1. Pilot study of [64Cu]-histidine2 PET imaging
Hervé Boutin
University of Manchester, UK

2. Background
Defective copper regulation is implicated in several diseases:
Wilson’s disease:
Severe copper (Cu) overload in liver, eye, CNS
autosomal recessive; cause = loss-of-function mutations in Cu-transporting ATPase, ATP7B
Treatment: Cu-selective chelation
Menkes’ disease:
Variable Cu overload or deficiency in several organs including CNS
Cause = sex-linked genetics; loss-of-function mutations in ATP7A
Treatment: parenteral copper therapy
Diabetes mellitus:
Cu deficiency in heart → heart failure (mechanism = Cu trapping by Advanced Glycation End-products in ECM causing impaired myocellular-Cu uptake
Cu overload in kidney (nephropathy)
Role in pathogenesis uncertain
Experimental treatment by Cu(II)-selective chelation at P2B
Dementia:
Alzheimer: Severe widespread brain-Cu deficiency (similar deficiency to that in Menkes’ disease):
Localized Cu deficiency also present in Parkinson’s disease & Lewy body disease
Contribution to pathogenesis and status as drug target are unknown

3. Methodology
Histidine labelled with 64Cu: 1 Cu ion for 2 histidine ([64Cu]-histidine2)
[64Cu]-histidine2 injected i.v. at start of body scan (thorax and abdomen in FOV)
60min dynamic acquisition
Static 15min Brain scan acquired after body scan (~1:30 post-injection)
ROI delineation by dynamic PET image segmentation for body scan
MR Brain template co-registered with CT scan for brain quantification
Data expressed as:
% of injected dose per cm³ (%ID/cm³)
Or standard uptake value (SUV = correction for ID and body weight)
Data uncorrected (mean) or corrected (GTM20) for partial volume effect

4. Results Non-significant difference in body-weight
But still can influence the quantification of PET
Need to compare %ID/cm³ vs. SUV

5. Results: Cu-histidine uptake
-44%
Liver
Kidney (cortex)
Control 10wks
STZ 10wks

6. Results: Cu-histidine uptake
-59%
-44%
-55% NS

7. Results: Cu-histidine uptake all organs
Decrease in Cu-Hist uptake in heart = cardiopathy?
Decrease in Cu-Hist uptake in Kidneys!? = saturation of Cu transporter by endogenous Cu  tracer dose is competing with excess of endogenous Cu in kidneys?
No major change in liver, no group difference.

8. Results: Cu-histidine uptake in brain
Very low levels of uptake in brain (close to background signal)
Overall decrease in [64Cu] uptake in brain in STZ animals from 2 weeks post-STZ (-27% %)
Partial recovery in some brain areas (hippocampus)?

9. Conclusions
Results in agreement with MS/ex vivo results except for kidneys
Saturation of kidneys by endogenous copper =  uptake ?
Need to assess blood and plasma concentration in 64Cu-histidine2 (control vs. STZ)
Modelling of PET data
Feasibility of 64Cu-histidine2 PET imaging to track alterations in Cu metabolism?
Lower levels of Cu uptake in brain than in periphery (as observed ex vivo)
Feasibility to monitor therapy efficacy?
Further work needed before translation to clinical imaging.

10. Acknowledgements Radiochemistry Image analysis Preclinical imaging
Dr Christian Prenant
Dr Michael Fairclough
Image analysis
Mr Daniel Jones
Ms Leonie Diffley
Preclinical imaging
Ms Alison Smigova
All the personnel of WMIC
Animal model
Dr Natalie Gardiner
Funding
Prof Garth Cooper
Dr Hervé Boutin (WMIC)