Comparison of Integrin _v3 Expression and Glucose Metabolism in Primary and Metastatic Lesions in Cancer Patients: A PET Study Using ¹⁸F-Galacto-RGD and ¹⁸F-FDG

¹ Department of Nuclear Medicine, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
² Department of Hematology and Oncology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
³ Department of Radiology, Klinikum rechts der Isar, Technische Universität München

^* To whom correspondence should be addressed. E-mail: beer{at}roe.med.tum.de.

	Abstract

The expression of _v3 and glucose metabolism are upregulated in many malignant lesions, and both are known to correlate with an aggressive phenotype. We evaluated whether assessment of _v3 expression and of glucose metabolism with PET using ¹⁸F-galacto-RGD and ¹⁸F-FDG provides complementary information in cancer patients. Methods: Eighteen patients with primary or metastatic cancer (non–small cell lung cancer [NSCLC], n = 10; renal cell carcinoma, n = 2; rectal cancer, n = 2; others, n = 4) were examined with PET using ¹⁸F-galacto-RGD and ¹⁸F-FDG. Standardized uptake values (SUVs) were derived by volume-of-interest analysis. ¹⁸F-Galacto-RGD and ¹⁸F-FDG PET results were compared using linear regression analysis for all lesions (n = 59; NSCLC, n = 39) and for primaries (n = 14) and metastases to bone (n = 11), liver (n = 10), and other organs (n = 24) separately. Results: The sensitivity of ¹⁸F-galacto-RGD PET compared with clinical staging was 76%. SUVs for ¹⁸F-FDG ranged from 1.3 to 23.2 (mean ± SD, 7.6 ± 4.9) and were significantly higher than SUVs for ¹⁸F-galacto-RGD (range, 0.3–6.8; mean ± SD, 2.7 ± 1.5; P < 0.001). There was no significant correlation between the SUVs for ¹⁸F-FDG and ¹⁸F-galacto-RGD for all lesions (r = 0.157; P = 0.235) or for primaries, osseous or soft-tissue metastases separately (P > 0.05). For the subgroup of lesions in NSCLC, there was a weak correlation between ¹⁸F-FDG and ¹⁸F-galacto-RGD uptake (r = 0.353; P = 0.028). Conclusion: Tracer uptake of ¹⁸F-galacto-RGD and ¹⁸F-FDG does not correlate closely in malignant lesions. Whereas ¹⁸F-FDG PET is more sensitive for tumor staging, ¹⁸F-galacto-RGD PET warrants further evaluation for planning and response evaluation of targeted molecular therapies with antiangiogenic or _v3-targeted drugs.

Key Words: _v3, ¹⁸F-galacto-RGD, ¹⁸F-FDG, PET, oncology

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