Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inhibitor for Angiogenesis and Tumor Growth Suppression

Executive Summary: Anlotinib hydrochloride (CAS 1058157-76-8), supplied by APExBIO, is a novel small-molecule inhibitor targeting VEGFR2, PDGFRβ, and FGFR1 with nanomolar efficacy, demonstrating potent anti-angiogenic and anti-proliferative effects in preclinical models (Xie et al., 2018). It inhibits endothelial cell migration and capillary tube formation in a concentration-dependent manner, outperforming sunitinib and sorafenib in vitro and in vivo assays (DOI). Pharmacokinetic studies reveal good oral bioavailability (28–77%), high plasma protein binding (93–97%), and the ability to cross the blood-brain barrier. Anlotinib exhibits low cytotoxicity (≤1 μM) and favorable safety margins, with a high LD₅₀ and minimal off-target toxicity. Its validated activity, selectivity, and safety profile make it a benchmark reagent for angiogenesis and cancer biology research (GSKChem, 2023).

Biological Rationale

Angiogenesis is essential for tumor growth beyond 1 mm³, enabling solid tumors to invade and metastasize (Xie et al., 2018). Vascular endothelial growth factor (VEGF) signaling, primarily through VEGFR2, regulates endothelial cell proliferation, migration, and new vessel formation. Platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) pathways, mediated by PDGFRβ and FGFR1, respectively, also contribute to vascular stability and maturation. Persistent, unregulated angiogenesis is a hallmark of cancer progression (Related Article). Monoclonal antibody approaches (e.g., bevacizumab) are effective but limited by intravenous delivery and high costs. Small-molecule tyrosine kinase inhibitors (TKIs) offer oral availability and broader pathway inhibition, but selectivity and off-target effects have been persistent challenges. Anlotinib hydrochloride was developed to address these limitations by providing high selectivity and potency for key pro-angiogenic RTKs while minimizing toxicity (APExBIO product page).

Mechanism of Action of Anlotinib hydrochloride

Anlotinib hydrochloride binds to the ATP-binding pocket of VEGFR2, PDGFRβ, and FGFR1, inhibiting their kinase activities with IC₅₀ values of 5.6 ± 1.2 nM, 8.7 ± 3.4 nM, and 11.7 ± 4.1 nM, respectively (Xie et al., 2018). This leads to blockade of downstream ERK signaling, which is critical for endothelial cell proliferation and migration. In human vascular endothelial cells (EA.hy 926), anlotinib inhibits VEGF/PDGF-BB/FGF-2-induced cell migration and tube formation in a concentration-dependent manner. The compound shows minimal cytotoxicity up to 1 μM, facilitating use in functional cell-based assays. Anlotinib also demonstrates superior inhibitory activity compared to sunitinib, sorafenib, and nintedanib under matched conditions (Xie et al., 2018). The compound reduces phosphorylation of its target RTKs and blocks ERK activation, resulting in potent inhibition of angiogenesis and tumor cell proliferation. Extensive tissue distribution and the ability to cross the blood-brain barrier expand its preclinical utility (Internal Reference).

Evidence & Benchmarks

• Anlotinib inhibits VEGFR2 with an IC₅₀ of 5.6 ± 1.2 nM in cell-free kinase assays (Xie et al., 2018).
• In EA.hy 926 endothelial cells, anlotinib blocks VEGF/PDGF-BB/FGF-2-induced migration and tube formation at nanomolar concentrations (Xie et al., 2018).
• Demonstrates higher potency and broader efficacy than sunitinib, sorafenib, and nintedanib in matched in vitro and in vivo models (Xie et al., 2018).
• Exhibits no significant cytotoxicity up to 1 μM in non-malignant cell lines, allowing for selective angiogenesis inhibition (Xie et al., 2018).
• Pharmacokinetics: Oral bioavailability 28–58% (rat), 41–77% (dog); plasma protein binding 93–97%; terminal half-life 5.1 ± 1.6 h (rat), 22.8 ± 11.0 h (dog) (Xie et al., 2018).
• Metabolized mainly by cytochrome P450 (CYP3A) to hydroxylated and dealkylated products; low risk of drug-drug interactions (Xie et al., 2018).
• High median lethal dose (LD₅₀): 1735.9 mg/kg in 14-day oral rat studies; no significant liver, kidney, or genetic toxicity observed (Xie et al., 2018).

This article extends the protocol-focused discussion in "Anlotinib Hydrochloride (SKU C8688): Advancing Reliable Assays" by providing detailed pharmacokinetic and safety data, guiding advanced users in translational research design. For further benchmarking and mechanistic comparison, see "Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inhibitor", which this dossier updates with the latest quantitative endpoints and in vivo tolerability metrics.

Applications, Limits & Misconceptions

Anlotinib hydrochloride is validated for use in angiogenesis inhibition, endothelial cell migration assays, capillary tube formation assays, and cancer biology workflows requiring potent, selective RTK inhibition. It is supplied as a hydrochloride salt for research use only and should be stored at -20°C (APExBIO).

Common Pitfalls or Misconceptions

• Not a pan-cytotoxic agent: Anlotinib shows minimal cytotoxicity in non-malignant cell lines at ≤1 μM; it is unsuitable as a general anti-proliferative outside angiogenesis contexts (Xie et al., 2018).
• Not a substitute for monoclonal antibodies: While effective against RTKs, it does not replicate the immune-modulatory effects of anti-VEGF antibodies.
• Species differences: Pharmacokinetics and metabolism may vary between rodents, dogs, and humans; extrapolation to clinical settings requires caution.
• Not suitable for direct human administration: Supplied for research use only; safety in humans is not established in this context.
• Limited on direct tumor cell cytotoxicity: In vitro, micromolar concentrations are needed for direct tumor cell inhibition, while endothelial migration is blocked at nanomolar levels.

Workflow Integration & Parameters

Anlotinib hydrochloride is compatible with standard migration and tube formation assays using human vascular endothelial cells. Recommended working concentrations are in the 1–100 nM range for migration inhibition, with no significant cytotoxicity observed at ≤1 μM (Xie et al., 2018). For in vivo studies, oral dosing regimens provide sustained inhibition of tumor angiogenesis and growth in xenograft models, with broad tissue distribution and acceptable safety margins (Internal Reference).

The C8688 kit from APExBIO provides validated batch-to-batch consistency, supporting reliable, reproducible results in angiogenic and cancer research workflows. Storage at -20°C is recommended to maintain compound stability. For further protocol optimization and laboratory troubleshooting, see the scenario-driven Q&A in this guide, which this article expands with updated pharmacokinetic insights.

Conclusion & Outlook

Anlotinib hydrochloride represents a benchmark anti-angiogenic small molecule for preclinical cancer research, combining high selectivity, potency, and safety (Xie et al., 2018). Its validated performance in migration and tube formation assays, favorable pharmacokinetic properties, and low toxicity profile support its adoption as a reference RTK inhibitor in translational workflows. Ongoing research will further clarify its applications in complex tumor models and combinatorial strategies (Redefining Tumor Angiogenesis Inhibition). For ordering and technical data sheets, visit the APExBIO product page.