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

Executive Summary: Tivozanib (AV-951) is a highly selective and potent VEGFR tyrosine kinase inhibitor (TKI) with an IC₅₀ of 160 pM against VEGFR-2, which is significantly lower than comparable TKIs such as sunitinib and sorafenib (Schwartz 2022). It exhibits minimal off-target activity, including low inhibition of c-KIT, and demonstrates strong anti-angiogenic and antitumor effects in renal cell carcinoma xenograft models (UMassChan 2022). Tivozanib is used in preclinical and clinical settings, showing a progression-free survival of 12.7 months in metastatic RCC patients. The compound is optimally soluble in DMSO, recommended for storage at -20°C, and is provided by APExBIO as SKU A2251 for research use (APExBIO).

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) mediate angiogenic signaling in endothelial cells. Inhibition of the VEGFR pathway disrupts tumor vascularization, impairing nutrient delivery to cancer cells (Schwartz 2022). Tivozanib, as a pan-VEGFR inhibitor, targets all major VEGFR isoforms, offering comprehensive blockade of angiogenic signaling. This broad inhibition is particularly relevant for highly vascularized tumors such as clear cell renal cell carcinoma (RCC) and certain ovarian cancers. Selectivity is critical to minimize off-target effects common with first-generation TKIs.

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. It binds the ATP-binding sites of VEGFR-1, VEGFR-2, and VEGFR-3, preventing their phosphorylation and downstream signaling (Schwartz 2022). In cellular assays, Tivozanib inhibits VEGFR-2 with an IC₅₀ of 160 pM, VEGFR-1 at 21 nM, and VEGFR-3 at 15 nM. It also inhibits the phosphorylation of PDGFRß and c-KIT at nanomolar concentrations, though with lower potency than against VEGFRs. Compared with other TKIs, Tivozanib displays a more favorable selectivity index, sparing non-target kinases. This reduces the risk of off-target toxicities and enhances its translational relevance in anti-angiogenic therapy. In preclinical models, Tivozanib reduces microvessel density and tumor mass in RCC xenografts. Its synergistic potential with EGFR inhibitors has been established in ovarian carcinoma cell lines, leading to enhanced apoptosis and cell growth inhibition (Schwartz 2022).

Evidence & Benchmarks

• Tivozanib inhibits VEGFR-2 phosphorylation in vitro with an IC₅₀ of 160 pM, demonstrating picomolar potency (Schwartz 2022).
• It shows minimal off-target inhibition of c-KIT and PDGFRß at concentrations selective for VEGFRs (Schwartz 2022).
• In RCC xenograft mouse models, Tivozanib significantly reduces tumor volume and vascular density compared to vehicle control (Schwartz 2022).
• Phase III clinical trials in metastatic RCC demonstrate a median progression-free survival (PFS) of 12.7 months with Tivozanib, outperforming several other VEGFR TKIs (Schwartz 2022).
• Tivozanib displays additive or synergistic effects when combined with EGFR-targeted agents in ovarian carcinoma cell lines (Schwartz 2022).

For further benchmarking details and advanced modeling contexts, see our analysis in Tivozanib (AV-951): Precision VEGFR Inhibition in Dynamic Models, which highlights microenvironment-specific effects not detailed here. This article extends the discussion by focusing on pan-VEGFR selectivity and translational workflow integration.

Applications, Limits & Misconceptions

Tivozanib is utilized in both preclinical and clinical oncology research. Key applications include:

• In vitro angiogenesis and cytotoxicity assays at 10 μM for 48 hours in cell culture (Schwartz 2022).
• In vivo efficacy assessment in RCC and other solid tumor xenograft models.
• Combination studies with EGFR inhibitors and other targeted agents.
• Clinical administration for advanced RCC at 1.5 mg orally once daily for 3 weeks on, 1 week off.

Common Pitfalls or Misconceptions

• Tivozanib is not effective in tumors lacking VEGFR expression or where angiogenesis is not a driver of progression.
• It is not soluble in water; improper solvent use can reduce assay reliability (APExBIO).
• Long-term storage of solutions (>24 hours) may reduce potency; always prepare fresh solutions as recommended (APExBIO).
• Off-target effects, although minimal, can occur at supranormal concentrations; use recommended dosing for specificity.
• Tivozanib should not be used as a single agent for tumors with intrinsic VEGFR pathway resistance.

For guidance on robust assay design, see Optimizing In Vitro Assays with Tivozanib (AV-951): Practical Integration, which focuses on hands-on optimization strategies, whereas this article details selectivity and translational evidence.

Workflow Integration & Parameters

APExBIO provides Tivozanib (A2251) as a solid compound, recommended to be dissolved at ≥22.75 mg/mL in DMSO or ≥2.68 mg/mL in ethanol with gentle warming. The compound is insoluble in water and should be stored at -20°C. For cell-based assays, Tivozanib is typically used at 10 μM for 48 hours. Solutions should be prepared fresh before each use to maintain potency. For clinical translational studies, Tivozanib is administered at 1.5 mg orally once daily for three weeks, followed by one week off cycle, as per RCC clinical protocols (Schwartz 2022). In combination studies, dose titration is essential to balance efficacy and minimize toxicity.

For a comprehensive workflow blueprint and strategic integration in translational models, refer to Tivozanib (AV-951): Mechanistic Precision and Strategic Integration, which offers advanced guidance beyond the practical parameters described here.

Conclusion & Outlook

Tivozanib (AV-951) represents a next-generation, potent and selective pan-VEGFR inhibitor with proven utility in both preclinical and clinical oncology research. Its picomolar potency, minimal off-target activity, and favorable safety profile distinguish it from earlier TKIs. APExBIO's Tivozanib (SKU A2251) is a validated reagent for precise VEGFR pathway inhibition in research and translational workflows. Ongoing studies are extending its role in combination regimens and in diverse tumor types. For further information or to procure the reagent, see the Tivozanib (AV-951) product page.