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PET/SPECT Imaging of Multidrug Resistance P-glycoprotein:

PET/SPECT Imaging of Multidrug Resistance P-glycoprotein: Transport Activity Monitoring Associated with Blood-Brain Barrier Function David Piwnica -Worms, M.D., Ph.D. Director, Molecular Imaging Center Mallinckrodt Institute of Radiology and Department of Developmental Biology

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PET/SPECT Imaging of Multidrug Resistance P-glycoprotein:

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  1. PET/SPECT Imaging of Multidrug Resistance P-glycoprotein: Transport Activity Monitoring Associated with Blood-Brain Barrier Function David Piwnica-Worms, M.D., Ph.D. Director, Molecular Imaging Center Mallinckrodt Institute of Radiology and Department of Developmental Biology Washington University Medical School St. Louis, MO

  2. Molecular Imaging of Drug Transport In Vivo: Multidrug Resistance (MDR1) P-glycoprotein -Efflux transporter -Normally expressed in liver, kidney, bowels, choroid plexus, capillaries of BBB -Pumps xenobiotics and cancer chemotherapeutic drugs out of MDR cancer cells and prevents drugs from entering brain via BBB -MDR drugs include: taxol, doxorubicin, vinblastine, vincristine, VP16, TKI’s (e.g., Gleevec), HIV protease inhibitors, antibiotics, antidepressants, peptides, lipophiliccations -Pumps b-amyloid out of the brain across BBB -MDR modulators (inhibitors) in clinical trials -MDR1 polymorphisms impact drug PK/PD Immunotech

  3. Crystal Structure: Mouse P-Glycoprotein Front View Back View Probable Model for Transport of Recognized Substrates Science 2009, 323, 1718-1723

  4. Radiopharmaceuticals Targeting MDR1 P-glycoprotein SPECT AgentsPET Agents 99mTc-Sestamibi 99mTc -Tetrofosmin 99mTc-Q58, 99mTc-Q63 99mTc-CO-mibi 67Ga-ENBPI 68Ga-ENBPI 64Cu-dioxime 11C-verapamil 11C-daunorubicin 11C-colchicine 94mTc-Sestamibi 18F-paclitaxol 11C-loperamide

  5. T c - 9 9 m - B a s e d A g e n t s O M e O M e M e O O E t O E t O M e M e O P M e O P O M e E t O O E t N M e O O M e N N C N N P O P N C N C T c T c M e O T c T c O O O O C C O O C P P O N N O M e M e O P N M e O P O M e E t O O E t M e O O M e O E t O E t M e O O M e M e O M e O T c - 9 9 m - S e s t a m i b i T c - 9 9 m - T e t r o f o s m i n T c - 9 9 m - F u r i f o s m i n T c - 9 9 m - Q 5 8 P o s i t r o n E m i s s i o n T o m o g r a p h y A g e n t s M e O O M e O O H O M e O 1 1 C H 3 N H C O C H O 3 N N H O H M e O G a N N H O M e O M e O O H O O O O 1 1 O C H 3 N H 2 M e O O M e O H C - 1 1 - D a u n o r u b i c i n G a - 6 8 - 4 , 6 - D i M e O - E N B P I C - 1 1 - C o l c h i c i n e Conventional Radiopharmaceuticals Targeting MDR1 P-glycoprotein

  6. Conventional SPECT Agents Recognized by MDR1Pgpas Transport Substrates

  7. New SPECT Agent Recognized by MDR1Pgpas a Transport Substrate 67Ga-ENBPI

  8. New PET Agent Recognized by MDR1Pgpas a Transport Substrate 11C-Loperamide Robert Innis, et al.

  9. MDR + Inh wt max ADP MDR1 P-glycoprotein Tc-Complex MDR ATP (-) min High Potency MDR Inhibitors: Cell Uptake Glaxo GG918 Novartis PSC 833 Vertex 710 Eli Lilly 335979 XR9576 • MODEL OF [99mTc]-SESTAMIBI ACCUMULATION • IN TUMOR CELLS: • MEMBRANE POTENTIAL-DRIVEN PASSIVE INFLUX • MDR1 P-GLYCOPROTEIN-MEDIATED EFFLUX TRANSPORT cell membrane Tc-Complex Tc-Complex mito

  10. Electron Probe X-ray Microanalysis (EPXMA) of a Cultured Heart Cell Incubated in Technetium-99-Sestamibi Electron Density Map Technetium Map Mitochondrial rich tissue; No P-glycoprotein expression

  11. Pgp o WILD TYPE VIRUS 300 Sf9 MDR1 WT Tc-SESTAMIBI CONTENT ( fmol / mg protein nM ) 200 Pgp- 100 RECOMBINANT MDR1 TIME (min) 0 [99mTc]-Sestamibi 0 10 20 30 40 50 60 Baculoviral Expression of Recombinant Human MDR1 in Host Sf9 Cells: Effect on [99mTc]-Sestamibi Accumulation

  12. ABC Transporter-Mediated Efflux of [99mTc]-Sestamibi In Cultured Cell Monolayer Assays High Avidity Transport MDR1 Pgp Modest Avidity Transport MRP1 Minimal or Non-detectable Transport MDR3 Pgp MRP2, MRP3, MRP4, MRP5, MRP6 BCRP1/MXR

  13. [99mTc]-Sestamibi Imaging MDR1 P-glycoprotein Transport Activity in Breast Cancer: Dynamic [99mTc]-Sestamibi Mammoscintigraphy 1 hr post-injection 1° Tumor 4 hr post-injection

  14. [99mTc]-Sestamibi Clearance From Breast Cancers In Vivo Low Pgp High Pgp Del Vecchio, et al, Eur J Nucl Med 24:150, 1997

  15. Pgp Expressed Only on the Luminal Surface of Brain Capillaries: Provides Unidirectional Drug Transport Function at the BBB BBB Blood CSF Pgp Drug Barrier Compound Efflux Capillary Endothelial Cells

  16. Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with 99mTc-Sestamibi T1 MRI Co-Registration Tc-MIBI SPECT PNAS, 1999

  17. Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with 11C-Verapamil Sasongko, et al, 2005

  18. Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with 11C-Loperamide Lop 11C-N-Desmethyl-Loperamide Robert Innis, et al., 2009

  19. WT mdr1a/1b-/- brain mdr1a/1b-/- WT MicroPET: 10 min p.i. Biodistribution Analysis Molecular Imaging of mdr1 P-glycoprotein Transport Activity at the Capillary Blood-Brain Barrier in vivo with ENBPI Ga-Complexes: Correlation between Biodistribution and MicroPET Analysis 68Ga-3EtO-ENBPI

  20. Bidirectional Dynamic Model for Influx and Efflux of b-Amyloid (Aβ) Across the BBB: Pgp Transports b-Amyloid out of the CNS

  21. Pgp-null mice microinjected into CNS with b-Amyloid: Enhanced retention and reduced clearance from the brain Acute inhibition of Pgp with XR9576: Enhancement of CNS b-Amyloid content Enhanced amyloid plaque content in aged APPsw, Pgp-null mice mdr1 P-glycoprotein Deficiency at the Blood Brain Barrier Increases b-Amyloid Deposition in an Alzheimer Disease Mouse Model:P-glycoprotein Pumps b-Amyloid out of the Brain J Clin Invest 115: 3285, 2005

  22. APPsw/PS1-PgpWT APPsw/PS1-Pgp Null NanoSPECT Imaging: Comparative Uptake of 99mTc-Sestamibi inAPPsw/PS1-PgpWT and APPsw/PS1-Pgp-Null Mice Brain 2h Post Injection; 3-months old mice

  23. [99mTc]-Sestamibi Molecular Imaging of Multidrug Resistance (MDR1) P-glycoprotein (Pgp) Transport Activity at the BBB Pgp • Pgp pumps drugs and substrates • off the plasma membrane • Several PET and SPECT tracers show promise • as transport substrates for monitoring Pgp • Pgp is an important component of the BBB • and can be functionally imaged by • PET and SPECT LOW Pgp HIGH Pgp Tc-99m-Sestamibi • Pgp pumps b-Amyloid out of the brain across • the BBB. Pgp polymorphisms may be • an imagable risk factor for AD.

  24. Seth Gammon Piwnica-Worms Lab, Molecular Imaging Center Vijay Sharma Funding: NIH P50, RO1, DOD

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