In vitro activity: 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. SAR131675 dose dependently inhibits rh-VEGFR-3–TK activity with an IC50 of 23 nM. SAR131675 inhibits VEGR-3–TK activity with a Ki of about 12 nM. SAR131675 inhibits VEGFR-1–TK activity with an IC50 of> 3 μM and VEGFR-2–TK activity with an IC50 of 235 nM. SAR131675 inhibits VEGFR-1 autophosphorylation with an IC50 of about 1 μM and VEGFR-2 with an IC50 of about 280 nM. SAR131675 moderately inhibits VEGFR-2 and has very little effect on VEGFR-1, showing a good selectivity for VEGFR-3. SAR131675 inhibits VEGFA-induced VEGFR-2 phosphorylation in a dose-dependent manner, with an IC50 of 239 nM. SAR131675 potently inhibits lymphatic cell survival induced by VEGFC and VEGFD with IC50 of 14 nM and 17 nM, respectively. SAR131675 inhibits VEGFA-induced survival with an IC50 of 664 nM. SAR131675, significantly and dose dependently inhibits VEGFC-induced Erk phosphorylation, with an IC50 of about 30 nM.

Kinase Assay: Multiwell plates are precoated with a synthetic polymer substrate poly-Glu-Tyr (polyGT 4:1). The reaction is carried out in the presence of kinase buffer (10×: 50 mM HEPES buffer, pH 7.4, 20 mM MgCl2, 0.1 mM MnCl2, and 0.2 mM Na3VO4) supplemented with ATP and dimethyl sulfoxide (DMSO) for the positive control (C+) or SAR131675 (ranging from 3-1,000 nM). ATP is used at 30 μM for VEGFR-1 and VEGFR-3 and at 15 μM for VEGFR-2. The phosphorylated poly-GT is probed with a phosphotyrosine specific monoclonal antibody (mAb) conjugated to horseradish peroxidase and developed in the dark with the HRP chromogenic substrate (OPD). The reaction is then stopped by the addition of 100 μL 1.25 mol/L H2SO4, and absorbance is determined using an Envision spectrophotometer at 492 nm.

Cell Assay: HLMVECs are seeded in 96-well plates coated with 0.3% gelatin (5000 cells per well). Cells are incubated in RPMI 0.1% FCS with VEGFA (10 ng/mL) VEGFC (300 ng/mL), VEGFD (300 ng/mL), or FGF2 (10 ng/mL) in the absence or presence of SAR131675. Five days later, viable cells are quantified with the cell Titer-glo luminescent cell viability assay.