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

Executive Summary: Tivozanib (AV-951) is a second-generation quinoline-urea tyrosine kinase inhibitor that targets VEGFR-1, VEGFR-2, and VEGFR-3 with picomolar potency (IC50 160 pM for VEGFR-2) (Schwartz 2022). It exhibits minimal off-target kinase inhibition, notably sparing c-KIT at therapeutic doses (APExBIO). Clinically, Tivozanib achieves a progression-free survival of 12.7 months in metastatic renal cell carcinoma (RCC) when administered at 1.5 mg orally once daily for 3 weeks (Schwartz 2022). Its favorable solubility in DMSO (≥22.75 mg/mL) and ethanol (≥2.68 mg/mL) facilitates integration into in vitro workflows. Synergistic effects are observed when combined with EGFR inhibitors in ovarian carcinoma models (Schwartz 2022).

Biological Rationale

Angiogenesis is a hallmark of cancer, supporting tumor growth and metastasis (Schwartz 2022). Vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) mediate angiogenic signaling. Inhibiting VEGFR signaling disrupts vascular supply to tumors and suppresses tumor proliferation. Renal cell carcinoma (RCC) and other solid tumors frequently display upregulated VEGFR pathways, making them susceptible to anti-angiogenic therapy. Tivozanib (AV-951) was engineered to maximize VEGFR blockade while minimizing off-target effects, addressing limitations of earlier multi-kinase inhibitors (APExBIO).

Mechanism of Action of Tivozanib (AV-951)

Tivozanib selectively binds to the ATP-binding site of VEGFR-1, VEGFR-2, and VEGFR-3, preventing autophosphorylation and downstream signaling. The compound demonstrates an IC50 of 160 pM against VEGFR-2 in biochemical assays. In cellular models, Tivozanib inhibits phosphorylation of PDGFRβ and c-KIT at nanomolar concentrations, though with substantially lower potency than for VEGFR isoforms (Schwartz 2022). This selectivity profile underpins its lower adverse event rate compared to multi-targeted TKIs such as sunitinib or sorafenib. By abrogating VEGFR-mediated signaling, Tivozanib disrupts angiogenesis and induces tumor regression in preclinical models. Its quinoline-urea scaffold enhances both its potency and metabolic stability (APExBIO).

Evidence & Benchmarks

• Tivozanib exhibits an IC50 of 160 pM for VEGFR-2 in cell-free kinase assays (Schwartz 2022).
• In RCC xenograft models, Tivozanib produces significant tumor regression and anti-angiogenic effects (Schwartz 2022).
• Tivozanib shows superior VEGFR-2 inhibition compared to sunitinib, sorafenib, and pazopanib under matched conditions (Schwartz 2022).
• Combination with EGFR inhibitors results in synergistic inhibition of cell growth and enhanced apoptosis in ovarian carcinoma cell lines (Schwartz 2022).
• Clinical phase III studies report a median progression-free survival of 12.7 months in metastatic RCC patients receiving Tivozanib (1.5 mg QD, 3 weeks on/1 week off) (Schwartz 2022).
• Tivozanib is soluble at ≥22.75 mg/mL in DMSO and ≥2.68 mg/mL in ethanol with gentle warming; insoluble in water (APExBIO).
• Minimal off-target kinase inhibition, including low activity against c-KIT at therapeutic doses (Schwartz 2022).

This article extends and clarifies prior overviews, such as 'Tivozanib (AV-951): Mechanistic Precision and Translation...', by providing updated clinical benchmarks and detailed solubility profiles for laboratory integration.

For a broader context on workflow integration, see 'Tivozanib (AV-951): Potent VEGFR Tyrosine Kinase Inhibitor…'. This article focuses more on practical parameters and boundaries in oncology research.

Applications, Limits & Misconceptions

Tivozanib (AV-951) is used widely in oncology research as a tool for dissecting VEGFR signaling, modeling anti-angiogenic therapy, and optimizing combination regimens. It is especially valuable in RCC, where VEGFR-driven angiogenesis is a key driver of pathogenesis. In vitro, Tivozanib is applied at 10 μM for 48 hours to assess effects on cell proliferation and apoptosis. Its favorable safety and efficacy profile under clinical conditions makes it a preferred agent for translational studies.

Common Pitfalls or Misconceptions

• Tivozanib is not a pan-kinase inhibitor: Its selectivity for VEGFRs means it has minimal off-target effects, especially on c-KIT or PDGFRα, compared to older TKIs.
• Not effective in VEGFR-independent tumors: Tumors lacking VEGFR dependency generally do not respond to Tivozanib.
• Solubility constraints: The compound is insoluble in water and requires DMSO or ethanol for stock preparation; improper dissolution leads to inaccurate dosing.
• Storage and solution stability: Tivozanib should be stored at -20°C and solutions used promptly; long-term storage of solutions is not recommended.
• Synergy is context-dependent: Synergistic effects with EGFR inhibitors are observed in select cell lines (e.g., ovarian carcinoma) and are not universal.

Workflow Integration & Parameters

Preparation: Dissolve Tivozanib at ≥22.75 mg/mL in DMSO or ≥2.68 mg/mL in ethanol with gentle warming. Avoid water as a solvent. For cell-based assays, dilute the stock to a final working concentration of 10 μM; incubate cells for 48 hours. Store powder at -20°C; prepare fresh solutions before use.

Experimental Controls: Include vehicle (DMSO or ethanol) controls and parallel testing with other VEGFR inhibitors for benchmarking. Evaluate both cell viability (relative) and cell death (fractional) to distinguish cytostatic from cytotoxic effects (Schwartz 2022).

Clinical Translation: In clinical protocols, Tivozanib is administered orally at 1.5 mg QD for 3 weeks, followed by 1 week off. Monitor for hypertension and proteinuria as class-specific adverse events. Direct comparison with other TKIs should account for differences in dosing schedules and selectivity.

For additional guidance on advanced integration, see 'Tivozanib (AV-951): Precision VEGFR Inhibition for Advanc…', which discusses next-generation combination strategies. This article updates those workflows with refined dosing and solubility recommendations.

Conclusion & Outlook

Tivozanib (AV-951) stands as a benchmark pan-VEGFR inhibitor for preclinical and clinical oncology research. Its potency, selectivity, and favorable safety profile differentiate it from first-generation TKIs. Reliable supply and technical support are available from APExBIO. Research continues to explore its role in combination regimens and resistance mechanisms. For detailed mechanistic modeling and translational guidance, refer to the cited literature and product documentation.