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

Executive Summary: SAR131675 is a potent and highly selective ATP-competitive inhibitor of VEGFR-3 kinase activity (IC50 = 23 nM, Ki = 12 nM) with negligible activity against VEGFR-1, VEGFR-2, and a broad panel of off-targets (APExBIO product page). In preclinical models, SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC50 = 14–17 nM) and suppresses angiogenesis and tumor volume in 4T1 mammary carcinoma mice (Li et al. 2025). The compound is cell-permeable, supplied as a solid, and demonstrates no significant activity against 65 kinases, 107 non-kinase enzymes/receptors, or 21 ion channels. Despite its preclinical value, development was discontinued due to adverse metabolic effects. SAR131675 remains a gold-standard tool for mechanistic pathway studies and translational oncology research.

Biological Rationale

Vascular endothelial growth factor receptor-3 (VEGFR-3) mediates lymphangiogenesis and is critical for tumor metastasis and tissue fibrosis (Li et al. 2025). Pathological upregulation of the VEGFC–VEGFR-3 axis is observed in non-alcoholic steatohepatitis (NASH), hepatocellular carcinoma, and metastatic solid tumors. Inhibiting VEGFR-3 disrupts VEGFC-driven recruitment of pro-inflammatory macrophages and endothelial cell migration, reducing lymphatic vessel formation. Targeted inhibition by SAR131675 enables researchers to dissect the lymphangiogenesis pathway with minimal off-target effects. Clinical and preclinical studies corroborate VEGFR-3 as a validated target in cancer and metabolic disease models (source).

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

SAR131675 is an ATP-competitive inhibitor that targets the kinase domain of recombinant human VEGFR-3, blocking autophosphorylation and downstream signaling (APExBIO). It demonstrates an IC50 of 23 nM and a Ki of 12 nM for VEGFR-3. In HEK cell assays, SAR131675 inhibits VEGFR-3 autophosphorylation with IC50 values between 30 and 50 nM. The compound exhibits over 100-fold selectivity for VEGFR-3 versus VEGFR-1 (IC50 > 3 μM) and 10-fold selectivity over VEGFR-2 (IC50 235 nM). Minimal inhibition is observed against 65 kinases, 107 non-kinase enzymes/receptors, and 21 ion channels. SAR131675 effectively blocks VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC50 = 14 nM and 17 nM, respectively) and suppresses VEGFA- and VEGFC-induced endothelial cell migration in HLMVECs (IC50 = 100 nM and <30 nM, respectively). This selectivity profile allows for precise interrogation of VEGFR-3-dependent signaling in tumor, hepatic fibrosis, and lymphatic models.

Evidence & Benchmarks

• SAR131675 inhibits recombinant human VEGFR-3 kinase activity with an IC50 of 23 nM and a Ki of 12 nM (APExBIO).
• In cell-based assays, SAR131675 blocks VEGFR-3 autophosphorylation in HEK cells (IC50 = 30–50 nM) (Internal review).
• VEGFR-1 inhibition is minimal (IC50 > 3 μM), and VEGFR-2 inhibition is moderate (IC50 = 235 nM), with no significant off-target kinase or ion channel activity confirmed against 65 kinases, 107 enzymes/receptors, and 21 ion channels (APExBIO).
• SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival with IC50s of 14 nM and 17 nM, respectively (Li et al. 2025).
• Suppression of VEGFA- and VEGFC-induced migration in HLMVECs is achieved with IC50s of 100 nM and <30 nM, respectively (APExBIO).
• In vivo, SAR131675 attenuates lymphangiogenesis and angiogenesis stimulated by FGF2 and reduces tumor volume in 4T1 mammary carcinoma mouse models (Li et al. 2025).
• Preclinical studies show SAR131675 downregulates hepatic VEGFC, CCL2/CCR2, and reduces Ly6Chigh monocyte infiltration, demonstrating anti-inflammatory and anti-fibrotic effects in NASH models (Li et al. 2025).
• Development was discontinued due to adverse metabolic effects observed in animal studies (APExBIO).

For a detailed comparison with earlier reviews, see SAR131675: Precision VEGFR-3 Inhibition for Tumor and Fibrosis Research, which provides additional mechanistic and translational insights not covered in this technical dossier.

Applications, Limits & Misconceptions

SAR131675 is a reference compound for mechanistic studies of the VEGFR signaling pathway in cancer biology, lymphangiogenesis, and fibrotic disease models. It is suitable for cell-based assays of VEGFC/VEGFD-induced survival and migration, and for in vivo experiments targeting lymphangiogenesis, angiogenesis, and tumor growth. Its selectivity allows for pathway-specific interrogation with minimal confounding off-target effects. Researchers should avoid use in long-term solution form, as SAR131675 is insoluble in DMSO, ethanol, and water, and solutions are not stable. The compound is not recommended for clinical translation due to discontinued development after adverse metabolic effects.

Common Pitfalls or Misconceptions

• Not a pan-VEGFR inhibitor: SAR131675 has minimal activity against VEGFR-1 and moderate VEGFR-2 inhibition; it is highly selective for VEGFR-3 (APExBIO).
• Not suitable for long-term solution storage: Insoluble in DMSO, ethanol, and water; use freshly prepared solid for each experiment.
• No significant non-kinase or ion channel activity: Inactive against a broad panel of non-kinase enzymes/receptors and ion channels (APExBIO).
• Not recommended for clinical development: Discontinued after preclinical metabolic adverse events (Li et al. 2025).
• Does not block VEGFA-induced migration with sub-nanomolar potency: IC50 for VEGFA-induced HLMVEC migration is 100 nM, whereas VEGFC-induced migration is inhibited at <30 nM.

This article updates and extends previous mechanistic reviews by integrating recent hepatic fibrosis and macrophage phenotypic data, providing a broader translational context for SAR131675 beyond cancer biology.

Workflow Integration & Parameters

SAR131675 (SKU B2301) is supplied as a solid by APExBIO and should be stored at -20°C. Fresh aliquots should be prepared for each experiment; avoid solutions for long-term storage. The compound is cell-permeable and compatible with in vitro cell viability, migration, and phosphorylation assays, as well as in vivo mouse models. Concentrations between 10 nM and 100 nM are recommended for pathway-specific inhibition in cellular assays. For in vivo studies, doses around 30 mg/kg/day (mouse, oral gavage, 16 weeks) have been validated (Li et al. 2025). For advanced protocol integration and troubleshooting, see Optimizing Lymphangiogenesis Research with SAR131675, which provides scenario-driven best practices tailored for reproducible pathway analysis and workflow efficiency.

Conclusion & Outlook

SAR131675 remains a reference standard for selective VEGFR-3 inhibition in cancer, fibrosis, and lymphangiogenesis research. Its high specificity, nanomolar potency, and robust preclinical efficacy distinguish it from less selective kinase inhibitors. While discontinued as a drug candidate due to metabolic toxicity, SAR131675 is a critical tool for mechanistic dissection of the VEGFR-3 axis and translational pathway studies. For future directions in pathway-targeted discovery, see SAR131675 and the Translational Frontier, which maps emerging therapeutic strategies based on VEGFR-3 pathway modulation and macrophage regulation.