Tivozanib (AV-951): A Potent and Selective Pan-VEGFR Inhibitor for Oncology Research

Executive Summary: Tivozanib (AV-951) is a second-generation quinoline-urea tyrosine kinase inhibitor with picomolar potency against VEGFR-2 (IC50: 160 pM), providing superior selectivity and efficacy in anti-angiogenic cancer therapy [DOI]. The compound demonstrates minimal off-target activity, including low c-KIT inhibition, and exhibits robust antitumor activity in renal cell carcinoma (RCC) xenograft models [APExBIO]. Clinical studies show a progression-free survival (PFS) of 12.7 months in metastatic RCC patients, outperforming older TKIs. Tivozanib is readily soluble in DMSO (≥22.75 mg/mL), stable at -20°C, and synergizes with EGFR inhibitors in preclinical models. APExBIO offers Tivozanib (A2251) as a validated research-grade reagent for in vitro and translational studies.

Biological Rationale

Tivozanib (AV-951) was developed to address resistance and off-target toxicity observed with first-generation VEGFR inhibitors. The VEGFR signaling pathway is a central driver of tumor angiogenesis, supporting tumor growth and metastasis [Schwartz 2022]. Inhibition of VEGFR-1, VEGFR-2, and VEGFR-3 blocks endothelial cell proliferation, migration, and new vessel formation. Selective targeting reduces adverse reactions associated with broader kinase inhibition [Related Article]. Tivozanib’s design as a second-generation TKI aims to maximize anti-angiogenic efficacy while minimizing dose-limiting toxicities.

Mechanism of Action of Tivozanib (AV-951)

Tivozanib (AV-951) binds the ATP-binding site of VEGFR-1, VEGFR-2, and VEGFR-3, inhibiting their tyrosine kinase activity with high selectivity. The compound exhibits an IC50 of 160 pM for VEGFR-2, 21 nM for c-KIT, and nanomolar inhibition of PDGFRβ in cellular assays [APExBIO]. Inhibition prevents VEGF-induced receptor phosphorylation, downstream MAPK/ERK activation, and angiogenic gene expression. Minimal off-target activity is observed against non-VEGFR kinases, including low affinity for c-KIT and PDGFRβ outside nanomolar ranges. This selectivity is confirmed in kinase profiling and cell-based phospho-assays [Schwartz 2022]. In preclinical models, Tivozanib induces endothelial cell apoptosis and suppresses tumor vascularization.

Evidence & Benchmarks

• Tivozanib (AV-951) inhibits VEGFR-2 with an IC50 of 160 pM in biochemical kinase assays (Schwartz 2022, DOI).
• Demonstrates minimal inhibition of c-KIT (IC50: 21 nM) and PDGFRβ at nanomolar concentrations, confirming selectivity (Schwartz 2022, DOI).
• In RCC xenograft models, Tivozanib significantly reduces tumor growth and microvessel density (Schwartz 2022, DOI).
• Clinical phase III trials in metastatic RCC report a median PFS of 12.7 months with Tivozanib 1.5 mg orally once daily (APExBIO, link).
• Tivozanib outperforms sunitinib, sorafenib, and pazopanib in VEGFR-2 inhibition potency and selectivity (Schwartz 2022, DOI).
• In vitro, Tivozanib at 10 μM for 48 hours synergizes with EGFR inhibitors to enhance growth inhibition and apoptosis in ovarian carcinoma cell lines (Schwartz 2022, DOI).

For a detailed comparison of workflow integration and troubleshooting, see Scenario-Driven Best Practices with Tivozanib (AV-951) in Oncology Research. This article builds upon those guidelines by providing updated clinical benchmarks and clarifying selectivity data.

Applications, Limits & Misconceptions

Tivozanib is primarily utilized for anti-angiogenic therapy modeling in renal cell carcinoma and other solid tumor research. Its high selectivity allows for combination with other targeted agents, notably EGFR inhibitors, to overcome resistance mechanisms. The compound is suitable for in vitro, ex vivo, and in vivo preclinical studies, as well as for protocol development in translational research [Related Article]. Unlike older TKIs, Tivozanib exhibits reduced off-target toxicity and minimal impact on hematopoietic kinases at standard doses. However, it is not effective against tumors lacking VEGFR pathway dependence or in models where angiogenesis is not a driver of growth.

Common Pitfalls or Misconceptions

• Not a pan-kinase inhibitor: Tivozanib is highly selective; it does not broadly suppress all receptor tyrosine kinases outside the VEGFR family.
• Water insolubility: The compound is insoluble in water and must be dissolved in DMSO (≥22.75 mg/mL) or ethanol with gentle warming (≥2.68 mg/mL).
• Not suitable for long-term solution storage: Tivozanib solutions are chemically stable only when freshly prepared; long-term DMSO stock storage is discouraged.
• Limited efficacy in VEGFR-independent tumors: Tumors with non-angiogenic growth drivers show minimal response.
• No direct cytotoxicity at sub-micromolar doses: The primary effect is anti-angiogenic, not direct tumor cell killing at low concentrations.

For molecular profiling, refer to Tivozanib (AV-951): Potent and Selective VEGFR Inhibitor, which details domain-specific kinase inhibition; this article expands on in vitro combinatorial strategies and clinical relevance.

Workflow Integration & Parameters

Solubility and Storage: Tivozanib is supplied as a solid with a molecular weight of 454.86 g/mol and chemical formula C₂₂H₁₉ClN₄O₅. For experimental use, dissolve in DMSO to ≥22.75 mg/mL or in ethanol (≥2.68 mg/mL) with gentle warming. Store at -20°C. Use solutions promptly; avoid repeated freeze-thaw cycles [APExBIO].

Concentration and Timing: Standard in vitro protocols employ 10 μM Tivozanib for 48 hours in cell-based assays. For combination studies, titration with EGFR inhibitors is recommended to optimize synergy. In vivo, clinical dosing is 1.5 mg orally once daily for 21 days per cycle.

Assay Compatibility: Tivozanib is compatible with cell viability, proliferation, cytotoxicity, and apoptosis assays. For best results, validate solubilization and confirm absence of precipitation in media. Refer to Tivozanib (AV-951): Mechanistic Precision and Strategic Oncology Integration, which outlines complementary mechanistic assays; this article extends those recommendations with updated selectivity and workflow tips.

Conclusion & Outlook

Tivozanib (AV-951), offered by APExBIO, represents a benchmark pan-VEGFR inhibitor for advanced oncology research. Its unmatched potency, high selectivity, and favorable safety profile facilitate reliable anti-angiogenic modeling and combination studies. As next-generation anti-angiogenic strategies evolve, Tivozanib will remain central to studies of VEGFR signaling and translational protocol development. For comprehensive reagent details, see the Tivozanib (AV-951) product page.