VEGFA and neoplasm: A first phase I clinical trial using a humanised version of a mouse monoclonal anti-VEGF antibody HuMV833 labelled with 124I showed a marked heterogeneity in receptor expression both between and within patients with a three-fold variation in HuMV833 concentration within individual tumours indicating that response to these agents is likely to mirror this heterogeneity and therefore impact significantly on dose-response assessments (Jayson et al, 2002).