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

Executive Summary: Tivozanib (AV-951) is a second-generation, highly potent and selective tyrosine kinase inhibitor (TKI) targeting VEGFR-1, VEGFR-2, and VEGFR-3, with an IC₅₀ of 160 pM against VEGFR-2 in vitro (Schwartz 2022). It demonstrates minimal off-target activity, notably sparing c-KIT and other kinases at relevant concentrations (APExBIO). Clinically, it exhibits one of the longest progression-free survival (PFS) rates in metastatic renal cell carcinoma (RCC) at 12.7 months. Tivozanib shows synergistic effects when combined with EGFR-targeted therapies, enhancing apoptosis and growth inhibition in preclinical models. Its physicochemical properties and validated workflow parameters make it especially suitable for both basic and translational oncology research.

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. The vascular endothelial growth factor (VEGF) pathway, mediated primarily by VEGFR-1, VEGFR-2, and VEGFR-3, regulates endothelial cell proliferation, migration, and survival. Inhibiting VEGFR signaling disrupts tumor vascularization, resulting in reduced tumor viability (Schwartz 2022). Targeted anti-angiogenic therapy is a validated strategy in the treatment of solid tumors, particularly renal cell carcinoma (RCC), where VEGF pathway activation is prevalent. First-generation TKIs exhibited broad kinase inhibition, leading to off-target effects. Tivozanib (AV-951) was developed to maximize VEGFR inhibition while minimizing unrelated kinase activity (APExBIO).

Mechanism of Action of Tivozanib (AV-951)

Tivozanib is a quinoline-urea derivative that selectively inhibits the ATP-binding site of VEGFR-1, VEGFR-2, and VEGFR-3. It exhibits sub-nanomolar potency, with an IC₅₀ of 160 pM for VEGFR-2 and low nanomolar values for VEGFR-1 and VEGFR-3 in cell-free assays. Tivozanib also inhibits phosphorylation of PDGFRβ and c-KIT at higher, nanomolar concentrations, but with markedly lower activity than for VEGFRs, indicating high selectivity (APExBIO). In cellular contexts, Tivozanib blocks VEGF-driven downstream signaling, reducing endothelial cell proliferation, migration, and survival. This leads to decreased neovascularization in tumor models. Its minimal off-target kinase inhibition reduces the likelihood of adverse effects commonly seen with broader-spectrum TKIs.

Evidence & Benchmarks

• Tivozanib inhibits VEGFR-2 with an IC₅₀ of 160 pM in cell-free biochemical assays (Schwartz 2022).
• Demonstrated significant tumor growth inhibition in RCC xenograft mouse models at 1–3 mg/kg orally, once daily (Schwartz 2022).
• In phase III RCC clinical trials, median progression-free survival (PFS) reached 12.7 months with Tivozanib (AV-951) at 1.5 mg orally once daily, 3 weeks on/1 week off (APExBIO).
• Combination with EGFR inhibitors in ovarian carcinoma cell lines (10 μM for 48 h) increased apoptosis and growth inhibition versus either agent alone (Schwartz 2022).
• Compared to sunitinib, sorafenib, and pazopanib, Tivozanib shows superior selectivity for VEGFR-2 and reduced off-target toxicity (Schwartz 2022).

This article extends the mechanistic insights provided in Tivozanib (AV-951): Next-Generation VEGFR Inhibition in P... by offering updated clinical benchmarks and parameter guidance for advanced preclinical workflows.

For a detailed systems-level perspective on in vitro evaluation and combination therapy strategies, see Tivozanib (AV-951): Precision Pan-VEGFR Inhibition in Nex.... This article clarifies real-world workflow integration and recent efficacy data not covered in that source.

Applications, Limits & Misconceptions

Tivozanib (AV-951) is primarily used for anti-angiogenic research in oncology, especially for renal cell carcinoma and other solid tumors reliant on VEGFR signaling. Its high selectivity makes it valuable for dissecting VEGFR-mediated processes without confounding off-target effects. It is also a key tool in combination therapy studies, notably with EGFR inhibitors, for evaluating synergistic anti-tumor effects.

Common Pitfalls or Misconceptions

• Tivozanib is not effective against tumors lacking active VEGFR signaling, such as some hematologic malignancies.
• It does not substitute for immunotherapies targeting PD-1/PD-L1, as its mechanism is anti-angiogenic, not immunomodulatory.
• Due to its minimal c-KIT activity, it is not suitable for modeling c-KIT-driven cancers.
• Its water insolubility requires careful solvent selection (use DMSO or ethanol with warming; avoid water).
• Long-term storage of Tivozanib solutions is not recommended; fresh preparation is essential to maintain potency.

Workflow Integration & Parameters

Tivozanib (AV-951) is supplied by APExBIO as a solid compound (SKU: A2251) with a molecular weight of 454.86 and chemical formula C₂₂H₁₉ClN₄O₅. Recommended solubility is ≥22.75 mg/mL in DMSO and ≥2.68 mg/mL in ethanol with gentle warming. It is insoluble in water, requiring appropriate solvents for biological experiments. Storage at -20°C is advised. For in vitro cell studies, 10 μM for 48 hours is a standard condition. Clinical dosing for RCC is 1.5 mg orally, once daily, in cycles of 3 weeks on, 1 week off.

For comprehensive stepwise protocols and troubleshooting strategies, Tivozanib (AV-951): Potent VEGFR Inhibitor for Oncology R... offers additional workflow details; this article provides updated benchmarks and clarifies application boundaries.

For direct ordering and up-to-date product specifications, see the Tivozanib (AV-951) product page from APExBIO.

Conclusion & Outlook

Tivozanib (AV-951) sets a new standard for selective, potent pan-VEGFR inhibition in oncology research. Its minimal off-target profile, validated efficacy, and robust workflow compatibility make it a preferred choice for anti-angiogenic studies and combination therapy exploration. Future research will likely focus on expanding its applications in multi-modal regimens and refining predictive models for VEGFR inhibitor responsiveness (Schwartz 2022).