AR131675 is highly selective for VEGFR-3 versus 107 receptors, enzymes, ion channels, and 65 kinases. However, it is moderately active on VEGFR-2 with a VEGFR-3/VEGFR-2 ratio of about 10. SAR131675 inhibits VEGFR-3 tyrosine kinase activity and VEGFR-3 autophosphorylation in HEK cells with IC50 values of 20 and 45 nM, respectively. SAR131675 dose dependently inhibits the proliferation of primary human lymphatic cells, induced by the VEGFR-3 ligands VEGFC and VEGFD, with an IC50 of about 20 nM. SSAR131675 has no antiproliferative activity on a panel of 30 tumors and primary cells, further showing its high specificity and indicating that SAR131675 is not a cytotoxic or cytostatic agent.