A shows an illustrated view of blood vessels in a cancerous tumor, B shows blood vessels in healthy tissue. On the right, signals for blood vessel growth are shown schematically. The main inducers of blood vessel growth are vascular endothelial growth factor (VEGF) and VEGF-C. The signals are mediated via VEGF receptor-2 and VEGFR-3, as illustrated with the arrows. The sites of action of the inhibitory antibodies (Ab) are indicated in red. The antibodies against VEGF are already used in the treatment of patients. Antibodies against VEGFR-2 are in clinical trials. The newly discovered antibody combination providing increased efficacy is directed against VEGFR-3.