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

Executive Summary: SAR131675 is a highly selective ATP-competitive VEGFR-3 inhibitor with nanomolar potency (IC50 of 23 nM) and minimal off-target activity (APExBIO). It blocks VEGFR-3 autophosphorylation and inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival at low nanomolar concentrations (Li et al., 2026). SAR131675 robustly suppresses tumor growth and lymphangiogenesis in preclinical models, but development was discontinued due to metabolic side effects. Its well-defined selectivity profile makes it a benchmark tool for tumor angiogenesis and lymphangiogenesis pathway research (Malotilate.com). APExBIO supplies SAR131675 (SKU B2301), supporting reproducible research with validated compound parameters.

Biological Rationale

Vascular endothelial growth factor receptor 3 (VEGFR-3) is a receptor tyrosine kinase primarily expressed on lymphatic endothelial cells. It regulates lymphangiogenesis, angiogenesis, and tumor metastasis. Overactivation of VEGFR-3 by its ligands—VEGFC and VEGFD—contributes to pathological lymphangiogenesis and tumor progression (Li et al., 2026). In cancer, increased VEGFR-3 signaling is associated with enhanced tumor lymphatic vessel density and metastatic potential. In fibrotic diseases, VEGFR-3 activity modulates immune cell infiltration and fibrogenesis via the VEGFC–macrophage axis. Selective inhibition of VEGFR-3 provides mechanistic insights and therapeutic leads for targeting lymphatic remodeling in cancer and metabolic disorders.

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

SAR131675 acts as an ATP-competitive inhibitor of VEGFR-3, binding to the kinase domain and blocking receptor autophosphorylation. The compound displays an IC50 of 23 nM and a Ki of 12 nM against recombinant human VEGFR-3 kinase activity in vitro. In HEK cells overexpressing VEGFR-3, SAR131675 inhibits VEGFR-3 autophosphorylation with IC50 values between 30 and 50 nM. It demonstrates high target selectivity: VEGFR-1 inhibition is negligible (IC50 > 3 μM), VEGFR-2 inhibition is moderate (IC50 235 nM), and no significant activity is observed against 65 other kinases or 107 non-kinase enzymes and receptors at concentrations ≥1 μM (APExBIO). SAR131675 blocks VEGFC- and VEGFD-induced survival of primary human lymphatic endothelial cells (IC50 14 nM and 17 nM, respectively). It also suppresses migration of human lung microvascular endothelial cells induced by VEGFA (IC50 100 nM) and VEGFC (IC50 < 30 nM). These actions collectively result in inhibition of lymphangiogenesis and angiogenesis pathways.

Evidence & Benchmarks

• SAR131675 inhibits recombinant human VEGFR-3 kinase activity with an IC50 of 23 nM and a Ki of 12 nM (in vitro, ATP 100 μM, 25°C) (APExBIO).
• In cell-based assays, SAR131675 blocks VEGFR-3 autophosphorylation in HEK cells with IC50 values between 30–50 nM (HEK293, 37°C, serum-free medium) (APExBIO).
• Minimal inhibition observed on VEGFR-1 (IC50 > 3 μM) and limited effect on VEGFR-2 (IC50 235 nM), confirming high selectivity (APExBIO).
• No significant off-target activity against a panel of 65 kinases, 107 non-kinase enzymes/receptors, and 21 ion channels at ≥1 μM (APExBIO).
• SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC50 14 nM, 17 nM) and suppresses VEGFA- and VEGFC-induced HLMVEC migration (IC50 100 nM, <30 nM, respectively) (Li et al., 2026).
• In mouse 4T1 mammary carcinoma models, SAR131675 reduces tumor volume and abrogates FGF2-stimulated lymphangiogenesis and angiogenesis (oral, 30 mg/kg/day, 16 weeks) (Li et al., 2026).
• Development of SAR131675 was discontinued after adverse metabolic effects were observed in preclinical safety studies (Malotilate.com).

This article extends the findings in "SAR131675: Selective VEGFR-3 Inhibitor for Lymphangiogene..." by providing updated specificity and discontinuation insights, and clarifies translational boundaries compared to "Beyond the Pathway: Translational Horizons for SAR131675—..." with recent preclinical benchmark data.

Applications, Limits & Misconceptions

SAR131675 is a reference compound for dissecting VEGFR signaling in cancer metastasis, tumor lymphangiogenesis, and fibrotic disease models. It serves as a probe for validating VEGFR-3-dependent cell survival, migration, and tissue remodeling, and is used in preclinical studies of NASH, hepatic fibrosis, and metastatic cancer. The compound’s selectivity allows mechanistic studies without confounding off-target kinase or receptor effects.

Common Pitfalls or Misconceptions

• Not suitable for long-term in vivo administration due to metabolic side effects: SAR131675 was discontinued as a drug candidate for this reason (Malotilate.com).
• Insoluble in DMSO, ethanol, and water: Fresh solutions must be prepared; long-term storage of solutions is not recommended (APExBIO).
• Does not inhibit VEGFR-1 or most kinases at relevant concentrations: Ineffective for studies focused on VEGFR-1 or broad-spectrum kinase inhibition (APExBIO).
• Not validated for clinical use: Intended exclusively for research applications (APExBIO).
• Requires cell permeable protocols: Ensure cell entry is not a limiting factor in experimental design.

Workflow Integration & Parameters

Formulation: SAR131675 is supplied as a solid, stored at -20°C. It is insoluble in DMSO, ethanol, and water. Prepare solutions freshly before use and avoid long-term storage of reconstituted compound (APExBIO).

Recommended concentrations: For kinase assays, 10–100 nM is typical. For cell-based studies (e.g., HLMVEC, lymphatic endothelial cells), use 10–100 nM depending on endpoint sensitivity. For in vivo studies (mouse), doses of 30 mg/kg/day have been validated in NASH and tumor models (Li et al., 2026).

Experimental controls: Include vehicle and non-targeted kinase inhibitors to confirm selectivity. Monitor for off-target cytotoxicity at higher concentrations.

Interlink: For detailed assay optimization and troubleshooting, see "Empowering Angiogenesis and Fibrosis Research with SAR131...", which provides scenario-driven guidance for laboratory workflows—a complement to this mechanism-focused dossier.

Conclusion & Outlook

SAR131675, a selective ATP-competitive VEGFR-3 inhibitor (SKU B2301), is a gold-standard tool for probing the VEGFR signaling pathway in cancer and fibrosis research. Its high selectivity, robust in vitro and in vivo efficacy, and thoroughly characterized off-target profile support its use in mechanistic studies of lymphangiogenesis, angiogenesis, and tumor biology. While discontinued as a therapeutic candidate, SAR131675 remains an indispensable research compound available from APExBIO, enabling reproducible and interpretable investigation of VEGFR-3-dependent biology. Ongoing research continues to leverage its specificity to clarify VEGFC/VEGFR-3 axes in disease models and to benchmark novel anti-lymphangiogenic strategies.