incubated twice with 0.5 mL glycine-HCl in PBS (50 mM, pH=2.8) for 5 min. The cells were washed with 1 mL of ice-cold PBS and lysed using 0.3 N NaOH (0.5 mL). The surface-bound and the internalized fractions were measured in a gamma counter. The cell uptake was calculated as percent of the initially added radioactivity bound to 10.sup.5 cells [% ID/10.sup.5 cells].
Biodistribution
[0375] For the experimental tumor models 510.sup.6 cells of LNCaP or PC-3 (in 50% Matrigel; Becton Dickinson) were subcutaneously inoculated into the right trunk of 7- to 8-week-old male BALB/c nu/nu mice (Janvier). The tumors were allowed to grow until approximately 1 cm.sup.3 in size. The .sup.177Lu-labeled compounds were injected into a tail vein (1-2 MBq; 60 mol). At 1 h or 2 h after injection (p.i.) the animals were sacrificed. Organs of interest were dissected, blotted dry, and weighed. The radioactivity was measured using a gamma counter and calculated as % ID/g. All animal experiments complied with the current laws of the Federal Republic of Germany.
PET/MR and Optical Imaging
[0376] For imaging studies, mice were anesthetized (2% isoflurane) and 0.5 nmol of the .sup.68Ga-labeled compound in 0.9% NaCl (pH 7) were injected into the tail vein. PET imaging was performed with PET/MRI scanner (BioSpec 3T, Bruker) with a dynamic scan for 60 min. The images were iteratively reconstructed (MLEM 0.5 algorithm, 12 iterations) and were converted to SUV images. Quantification was done using a ROI (region of interest) technique and data in expressed in time activity curves as SUV.sub.bodyweight. Mice were sacrificed after PET/MR imaging and optical imaging of the subcutaneous tumor and organs of interest was performed with the Odyssey CLx system (LI-COR Biosciences, excitation wavelength 700 nm). All animal experiments complied with the current laws of the Federal Republic of Germany.
Statistical Aspects
[0377] All experiments were performed at least in triplicate and repeated at least for three times. Quantitative data were expressed as meanSD. If applicable, means were compared using Student's t test. P values <0.05 were considered statistically significant.
Results
In Vitro Characterization
[0378] The final product was identified using reversed-phase HPLC/matrix-assisted laser desorption/ionization mass spectrometry. The .sup.68Ga and .sup.177Lu complexation of all compounds resulted in radiochemical yields higher than 95%. All compounds showed a high PSMA-binding affinity in the nanomolar range, which was reduced as compared to the reference PSMA-617 (Table 1) (3). Remarkably, a PSMA-specific cell surface binding and specific internalization comparable to PSMA-617 was detected for all tested .sup.68Ga-labeled compounds.
TABLE-US-00001 TABLE 1 Cell binding and internalization data of the compounds*. Affinity to PSMA and internalization properties of the compounds were determined in vitro using PSMA.sup.+-cells (LNCaP). For all compounds PSMA-specific internalization and a binding affinity to PSMA in the nanomolar range were detected. Specifically cell Specifically surface bound internalized k.sub.i [nM].sup. Compound [% AR/10.sup.5 cells].sup. [% AR/10.sup.5 cells].sup. free ligands BP-2 1.2 0.8 0.5 0.4 71.91 21.18 BP-1 1.3 0.6 1.1 1.0 62.43 16.53 BP-4 0.8 1.0 0.4 0.7 64.94 6.82 PSMA-617 0.3 0.1 1.2 0.6 2.3 2.9 *Data are expressed as mean SD (n = 3), .sup.68Ga-labeled compounds; k.sub.i-value for PSMA-617 from Benesova et al. (3). Specific cell uptake was determined by blockage using 500 M 2-PMPA. Values are expressed as % of applied radioactivity (AR) bound to 10.sup.5 cells. .sup.radioligand: .sup.68Ga-PSMA-10 (K.sub.d: 3.8 1.8 nM (1), c.sub.radioligand: 0.8 nM)
In Vivo Characterization
[0379] All tested .sup.177Lu-labeled compounds revealed a PSMA-specific tumor uptake in LNCaP xenograft tumors (p>0.05), which is not significantly different compared to reference compound .sup.177Lu-PSMA-617 at 1 h p.i. (8.474.09% ID/g) and .sup.68Ga-Glu-urea-Lys-2-Nal-Chx-Lys(IRDye800CW)-DOTA (4.130.15% ID/g) (Table 2) (4). At the same time, the kidney uptake of 177LuBP-2 (19.059.52% ID/g) was surprisingly significantly reduced compared to .sup.177Lu-PSMA-617 (137.277.8% ID/g), .sup.68Ga-Glu-urea-Lys-2-Nal-Chx-Lys(IRDye800CW)-DOTA (65.646.60% ID/g) and the other tested compounds .sup.177LuBP-1 and .sup.177LuBP-4. The uptake of BP-2 in muscle, blood, spleen, lung and liver was found to be comparable to the other tested compounds at 1 h p.i. (Table 3). Fast renal clearance is confirmed by further decreased BP-2 uptake found in the kidney (4.610.45% ID/g) accompanied by decreased uptake in e.g. blood and spleen at 2 h p.i. The tumor uptake differs not significantly at 2 h p.i. as compared to 1 h p.i., indicating tracer enrichment over time. Tumor specificity of BP-2 was proven in PC-3 tumor-bearing mice, showing only negligible tumor uptake at 1 h p.i. (Table 2).
TABLE-US-00002 TABLE 2 Organ distribution of 0.06 nmol .sup.177Lu-labeled compounds in tumor bearing BALB/c nu/nu mice 1 h*. .sup.177Lu-BP-2 .sup.177Lu-BP-1 .sup.177Lu-BP-4 .sup.177Lu-BP-2 LNCaP Tumor- .sup.177Lu-BP-1 LNCaP Tumor- .sup.177Lu-BP-4 LNCaP Tumor- [% ID/g] to-Organ ratio [% ID/g] to-Organ ratio [% ID/g] to-Organ ratio Blood 0.16 0.01 34.73 14.72 0.16 0.02 39.99 4.75 0.23 0.08 25.89 9.14 Heart 0.07 0.01 90.47 45.17 0.10 0.004 64.45 12.77 0.12 0.02 48.59 15.65 Lung 0.27 0.01 19.88 6.95 0.38 0.03 18.17 4.54 0.40 0.04 12.10 2.03 Spleen 1.65 0.86 6.35 6.16 0.78 0.03 8.05 1.05 0.59 0.12 7.83 0.85 Liver 1.18 0.61 7.93 7.53 0.24 0.03 27.78 5.94 0.14 0.01 36.13 6.70 Kidney 8.49 3.38 0.66 0.20 18.86 4.56 0.34 0.04 37.50 12.13 0.17 0.08 Muscle 0.03 0.01 186.23 31.89 0.04 0.004 165.23 31.45 0.06 0.002 110.15 51.69 Intestine 0.10 0.06 83.92 53.16 0.08 0.01 76.31 13.13 0.12 0.04 49.30 18.19 Brain 0.02 0.005 286.72 78.41 0.02 0.001 423.06 81.33 0.02 0.002 275.08 63.60 Tumor 5.38 2.03 5.85 1.16 4.30 0.27 LNCaP Tumor 0.37 0.03 PC-3 *Data are expressed as mean % ID/g tissue SD (n = 3, for BP-2 n = 4) and Tumor-to-Organ ratios
TABLE-US-00003 TABLE 3 Organ distribution of 0.06 nmol .sup.177Lu-labeled BP-2 in LNCaP-tumor bearing BALB/c nu/nu mice 2 h p.i.*. .sup.177Lu-BP-2 .sup.177Lu-BP-2 [% ID/g] Tumor-to-Organ ratio Blood 0.05 0.01 88.59 20.90 Heart 0.03 0.003 124.71 13.31 Lung 0.12 0.02 36.31 5.39 Spleen 1.37 0.10 3.10 0.24 Liver 1.25 0.13 3.41 0.27 Kidney 4.61 0.45 0.93 0.14 Muscle 0.06 0.07 181.13 119.38 Intestine 0.03 0.004 147.74 23.30 Brain 0.01 0.003 419.27 102.70 Tumor 4.23 0.19 *Data are expressed as mean % ID/g tissue SD (n = 3) and Tumor-to-Organ ratios
[0380] The organ distribution findings were confirmed by PET/MR imaging. The pharmacokinetic properties of BP-2 are enhanced compared to PSMA-617 characterized by an accelerated excretion profile. The tumor targeting properties of BP-2 were found to be comparable to the parental reference PSMA-617 (
[0381] Optical imaging confirmed the findings of PSMA-specific tumor enrichment (
REFERENCES
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