SAR131675: Selective ATP-Competitive VEGFR-3 Inhibitor for Cancer and Lymphangiogenesis Research

Executive Summary: SAR131675 is a highly selective ATP-competitive VEGFR-3 inhibitor with an IC₅₀ of 23 nM, enabling precise dissection of lymphangiogenesis and angiogenesis pathways in preclinical models (APExBIO). The compound shows negligible activity against VEGFR-1 (>3 μM) and low activity against VEGFR-2 (235 nM), with no significant off-target effects on 65 kinases, 107 non-kinase enzymes/receptors, or 21 ion channels (Li et al., 2026). SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival at IC₅₀ values of 14 nM and 17 nM, respectively, and suppresses tumor growth in 4T1 mouse models. Preclinical use was discontinued due to metabolic side effects observed in animal studies. The compound remains a reference tool for mechanistic, translational, and cancer research (Avacopan Catalog).

Biological Rationale

VEGFR-3 (vascular endothelial growth factor receptor 3) is a receptor tyrosine kinase primarily expressed on lymphatic endothelial cells. It is activated by its ligands VEGFC and VEGFD, which promote lymphangiogenesis, endothelial cell survival, and migration. Aberrant VEGFR-3 signaling is implicated in tumor metastasis, chronic inflammation, and fibrotic diseases (Li et al., 2026). Inhibition of VEGFR-3 disrupts lymphatic vessel formation and function, suppressing tumor cell dissemination and the progression of hepatic fibrosis. SAR131675, a selective ATP-competitive VEGFR-3 inhibitor, enables mechanistic studies by providing potent, pathway-specific blockade with minimal off-target interference (SAR131675 and the Future of VEGFR-3 Pathway Inhibition).

Mechanism of Action of SAR131675, a selective and ATP-competitive VEGFR-3 inhibitor

SAR131675 acts as a reversible, ATP-competitive inhibitor targeting the kinase domain of VEGFR-3. It exhibits an IC₅₀ of 23 nM and a K_i of 12 nM against recombinant human VEGFR-3 kinase in biochemical assays at 25°C in buffered aqueous conditions (APExBIO). In HEK cells expressing VEGFR-3, SAR131675 inhibits ligand-induced autophosphorylation with an IC₅₀ ranging from 30 to 50 nM. The compound demonstrates high selectivity, displaying negligible inhibition of VEGFR-1 (IC₅₀ > 3 μM), low activity on VEGFR-2 (IC₅₀ 235 nM), and no significant effects on other kinases, enzymes, or ion channels at concentrations up to 10 μM (Li et al., 2026). By blocking VEGFR-3 phosphorylation, SAR131675 suppresses downstream signaling involved in lymphatic endothelial cell survival, migration, and vessel formation. The compound also inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC₅₀ 14 nM and 17 nM, respectively), and blocks VEGFA- and VEGFC-induced migration in human lung microvascular endothelial cells with IC₅₀ values of 100 nM and <30 nM, respectively (SAR131675: Selective ATP-Competitive VEGFR-3 Inhibitor).

Evidence & Benchmarks

• SAR131675 inhibits recombinant human VEGFR-3 kinase with IC₅₀ of 23 nM and K_i of 12 nM (25°C, in vitro) (APExBIO).
• In HEK cells, SAR131675 blocks VEGFR-3 autophosphorylation with IC₅₀ values between 30–50 nM (cellular assay, 37°C) (Li et al., 2026).
• Demonstrates minimal inhibition of VEGFR-1 (IC₅₀ >3 μM) and VEGFR-2 (IC₅₀ 235 nM), confirming selectivity (enzyme panel, 25°C) (SAR131675: Selective VEGFR-3 Inhibitor for Advanced Tumor Models).
• No significant activity against 65 kinases, 107 non-kinase enzymes/receptors, or 21 ion channels at ≤10 μM (broad off-target screening) (APExBIO).
• Suppresses VEGFC- and VEGFD-induced lymphatic endothelial cell survival at IC₅₀ values of 14 nM and 17 nM, respectively (cell survival assay) (Li et al., 2026).
• Inhibits VEGFA- and VEGFC-induced migration in HLMVECs at IC₅₀ values of 100 nM and <30 nM (migration assay) (SAR131675: Selective ATP-Competitive VEGFR-3 Inhibitor).
• Abrogates FGF2-stimulated lymphangiogenesis and angiogenesis in vivo (mouse model, 4T1 carcinoma) (Li et al., 2026).
• Significantly reduces tumor volume in 4T1 mammary carcinoma mouse models (in vivo efficacy) (SAR131675: Selective VEGFR-3 Inhibitor for Advanced Tumor Models).
• Development discontinued due to adverse metabolic effects in preclinical species (toxicity studies) (Li et al., 2026).

Applications, Limits & Misconceptions

SAR131675 serves as a reference inhibitor for studies of lymphangiogenesis, angiogenesis, tumor metastasis, and hepatic fibrosis. It enables the specific interrogation of VEGFR-3-dependent pathways in both in vitro and in vivo models. Key applications include:

• Preclinical cancer research to dissect tumor lymphangiogenesis and angiogenesis (SAR131675 and the Future of VEGFR-3 Pathway Inhibition).
• Hepatic fibrosis models, particularly for examining the VEGFC-VEGFR-3 axis (Li et al., 2026).
• Testing the role of VEGFR-3 in endothelial cell migration and survival (SAR131675: Selective ATP-Competitive VEGFR-3 Inhibitor).

Common Pitfalls or Misconceptions

• SAR131675 is not suitable for long-term in vivo studies targeting human metabolic disease due to adverse metabolic effects observed in preclinical models (Li et al., 2026).
• The compound is insoluble in DMSO, ethanol, and water; improper solvent selection can compromise experimental outcomes (APExBIO).
• SAR131675 does not significantly inhibit VEGFR-1 or non-VEGFR kinases, so it cannot be used as a pan-VEGFR inhibitor (Selective VEGFR-3 Inhibition: Mechanistic Insights).
• It has no significant activity against non-kinase enzymes or ion channels, so off-pathway effects are unlikely at recommended concentrations (APExBIO).
• Solutions are not recommended for long-term storage due to stability limitations; always prepare fresh (APExBIO).

Workflow Integration & Parameters

SAR131675 (APExBIO B2301) is supplied as a solid, stored at -20°C. It is cell-permeable and intended for in vitro and in vivo research use. Due to its insolubility in common organic solvents and water, specialized formulation is required for administration. For in vitro kinase assays, concentrations from 1 nM to 1 μM are typical. In cell-based studies, 10–100 nM is effective for autophosphorylation inhibition. In mouse models, dosing at 30 mg/kg/day was used for hepatic fibrosis and tumor inhibition studies (Li et al., 2026). APExBIO, the manufacturer, recommends against long-term storage of dissolved compound. For advanced study design and troubleshooting, see the detailed mechanistic analysis in Selective VEGFR-3 Inhibition: Mechanistic Insights (this article extends the analysis by incorporating the latest in vivo efficacy and metabolic safety data).

Conclusion & Outlook

SAR131675 represents a reference standard for selective VEGFR-3 pathway inhibition, empowering precise investigation of lymphangiogenesis, angiogenesis, and tumor metastasis. Despite discontinuation as a drug candidate due to metabolic toxicity, its unmatched selectivity and potency have solidified its role in preclinical cancer and fibrosis research. Future work will leverage SAR131675’s unique profile to differentiate VEGFR-3-driven biology from off-pathway mechanisms and to benchmark next-generation inhibitors. For ordering and technical documentation, refer to the SAR131675, a selective and ATP-competitive VEGFR-3 inhibitor product page. For comparative and translational discussion, this review offers further strategic guidance (the present article updates prior reviews by including new data on fibrosis and metabolic toxicity).