Radiolabeled tracers for poly (ADP-ribose) polymerase-1 (PARP-1), methods and uses therefor
09993570 ยท 2018-06-12
Assignee
Inventors
- Robert Mach (Philadelphia, PA, US)
- Wenhua Chu (Saint Louis, MO, US)
- Dong Zhou (Ballwin, MO, US)
- Loren Michel (Clayton, MO, US)
- Delphine Chen (Brentwood, MO, US)
Cpc classification
A61P35/00
HUMAN NECESSITIES
A61P29/00
HUMAN NECESSITIES
C07D403/12
CHEMISTRY; METALLURGY
C07D235/18
CHEMISTRY; METALLURGY
A61K51/0468
HUMAN NECESSITIES
International classification
A61K51/00
HUMAN NECESSITIES
C07D235/18
CHEMISTRY; METALLURGY
Abstract
Disclosed are PARP-1 inhibitors, which can be .sup.18F-labeled for use as tracers in positron emission tomographic (PET) imaging. Further disclosed are methods of synthesis. Of the compounds synthesized, 2-[p-(2-Fluoroethoxy)phenyl]-1.3.10-triazatricyclo[6.4.1.0.sup.4,13]trideca-2,4(13),5,7-tetraen-9-one (12) had the highest inhibition potency for PARP-1 (IC.sub.50=6.3 nM). Synthesis of [.sup.18F]-12 is disclosed under conventional conditions in high specific activity with 40-50% decay-corrected yield. MicroPET imaging using [.sup.18F]-12 in MDA-MB-436 tumor-bearing mice demonstrated accumulation of [.sup.18F]-12 in a tumor. Binding, can be blocked by olaparib. The compounds have utility for tumor imaging.
Claims
1. A compound or pharmaceutically acceptable salt thereof of structure ##STR00023##
2. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the fluorine designated F is an .sup.18F fluorine.
3. A method of imaging a tissue in a subject, comprising: administering to a subject a compound or pharmaceutically acceptable salt thereof of structure ##STR00024## and subjecting the subject to positron emission tomography (PET) scanning.
4. The method of imaging a tissue in a subject according to claim 3, wherein the tissue is a tumor tissue.
5. The method of imaging a tissue in a subject according to claim 3, wherein the tissue is an inflamed tissue.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION
(9) The present teachings in various embodiments include tracers that can be used for imaging of tumors or of inflammation by PFT scanning. In various aspects, the tracers can bind PARP-1 with high affinity. In various embodiments, the present teachings also include methods of synthesis of the tracers. Tracers of the present teachings, when labeled with a positron-emitting radioisotope such as .sup.18F, can be administered to a subject by intravenous or other suitable means.
(10) The methods described herein utilize laboratory techniques well known to skilled artisans, and guidance can be found in laboratory manuals and textbooks such as Sambrook, J., et al., Molecular Cloning: A Laboratory Manual 3rd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 2001; Spector, D. L. et al., Cells: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. 1998; Hendrickson et al., Organic Chemistry 3rd edition, McGraw Hill, New York, 1970; Carruthers, W., and Coldham, I., Modern Methods of Organic Synthesis (4th Edition), Cambridge University Press, Cambridge, U.K., 2004; Curati, W. L., Imaging in Oncology, Cambridge University Press, Cambridge, U.K., 2004; Welch, M. J., and Redvanly, C. S., eds. Handbook of Radiopharmaceuticals: Radiochemistry and Applications, J. Wiley, New York, 2003. Methods of administration of pharmaceuticals and dosage regimes, can be determined according to standard principles of pharmacology well known skilled artisans, using methods provided by standard reference texts such as Remington: the Science and Practice of Pharmacy (Alfonso R, Gennaro ed. 19th ed. 1995): Hardman, J. G., et al., Goodman & Gilman's The Pharmacological Basis of Therapeutics, Ninth Edition, McGraw-Hill, 1996; and Rowe, R. C., et al. Handbook of Pharmaceutical Excipients, Fourth Edition, Pharmaceutical Press, 2003.
(11) In the experiments described herein, reagents and materials were purchased from commercial suppliers and used without further purification unless otherwise stated. Chemicals were purchased from Sigma-Aldrich Chemical Co. (St. Louis, Mo. USA) unless otherwise specified. All reactions were earned out by standard air-free and moisture-free techniques under an inert nitrogen atmosphere with dry solvents unless otherwise stated.
(12) Flash column chromatography can be conducted using a variety of methods and instruments including Scientific Adsorbents, Inc. silica gel, 60A. 40 Micron Flash (32-63 m). Melting points can be determined using a variety of methods and instruments well known in the art, including the MEL-TEMP 3.0 apparatus. In some configurations, melting point data is uncorrected. .sup.1H and .sup.13C NMR spectra at 300 MHz can be recorded through a variety of routine methods on a variety of instruments, including a Varian Mercury-VX spectrometer. In some configurations, chemical shifts can be reported as parts per million (ppm) downfield from tetramethylsilane (TMS). All coupling constants (J) are given in Hertz (Hz). Splitting patterns are typically described as follows: s, singlet; d, doublet: t, triplet; m, multiplet.
(13) Elemental analysis (C, H, N) can be determined by a variety of commercial contract organizations such as Atlantic Microlab, Inc., Norcross, Ga. High performance liquid chromatography (HPLC) can be performed with an ultraviolet detector and a well-scintillation NaI (TI) detector and associated electronics for radioactivity detection. A Grace Altima C18 25010 mm 10 semi-preparative column (A) and au Altima C18 2504.6 mm 10 analytical column (B) can be used for preparation and analysis respectively. [.sup.18F]Fluoride can be produced by the .sup.18O(p,n).sup.18F reaction through proton irradiation of enriched (95%) [.sup.18O] water in the RDS111 cyclotron. Radio-TLC can be accomplished using a Bioscan AR-2000 imaging scanner (Bioscan, Inc., Washington, D.C.). Published methods were used for the synthesis of compound 5.sup.27 and 11.sup.22. All animal experiments were conducted under Washington University Animal Studies Committee IACUC-approved protocols in accordance with the recommendations of the National Research Council's Guide for the Care and Use of Laboratory Animals.
EXAMPLES
(14) The present teachings including descriptions provided in the Examples that are not intended to limit the scope of any claim. Unless specifically presented in the past tense, an example can be a prophetic or an actual example. The following non-limiting examples are provided to further illustrate the present teachings. Those of skill in the art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments that are disclosed and still obtain a like or similar result without departing from the spirit and scope of the present teachings.
Example 1
(15) This example illustrates synthesis of PARP-1 inhibitors. Compound numbers refer to Schemes 1 and 2, infra.
(16) The syntheses of PARP-1 inhibitors of the present teachings are shown in Schemes 1 and 2. Methyl 2,3-diaminobenzate (5) was reacted with 4-(2-fluoroethoxy)benzoyl chloride in pyridine and dichloromethane to afford a mixture of intermediate 6a and the benzimidazole compound 6. After evaporation of the solvent, the mixture was refluxed with methanesulfonic acid in methanol to give 6. Then the methyl ester of 6 was compound to the amide compound 8 using ammonium in methanol. Similarly, the alkyne analog 9 was synthesized starting from 5 and 4-(prop-2-ynyloxy)benzoyl chloride. The triazole compound 10 was prepared by the copper(I) catalyzed click reaction of 2-fluoroethylazide and 9 using CuSO.sub.4.5H.sub.2O and sodium ascorbate in DMF.
(17) The tricycle compounds were synthesized from the diamine intermediate 11. Compound 11 was reacted with 4-(2-fluoroethoxy)benzoyl chloride in pyridine and dichloromethane to afford a mixture of intermediate 12a and the benzimidazole 12. After evaporation of the solvent, the mixture was refluxed with methanesulfonic acid in methanol to give 12. Similarly, 13 and 14 were made from the corresponding benzyl chlorides. Compound 15 was prepared by the click reaction under the same condition as for 10 using 2-fluoroethylazide and 13. The mesylate precursor 16 for the labeling of 12 with .sup.18F was synthesized by reflux of 14 and silver methanesulfonate in acetonitrile.
(18) ##STR00019##
(19) ##STR00020##
Example 2
(20) This example illustrates the synthesis of Methyl 2-(4-(2-fluoroethoxy)phenyl)-1H-benzo[d]imidazole-4-carboxylate (6). Compound numbers refer to Schemes 1 and 2, supra.
(21) A mixture of methyl 2,3-diaminobenzoate 5 (500 mg, 3 mmol) and 4-(2-fluoroethoxy)benzoyl chloride (638 mg, 3.15 mmol) in CH.sub.2Cl.sub.2 (10 mL) and pyridine (10 mL) was stirred overnight at 23 C., After removal of the solvent under reduced pressure, the residue was dissolved in methanol (50 mL), and followed by addition of CH.sub.3SO.sub.3H (1 mL). After the mixture was refluxed for 3 h, methanol was removed under reduced pressure, and the residue was dissolved in ethyl acetate (75 mL). The solution was washed with saturated Na.sub.2CO.sub.3 (50 mL), water (50 mL) and saturated NaCl (50 mL), and dried over Na.sub.2SO.sub.4. After evaporation of the solvent, the crude product was purified by silica gel column chromatography eluting with hexane-ethyl acetate (1:1) to afford 6 as white solid (686 mg, 73%), mp 134.2-134.6 C. .sup.1H NMR (300 MHz, CDCl.sub.3) 10.58 (s, 1H), 7.98 (d, J=8.7 Hz, 2H), 7.95 (d, J=8.7 Hz, 1H), 7.83 (d, J=7.2 Hz, 1H), 7.26 (t, J=7.8 Hz, 1H), 6.98 (d, J=9.0 Hz, 2H), 4.75 (dt, J=47.1 Hz, 4.2 Hz, 2H), 4.22 (dt, J=27.6 Hz, 4.2 Hz, 2H), 3.96 (s, 3H). .sup.13C NMR (75 MHz, CDCl.sub.3) 167.0, 160.2, 152.3, 144.8, 135.0, 128.2, 124.4, 124.2, 122.3, 121.7, 114.9, 113.0, 81.6 (d, J=169.7 Hz), 67.1 (d, J=20.6 Hz), 52.0.
Example 3
(22) This example illustrates the synthesis of Methyl 2-(4-(prop-2-ynyloxy)phenyl)-1H-benzo[d]imidazole-d-carboxylate (7). Compound numbers refer to Schemes 1 and 2, supra.
(23) Compound 7 was prepared according to the same procedure for compound 6 (Example 2), except using compound 5 (500 mg, 3 mmol) and 4-(prop-2-ynyloxy)benzoyl chloride (613 mg, 3.15 mmol) as starting materials. The crude product was purified by silica gel column chromatography eluting with hexane-ethyl acetate (1:1) to afford 7 as white solid (724 mg, 79%), mp 176.0-176.8 C. .sup.1H NMR (300 MHz, CDCl.sub.3) 10.58, 8.03 (d, J=9.0 Hz. 2H), 7.98 (d, J=8.1 Hz, 1H), 7.86 (d, J=7.8 Hz, 1H), 7.29 (t, J=8.1 Hz, 1H), 7.10 (d, J=9.0 Hz, 2H), 4.76 (d, J=2.4 Hz, 2H), 4.00 (s, 3H), 2.57 (t J=2.4 Hz, 1H), .sup.13C NMR (75 MHz, CDCl.sub.3) 167.1, 159.4, 152.4, 144.9, 135.1, 128.2, 124.6, 124.3, 122.8, 121.8, 115.4, 113.0, 77.9, 76.0, 55.8, 52.1.
Example 4
(24) This example illustrates the synthesis of 2-(4-(2-Fluoroethoxy)phenyl)-1H-benzo[d]imidazole-4-carboxamide (8). Compound numbers refer to Schemes 1 and 2, supra.
(25) A solution of Compound 6 (315 mg, 1 mmol) in 7 N NH.sub.3 in methanol (10 mL) was stirred for 3 days at 23 C. After evaporation of the solvent, the crude product was purified by silica gel column chromatography eluting with hexane-ethyl acetate (1:2) to afford 8 as white solid (245 mg, 82%), mp 195.8-197.4 C. .sup.1H NMR (300 MHz, DMSO-d.sub.6) 9.44 (s, 1H), 8.23 (d, J=9.0 Hz, 2H), 7.89 (d, J=7.5 Hz, 1H), 7.80 (s, 2H), 7.74 (d, J=7.8 Hz, 1H), 7.34 (t, J=7.5 Hz, 1H), 7.20 (d, J=8.4 Hz, 2H), 4.81 (dt, J=47.7 Hz, 3.6 Hz, 2H), 4.37 (dt, J=30.0 Hz, 3.9 Hz, 2H). .sup.13C NMR (75 MHz, DMSO-d.sub.6) 166.4, 160.1, 152.0, 135.5, 128.6, 122.7, 122.0, 115.1, 82.1 (d, J=166.2 Hz), 67.3 (d, J=19.4 Hz). Anal. Calcd for C.sub.16H.sub.14FN.sub.3O.sub.2.0.5H.sub.2O: C, 62.33; H, 4.90; N, 13.63. Found: C. 62.54; H, 4.87; N, 13.67.
Example 5
(26) This example illustrates the synthesis of 2-(4-(Prop-2-ynloxy)phenyl)-1H-benzo[d]imidazole-4-carboxamide (9). Compound numbers refer to Schemes 1 and 2, supra.
(27) Compound 9 was prepared according to the same procedure for compound 8, except using compound 7 (460 mg, 1.5 mmol) as starting material. The crude product was purified by silica gel column chromatography eluting with hexane-ethyl acetate (1:2) to afford 9 as white solid (378 mg, 86%), mp 183.4-183.9 C. .sup.1H NMR (300 MHz, DMSO-d.sub.6) 9.39 (s, 1H), 8.21 (d, J=8.4 Hz, 2H). 7.87 (d, J=7.8 Hz, 1H), 7.78 (s, 2H), 7.72 (d, J=7.8 Hz, 1H), 7.32 (t, J=7.8 Hz, 1H), 7.20 (d, J=9.0 Hz, 2H) 4.92 (d, J=1.8 Hz, 2H), 3.63 (s, 1H). .sup.13C NMR (75 MHz, DMSO-d.sub.6) 166.4, 159.0, 152.0, 128.5, 122.7, 122.3, 121.9, 115.4, 78.9, 78.6, 55.7. Anal. Calcd for C.sub.17H.sub.18N.sub.3O.sub.2.0.5H.sub.2O: C, 67.99; H, 4.70; N, 13.99. Found: C, 67.97; H, 4.72; N, 13.71.
Example 6
(28) This example illustrates the synthesis of 2-(4-((1-(2-Fluoroethyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazole-4-carboxamide (10). Compound numbers refer to Schemes 1 and 2 supra.
(29) A mixture of 9 (291 mg, 1.0 mmol). 1-azido-2-fluoroethane (1.68 mmol), sodium ascorbate (990 mg, 5.0 mmol), and CuSO.sub.4.5H.sub.2O (125 mg, 0.5 mmol) in DMF (10 ml) was stirred overnight at 23 C. The reaction mixture was diluted with ethyl acetate (75 mL), and washed with water (250 mL), and saturated NaCl (50 mL), dried over Na.sub.2SO.sub.4. After evaporation of the solvent, the crude product was purified by silica gel column chromatography eluting with ethyl acetate to afford 10 as white solid (255 mg, 67%) mp 256.4-257.3 C. .sup.1H NMR (300 MHz, DMSO-d.sub.6) 9.42 (s, 1H), 8.33 (s, 1H), 8.21 (d, J=8.7 Hz, 2H), 7.87 (d, J=7.5 Hz, 1H), 7.78 (s, 2H), 7.71 (d, J=7.8 Hz, 1H), 7.32 (t, J=7.8 Hz, 1H), 7.27 (d, J=8.7 Hz, 2H), 5.28 (s, 2H), 4.85 (dt, J=46.8 Hz, 4.5 Hz, 2H), 4.76 (dt, J=27.6 Hz, 4.2 Hz, 2H). .sup.13C NMR (75 MHz, DMSO-d.sub.6) 166.3, 159.9, 152.0, 142.5, 142.5, 141.6, 135.3, 128.6, 125.1, 122.7, 122.1, 121.9, 115.3, 114.7, 99.5, 81.9 (d, J=167.3 Hz), 61.3, 50.1 (d, J=20.5 Hz). Anal. Calcd for C.sub.19H.sub.17FN.sub.6O.sub.2: C, 59.99; H, 4.50; N, 22.09. Found: C, 60.10; H, 4.67; N, 21.49.
Example 7
(30) This example illustrates the synthesis of 5,6-Dihydro-2-(4-(2-fluoroethoxy)phenyl)-imidazo [4,5,1-jk][1,4]benezodiazepin-7(4H)-one (12). Compound numbers refer to Schemes 1 and 2, supra.
(31) Compound 12 (WC-4-138) was prepared according to the same procedure for compound 6, except using compound 11 (177 mg, 1 mmol) and 4-(2-fluoroethoxy)benzoyl chloride (213 mg, 1.05 mmol) as starling materials. The crude product was purified by silica gel column chromatography eluting with ethyl acetate-methanol (10:1) to afford 12 as white solid (247 mg, 76%), mp 236.0-237.5 C. .sup.1H NMR (300 MHz/DMSO-d.sub.6) 8.44 (t, J=5.1 Hz, 1H), 7.89-7.80 (m, 4H), 7.34 (d, J=7.9 Hz, 1H), 7.17 (d, J=8.7 Hz, 2H), 4.79 (dt, J=48.9 Hz, 3.6 Hz, 2H), 4.44 (m, 2H), 4.35 (dt, J=31.2 Hz, 3.9 Hz, 2H), 3.53 (m, 2H). .sup.13C NMR (75 MHz, DMSO-d.sub.6) 167.8, 159.9, 154.1, 143.7, 132.9, 131.7, 125.5, 123.1, 122.5, 121.9, 118.1, 115.1, 82.5 (d, J=165.0 Hz), 67.7 (d, J=19.3 Hz), 50.9, 40.8. Anal. Calcd for C.sub.18H.sub.16FN.sub.3O.sub.3: C, 66.45; H, 4.96; N, 12.92. Found; C, 66.43; H, 5.03; N, 12.92.
Example 8
(32) This example illustrates the synthesis of 5,6-Dihydro-2-(4-(prop-2-ynyloxy)phenyl)-imidazo[4,5,1-jk][1,4]benzodiazepine-7(4H)-one (13). Compound numbers refer to Schemes 1 and 2, supra.
(33) Compound 13 was prepared according to the same procedure for compound 6, except using, compound 11 (177 mg, 1 mmol) and 4-(prop-2-ynyloxy)benzoyl chloride (204 mg, 1.05 mmol) as starting materials. The crude product was purified by silica gel column chromatography eluting with ethyl acetate-methanol (10:1) to afford 13 as white solid (268 mg, 84%), mp 258.0-259.1 C. .sup.1H NMR (300 MHz, DMSO-d.sub.6) 8.47 (s, 1H), 7.85 (m, 4H), 7.34 (t, J=7.8 Hz, 1H), 7.18 (d, J=6.9 Hz, 2H), 4.93 (s, 2H), 4.46 (m, 2H), 3.64 (s, 1H), 3.54 (m, 2H), .sup.13C NMR (75 MHz, DMSO-d.sub.6) 167.4, 158.5, 153.6, 143.3, 132.5, 131.1, 125.1, 122.7, 122.4, 121.5, 117.7, 115.0, 79.0, 78.5, 55.6, 50.5. Anal. Calcd for C.sub.19H.sub.15N.sub.3O.sub.2: C, 71.91; H, 4.76; N, 13.24. Found; C, 71.71; H, 4.82; N, 12.98.
Example 9
(34) This example illustrates the synthesis of 2-(4-(2-Bromoethoxy)phenyl)-5,6-dihydro-imidazo[4,5,1-jk][1,4]benzodiazepin-7(4H)-one (14). Compound numbers refer to Schemes 1 and 2, supra.
(35) Compound 14 was prepared according to the same procedure for compound 6, except using compound 11 (177 mg, 1 mmol) and 4-(2-bromoethoxy)benzoyl chloride (277 mg, 1.05 mmol) as starting materials. The crude product was purified by silica gel column chromatography eluting with ethyl acetate-methanol (10:1) to afford 14 as white solid (255 mg, 66%), mp decomposed 280 C. .sup.1H NMR (400 MHz, DMSO-d.sub.6) 8.44 (t, J=5.6 Hz, 1H), 7.87 (d, J=8.0 Hz, 1H), 7.85 (d, J=8.0 Hz, 1H), 7.82 (d, J=8.4 Hz, 2H), 7.34 (t, J=7.6 Hz, 1H), 7.16 (d, J=8.4 Hz, 2H), 4.44 (m, 4H), 3.86 (t, J=5.2 Hz, 2H), 3.53 (m, 2H). .sup.13C NMR (100 MHz, DMSO-d.sub.6) 167.8, 159.7, 154.1, 143.7, 132.9, 131.7, 125.5, 123.1, 122.6, 122.0, 118.1, 115.2, 68.4, 50.5, 40.8.
Example 10
(36) This example illustrates the synthesis of 5,6-Dihydro-2-(4-((1-(2-fluoroethyl)-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-imidazo[4,5,1-jk][1,4]benzodiazepin-7(4H)-one (15). Compound numbers refer to Schemes 1 and 2, supra.
(37) Compound 15 was prepared according to the same procedure for compound 10, except using compound 13 (159 mg, 0.5 mmol) as starting material. The crude product was purified by silica gel column chromatography eluting with ethyl acetate-methanol (10:1) to afford 15 as white solid (147 mg, 72%), mp 226.5-227.6 C. .sup.1H NMR (300 MHz, DMSO-d.sub.6) 8.46 (t, J=5.7 Hz, 1H), 8.33 (s, 1H), 7.8-7.81 (m, 4H), 7.34 (t, J=7.8 Hz, 1H), 7.25 (d, J=8.4 Hz, 2H), 5.28 (s, 2H), 4.85 (dt. J=47.1 Hz, 4.2 Hz, 2H), 4.76 (dt. J=27.6 Hz, 4.2 Hz, 2H), 4.45 (m, 2H), 3.54 (m, 2H). .sup.13C NMR (75 MHz, DMSO-d.sub.6) 167.4, 159.4, 143.3, 142.6, 131.2, 125.1, 125.0, 122.7, 122.0, 121.5, 117.7, 114.8, 81.9 (d, J=167.3 Hz), 61.2, 50.5, 50.1 (d, J=20.5 Hz), 40.4. Anal. Calcd for C.sub.21H.sub.19FN.sub.6O.sub.2.1.5H.sub.2O: C, 58.19; H, 5.12; N, 19.39. Found: C, 57.89; H, 4.54; N, 18.92.
Example 11
(38) This example illustrates the synthesis of 5,6-Dihydro-2-(4-(2-(methylsulfonyloxy)ethoxy)phenyl)-imidazo[4,5,1-jk][1,4]benzodiazepin-7(4H)-one (16). Compound numbers refer to Schemes 1 and 2, supra.
(39) A mixture of 14 (193 mg, 0.5 mmol) and AgOMs (508 mg, 2.5 mmol) was refluxed for 8 h. After evaporation of the solvent, the crude product was purified by silica gel column chromatography eluting with ethyl acetate-methanol (10:1) to afford 16 as white solid (129 mg, 64%), mp 253.2-254.1 C. .sup.1H NMR (400 MHz, CD.sub.3OD) 7.97 (d, J=8.0 Hz, 1H), 7.88 (d, J=8.0 Hz, 1H), 7.76 (d, J=8.8 Hz, 2H), 7.40 (t, J=8.0 Hz, 1H), 7.17 (d, J=8.8 Hz, 2H), 4.59 (t, J=4.0 Hz, 2H), 4.49 (t, J=4.0 Hz, 2H), 4.35 (t, J=4.0 Hz, 2H), 3.65 (m, 2H), 3.12 (s, 3H). .sup.13C NMR (100 MHz, CD.sub.3OD) 160.2, 148.1, 142.7, 135.7, 132.2, 131.1, 131.0, 125.8, 122.6, 122.1, 121.4, 116.9, 114.6, 68.3, 66.0, 50.5, 40.6, 36.0.
Example 12
(40) This example illustrates PARP-1 activity assays.
(41) Newly synthesized PARP-1 inhibitors were assessed for their ability to inhibit active PARP-1 using the method described by Putt and Hergenrother..sup.23 The results are shown in Table 1. The tricycle benzimidazole compounds had higher inhibition potency than their respective benzimidazole analogs (e.g., 12 vs. 8, 15 vs. 10). In both benzimidazole and tricycle benzimidazole analogs, the analogs with fluoroethoxy substituent had three times higher inhibition potencies than the respective analogs with fluoroethyl triazole group (e.g., 8 vs. 10, 12 vs. 15). Therefore, the most potent inhibitor, 12, was selected for .sup.18F-labeling.
(42) ##STR00021##
(43) TABLE-US-00001 TABLE 1 Inhibition efficiency of PARP-1 inhibitors Compound Structure R IC.sub.50 (nM) 1 PJ34 / / 170.2 8.3.sup.a 8 A a 10.8 0.4 9 A b 25.8 3.3 10 A c 30.3 5.6 12 B a 6.3 1.3 13 B b 18.7 2.7 15 B c 22.1 6.3 .sup.aReported values: IC.sub.50 = 20 nM, EC.sub.50 = 35 nm;.sup.3,24
Example 13
(44) This example illustrates a PARP-1 enzymatic activity assay.
(45) This assay is based on the chemical quantification of NAD.sup.+, i.e. the amount of NAD.sup.+ consumed when the active PARP-1 C-terminal catalytic domain sequentially transfers ADP-ribose subunits from nicotinamide adenine dinucleotide (NAD.sup.+) to protein acceptors..sup.7
(46) High-specific-activity PARP-1 and activated DNA were purchased from Trevigen (Gaithersburg, Md.). All other reagents required for this assay including NAD.sup.+ were purchased from Sigma-Aldrich (St. Louis, Mo.). Known PARP-1 inhibitor PJ-34, used as a control in these experiments, was synthesized in-house. To test the compounds for PARP-1 inhibition, a solution of 250 nM NAD.sup.+ was first made in 50 mM Tris-HCl. 2 mM MgCl.sub.2, at pH 8.0 PARP assay buffer) and 20 L transferred to each well of a 96-well black fluorescence plate. A solution of 50 g/mL of activated DNA was made in PARP assay buffer and 10 L was added to each well. Stock solutions of test compounds were first prepared in DMSO, diluted to varying concentrations in PARP assay buffer, and 10 L was added to each well. To initiate the reaction, 10 L of 10 g/mL PARP-1 enzyme in PARP assay buffer was added to each well. The total volume was 50 L, bringing the final concentrations to 2 g/mL PARP-1 enzyme, 10 g mL activated DNA, and 100 nM NAD.sup.+ per well. The plate was then incubated at room temperature for 20 min. The amount of NAD.sup.+ present was then determined by first adding 20 L 2 M KOH, followed by 20 L of 20% acetophenone (in ethanol) to each well. The plate was allowed to incubate at 4 C. for 10 min. Then 90 L of 88% formic acid was added, resulting in a final concentration of 222 mM KOH, 2.2% acetophenone, 44% formic acid, and varying concentrations of NAD.sup.+. The plate was incubated at 100 C. for 5 min., allowed to cool, and then, read on a Perkin Elmer Victor microplate fluorometer (Waltham, Mass.) using 360 nm excitation and 450 nm emission filters. Dose-response curves were generated using GraphPad Prism version 5.04 for Windows (San Diego, Calif.) where control wells containing NAD.sup.+ only were set at 0% PARP activity and control wells containing PARP-1 only were set at 100% PARP activity. IC.sub.50 values were calculated from the dose-response curves generated from at least three independent experiments and reported in Table 1 as meanstandard deviation (SD).
Example 14
(47) This example illustrates the synthesis of radio-labeled PARP-1 inhibitors.
(48) [.sup.18F]12 was synthesized by the nucleophilic substitution of the mesylate precursor 16 under conventional conditions (K.sub.222/K.sub.2CO.sub.3) in DMF at 105 C. (Scheme 3), affording [.sup.18F]12 in 40-50% yield (decay corrected) after reversed phase HPLC purification and solid phase extraction (
(49) ##STR00022##
Example 15
(50) This example further illustrates the synthesis [.sup.18F]Compound 12 (WC-4-138).
(51) [.sup.18F]fluoride (up to 50 mCi in 100-500 L [.sup.18O]water) was transferred to a BD vacutainer (1375 mm, 5 mL, glass, no additives) containing K.sub.222 (2.2 mg, 5.8 mol) and K.sub.2CO.sub.3 (0.3 mg. 2.2 mol). The mixture was then dried by azeotropic distillation at 105 C. using acetonitrile (31 mL) under a gentle flow of N.sub.2 gas. When the drying was nearly finished, the vacutainer was removed from the oil bath and the solvent residue (100 L) was removed by a flow of N.sub.2 at room temperature. A solution of 16 (0.65 mg. 1.6 mol) in DMF (300 L) was added to the vacutainer and then shaken and heated at 105 C. for 10 min. At room temperature, the reaction mixture was diluted with water (2 mL) and then loaded onto a semi-preparative column (A) for purification (18% acetonitrile/82% water/0.1% TFA, 4 mL/min, 251 nm). The HPLC fraction containing [.sup.18F]12 was collected, and [.sup.18F]12 was obtained in ethanol using standard solid phase extraction method. The dose was diluted to 10% ethanol in saline. An analytical column (B) was used to analyze the dose (32% acetonitrile/68% 0.1 M ammonium formate buffer pH=4.5, 2 mL/min, 251 nm). The total synthesis time was 90 min, the decay corrected yields 40-50%, the radiochemical purity 100%, and the specific activity ranged from 5500 to 18000 mCi/mol at the end of synthesis.
Example 16
(52) This example illustrates the visualization of tumor tissue in microPET in mice. MDA-MB-436 human breast cancer xenograft tumors in immune-deficient mice were visualized by PET using [.sup.18F]12. These tumors demonstrated increased uptake that was distinguishable from background at 60 min post-tracer injection (
(53) The time-radioactivity curves of [.sup.18F]12 in the tumors from 0-60 min of the microPET studies confirmed the visual assessment of the microPET images (
(54) MDA-MB-436 is a human breast cancer cell line with innately high levels of PARP-1 activity.sup.19 and has been used in a mouse models to assess the efficacy of the .sup.18F-labeled olaparib derivative for imaging PARP-1 activity with micro PET. [.sup.18F]12 progressively accumulated in the tumor during the 1 hour microPFT acquisition, and [.sup.18F]12 uptake was blocked in animals pretreated with either olaparib or 12. Both olaparib and 12 are competitive PARP-1 inhibitors with high inhibition potencies (IC.sub.50=5 nM.sup.31 and 6.3 nM, respectively). Thus, our data indicate that [.sup.18F]12 uptake in the mouse model is due to PARP-1 expression, and that [.sup.18F]12 is an effective PET tracer for in vivo imaging of PARP-1 expression specifically.
Example 17
(55) This example illustrates the visualization of tumor tissue in mice using PET.
(56) MDA-MB-436 and MDA-MB-231 human breast cancer cells were maintained in cell culture under standard conditions with 5% CO.sub.2 atmosphere using Eagle's minimum essential medium (with Earle's balanced salt solution and 2 mM L-glutamine) supplemented with 2 mM E-glutamine, 1 mM sodium pyruvate, 0.1 mM non-essential amino acids 2% vitamins for MEM, and 5% fetal bovine serum. Cells in exponential growth were trypsinized and harvested for tumor implantation. After counting, cells were re-suspended in ice-cold 1:1 Matrigel and PBS to give the desired concentration and held on ice.
(57) Mature female athymic nu/nu mice from Charles River Laboratories are allowed to acclimate in an AALAC accredited housing facility for at least 1 week prior to tumor implantation for these serial imaging studies. Female nu/nu mice were implanted in the mammary fat pads (near the auxiliary lymph nodes) with 810.sup.6 MDA-MB-436 breast cancer cells in 100 L of 1:1 Matrigel:PBS. Imaging studies were conducted 2-3 weeks post implantation.
(58) Tumor-bearing mice were placed in an induction chamber containing 2% isoflurane/oxygen and then secured to a custom double bed for placement of tail vein catheters; anesthesia was maintained via nose-cone at 1% isoflurane/oxygen for the dynamic imaging procedure. The mice were injected with 150-200 Ci of [.sup.18F]12 and scanned for 0-60 min using Focus 220 and Inveon PET/CT scanners. The standard uptake values (SUVs) were generated from manually drawn regions of interests for tumors and surrounding background tissue. Visualization of specific uptake was determined by comparison of baseline scans with images acquired by tracer injection 20 minutes after pre-treatment with the blocking agents olaparib (50 mg/kg, IP) or 12 (1 mg/kg, IP).
Example 18
(59) This example illustrates the uptake of [.sup.18F]WC-4-138 (Compound 12) in cell culture assays.
(60) In these experiments, the head and neck squamous cell carcinoma lines SCC1, SCC15, and SCC25 (ATCC) were propagated in Dulbecco's Modified Eagle's Medium (DMEM, Gibco) supplemented with 10% Fetal Bovine Serum (FBS, Gibco), Penicillin-Streptomycin (P/S, Gibco), and 100 ng/ml hydrocortisone (Sigma-Aldrich). The small cell lung cancer lines NCI-h69 and NCI-h82 (ATCC) were propagated m RPMI Medium (Gibco) supplemented with 10% FBS and 1% P/S. The human breast cancer cell line MDA-MB-231 (ATCC) was propagated in Eagle's Minimum Essential Medium (Gibco) supplemented with 5% FBS, 2% Vitamins for MEM (Gibco), 1% 200 mM L-glutamine (Gibco), 1% 10 mM Non-Essential Amino Acid (NEAA, Gibco).
(61) For each experimental replicate, approximately 1 Ci of [.sup.18F]WC-4-138 was diluted in 1 ml of cell culture medium and added to 10.sup.6 cells. After 5, 30, or 60 minutes, the medium was collected and cells were washed twice in 0.7 ml Phosphate Buffered Saline (PBS, Gibco). Adherent cells were collected by scraping the cell culture dish and transferring to a microfuge tube. Radioactivity was measured in the collected medium, PBS, or cell pellets. Protein from the cell pellet was quantified using a standard chemiluminescent PARP ELISA kit (Trevigen #4520-096-K). All data were decay-corrected and normalized to total protein quantity in the cell pellet. For drug treatment studies, cells were incubated with 10 M Olaparib or Iniparib twenty-hours prior to incubation with [.sup.18F]WC-4-138.
(62) The head and neck cell lines SCC1 and SCC25 constitutively take up small amounts of tracer, registering as 0.001-0.002 Ci/g in the cell pellet (
(63) This activity is abolished by Olaparib (
Example 19
(64) This example illustrates metabolic stability of Compound 12 ([.sup.18F]WC-4-138).
(65) In these experiments, the metabolic stability of [.sup.18]-WC-4-138 was assessed after injecting 400 Ci into the tail veins of adult male C57BL/6J mice (Jackson Laboratory). Mice were sacrificed by cervical dislocation 5 or 30 minutes post-injection. The inferior vena cava was lacerated and blood was collected from the abdominal cavity. The plasma was separated from the red blood cells by centrifugation at 14000 rpm. Plasma (100 l) was mixed with acetonitrile at a 1:1.5 ratio and centrifuged at 14000 rpm. Radioactivity associated with the red blood cell pellet, whole plasma, and acetonitrile-soluble and insoluble fractions was measured. The liver of each animal was also collected at the indicated times and frozen on dry ice. Livers were homogenized in 2 ml acetonitrile and 1 ml of the homogenized liver was centrifuged at 14000 rpm. Radioactivity associated with the supernatant and pellet was measured.
(66) Acetonitrile-soluble plasma or liver supernatant (100 l) was mixed at a 1:1 ratio with water and separated by reverse phase HPLC. The parent compound was also separated by HPLC as a reference. The radioactivity associated with each HPLC fraction was measured. The percent parent compound of each sample was calculated as the portion radioactivity associated with the HPLC fractions expected to contain the parent compound.
(67) Compound 12 ([.sup.18F]WC-4-138) was rapidly metabolized in the blood, with 50% relative to the reference compound present 5 minutes post-injection and only about 10% of the compound relative to the reference compound was observed 30 minutes post-injection (
Example 20
(68) This example illustrates biodistribution of Compound 12 ([.sup.18F]WC-4-138) in mice. Eight week old, female, athymic nude mice (Harlan) were injected via tail vein with [.sup.18F]WC4-138. Mice were sacrificed by cervical dislocation 5 or 30 minutes after IV tracer injection of 30 Ci, 1 or 2 hours after injection of 45 Ci, or 4 hours after injection of 60 Ci of [.sup.18F]WC-4-138. The acetonitrile-soluble fractions of plasma or liver and the control parent compound were separated via reverse-phase high performance liquid chromatography (HPLC) and the radioactivity of each fraction was quantified. The percent parent compound of each sample was calculated as the portion of radioactivity associated with the HPLC fractions that contained the parent compound. Data are presented as meanSD, n=3.
(69) Four mice were sacrificed at each timepoint, with the exception of the 2 hour timepoint (n=3). Blood, heart, lung, muscle, liver, spleen, fat, adrenal glands, kidney, uterus, ovaries, bone, bone marrow, pancreas, stomach, small intestine, and large intestine were collected from each animal. All organs were blotted to remove excess blood, weighed, and counted in a Beckmann 6000 gamma counter. The percent injected dose per gram (% ID/g) of tissue was determined for each organ. Results varied from 0.5 to 1.5% infected dose per gram of tissue and are reported in Tables 1 and 2.
(70) TABLE-US-00002 TABLE 1 Organ biodistribution of [.sup.18F] WC-4-138 in athymic nude mice % ID/g 5 min 30 min 60 min 120 min 240 min Blood 1.60 +/ 0.21 2.07 +/ 0.16 2.30 +/ 0.28 2.54 +/ 0.13 1.61 +/ 0.05 Heart 6.57 +/ 0.45 3.44 +/ 0.30 2.88 +/ 0.23 2.68 +/ 0.09 1.67 +/ 0.06 Lung 11.89 +/ 0.89 5.33 +/ 0.48 3.99 +/ 0.29 3.17 +/ 0.28 2.03 +/ 0.43 Muscle 2.05 +/ 0.48 2.39 +/ 0.15 2.21 +/ 0.31 2.07 +/ 0.11 1.35 +/ 0.09 Liver 12.50 +/ 1.08 8.24 +/ 0.62 6.50 +/ 0.52 4.58 +/ 0.29 2.43 +/ 0.25 Spleen 12.47 +/ 6.69 26.85 +/ 3.52 25.75 +/ 1.95 17.19 +/ 1.08 9.80 +/ 1.01 Fat 1.16 +/ 0.49 1.22 +/ 0.25 1.16 +/ 0.45 1.07 +/ 0.11 0.62 +/ 0.44 Adrenals 11.80 +/ 0.46 5.18 +/ 0.94 3.51 +/ 1.08 2.69 +/ 0.44 1.74 +/ 0.34 Kidney 35.63 +/ 3.33 21.14 +/ 2.21 14.02 +/ 1.84 8.77 +/ 0.72 3.67 +/ 0.54 Uterus 3.44 +/ 2.01 4.53 +/ 1.45 5.51 +/ 0.79 4.13 +/ 0.20 2.05 +/ 0.31 Ovaries 4.71 +/ 1.21 5.31 +/ 0.82 4.75 +/ 0.36 4.25 +/ 0.52 2.00 +/ 0.41 Bone 3.40 +/ 0.74 4.49 +/ 0.34 5.21 +/ 0.40 6.56 +/ 0.80 9.29 +/ 1.17 Marrow 0.06 +/ 0.02 0.11 +/ 0.02 0.13 +/ 0.04 0.07 +/ 0.01 0.04 +/ 0.01 Pancress 9.67 +/ 1.98 10.27 +/ 1.28 9.18 +/ 1.37 5.37 +/ 0.64 2.75 +/ 0.44 Stomach 3.17 +/ 0.66 3.77 +/ 0.73 3.62 +/ 0.37 2.56 +/ 0.27 1.20 +/ 0.08 Small 12.64 +/ 1.45 13.00 +/ 0.75 8.85 +/ 1.49 6.62 +/ 0.75 3.04 +/ 0.25 Intestine Upper Large 7.84 +/ 1.02 14.07 +/ 1.72 15.62 +/ 2.31 10.28 +/ 0.65 4.33 +/ 0.57 Intestine Lower Large 4.17 +/ 0.42 7.43 +/ 0.59 10.53 +/ 1.45 13.35 +/ 0.87 7.17 +/ 0.50 Intestine Thyroid 4.18 +/ 1.18 4.03 +/ 0.28 3.32 +/ 0.19 3.46 +/ 0.10 3.23 +/ 0.49 Brain 0.55 +/ 0.16 1.03 +/ 0.11 1.24 +/ 0.13 1.58 +/ 0.19 1.17 +/ 0.05 % ID/g = Percent injected dose per gram of tissue. All data are mean SD. n = 4 for all groups, with the exception of n = 3 at 120 min.
(71) TABLE-US-00003 TABLE 2 Estimated human dosimetry from mouse biodistribution study Male Female Organ (rad/mCi) (rad/mCi) Adrenals 0.043 0.052 Brain 0.019 0.022 Breasts 0.019 Gallbladder Wall 0.028 0.033 LLI Wall 0.029 0.036 Small Intestine 0.026 0.030 Stomach Wall 0.024 0.030 ULI Wall 0.025 0.031 Heart Wall 0.038 0.047 Kidneys 0.083 0.093 Liver 0.050 0.065 Lungs 0.035 0.045 Muscle 0.026 0.035 Ovaries 0.045 Pancreas 0.055 0.064 Red Marrow 0.061 0.069 Osteogenic Cells 0.155 0.203 Skin 0.016 0.019 Spleen 0.110 0.133 Testes 0.022 Thymus 0.020 0.026 Thyroid 0.033 0.038 Urinary Bladder Wall 0.220 0.301 Uterus 0.053 Total Body 0.031 0.039 Effective Dose Equivalent 0.062 0.075 Effective Dose (rem/mCi) 0.047 0.057
(72) Estimates were obtained from the organ residence times calculated from the mouse biodistribution data, shown in Table 1, using standard MIRD methodology.
Example 21
(73) This example illustrates uptake of Compound 12 ([.sup.18F]WC-4-138) in mice. Mature female athymic nude mice (Charles River Laboratories) were implanted with 10.sup.6 SCC1 cells or 10.sup.7 MDA-MB-231 cells into the mammary fat pads. Mice bearing SCC1 tumors were imaged at 5 weeks and mice bearing MDA-MB-231 cells were imaged at 2.5 weeks after implant. Mice were anesthetized with 2% isoflurane/oxygen and maintained at 1% isoflurane/oxygen via nose cone throughout the imaging procedure. Whole animal microCT images were acquired on an Inveon PET/CT scanner. The mice were injected via tail vein with 11.360.5 MBq (30713 Ci) of [.sup.18F]WC(4)-138 and underwent a 60 minute dynamic scan using Focus 220 or Inveon PET/CT scanners. The microPET and microCT images were coregistered using Integrated Research Workflow software (Siemens). Regions of interest were drawn over tumors to determine time activity curves. For drug treatment studies, animals reached intraperitoneal injections of 50 mg/kg olaparib or iniparib 30 minutes before imaging. Mice were imaged at baseline, or 30 minutes after IP injection of olaparib or iniparib. Transverse views of MDA-MB-231 tumor-bearing mice are shown in
Example 22
(74) This example illustrates a quantitative analysis that shows significant decreases in injected dose per ml between baseline and drug treatment for both MDA-MB-231 tumors (
Example 23
(75) A subject presents with symptoms of potential PARP-1 associated breast cancer. A physician orders PET scanning, and a technician administers an effective amount of [.sup.18F]WC(4)-138 and performs the PET scan. The tumor exhibits a large amount of tracer uptake compared to the surrounding tissues of the subject. The physician diagnoses PARP-1 associated cancer and prescribes PARP-1 inhibitors as part of a treatment regime.
Example 24
(76) A subject presents with abnormal inflammation of the lungs. A physician orders PET scanning, and a technician administers an effective amount of [.sup.18F]WC(4)-138 and performs the PET scan. The lung tissue exhibits large amounts of tracer uptake relative to control lung tissue, and the physician diagnoses PARP-1 related inflammation and prescribes PARP-1 inhibitors as part of a treatment regime.
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(78) All publications cited herein are incorporated by reference, each in its entirety. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context indicates otherwise.