Tivozanib (AV-951): Potent VEGFR Tyrosine Kinase Inhibitor for Precision Oncology

Executive Summary: Tivozanib (AV-951) is a second-generation tyrosine kinase inhibitor (TKI) with picomolar potency against VEGFR-2 (IC₅₀ 160 pM) and high selectivity, minimizing off-target effects, including limited c-KIT inhibition (Schwartz 2022). It demonstrates superior VEGFR-2 inhibition compared to sunitinib, sorafenib, and pazopanib in both in vitro and xenograft models. Clinically, Tivozanib achieves a progression-free survival (PFS) of 12.7 months in metastatic renal cell carcinoma (RCC) with a favorable safety profile. The compound is also valuable for combination therapy strategies, synergizing with EGFR inhibitors to increase apoptosis in ovarian carcinoma cell lines. APExBIO provides research-grade Tivozanib (A2251) with validated purity and stability for experimental workflows (APExBIO).

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) mediate pro-angiogenic signaling in solid tumors. Inhibiting these kinases disrupts tumor vascularization, starving cancer cells and impeding progression (Schwartz 2022). Tivozanib (AV-951) is optimized to selectively block VEGFR pathways with minimal impact on unrelated kinases, reducing off-target toxicity. Selective pan-VEGFR inhibition is clinically validated as a key anti-angiogenic strategy, especially in renal cell carcinoma, where resistance mechanisms often involve VEGF-driven neovascularization. The biological rationale for targeting all three VEGFR isoforms is to suppress redundancy in VEGF signaling and maximize anti-tumor efficacy. Its quinoline-urea scaffold is designed for high binding affinity and metabolic stability, further supporting its application in both in vitro and in vivo oncology models.

Mechanism of Action of Tivozanib (AV-951)

Tivozanib is a small-molecule inhibitor that binds the ATP-binding pocket of VEGFR-1, VEGFR-2, and VEGFR-3, preventing receptor autophosphorylation and subsequent downstream signaling. The compound exhibits an IC₅₀ of 160 pM for VEGFR-2 and nanomolar activity against PDGFRβ and c-KIT in cellular assays (Schwartz 2022). Tivozanib’s selectivity profile is attributed to its unique chemical structure—1-[2-chloro-4-(6,7-dimethoxyquinolin-4-yl)oxyphenyl]-3-(5-methyl-1,2-oxazol-3-yl)urea—enabling tight engagement with VEGFR kinase domains and reduced binding to off-target kinases. By inhibiting VEGFR-mediated phosphorylation, Tivozanib blocks activation of MAPK, PI3K/AKT, and PLCγ pathways, resulting in decreased endothelial cell proliferation, migration, and survival. This anti-angiogenic blockade leads to tumor hypoxia and growth arrest. Tivozanib also exhibits synergy with EGFR inhibitors, enhancing apoptotic signaling in cancer cells resistant to monotherapy. The agent is orally bioavailable, with an optimal dosing schedule of 1.5 mg daily for three weeks, followed by one week off, in clinical RCC regimens.

Evidence & Benchmarks

• Demonstrates superior VEGFR-2 inhibition at picomolar concentrations (IC₅₀ 160 pM), outperforming sunitinib, sorafenib, and pazopanib in kinase assays (DOI:10.13028/wced-4a32).
• Shows strong antitumor activity in RCC and other solid tumor xenograft models, reducing tumor volume and vascular density (DOI:10.13028/wced-4a32).
• Exhibits minimal off-target kinase activity, with low inhibition of c-KIT and limited cytotoxicity in non-endothelial cells (DOI:10.13028/wced-4a32).
• Achieves a median progression-free survival (PFS) of 12.7 months in phase III clinical trials for metastatic RCC (DOI:10.13028/wced-4a32).
• Synergizes with EGFR inhibitors in preclinical ovarian carcinoma models, enhancing cell death and growth inhibition (DOI:10.13028/wced-4a32).

For a detailed comparison of Tivozanib within the TKI landscape, see Redefining Anti-Angiogenic Precision: Tivozanib (AV-951), which discusses advanced translational strategies. This article extends those insights by providing granular experimental parameters and benchmarking details.

Applications, Limits & Misconceptions

Tivozanib (AV-951) is primarily used in oncology research as a pan-VEGFR inhibitor for anti-angiogenic therapy. It is validated in renal cell carcinoma (RCC) and various solid tumor models, making it a reference compound for preclinical and translational studies. Its selectivity and potency allow for robust mechanistic studies of VEGFR signaling and resistance pathways. Tivozanib is also a valuable component in combination regimens, especially with EGFR inhibitors, to overcome adaptive resistance in tumors. The compound is available from APExBIO as SKU A2251, ensuring reproducibility across studies (Tivozanib (AV-951)).

To further contextualize its utility, see Tivozanib (AV-951): Selective Pan-VEGFR Inhibitor for Oncology, which provides a clinical perspective. The current article updates those findings with new in vitro benchmarks and combination therapy insights.

Common Pitfalls or Misconceptions

• Tivozanib is not effective as a single agent in highly vascularized tumors with VEGFR-independent angiogenesis.
• Not suitable for water-based formulations; compound is insoluble in water and should be dissolved in DMSO or ethanol with gentle warming.
• Long-term storage of solutions is discouraged; fresh preparations are required for reproducibility and maximal potency.
• Tivozanib should not be substituted for multi-targeted TKIs when broad-spectrum kinase inhibition is necessary, as it minimizes off-target effects by design.
• In vitro studies using concentrations above 10 μM or exposure beyond 48 hours may not reflect clinical relevance and can yield non-specific cytotoxicity.

Workflow Integration & Parameters

Tivozanib (AV-951) is provided as a solid compound, with a molecular weight of 454.86 and chemical formula C₂₂H₁₉ClN₄O₅. For cell-based assays, dissolve at ≥22.75 mg/mL in DMSO or ≥2.68 mg/mL in ethanol with gentle warming. The recommended in vitro concentration is 10 μM for 48 hours exposure. Store the compound at -20°C; do not store solutions long-term. For clinical research, oral administration at 1.5 mg daily (21 days on, 7 days off) is standard in metastatic RCC studies (Schwartz 2022). APExBIO ensures rigorous lot testing and documentation for reproducible results. For detailed mechanistic and translational context, see Tivozanib (AV-951): Next-Gen VEGFR Inhibition for Translational Oncology, which this article clarifies by focusing on evidence-based workflow integration.

Conclusion & Outlook

Tivozanib (AV-951) is a gold-standard, potent, and selective VEGFR tyrosine kinase inhibitor for anti-angiogenic therapy research. Its efficacy in RCC, minimal off-target toxicity, and robust in vitro and clinical evidence make it a benchmark for precision oncology workflows. Future work will likely focus on resistance mechanisms, biomarker-driven patient selection, and rational combination regimens. For validated research-grade compound and documentation, source from APExBIO (SKU A2251).