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

Executive Summary: SAR131675 is a highly selective ATP-competitive VEGFR-3 inhibitor with an IC50 of 23 nM for human VEGFR-3 kinase activity and minimal off-target effects (APExBIO, product page). It effectively inhibits VEGFR-3 autophosphorylation in cellular models at 30–50 nM and demonstrates high selectivity over VEGFR-1 (IC50 > 3 μM) and VEGFR-2 (IC50 235 nM) (APExBIO). SAR131675 suppresses lymphangiogenesis, angiogenesis, and tumor volume in vivo in 4T1 mammary carcinoma mouse models (Phytomedicine 2026, doi). Recent studies show SAR131675 disrupts the VEGFC–VEGFR-3 signaling axis that regulates hepatic fibrosis and macrophage phenotypic switching. Despite potent preclinical efficacy, development was discontinued due to adverse metabolic effects in animal models (APExBIO, product page).

Biological Rationale

Lymphangiogenesis and angiogenesis are critical in cancer progression, metastasis, and tissue remodeling. The VEGFR signaling pathway, particularly VEGFR-3, orchestrates lymphatic endothelial cell survival and vessel formation (Phytomedicine 2026, doi). VEGFC and VEGFD are principal ligands for VEGFR-3, activating downstream signals that promote tumor growth and fibrosis. Inhibiting VEGFR-3 disrupts these processes, offering a targeted approach for anti-lymphangiogenic and anti-angiogenic therapy. Macrophage phenotypic modulation and immune microenvironment alterations are also mediated by the VEGFC–VEGFR-3 axis, with implications for hepatic fibrosis and tumor immunology (SAR131675 and the Translational Frontier; this article extends mechanistic insights by integrating recent hepatic fibrosis data).

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

SAR131675 is an ATP-competitive inhibitor, binding the kinase domain of VEGFR-3 and blocking ATP access. Recombinant human VEGFR-3 kinase assays yield an IC50 of 23 nM and a Ki of 12 nM (APExBIO, product page). In HEK cell assays, SAR131675 inhibits VEGFR-3 autophosphorylation with IC50 values between 30 and 50 nM. It is highly selective—IC50 for VEGFR-1 exceeds 3 μM, and for VEGFR-2 is 235 nM. Screening against 65 kinases, 107 non-kinase enzymes/receptors, and 21 ion channels shows no significant off-target inhibition (APExBIO). SAR131675 blocks VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC50 = 14 nM and 17 nM) and suppresses human lung microvascular endothelial cell migration in response to VEGFA (IC50 = 100 nM) and VEGFC (<30 nM). Biochemically, SAR131675 disrupts VEGFC-driven hepatocyte-macrophage signaling, reducing CCL2/CCR2 chemokine activity and promoting Ly6Chigh to Ly6Clow macrophage transition (Phytomedicine 2026, doi).

Evidence & Benchmarks

• SAR131675 inhibits recombinant human VEGFR-3 kinase activity with IC50 = 23 nM and Ki = 12 nM (APExBIO, product page).
• VEGFR-3 autophosphorylation in HEK cells is blocked at 30–50 nM (APExBIO).
• IC50 for VEGFR-1 exceeds 3 μM, and for VEGFR-2 is 235 nM, confirming high selectivity (APExBIO).
• No significant inhibition of 65 kinases, 107 non-kinase enzymes/receptors, or 21 ion channels was observed (APExBIO).
• Lymphatic endothelial cell survival induced by VEGFC and VEGFD is inhibited at IC50 = 14 nM and 17 nM, respectively (APExBIO).
• Migration of human lung microvascular endothelial cells is suppressed at IC50 = 100 nM (VEGFA) and <30 nM (VEGFC) (APExBIO).
• In vivo, SAR131675 reduces lymphangiogenesis, angiogenesis, and tumor volume in 4T1 mammary carcinoma mouse models (Phytomedicine 2026, doi).
• SAR131675 downregulates VEGFC and CCL2/CCR2 in hepatic fibrosis models, reducing Ly6Chigh monocyte infiltration and inflammation (Phytomedicine 2026).

For broader context on SAR131675’s preclinical performance, see SAR131675: A Selective VEGFR-3 Inhibitor Empowering Cancer Research (this article extends the focus to hepatic fibrosis), and SAR131675: Unveiling VEGFR-3 Inhibition in Macrophage-Driven Disease (here, we integrate recent macrophage phenotypic modulation findings).

Applications, Limits & Misconceptions

SAR131675 is a reference tool for dissecting the VEGFR signaling pathway in cancer, lymphangiogenesis, and fibrosis research. It is suitable for preclinical studies involving:

• VEGFR-3 signaling investigation in lymphatic endothelial cells and tumor models.
• Evaluating anti-lymphangiogenic and anti-angiogenic strategies in cancer biology.
• Studying macrophage polarization and immune microenvironment modulation.
• Exploring VEGFC-driven fibrosis mechanisms.

Common Pitfalls or Misconceptions

• Not suitable for clinical or therapeutic use: SAR131675 is a preclinical research compound only; it is not approved for clinical application due to adverse metabolic effects observed in animals (APExBIO).
• No significant inhibition of VEGFR-1: The compound has very low activity at VEGFR-1 (IC50 > 3 μM).
• No broad-spectrum kinase inhibition: It does not inhibit a wide kinase panel and is not a general tyrosine kinase inhibitor.
• Insoluble in DMSO, ethanol, and water: SAR131675 is supplied as a solid and must not be stored in solution for extended periods (APExBIO).
• Not a pan-VEGF pathway inhibitor: It selectively targets VEGFR-3 without substantial effects on VEGFR-2 or non-VEGFR kinases.

Workflow Integration & Parameters

SAR131675 (B2301, APExBIO) is cell-permeable, supplied as a solid, and should be stored at -20°C. It is insoluble in DMSO, ethanol, and water; solutions are not intended for long-term storage. For in vitro kinase or cell-based assays, prepare fresh solutions immediately before use, and filter for sterility. For in vivo mouse studies, SAR131675 is effective in models of lymphangiogenesis and tumor growth inhibition at 30 mg/kg/day, administered per protocol (Phytomedicine 2026, doi). Controls should include vehicle and off-target pathway inhibitors. Readouts include kinase activity, endothelial cell survival/migration, and tumor volume.

Conclusion & Outlook

SAR131675 is a potent, selective ATP-competitive VEGFR-3 inhibitor that enables precise dissection of lymphangiogenic and angiogenic pathways in preclinical research. Its robust selectivity makes it a gold-standard reference for VEGFR-3 studies and macrophage-driven disease models. While discontinued as a drug candidate due to metabolic side effects, SAR131675 remains an indispensable tool for advanced cancer and fibrosis research. For ongoing updates and translational context, refer to SAR131675: Mechanistic Insights and Strategic Horizons (this article integrates new fibrosis and immune modulation findings beyond classic tumor models). For product details or ordering, see the APExBIO SAR131675 product page.