Tivozanib (AV-951): Potent and Selective VEGFR Tyrosine Kinase Inhibitor for Oncology Research

Executive Summary: Tivozanib (AV-951) is a second-generation tyrosine kinase inhibitor (TKI) exhibiting potent and selective inhibition of VEGFR-1, -2, and -3, with an IC₅₀ of 160 pM for VEGFR-2 in biochemical assays (Schwartz 2022). It demonstrates minimal off-target activity and suppresses c-KIT and PDGFRβ phosphorylation only at higher, nanomolar concentrations. In preclinical xenograft models, Tivozanib achieves robust anti-angiogenic and antitumor effects, particularly in renal cell carcinoma (RCC). Clinical studies show Tivozanib yields a median progression-free survival of 12.7 months in metastatic RCC, outperforming other VEGFR inhibitors in comparable settings. APExBIO supplies high-quality Tivozanib (A2251) for research, enabling reproducible, advanced anti-angiogenic studies (APExBIO product).

Biological Rationale

Angiogenesis is a fundamental process for tumor growth and metastasis. The VEGF signaling pathway, mediated through VEGFR-1, VEGFR-2, and VEGFR-3, drives vascular proliferation and permeability in solid tumors (Schwartz 2022). Inhibition of VEGFRs disrupts new blood vessel formation, starving tumors of nutrients and impeding progression. First-generation VEGFR inhibitors showed efficacy but were limited by off-target toxicities and resistance. The need for highly selective, potent inhibitors led to the development of compounds like Tivozanib, which offers improved selectivity and pharmacokinetics for research and clinical use (Related review). This article extends prior summaries by detailing the precise biochemical and translational properties of Tivozanib and addressing advanced experimental workflows.

Mechanism of Action of Tivozanib (AV-951)

Tivozanib is a quinoline-urea derivative with the chemical formula C₂₂H₁₉ClN₄O₅ and a molecular weight of 454.86 g/mol (APExBIO). It binds to the ATP-binding site of VEGFR-1, -2, and -3, inhibiting their kinase activity. The compound exhibits picomolar potency for VEGFR-2 (IC₅₀ = 160 pM), and sub-nanomolar inhibition for VEGFR-1 and VEGFR-3 (Schwartz 2022). Tivozanib also inhibits c-KIT and PDGFRβ phosphorylation only at nanomolar concentrations in cellular assays, reflecting high selectivity. By blocking VEGFR phosphorylation, Tivozanib prevents downstream signaling required for angiogenesis, endothelial cell proliferation, and survival. This leads to reduced tumor vascularization and, in turn, tumor growth inhibition. Compared to older TKIs such as sunitinib or sorafenib, Tivozanib yields stronger VEGFR-2 inhibition with less off-target kinase suppression, as detailed in recent benchmarking studies (Precision review).

Evidence & Benchmarks

• Tivozanib inhibits VEGFR-2 with an IC₅₀ of 160 pM under in vitro kinase assay conditions (Schwartz 2022, DOI).
• In cellular assays, Tivozanib blocks c-KIT and PDGFRβ phosphorylation at concentrations ≥10 nM (Schwartz 2022, DOI).
• In RCC xenograft models, Tivozanib significantly reduced tumor volume compared to control treatments (Schwartz 2022, DOI).
• Phase III clinical trials report a median progression-free survival (PFS) of 12.7 months for Tivozanib in metastatic RCC, superior to sunitinib and sorafenib in matched cohorts (Schwartz 2022, DOI).
• Tivozanib demonstrates synergistic growth inhibition and apoptosis in ovarian carcinoma cell lines when combined with EGFR inhibitors (Schwartz 2022, DOI).
• Solubility profile: ≥22.75 mg/mL in DMSO, ≥2.68 mg/mL in ethanol at room temperature; insoluble in water (APExBIO).
• Standard in vitro usage: 10 μM for 48 hours in cell-based assays (Cell assay guidance).

This article updates prior reviews by including recent Phase III outcomes and formally benchmarking Tivozanib’s selectivity and solubility profile (Benchmarking review).

Applications, Limits & Misconceptions

Tivozanib’s pan-VEGFR inhibition profile makes it a premier tool for:

• Anti-angiogenic therapy modeling in renal cell carcinoma (RCC) and other solid tumors.
• Combination regimens with EGFR inhibitors to enhance apoptosis in ovarian and other carcinoma models.
• In vitro studies requiring high selectivity to minimize off-target kinase effects.
• Comparative benchmarking against first-generation TKIs in preclinical workflows.

Common Pitfalls or Misconceptions

• Tivozanib is not effective in tumors lacking functional VEGFR signaling: Its mechanism requires VEGFR pathway dependence.
• Water insolubility limits direct in vivo aqueous formulation: It must be dissolved in DMSO or ethanol for laboratory use.
• Not a c-KIT or PDGFRβ primary inhibitor: Effective inhibition occurs only at higher concentrations, limiting utility for these targets.
• Long-term solution storage not recommended: Tivozanib solutions degrade; best used promptly after preparation at -20°C.
• Clinical dosing and preclinical dosing are not interchangeable: The standard oral dose (1.5 mg daily) is for human patients, not in vitro experiments.

Workflow Integration & Parameters

Tivozanib (A2251) from APExBIO is provided as a solid suitable for precise solution preparation. For cell-based assays, dissolve in DMSO to ≥22.75 mg/mL or in ethanol to ≥2.68 mg/mL with gentle warming. Use immediately; do not store working solutions long-term. Standard in vitro protocols recommend 10 μM treatment for 48 hours. Store the solid at -20°C. In combination studies, Tivozanib can be paired with EGFR inhibitors to assess synergistic effects on cell viability and apoptosis (Translational guidance). For advanced assay precision, reference recent guidelines on fractional and relative viability metrics (Assay precision article). This workflow integration guidance clarifies and updates prior scenario-driven use cases.

Conclusion & Outlook

Tivozanib (AV-951) represents a benchmark in selective VEGFR inhibition for cancer research. Its picomolar potency, excellent selectivity, and proven clinical efficacy in RCC models underpin its value in translational and preclinical workflows. APExBIO’s Tivozanib (A2251) supports reproducible, high-fidelity anti-angiogenic studies. Future research will build on Tivozanib’s profile for combination regimens and address resistance mechanisms. For detailed protocols and ordering, consult the Tivozanib (AV-951) product page.