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

Executive Summary: Tivozanib (AV-951) is a second-generation tyrosine kinase inhibitor (TKI) with picomolar potency against VEGFR-2, minimal off-target inhibition, and robust anti-tumor efficacy in renal cell carcinoma (RCC) and other solid tumors (APExBIO; Schwartz 2022). It exhibits an IC50 of 160 pM for VEGFR-2 and low nanomolar inhibition of PDGFRβ and c-KIT phosphorylation. Clinical trials have demonstrated a progression-free survival (PFS) of 12.7 months in metastatic RCC patients treated with oral Tivozanib (1.5 mg daily, 3 weeks on/1 week off) (doi:10.13028/wced-4a32). In vitro, Tivozanib is typically used at 10 μM for 48 hours in cell assays, showing synergy with EGFR-targeted therapies. The product is supplied as a solid with a molecular weight of 454.86 and is best stored at -20°C (APExBIO).

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. The vascular endothelial growth factor receptor (VEGFR) family—comprising VEGFR-1, VEGFR-2, and VEGFR-3—mediates pro-angiogenic signaling in the tumor microenvironment. Inhibition of VEGFR signaling is a validated strategy for anti-angiogenic therapy in various solid tumors, including RCC (Schwartz 2022). First-generation TKIs often lack selectivity, resulting in off-target toxicities. Tivozanib was engineered as a second-generation, pan-VEGFR inhibitor with high specificity and minimal off-target effects (APExBIO). By providing precise control over VEGFR signaling, Tivozanib enables researchers to dissect angiogenesis mechanisms and develop targeted combination therapies.

Mechanism of Action of Tivozanib (AV-951)

Tivozanib is a quinoline-urea derivative that inhibits VEGFR-1, VEGFR-2, and VEGFR-3 tyrosine kinase activity via ATP-competitive binding. Its IC50 for VEGFR-2 is 160 pM, demonstrating higher potency than sunitinib, sorafenib, or pazopanib under comparable conditions (Schwartz 2022). Tivozanib also suppresses phosphorylation of PDGFRβ and c-KIT at low nanomolar concentrations, but exhibits negligible inhibition of c-KIT compared to other TKIs. Downstream, this suppresses VEGF-driven endothelial cell proliferation, migration, and survival, effectively blocking neovascularization in tumor models. Due to its selectivity, Tivozanib minimizes disruption of non-VEGF pathways, reducing off-target effects.

Evidence & Benchmarks

• Tivozanib (AV-951) achieves an IC50 of 160 pM against VEGFR-2 kinase activity, outperforming sunitinib, sorafenib, and pazopanib in direct enzyme assays (Schwartz 2022, Table 2.1).
• In cellular assays, Tivozanib inhibits VEGFR-2 phosphorylation at low nanomolar concentrations (1–10 nM), with minimal impact on c-KIT or PDGFRβ at these doses (Schwartz 2022, Fig. 3.2).
• In RCC xenograft models, Tivozanib monotherapy results in significant tumor growth inhibition compared to vehicle controls, with effects correlating to pharmacodynamic inhibition of VEGFR signaling (Schwartz 2022).
• Clinical Phase III trials show that oral Tivozanib (1.5 mg daily, 3 weeks on/1 week off) yields a median progression-free survival (PFS) of 12.7 months in metastatic RCC, exceeding benchmarks for first-generation VEGFR TKIs (Schwartz 2022).
• In vitro, co-treatment with Tivozanib and EGFR inhibitors leads to synergistic cell growth inhibition and increased apoptosis in ovarian carcinoma cell lines (Schwartz 2022, Ch. 4).

This article extends the mechanistic and translational framework established in Tivozanib (AV-951): The Next Paradigm in Precision Anti-Angiogenic Therapy by providing updated in vitro benchmarks and clinical context. For a focus on experimental troubleshooting, see Tivozanib: Potent VEGFR Inhibitor for Precision Oncology Workflows, which details workflow integration strategies.

Applications, Limits & Misconceptions

Tivozanib (AV-951) is validated for academic and translational research in angiogenesis, oncology, and combination therapy development. Its high selectivity enables mechanistic studies of VEGFR pathway modulation and anti-angiogenic therapy optimization. The compound is suitable for both in vitro and in vivo applications, including RCC and other solid tumor models. In clinical settings, Tivozanib is approved for metastatic RCC treatment and under investigation for other malignancies.

Common Pitfalls or Misconceptions

• Tivozanib is not effective as monotherapy in tumors lacking VEGF-driven angiogenesis.
• The compound is insoluble in water; use DMSO or ethanol (≥22.75 mg/mL in DMSO, ≥2.68 mg/mL in ethanol with warming) for solution preparation (APExBIO).
• Do not use Tivozanib solutions stored long-term; loss of potency may occur.
• Inhibition of non-VEGFR kinases (e.g., c-KIT, PDGFRβ) is minimal at standard concentrations; do not expect broad-spectrum kinase inhibition.
• Tivozanib is not a cytotoxic agent; its primary action is anti-angiogenic, not direct tumor cell killing.

This article clarifies mechanism-specific and workflow boundaries compared to Tivozanib: Potent VEGFR Inhibitor for Advanced Oncology Research, which emphasizes translational synergies and troubleshooting.

Workflow Integration & Parameters

Tivozanib is supplied as a solid (molecular weight: 454.86, formula C22H19ClN4O5, chemical name: 1-[2-chloro-4-(6,7-dimethoxyquinolin-4-yl)oxyphenyl]-3-(5-methyl-1,2-oxazol-3-yl)urea) by APExBIO. Stock solutions should be prepared in DMSO or ethanol, with gentle warming for ethanol. For storage, keep at -20°C. Typical in vitro use involves 10 μM dosing for 48-hour exposures, with concentrations adjusted based on cell line sensitivity and experimental objectives. For in vivo studies, refer to published dosing regimens (e.g., oral 1.5 mg daily, 3 weeks on/1 week off) (Schwartz 2022). Tivozanib demonstrates additive or synergistic effects when combined with EGFR inhibitors or cytotoxic agents in select models. Avoid combining with agents that require intact VEGF signaling. The product page for Tivozanib (AV-951) A2251 kit provides further technical details.

For a systems biology perspective on drug response evaluation and emerging combination strategies, see Tivozanib (AV-951): Next-Gen VEGFR Inhibitor for Precision Oncology. This article emphasizes quantitative in vitro parameters and Phase III clinical benchmarks.

Conclusion & Outlook

Tivozanib (AV-951) represents a benchmark VEGFR inhibitor for anti-angiogenic research and clinical translation. Its high potency, selectivity, and favorable safety profile enable precise dissection of VEGF pathway biology and support rational combination therapy design. Future research will clarify its utility in additional tumor types and further optimize dosing strategies. For high-quality, research-grade Tivozanib, APExBIO provides validated protocols and technical support (product page).