Pathological angiogenesis is a hallmark of cancer and various ischaemic and inflammatory diseases. Concentrated efforts in this area of research are leading to the discovery of a growing number of pro- and anti-angiogenic molecules, some of which are already in clinical trials. The complex interactions among these molecules and how they affect vascular structure and function in different environments are now beginning to be elucidated. This integrated understanding is leading to the development of a number of exciting and bold approaches to treat cancer and other diseases. But owing to several unanswered questions, caution is needed.

Blood vessels deliver oxygen and nutrients to every part of the body, but also nourish diseases such as cancer. Over the past decade, our understanding of the molecular mechanisms of angiogenesis (blood vessel growth) has increased at an explosive rate and has led to the approval of anti-angiogenic drugs for cancer and eye diseases. So far, hundreds of thousands of patients have benefited from blockers of the angiogenic protein vascular endothelial growth factor, but limited efficacy and resistance remain outstanding problems. Recent preclinical and clinical studies have shown new molecular targets and principles, which may provide avenues for improving the therapeutic benefit from anti-angiogenic strategies.

Blood vessels constitute the first organ in the embryo and form the largest network in our body but, sadly, are also often deadly. When dysregulated, the formation of new blood vessels contributes to numerous malignant, ischemic, inflammatory, infectious and immune disorders. Molecular insights into these processes are being generated at a rapidly increasing pace, offering new therapeutic opportunities that are currently being evaluated.