Non-invasive assessment of inter-and intrapatient variability of integrin expression in metastasized prostate cancer by PET.

Due to the high expression of the integrin ?v?3 not only on endothelial cells, but also on mature osteoclasts and prostate cancer cells, imaging of osseous metastases with ?v?3-targeted tracers seems promising. However, little is known about the patterns of ?v?3-expression in metastasized prostate cancer lesions in-vivo. Thus we evaluated the uptake of the ?v?3-specific PET tracer [18F]Galacto-RGD for assessment of bone metastases in prostate cancer patients.[18F]Galacto-RGD PET identified 58/74 bone-lesions (detection rate of 78.4%) and lymph node metastases in 2/5 patients. The SUVmean was 2.12+/-0.94 (range 0.70-4.38; tumor/blood 1.36+/-0.53; tumor/muscle 2.82+/-1.31) in bone-lesions and 2.21+/-1.18 (range 0.75-3.56) in lymph node metastases. Good visualization and detection of bone metastases was feasible due to a low background activity of the surrounding normal bone tissue.12 patients with known metastasized prostate cancer according to conventional staging (including bone-scintigraphy and contrast-enhanced CT; median PSA 68.63 ng/ml, range 3.72-1935) were examined with PET after i.v.-injection of [18F]Galacto-RGD. Two blinded nuclear-medicine physicians evaluated the PET-scans in consensus concerning lesion detectability. Volumes-of-interest were drawn in the PET-scans over all metastases defined by conventional staging (maximum of 11 lesions/patient), over the left ventricle, liver and muscle and standardized-uptake-values (SUVs) were calculated.Our data show generally elevated uptake of [18F]Galacto-RGD in bone metastases from prostate cancer with a marked inter- and intrapatient variability. While [18F]Galacto-RGD PET is inferior to bone scintigraphy for detection of osseous metastases, it might be valuable in patient screening and monitoring of ?v?3-targeted therapies due to the high variability of ?v?3-expression.     «

Due to the high expression of the integrin ?v?3 not only on endothelial cells, but also on mature osteoclasts and prostate cancer cells, imaging of osseous metastases with ?v?3-targeted tracers seems promising. However, little is known about the patterns of ?v?3-expression in metastasized prostate cancer lesions in-vivo. Thus we evaluated the uptake of the ?v?3-specific PET tracer [18F]Galacto-RGD for assessment of bone metastases in prostate cancer patients.[18F]Galacto-RGD PET identified 58/74...     »