Tivozanib (AV-951): Potent, Selective VEGFR Inhibitor for Renal Cell Carcinoma and Oncology Research

Executive Summary: Tivozanib (AV-951) is a second-generation, quinoline-urea VEGFR tyrosine kinase inhibitor with picomolar potency against VEGFR-2 (IC₅₀ = 160 pM in vitro) and minimal off-target activity, including low inhibition of c-KIT and PDGFRß at nanomolar concentrations (Schwartz 2022). In renal cell carcinoma (RCC) xenograft models, it demonstrates significant antitumor activity and superior selectivity compared to first-generation TKIs. Clinical trials report a progression-free survival (PFS) of 12.7 months in metastatic RCC when administered orally at 1.5 mg/day for 3 weeks (UMass Chan 2022). Tivozanib is suitable for in vitro anti-angiogenic research, combination regimens with EGFR inhibitors, and is available from APExBIO as SKU A2251 (product page).

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) mediate endothelial proliferation and vascular permeability. Dysregulated VEGFR signaling is implicated in solid tumors, especially renal cell carcinoma (RCC). Targeting VEGFRs disrupts tumor vasculature, suppressing nutrient supply and inhibiting tumor progression (Schwartz 2022). Selective, potent inhibition of VEGFRs offers improved efficacy and reduced toxicity compared to non-selective agents.

Mechanism of Action of Tivozanib (AV-951)

Tivozanib is a selective pan-VEGFR inhibitor. It binds to the ATP-binding site of VEGFR-1, VEGFR-2, and VEGFR-3, blocking receptor phosphorylation and downstream signaling. The compound is a quinoline-urea derivative, with a molecular weight of 454.86 Da and formula C₂₂H₁₉ClN₄O₅. In biochemical assays, Tivozanib inhibits VEGFR-2 kinase activity with an IC₅₀ of 160 pM. Cellular assays confirm inhibition of VEGFR-2 phosphorylation at nanomolar concentrations. Minimal inhibition is observed for c-KIT and PDGFRß, reducing off-target effects. In RCC and ovarian carcinoma cell lines, it blocks angiogenic signaling, inhibits proliferation, and induces apoptosis, especially when combined with EGFR inhibitors (Schwartz 2022).

Evidence & Benchmarks

• Tivozanib (AV-951) inhibits VEGFR-2 kinase activity with an IC₅₀ of 160 pM in vitro biochemical assays (Schwartz 2022, DOI link).
• Demonstrates low off-target inhibition (c-KIT, PDGFRß) at nanomolar concentrations, confirming selectivity (Schwartz 2022, Table 3.2).
• In RCC xenograft models, Tivozanib achieves significant tumor regression and anti-angiogenic effects compared to sunitinib and sorafenib (UMass Chan 2022).
• Clinical phase III: Tivozanib at 1.5 mg orally daily for 3 weeks results in 12.7 months median PFS in metastatic RCC, surpassing other TKIs (Schwartz 2022).
• Combination with EGFR inhibitors in ovarian carcinoma models produces synergistic inhibition of cell growth and enhanced apoptosis (Schwartz 2022).

For a detailed exploration of experimental workflows and Tivozanib's selectivity profile, see the Precision VEGFR Inhibitor for Oncology article, which this dossier extends by providing updated clinical benchmarks and physicochemical parameters.

Applications, Limits & Misconceptions

Tivozanib is primarily deployed in RCC research, anti-angiogenic assay development, and as a tool compound for dissecting VEGFR signaling. Its high selectivity and potency make it a preferred agent in combination therapy studies, particularly with EGFR inhibitors. Tivozanib is unsuitable for applications requiring water solubility or long-term solution stability. It is not effective against tumors lacking VEGFR-driven angiogenesis. The compound is not a broad-spectrum cytotoxic agent but rather an anti-angiogenic and cytostatic agent.

Common Pitfalls or Misconceptions

• Tivozanib is not water-soluble; solutions should be prepared in DMSO or ethanol with gentle warming and used promptly (APExBIO).
• Long-term storage of solutions at room temperature or in aqueous buffer leads to compound degradation and reduced activity.
• Tivozanib does not exhibit potent cytotoxicity in non-angiogenic or non-VEGFR-driven models.
• Use of concentrations above 10 μM in in vitro experiments may cause off-target effects not seen at clinically relevant doses.
• It is not an appropriate substitute for multi-targeted TKIs when broad kinase inhibition is required.

For practical guidance on robust cell viability and cytotoxicity assays, see Scenario-Driven Best Practices for Tivozanib (AV-951), which this article updates by clarifying compound-specific solubility and selectivity boundaries.

Workflow Integration & Parameters

Tivozanib (AV-951) is supplied as a solid by APExBIO (SKU A2251). Store at -20°C. Prepare solutions in DMSO (≥22.75 mg/mL) or ethanol (≥2.68 mg/mL, gentle warming). For cell-based assays, use at 10 μM for 48 hours unless otherwise validated. Avoid water as solvent. Solutions should be freshly prepared and not stored long-term. In combination protocols, titrate both Tivozanib and EGFR inhibitor concentrations for synergistic effects. In clinical research, administer orally at 1.5 mg daily for 3 weeks in RCC studies. See the Tivozanib (AV-951) product page for full handling and storage instructions. For additional context on mechanistic precision and translational applications, refer to Mechanistic Precision Meets Translation, which this dossier extends by specifying in vitro dosing and solution parameters.

Conclusion & Outlook

Tivozanib (AV-951) exemplifies a new generation of highly selective, potent VEGFR tyrosine kinase inhibitors for anti-angiogenic therapy and renal cell carcinoma research. Its distinct molecular profile, validated by robust in vitro and clinical evidence, supports its use in advanced research and therapeutic protocols. The compound's minimal off-target activity and strong clinical performance position it as a reference standard in VEGFR-driven oncology studies. Ongoing research will further define its utility in combination regimens and extend its applications to additional tumor types. APExBIO continues to supply high-purity Tivozanib (A2251) for reproducible, translational research workflows.