Multimodality Imaging of Tumor Integrin αvβ3 Expression

Most solid tumors are angiogenesis dependent. Anti-angiogenic pharmaceuticals that inhibit the growth of new blood vessels offer considerable promise as anti-cancer agents. With increasing numbers of antiangiogenic drugs in clinical trials, there is an urgent need for detailed characterization of the heterogeneity of tumor vasculature and dissection of the complex network of mechanisms that control tumor angiogenesis. Non-invasive molecular imaging will play a key role in individualized anti-angiogenic therapy based upon molecular features of the new blood vessel growth. Integrin αvβ3, which binds several ligands via an RGD tripeptide sequence, is uniquely expressed in tumor vasculature and aggressive tumor cells, making it a potential target for anti-angiogenic interventions. This review highlights some recent advances in multimodality imaging of tumor integrin expression with emphasis on positron emission tomography (PET).