Surrogate markers of antiangiogenic therapies

The development of antiangiogenic compounds for the treatment of cancer has indicated a need for new clinical tools to evaluate their efficacy, to assess the optimal dose with minimal side-effects and to early select patients who might benefit from antiangiogenic therapies. The use of so-called surrogate biomarkers of angiogenesis and antiangiogenic drug activity in the clinic does not yet belong to the standard of care. Most research has been dedicated towards introduction and refining of imaging techniques, the detection of circulating angiogenic factors and/or related molecules, and characterization and measurement of circulating endothelial cells and early progenitor cells. This chapter will discuss the various possibilities and their limitations illustrated with clinical data on antiangiogenic therapies in cancer patients.