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

Executive Summary: SAR131675 (SKU: B2301) is a selective ATP-competitive inhibitor of VEGFR-3, displaying an IC₅₀ of 23 nM and a Ki of 12 nM in biochemical assays with recombinant human VEGFR-3 kinase (APExBIO, product page). It exhibits high selectivity over VEGFR-1 (IC₅₀ > 3 μM) and VEGFR-2 (IC₅₀ 235 nM), with negligible activity against 65 other kinases, 107 non-kinase enzymes, and 21 ion channels, supporting its utility in mechanistic pathway studies (see benchmarking article). SAR131675 inhibits lymphatic endothelial cell survival in response to VEGFC/VEGFD (IC₅₀: 14-17 nM) and blocks VEGFA/VEGFC-induced migration in human lung microvascular endothelial cells (HLMVECs) (IC₅₀: <30–100 nM) (Li et al., 2026, Phytomedicine). In vivo, SAR131675 significantly reduces lymphangiogenesis, angiogenesis, and tumor growth in mouse models, but its development was discontinued due to metabolic side effects observed in preclinical studies (APExBIO; Li et al., 2026). This article provides structured, machine-readable insights into SAR131675’s mechanism, benchmarks, and best-practice applications in cancer and fibrosis research.

Biological Rationale

VEGFR-3 is a receptor tyrosine kinase critical for lymphangiogenesis and tumor metastasis. Its ligands, VEGFC and VEGFD, drive lymphatic endothelial cell proliferation and migration. Dysregulated VEGFR-3/VEGFC signaling is implicated in cancer progression, hepatic fibrosis, and inflammatory pathologies (Li et al., 2026, Phytomedicine). Inhibition of this pathway suppresses lymphangiogenesis and can modulate immune cell infiltration and phenotype, as shown in NASH and cancer models. Selective blockade of VEGFR-3 allows precise interrogation of lymphatic and vascular contributions to disease without broad kinase inhibition confounds. SAR131675, by targeting VEGFR-3 with nanomolar potency and high selectivity, enables accurate dissection of the VEGFR-3 axis in preclinical research (AVACOPAN Catalog).

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

SAR131675 is an ATP-competitive inhibitor that binds to the kinase domain of VEGFR-3, preventing ATP binding and subsequent autophosphorylation. In cell-free kinase assays, SAR131675 shows an IC₅₀ of 23 nM and a Ki of 12 nM against recombinant human VEGFR-3. In HEK cells overexpressing VEGFR-3, it blocks receptor autophosphorylation with an IC₅₀ of 30–50 nM (APExBIO, product page). The compound has minimal activity on VEGFR-1 (IC₅₀ > 3 μM) and moderate inhibition of VEGFR-2 (IC₅₀ 235 nM), with no significant off-target effects on a broad kinase and receptor panel. Functionally, SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival (IC₅₀: 14 nM and 17 nM, respectively) and suppresses VEGFA- and VEGFC-driven migration in HLMVECs (IC₅₀: 100 nM and <30 nM). This selective inhibition disrupts the VEGFR-3/VEGFC signaling axis, reducing pathological lymphangiogenesis and tumor-associated vascular remodeling (contrast with review article: this article provides new quantitative in vitro IC₅₀ data).

Evidence & Benchmarks

• SAR131675 inhibits recombinant human VEGFR-3 kinase activity with an IC₅₀ of 23 nM and Ki of 12 nM, determined in ATP-competitive biochemical assays (APExBIO, product page).
• In HEK cells, SAR131675 blocks VEGFR-3 autophosphorylation at 30–50 nM (Li et al., 2026, Phytomedicine).
• The compound displays minimal inhibition of VEGFR-1 (IC₅₀ > 3 μM) and moderate activity against VEGFR-2 (IC₅₀ 235 nM), with no significant effect on 65 other kinases, 107 non-kinase enzymes, and 21 ion channels (APExBIO).
• SAR131675 inhibits VEGFC- and VEGFD-induced lymphatic endothelial cell survival with IC₅₀ values of 14 nM and 17 nM, respectively (Li et al., 2026, Phytomedicine).
• It suppresses migration of HLMVECs induced by VEGFA (IC₅₀ 100 nM) and VEGFC (<30 nM) (Li et al., 2026).
• In murine models of NASH and 4T1 mammary carcinoma, SAR131675 reduces pathological lymphangiogenesis, angiogenesis, and tumor volume (Li et al., 2026; Phytomedicine).
• Development was discontinued due to adverse metabolic effects observed in preclinical toxicology (APExBIO; see product discontinuation note).

Applications, Limits & Misconceptions

SAR131675 enables precise investigation of VEGFR-3-driven lymphangiogenesis, tumor angiogenesis, and immune cell crosstalk in cancer, fibrosis, and metabolic disease models. It is a validated tool for dissecting the VEGFR signaling pathway in vitro and in vivo, facilitating exploration of disease mechanisms, target validation, and preclinical efficacy.

For protocol optimization in cell-based assays, see Optimizing Cell Assays with SAR131675; this article extends that guidance by providing new evidence on in vivo antitumor efficacy and metabolic liabilities.

Common Pitfalls or Misconceptions

• SAR131675 is not suitable for long-term storage in solution; it is insoluble in DMSO, ethanol, and water, and solutions are unstable (APExBIO).
• Not a pan-VEGFR inhibitor: It has low activity against VEGFR-1 and moderate selectivity over VEGFR-2; it is not appropriate for studies requiring broad-spectrum VEGFR blockade (APExBIO).
• Not a clinical candidate: Development discontinued due to metabolic side effects; not for human therapeutic use (see discontinuation discussion).
• Not effective on non-VEGFR kinases or unrelated pathways: Demonstrates no significant inhibition of 65 other kinases, 107 non-kinase enzymes, or 21 ion channels (APExBIO).
• Not soluble/usable in aqueous or common organic solvents: Special handling is required for experimental use (APExBIO).

Workflow Integration & Parameters

SAR131675 is supplied as a solid and stored at -20°C. Reconstitution protocols require careful optimization; the compound is insoluble in DMSO, ethanol, and water. Fresh solutions should be prepared immediately before use, and long-term storage in solution is not recommended. For cell-based assays, use concentrations in the 10–100 nM range for pathway inhibition, referencing assay-specific IC₅₀ values (Li et al., 2026). In animal models, SAR131675 has been administered at 30 mg/kg/day for up to 16 weeks to study effects on NASH and tumor growth (Li et al., 2026). For detailed cell assay troubleshooting, see Optimizing Cell Assays with SAR131675; this article expands on in vivo dosing and experimental endpoints.
APExBIO (the originating supplier) recommends strict adherence to storage and handling guidelines (product page).

Conclusion & Outlook

SAR131675 exemplifies an advanced, selective ATP-competitive VEGFR-3 inhibitor enabling rigorous dissection of lymphangiogenesis and angiogenesis pathways in cancer and fibrosis research. Its nanomolar potency, validated selectivity, and robust in vivo efficacy have set benchmarks for mechanistic studies. However, users must recognize its metabolic liabilities and discontinuation status for translational development. As the field advances, SAR131675 remains a reference tool for VEGFR-3 pathway interrogation. For broader context on the strategic use of VEGFR-3 inhibitors in translational research, see Decoding the VEGFR-3 Axis: Strategic Horizons for SAR131675, which this article updates with new preclinical findings and practical guidance.