αvÎ23 integrin is expressed on activated endothelial cells and some tumor types. It binds to the RGD sequence of matrix proteins through interactions with talin and α-actinin. PET imaging of mice with [64Cu]DOTA-RGD peptide tracer showed tracer binding correlated with αvβ3 expression levels. A 4-kinetic constant model best described the tracer uptake and internalization over 1 hour and 22.5 hour scans, allowing quantification of specifically bound tracer related to αvβ3 levels.

6. αvβ3 integrin
α-chain β-chain
Ca2+
• Expressed on activated
Ca2+
endothelial cells and some tumor
Ca2+ SS
types (melanoma, glioblastoma)
• Binds to arginine, glycine,
aspartate sequence (RGD) of
talin
matrix proteins
α-actinin
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Slide provided by R. Dumont, UCLA

7. Anti-αvβ3 tracer: [64Cu]DOTA-RGD peptide
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10. Model fits to data from 60 min dynamic
PET scans of mice (with kint = 0)
αvβ3intermediate
αvβ3lo
αvβ3blocked
αvβ3hi
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11. Vd based on 4kc model
K1
VND =
k2
K1 ! k3
VS =
k2 ! k4
*Tumor located in thigh of mouse
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†90 minute PET scan

12. 4kc model with internalization
Model fit to dynamic + 22.5 hr
follow-up static scan
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13. KEY POINTS
• 4kc model best describes data
– Lowest AIC
• Model based VS strongly correlates
with αvβ3 expression
• Tracer internalization can be neglected
when modeling 1 hr dynamic scans
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14. Acknowledgements
UCLA Animal Imaging Huang Lab (UCLA)
Computer Support
Facility (Crump Institute)
David Truong
Dr. David Stout
David Vu
Dr. Arion Chatziioannou
Weber Shao
Waldemar Ladno
Judy Edwards
University of Innsbruck
Antonia Luu
Dr. Stephan Schwarz
UCLA Cyclotron Laboratory
UCLA SOMI Program
Dr. Nagichettiar Satyamurthy
Dr. Michael Phelps
and staff
Dr. Anna Wu
Funding
NCI Cancer Education Grant R25-CA098010
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