David J. Donnelly Sr. Research Investigator Bristol-Myers Squibb

Transcription

1 David J. Donnelly Sr. Research Investigator Bristol-Myers Squibb 1

2 Phosphodiesterases are a family of enzymes involved in the inactivation of the secondary messengers camp and cgmp These secondary messengers play a critical role in signal transduction in the CNS PDE10A is unique since, it has the most restricted expression, being exclusively expressed in the striatum of rodents and primates. It is involved in the inactivation of both camp and cgmp Abnormal levels of PDE10A impairs striatal output & may contribute to the pathophysiology of such conditions as: Schizophrenia, Alzheimer's, Parkinson's, and Huntington's diseases Selective Inhibitors of PDE10A have been become targets for the treatment these diseases A PET radioligand specific for PDE10A would provide an in-vivo biomarker for target engagement and receptor occupancy for these inhibitors 2

3 [ 11 C]-Papaverine [ 18 F]-FE-Mp-10 ([ 18 F]-JNJ ) [ 11 C]-Mp-10 References: 1) Nuc. Med Biol. 2010, 37, ) J. Nuc. Med. 2010, 51, ) Bio. Org. Med. Chem. 2011, 19, ) J, Med. Chem. 2011, 54, ) Pharmaceuticals 2012, 5,

4 B UV A Gamma A B Starting from 800 mci of [ 18 F]-fluoride 5.2 mci was isolated A mixture of regioisomers generated J. Nuc. Med. 2010, 51,

5 UV Gamma Starting from 800 mci of [ 18 F]-fluoride Only 3.2 mci (avg n=6) was isolated Specific Activity 4.0 Ci/µmol (avg n=6) 5

6 By installing deuterium, our goal was: To generate a more useful PET ligand for PDE10A by: Reducing the beta elimination side product Potentially slowing down the N-dealkylation metabolism 6

7 UV Starting from 800 mci of [ 18 F]-fluoride Gamma Isolated 31.2 mci (avg n=6) (H4 analog only 3.2) Specific Activity 7.1 Ci/µmol (avg n=6) 7

8 UV = 254 nm Gamma Luna C18(2): 100 x 4.5 mm, 3.5 micron, 1 ml/min 19% MeCN, 81% 0.1 % TFA, RCP 99.8% 8

9 Ex-vivo Autoradigraphy Micro PET imaging using wild type and knock out mice Non-human primate imaging ( Cyno ) Chase study in rodent Radiometabolite analysis in rodent and non-human primate Nature of activity in brain ( rodent ) 9

10 Baseline rodents injected with [ 18 F]-FE-Mp-10-d 4 ( 220 µci ) Rodents injected with Mp-10 at 3 mg/kg followed by an injection of [ 18 F]-FE-Mp-10-d 4 (150 µci ) 10 minutes later 1 hour after tracer injection, the animals sacrifice & sliced for brain tissue slides Overnight exposure and imaged on Fujifilm Fluorescent Image Analyzer FLA-9000 at 50µm pixel size 10

11 PSL Normalized with BW and ID [ 18 F]-FE-Mp-10-d 4 Uptake in Rat Striatum Baseline Blocked Baseline Blocked with Mp-10 50% signal reduction in Mp-10 treated animal 11

12 PDE10A KO and WT male mice (~28 g) were injected with [ 18 F]-FE-Mp-10-d 4 (~0.2 mci) The animals were maintained on 1-2% isoflurane during injection and imaging Positioned side-by-side in a custom-built, two-mouse tray in the Siemens Focus 120 micropet scanner 45 min emission scan starting at about 19 min after tracer injection Summed image reconstructed with filtered back projection and corrected for attenuation and scatter 12

13 Transverse Coronal Sagittal WT SUV 1.5 [ 18 F]-FE-Mp-10-d 4 KO 0 Loss of signal in KO mouse suggests specific binding 13

14 One male, 4.3 kg cynomolgous monkey was anesthetized (1-2% isoflurane) 10 min transmission scan using a 57 Co point source for attenuation correction The NHP was injected with [ 18 F]-FE-Mp-10-d 4 (~2 mci) 2 hr emission scan started immediately prior to tracer injection using a Siemens Focus 220 micropet scanner Summed image was reconstructed with filtered back projection and corrected for attenuation and scatter 14

15 PET / MRI fiducial markers Uptake in striatum consistent with rodent PET images Transverse Coronal view Sagittal view Increasing uptake These images are summed frames of a PET non-human primate imaging study collected over a 120 minute period. 15

16 Male, Sprague Dawley rats (~500 g) were injected with H 4 analog,[ 18 F]-FE- Mp-10 or D 4 analog [ 18 F]-FE-Mp-10-d 4 (~0.9 mci) 2 hr emission scan started immediately prior to tracer injection using a Siemens Focus 120 micropet scanner At 60 min after tracer injection, 3 mg/kg Mp-10 was administered via the tail vein catheter Listmode data was histogrammed into 52 dynamic frames. Images were reconstructed with filtered back projection and corrected for attenuation 3D volumes of interest were manually drawn over the striatum and cerebellum using ASIPro 16

17 Rat - D 4 VS. H 4 Mp 10 injected Striatum-D4 Cerebellum-D4 Striatum-H4 Cerebellum-H4 Mp SUV 1.0 D H Time (min)

18 Male, Sprague Dawley rats (~500 g) were injected with H4 [ 18 F]-FE-Mp-10 or D4 [ 18 F]-FE-Mp-10-d 4 (~1.5 mci) The animals were maintained on 1-2% isoflurane during injection, tracer uptake, and blood sampling 1 ml of blood was collected in lithium heparin coated tubes either from the contralateral tail vein or the retro-orbital plexus at 10, 30, 60 and 90 min after injection Samples were centrifuged for 10 min at 10,000 rpm for plasma separation at 4 C, washed with equal amounts of methanol and stored over ice. These samples were analyzed for radiochemical purity via radio-hplc and radio-tlc. 18

19 Rodent & Non-Human Primate Plasma Metabolite Analysis Plasma Metabolite Analysis D 4 % of Parent Remaining 100% 80% 60% 40% 20% 0% Time (Minutes) H4 Rodent D4 Rodent D4 Cyno H 4 Preliminary results suggest no significant difference in the metabolism between the H 4 ligand and D 4 ligand (Rodent n=4) 19

20 Male, Sprague Dawley rats (~500 g) were injected with H4 [ 18 F]-FE-Mp-10 or D4 [ 18 F]-FE-Mp-10-d 4 (~1.5 mci) The animals were maintained on 1-2% isoflurane during injection only and were conscious during the uptake period The rats were euthanized by CO 2 at 30 or 60 min after tracer injection After brains were isolated, the cerebellum was separated from the rest of the brain Samples were homogenized with acetonitrile and centrifuged at 8160 rpm for 30 min and submitted for analysis. These samples were analyzed for radiochemical purity via radio-hplc and radio-tlc. 20

21 % of Intact Tracer % of Intact Tracer in Perfused Rat Cerebrum & Cerebellum 30 Minutes P.I. 90% 60% 30% 0% 71% 72% 81% 82% 30 mins Cerebellum 30 mins Cerebrum D4 H4 n=4 No difference seen between D 4 and H 4 tracers: ~ 20% polar metabolite seen in cerebrum ~ 30% polar metabolite seen in cerebellum 21

22 % of Intact Tracer 90% 60% 30% 0% % of Intact Tracer in Perfused Rat Cerebrum & Cerebellum 60 Minutes P.I. 52% 50% 80% 73% 60 mins Cerebellum 60 mins Cerebrum D4 H4 n=4 No difference seen between D 4 and H 4 tracers ~ 20% polar metabolite seen in cerebrum ~ 50% polar metabolite seen in cerebellum 22

23 The D 4 ligand has the following advantages: Increased isolated yield 31.1 mci isolated (n= 6) compared directly to the H 4 ligand 3.2 mci (n=6) Increased specific activity from 4.0 to 7.1 Ci/µmol One step fluorination method is directly translatable to any radiochemistry system No significant difference in the metabolism between the H 4 and D 4 ligands in rodent The D 4 and H 4 ligands gave identical in-vivo micro PET imaging results 23

24 Neuroscience Chemistry Joanne Bronson Stephen Mercer Neuroscience Biology Yu-Wen Li Camellia Symonowicz Vet Sciences Caprice Vanderen Bob Scalese Imaging Adrienne Pena Patrick Chow Joonyoung Kim Dan Kukral Harry Malone Wendy Hayes Liliana Barreto Radiochemistry Tritin Tran Kevin Cao Sam Bonacorsi Doug Dischino 24

25 1. MAO-B C-11 labeled D2-deprenyl J.nuc.med 1995: C-11 labeled D2- acetate Nuc Med Biol 1994: D4-F18 labeled Choline derivative Cancer Res; (19) Deuterium substituted radioligand for peripheral benzodiazepine receptor Bioorg. Med. Chem. 2005; (13)