PET/SPECT Imaging of Multidrug PET/SPECT Imaging of Multidrug Resistance Resistance P-glycoprotein: P-glycoprotein: Transport Activity Monitoring Transport Activity Monitoring Associated with Blood-Brain Barrier Associated with Blood-Brain Barrier Function Function David Piwnica-Worms, M.D., Ph.D. David Piwnica-Worms, M.D., Ph.D. Director, Molecular Imaging Center Director, Molecular Imaging Center Mallinckrodt Institute of Radiology Mallinckrodt Institute of Radiology and and Department of Developmental Biology Department of Developmental Biology Washington University Medical School Washington University Medical School St. Louis, MO St. Louis, MO
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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 - PowerPoint PPT Presentation
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PET/SPECT Imaging of Multidrug Resistance PET/SPECT Imaging of Multidrug Resistance P-glycoprotein:P-glycoprotein:
Transport Activity Monitoring Associated with Transport Activity Monitoring Associated with Blood-Brain Barrier FunctionBlood-Brain Barrier Function
David Piwnica-Worms, M.D., Ph.D.David Piwnica-Worms, M.D., Ph.D.
Director, Molecular Imaging CenterDirector, Molecular Imaging CenterMallinckrodt Institute of RadiologyMallinckrodt Institute of Radiology
and and Department of Developmental BiologyDepartment of Developmental BiologyWashington University Medical School Washington University Medical School
St. Louis, MOSt. Louis, MO
Molecular Imaging of Drug Transport In Vivo:Molecular Imaging of Drug Transport In Vivo:Multidrug Resistance (Multidrug Resistance (MDR1MDR1) P-glycoprotein) P-glycoprotein
Immunotech
-Efflux transporter-Efflux transporter-Normally expressed in liver, kidney, bowels,-Normally expressed in liver, kidney, bowels,
choroid plexus, capillaries of BBBchoroid plexus, capillaries of BBB-Pumps xenobiotics and cancer chemotherapeutic -Pumps xenobiotics and cancer chemotherapeutic
drugs out of MDR cancer cells and drugs out of MDR cancer cells and prevents drugs from entering brain via BBBprevents drugs from entering brain via BBB
-Pumps -Pumps -amyloid out of the brain across BBB-amyloid out of the brain across BBB-MDR modulators (inhibitors) in clinical trials-MDR modulators (inhibitors) in clinical trials-MDR1 polymorphisms impact drug PK/PD -MDR1 polymorphisms impact drug PK/PD
Probable Model for TransportProbable Model for Transportof Recognized Substratesof Recognized Substrates
Mitochondrial rich tissue; No P-glycoprotein expressionMitochondrial rich tissue; No P-glycoprotein expression
Electron Density Map Technetium MapElectron Density Map Technetium Map
Electron Probe X-ray Microanalysis (EPXMA)Electron Probe X-ray Microanalysis (EPXMA) of a Cultured Heart Cell Incubated in Technetium-99-Sestamibiof a Cultured Heart Cell Incubated in Technetium-99-Sestamibi
6060505040403030202010100000
100100
200200
300300
TIME (min)TIME (min)
Tc-S
ESTA
MIB
I CO
NTE
NT
( fm
ol /
mg
prot
ein
nM
)Tc
-SES
TAM
IBI C
ON
TEN
T ( f
mol
/ m
g pr
otei
n n
M ) oo
WILD TYPE VIRUSWILD TYPE VIRUS
RECOMBINANT RECOMBINANT MDR1MDR1
Sf9 MDR1 WTSf9 MDR1 WT
Pgp-Pgp-
Baculoviral Expression of Recombinant Human Baculoviral Expression of Recombinant Human MDR1MDR1 in Host Sf9 in Host Sf9 Cells:Cells:
Effect on [Effect on [99m99mTc]-Sestamibi AccumulationTc]-Sestamibi Accumulation
[[99m99mTc]-SestamibiTc]-Sestamibi
Pgp
ABC Transporter-Mediated Efflux of [ABC Transporter-Mediated Efflux of [99m99mTc]-SestamibiTc]-SestamibiIn Cultured Cell Monolayer AssaysIn Cultured Cell Monolayer Assays
High Avidity TransportHigh Avidity TransportMDR1 PgpMDR1 Pgp
Minimal or Non-detectable TransportMinimal or Non-detectable TransportMDR3 PgpMDR3 PgpMRP2, MRP3, MRP4, MRP5, MRP6MRP2, MRP3, MRP4, MRP5, MRP6BCRP1/MXRBCRP1/MXR
Imaging MDR1 P-glycoprotein Transport Activity in Breast Cancer: Dynamic [99mTc]-Sestamibi Mammoscintigraphy
11 Tumor Tumor
1 hr post-injection1 hr post-injection
4 hr post-injection4 hr post-injection
[[99m99mTc]-SestamibiTc]-Sestamibi
Del Vecchio, et al, Eur J Nucl Med 24:150, 1997
[[99m99mTc]-Sestamibi Clearance From Breast Cancers Tc]-Sestamibi Clearance From Breast Cancers In VivoIn Vivo
Low Pgp
High Pgp
Pgp Expressed Only on the Luminal Surface of Brain Capillaries:Pgp Expressed Only on the Luminal Surface of Brain Capillaries:Provides Unidirectional Drug Transport Function at the BBBProvides Unidirectional Drug Transport Function at the BBB
Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with 99mTc-Sestamibi
PNAS, 1999PNAS, 1999
Functional Demonstration of the Drug-Permeability Barrier Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with at the BBB in Humans with 1111C-VerapamilC-Verapamil
Sasongko, et al, 2005Sasongko, et al, 2005
Robert Innis, et al., 2009Robert Innis, et al., 2009
Functional Demonstration of the Drug-Permeability Barrier Functional Demonstration of the Drug-Permeability Barrier at the BBB in Humans with at the BBB in Humans with 1111C-Loperamide C-Loperamide
0 20 40 60 80 100 120 %
Inje
cted
Dos
e[T
issu
e C
i(Inj
ecte
d C
i)-1g-1
x 1
00]
0.0
0.5
1.0
1.5
Time (min)0 20 40 60 80 100 120
0.0
0.2
0.4
0.6
0.8
0 20 40 60 80 100 1200
10
20
30Blood Brain Liver
MicroPET: 10 min p.i.MicroPET: 10 min p.i.
brain
WT mdr1a/1b -/-
Biodistribution AnalysisBiodistribution Analysis
mdr1a/1b -/-
WT
Molecular Imaging of Molecular Imaging of mdr1mdr1 P-glycoprotein Transport Activity P-glycoprotein Transport Activity at the Capillary Blood-Brain Barrier at the Capillary Blood-Brain Barrier in vivoin vivo with ENBPI Ga-Complexes: with ENBPI Ga-Complexes:
Correlation between Biodistribution and MicroPET AnalysisCorrelation between Biodistribution and MicroPET Analysis
6868Ga-3EtO-ENBPIGa-3EtO-ENBPI
Bidirectional Dynamic Model for Influx and Efflux Bidirectional Dynamic Model for Influx and Efflux of of -Amyloid (A-Amyloid (Aβ) β) Across the BBB:Across the BBB:
Pgp Transports Pgp Transports -Amyloid out of the CNS-Amyloid out of the CNS
mdr1mdr1 P-glycoprotein Deficiency at the Blood Brain Barrier Increases P-glycoprotein Deficiency at the Blood Brain Barrier Increases -Amyloid-Amyloid Deposition in an Alzheimer Disease Mouse Model: Deposition in an Alzheimer Disease Mouse Model:
P-glycoprotein Pumps P-glycoprotein Pumps -Amyloid-Amyloid out of the Brain out of the Brain
Pgp-null mice microinjected into CNS with Pgp-null mice microinjected into CNS with -Amyloid-Amyloid::Enhanced retention and reduced clearance from the brain Enhanced retention and reduced clearance from the brain
Acute inhibition of Pgp with XR9576:Acute inhibition of Pgp with XR9576:Enhancement of CNS Enhancement of CNS -Amyloid-Amyloid content content
NanoSPECT Imaging: Comparative Uptake of NanoSPECT Imaging: Comparative Uptake of 99m99mTc-Sestamibi inTc-Sestamibi in APPsw/PS1-PgpWT and APPsw/PS1-Pgp-Null Mice APPsw/PS1-PgpWT and APPsw/PS1-Pgp-Null Mice
Molecular Imaging of Multidrug Resistance (Molecular Imaging of Multidrug Resistance (MDR1MDR1) P-glycoprotein (Pgp) ) P-glycoprotein (Pgp) Transport Activity at the BBBTransport Activity at the BBB
LOW Pgp
HIGH Pgp
Tc-99m-Sestamibi
PgpPgp
Pgp pumps drugs and substratesPgp pumps drugs and substratesoff the plasma membraneoff the plasma membrane
[[99m99mTc]-SestamibiTc]-Sestamibi
Several PET and SPECT tracers show promiseSeveral PET and SPECT tracers show promise as transport substrates for monitoring Pgpas transport substrates for monitoring Pgp
Pgp is an important component of the BBB Pgp is an important component of the BBB and can be functionally imaged by and can be functionally imaged by PET and SPECTPET and SPECT
Pgp pumps Pgp pumps -Amyloid out of the brain across-Amyloid out of the brain acrossthe BBB. Pgp polymorphisms may bethe BBB. Pgp polymorphisms may bean imagable risk factor for AD.an imagable risk factor for AD.
Seth GammonSeth Gammon
Piwnica-Worms Lab, Molecular Imaging CenterPiwnica-Worms Lab, Molecular Imaging Center
Funding: NIH P50, RO1, DODFunding: NIH P50, RO1, DOD