Positron emission tomography using [18F]Galacto-RGD identifies the level of integrin αvβ3 expression in man

Ambros J. Beer, Roland Haubner, Mario Sarbia, Michael Goebel, Stephan Luderschmidt, Anca Ligia Grosu, Oliver Schnell, Markus Niemeyer, Horst Kessler, Hans Jürgen Wester, Wolfgang A. Weber, Markus Schwaiger

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338 Scopus citations

Abstract

Purpose: The integrin αvβ3 plays a key role in angiogenesis and tumor cell metastasis and is therefore an important target for new therapeutic and diagnostic strategies. We have developed [ 18F]Galacto-RGD, a highly αvβ3- selective tracer for positron emission tomography (PET). Here, we show, in man, that the intensity of [18F]Galacto-RGD uptake correlates with αvβ3 expression. Experimental Design: Nineteen patients with solid tumors (musculoskeletal system, n = 10; melanoma, n = 4; head and neck cancer, n = 2; gliobastoma, n = 2; and breast cancer, n = 1) were examined with PET using [18F] Galacto-RGD before surgical removal of the tumor lesions. Snap-frozen specimens (n = 26) were collected from representative areas with low and intense standardized uptake values (SUV) of [18F] Galacto-RGD. Immunohistochemistry was done using the αvβ3-specific antibody LM609. Intensity of staining (graded on a four-point scale) and the microvessel density of αvβ3-positive vessels were determined and correlated with SUV and tumor/blood ratios (T/B). Results: Two tumors showed no tracer uptake (mean SUV, 0.5 ± 0.1). All other tumors showed tracer accumulation with SUVs ranging from 1.2 to 10.0 (mean, 3.8 ± 2.3; T/B, 3.4 ± 2.2; tumor/muscle ratio, 7.7 ± 5.4). The correlation of SUV and T/B with the intensity of immunohistochemical staining (Spearman's r = 0.92; P < 0.0001) as well as with the microvessel density (Spearman's r = 0.84; P < 0.0001) were significant. Immunohistochemistry confirmed lack of αvβ3 expression in normal tissue (benign lymph nodes, muscle) and in the two tumors without tracer uptake. Conclusions: Molecular imaging of αvβ3 expression with [18F]Galacto-RGD in humans correlates with αvβ 3 expression as determined by immunohistochemistry. PET with [ 18F] Galacto-RGD might therefore be used as a new marker of angiogenesis and for individualized planning of therapeutic strategies with αvβ3-targeted drugs.

Original languageEnglish
Pages (from-to)3942-3949
Number of pages8
JournalClinical Cancer Research
Volume12
Issue number13
DOIs
StatePublished - 1 Jul 2006

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