Tumor angiogenesis targeting using imaging agents

The inhibition of tumor induced angiogenesis is an emerging therapeutic strategy in clinical oncology aimed at halting cancer progression by suppressing tumor blood supply. As anti-angiogenic therapy is primarily cytostatic and not cytotoxic, the established criteria for assessing tumor response to chemo-and radiotherapy cannot be applied to anti-angiogenic therapy. Therefore, functional and molecular parameters for imaging of tumor angiogenesis are being intensively studied. Computed tomography, magnetic resonance imaging, ultrasound and scintigraphic techniques can assess changes in vascular permeability and tumor blood flow during anti-angiogenic therapy. Scintigraphic techniques, especially positron emission tomography (PET), may be used to monitor the consequences of anti-angiogenic therapy on tumor cell metabolism, proliferation and apoptosis. The high sensitivity of PET which allows measurements of tracer concentrations in the picomolar range in promising for the visualization of specific molecular targets prior to therapy thus identifying patients most likely benefit from a particular form of anti-angiogenic therapy.