Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inhibitor for Tumor Angiogenesis Inhibition

Executive Summary: Anlotinib hydrochloride (CAS 1058157-76-8) is a novel, orally bioavailable small-molecule inhibitor targeting VEGFR2, PDGFRβ, and FGFR1 with nanomolar potency (IC₅₀ ≤ 12 nM) under defined in vitro assay conditions (Lin et al. 2018). It exhibits superior inhibition of endothelial cell migration and angiogenic tube formation compared to sunitinib, sorafenib, and nintedanib in matched cell-based assays. The compound’s pharmacokinetic profile features high plasma protein binding (93% in humans) and extensive tissue distribution, supporting its use in diverse animal and in vitro models. Safety data indicate a high median lethal dose (LD₅₀ 1735.9 mg/kg, 14-day oral rat), with no significant organ or genetic toxicity observed in preclinical studies. APExBIO provides Anlotinib (hydrochloride) (SKU C8688) for research applications, enabling reproducible, data-driven studies in tumor angiogenesis and tyrosine kinase pathway inhibition (product page).

Biological Rationale

Angiogenesis is essential for tumor progression, as neovascularization supplies nutrients and oxygen to proliferating cancer cells (Lin et al. 2018). The process is regulated by multiple pro-angiogenic factors, predominantly vascular endothelial growth factor (VEGF), platelet-derived growth factor-BB (PDGF-BB), and fibroblast growth factor 2 (FGF-2). VEGF binds to VEGFR2, triggering endothelial cell proliferation and migration. PDGF-BB and FGF-2 signal through PDGFRβ and FGFR1, respectively, activating downstream pathways including the ERK signaling cascade. Inhibiting these pathways is a validated strategy for restricting tumor growth and metastasis (Lin et al. 2018).

Mechanism of Action of Anlotinib (hydrochloride)

Anlotinib hydrochloride is a multi-target tyrosine kinase inhibitor (TKI). It exerts its anti-angiogenic effects by direct inhibition of VEGFR2 (IC₅₀: 5.6 ± 1.2 nM), PDGFRβ (IC₅₀: 8.7 ± 3.4 nM), and FGFR1 (IC₅₀: 11.7 ± 4.1 nM), as determined in cell-free kinase assays at 25°C, pH 7.4 (Lin et al. 2018). This inhibition blocks phosphorylation and downstream activation of the ERK signaling pathway, reducing endothelial cell migration and capillary-like tube formation in vitro. Comparative studies show Anlotinib suppresses VEGF/PDGF-BB/FGF-2-induced endothelial cell migration more effectively than sunitinib, sorafenib, or nintedanib at equivalent concentrations. The compound’s pharmacodynamic activity is confirmed in wound healing, transwell migration, and tube formation assays using EA.hy 926 human vascular endothelial cells. In vivo, Anlotinib reduces microvessel density in rat aortic ring and chicken chorioallantoic membrane (CAM) assays, supporting its anti-angiogenic mechanism (Lin et al. 2018).

Evidence & Benchmarks

• Anlotinib inhibits VEGFR2, PDGFRβ, and FGFR1 with IC₅₀ values of 5.6 ± 1.2 nM, 8.7 ± 3.4 nM, and 11.7 ± 4.1 nM, respectively, as measured in biochemical assays (DOI).
• In wound healing and transwell migration assays, Anlotinib reduces VEGF/PDGF-BB/FGF-2-induced endothelial cell migration in a concentration-dependent manner; inhibition is statistically significant at concentrations ≥10 nM in EA.hy 926 cells (DOI).
• Capillary tube formation assays reveal that Anlotinib suppresses endothelial tube formation more potently than sunitinib, sorafenib, or nintedanib at matched concentrations (10–100 nM) (DOI).
• Pharmacokinetic analysis in rats and dogs demonstrates good oral bioavailability (28–77%), high plasma protein binding (93% in humans), and wide tissue distribution including lung, liver, kidney, heart, and tumor tissue (DOI).
• Safety studies show a median lethal dose (LD₅₀) of 1735.9 mg/kg in rats (14-day oral administration), with no evidence of significant organ or genetic toxicity under these conditions (DOI).

For detailed methodology and troubleshooting for angiogenesis assays using Anlotinib (hydrochloride), see "Optimizing Angiogenesis Assays: Scenario-Based Insights", which provides scenario-driven assay optimization; this article extends those recommendations with updated comparative efficacy data and mechanistic clarity.

For a direct comparison of Anlotinib performance with other TKIs in cancer models, see "Anlotinib Hydrochloride: Transforming Tumor Angiogenesis"; the present article provides deeper pharmacokinetic and safety context for translational studies.

Applications, Limits & Misconceptions

Anlotinib (hydrochloride) is used in research to study anti-angiogenic mechanisms, inhibit endothelial cell migration, and modulate tyrosine kinase signaling pathways in cancer and vascular biology models. It is suitable for in vitro cellular assays (e.g., wound healing, tube formation, transwell migration) and in vivo angiogenesis models in rodents and avian systems. The compound's high specificity and potency enable its use in studies requiring robust inhibition of VEGFR2, PDGFRβ, and FGFR1. APExBIO’s product is intended for research use only and should not be used for diagnostic or therapeutic purposes.

For practical guidance on overcoming laboratory variability and maximizing assay reproducibility with Anlotinib, refer to "Solving Lab Assay Challenges with Anlotinib (hydrochloride)"; the present article clarifies product-specific parameters and safety considerations not covered in previous guides.

Common Pitfalls or Misconceptions

• Not a pan-kinase inhibitor: Anlotinib exhibits selectivity for VEGFR2, PDGFRβ, and FGFR1, but limited activity against unrelated kinases; off-target effects should not be assumed (Lin et al. 2018).
• Not a clinical or diagnostic agent: The C8688 kit is provided for research purposes only; it is not approved for human or veterinary use.
• Performance is model-dependent: Efficacy may vary by cell line, species, and assay design; data extrapolation requires validation in each context.
• Concentration-response is non-linear at high doses: Above 100 nM, incremental efficacy may plateau or induce cytotoxicity in some cell models.
• Storage and handling impact potency: The compound must be stored at -20°C and protected from light to maintain activity.

Workflow Integration & Parameters

Anlotinib (hydrochloride) is typically dissolved in DMSO and diluted to working concentrations (5–100 nM) in cell culture medium. For anti-angiogenic assays, pre-incubate endothelial cells (e.g., EA.hy 926) with Anlotinib for 1–2 hours prior to stimulation with VEGF, PDGF-BB, or FGF-2. Migration and tube formation endpoints should be measured at 8–24 hours post-treatment, depending on assay format. For in vivo models, dosing regimens should be informed by pharmacokinetic and tissue distribution data. The product is stable when stored at -20°C in an airtight container. For detailed protocol optimization, consult the Anlotinib (hydrochloride) product page (APExBIO, SKU C8688).

Conclusion & Outlook

Anlotinib hydrochloride represents a validated, highly selective option for inhibiting tumor angiogenesis through VEGFR2, PDGFRβ, and FGFR1 blockade. Its superior efficacy relative to other clinically relevant TKIs is supported by robust in vitro and in vivo evidence. Researchers are encouraged to select this compound for mechanistic, pharmacological, and translational studies of angiogenesis and tyrosine kinase signaling. Ongoing research is expected to further clarify its applications in preclinical oncology and vascular biology models.