In a paper in this month's freely-available online global health journal PLoS Medicine, Roland Haubner and colleagues describe how a compound they have developed can be used together with highly sensitive positron emission tomography (PET) scanning to measure the amount of new blood vessel growth in some tumors.
New blood vessel growth - angiogenesis - is important for the growth of tumors; several drugs target angiogenesis specifically. The compound previously developed by Haubner and colleagues is a fluorine-labeled glycopeptide, ([18F]Galacto-RGD), which binds tightly to a receptor - ávâ3 integrin -expressed in some tumors, especially in the blood vessels. As well as a role in angiogenesis, integrins are important in holding tumor cells together and connecting them with the extracellular matrix; what happens when these interactions break down is one of the keys to determining how tumors metastasize.
Haubner and colleagues' work, in a mouse with human melanoma and in a small study of patients with tumors including melanoma, suggests that the marker is truly reflecting the in vivo level of the integrin. Hence the marker could be used to identify tumors that express this marker, assess the degree of new vessel formation in tumors, and help in the planning and monitoring of anti-angiogenic therapies which target this integrin.