Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inhibitor for Anti-Angiogenic Research

Executive Summary: Anlotinib hydrochloride is a novel small-molecule inhibitor targeting VEGFR2, PDGFRβ, and FGFR1 with nanomolar potency (IC₅₀ values: 5.6 ± 1.2 nM, 8.7 ± 3.4 nM, and 11.7 ± 4.1 nM, respectively) (Lin et al., 2018). It exhibits superior anti-angiogenic activity compared to sunitinib, sorafenib, and nintedanib, suppressing both endothelial cell migration and capillary-like tube formation. Pharmacokinetic studies reveal high oral bioavailability (up to 77% in dogs) and strong plasma protein binding (93% in humans). Safety data indicate a high median lethal dose (LD₅₀ = 1735.9 mg/kg, 14-day oral study) with low systemic and organ toxicity. Anlotinib is supplied by APExBIO (SKU: C8688) for research use only and is recommended for preclinical tumor angiogenesis and cell signaling studies.

Biological Rationale

Angiogenesis, the formation of new blood vessels from pre-existing vasculature, is essential for tumor growth and metastasis (Lin et al., 2018). Tumor cells secrete pro-angiogenic factors, primarily VEGF, PDGF-BB, and FGF-2, which induce migration and tube formation in endothelial cells. VEGF binds with high affinity to VEGFR2, while FGF-2 and PDGF-BB primarily target FGFR1 and PDGFRβ, respectively (Lin et al., 2018). Activation of these receptors triggers downstream signaling pathways, including ERK, promoting proliferation, migration, and survival of endothelial cells. Inhibiting these kinases represents a validated strategy for restraining tumor angiogenesis and progression. Multi-targeted agents, such as Anlotinib hydrochloride, capitalize on this biology by simultaneously blocking several key angiogenic pathways.

Mechanism of Action of Anlotinib (hydrochloride)

Anlotinib hydrochloride is a next-generation, multi-target tyrosine kinase inhibitor (TKI) with nanomolar potency against VEGFR2 (IC₅₀: 5.6 ± 1.2 nM), PDGFRβ (IC₅₀: 8.7 ± 3.4 nM), and FGFR1 (IC₅₀: 11.7 ± 4.1 nM) measured in enzymatic assays (Table 1). Anlotinib inhibits ligand-induced phosphorylation of these receptors, suppressing downstream ERK signaling, which is critical for endothelial cell proliferation and migration. In vitro, Anlotinib blocks VEGF/PDGF-BB/FGF-2-stimulated migration and capillary tube formation in EA.hy 926 human endothelial cells in a dose-dependent manner. In vivo, it reduces microvessel density and vascular sprouting in rat aortic ring and chicken CAM assays. The compound demonstrates superior inhibition of pro-angiogenic processes compared to sunitinib, sorafenib, and nintedanib, key reference standards in the clinic (Lin et al., 2018). Anlotinib also shows effective tissue distribution, including accumulation in tumor, lung, liver, kidney, heart, and the ability to cross the blood-brain barrier.

Evidence & Benchmarks

• Anlotinib inhibits VEGFR2, PDGFRβ, and FGFR1 tyrosine kinase activities with IC₅₀ values of 5.6 ± 1.2 nM, 8.7 ± 3.4 nM, and 11.7 ± 4.1 nM, respectively (Lin et al., 2018 Table 1).
• Anlotinib suppresses VEGF/PDGF-BB/FGF-2-induced endothelial cell migration and tube formation in EA.hy 926 cells, measured by wound healing and tube formation assays (Fig. 2).
• In vivo, Anlotinib reduces microvessel density in rat aortic ring and CAM assays compared to vehicle and other TKIs (Fig. 3, 4).
• Anlotinib demonstrates higher anti-angiogenic potency than sunitinib, sorafenib, and nintedanib in matched in vitro and in vivo tests (Table 2).
• Oral bioavailability ranges from 28%–58% in rats and 41%–77% in dogs; plasma protein binding in humans is 93% (APExBIO product data).
• Median lethal dose (LD₅₀) in 14-day oral toxicity studies is 1735.9 mg/kg, with mild systemic toxicity and no significant organ/genetic toxicity (APExBIO).

This article extends the insights from "Anlotinib Hydrochloride: Optimizing Anti-Angiogenic Assay..." by providing updated quantitative benchmarks and mechanistic details. It clarifies and deepens the molecular context compared to "Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inh..." by detailing pharmacokinetics and safety profiles. For a translational outlook, this article expands upon "Translational Horizons in Tumor Angiogenesis..." with up-to-date research application scenarios and critical performance benchmarks.

Applications, Limits & Misconceptions

Anlotinib hydrochloride is well suited for cancer research where robust inhibition of tumor angiogenesis is required. It is routinely employed in cell-based assays (e.g., endothelial cell migration, capillary tube formation) and in vivo models of tumor angiogenesis. Its pharmacokinetics and multi-target profile allow for flexible experimental design. However, Anlotinib is for research use only and is not approved for diagnostic or therapeutic use in humans or animals (APExBIO).

Common Pitfalls or Misconceptions

• Anlotinib (hydrochloride) is not a selective inhibitor; it targets multiple receptor tyrosine kinases, which may complicate attribution of effects in pathway-specific studies.
• The compound is not suitable for clinical or diagnostic use; it is strictly for in vitro and preclinical research.
• Not all tumor models respond equally; efficacy may vary depending on angiogenic signaling dependence.
• High plasma protein binding may affect free drug concentration in certain in vitro systems.
• Storage at -20°C is required to maintain compound stability; repeated freeze-thaw cycles should be avoided.

Workflow Integration & Parameters

Anlotinib hydrochloride (SKU: C8688, APExBIO) is formulated for research applications requiring robust and reproducible angiogenesis inhibition. Standard workflows include:

• Cellular Assays: Use 0.1–100 nM concentration range for EA.hy 926 or HUVEC migration/tube formation assays, with endpoints at 24–48 h.
• Signal Pathway Studies: Analyze p-VEGFR2, p-PDGFRβ, p-FGFR1, and p-ERK levels by Western blot following ligand stimulation and compound treatment.
• In Vivo Models: Administer orally at 1–10 mg/kg/day in mouse or rat tumor angiogenesis models; confirm with microvessel density quantification.
• Pharmacokinetics: Collect plasma/tissue samples at 0.5, 1, 2, 4, 8, and 24 h post-administration; analyze for parent compound and metabolites.

For detailed anti-angiogenic workflow integration and advanced assay strategy, researchers may refer to "Translational Frontiers: Leveraging Anlotinib Hydrochloride...", which this article updates with the latest quantitative and mechanistic findings.

Conclusion & Outlook

Anlotinib hydrochloride is a validated, multi-target tyrosine kinase inhibitor with superior anti-angiogenic efficacy and favorable safety and pharmacokinetic profiles. It is a reliable choice for mechanistic and preclinical studies on tumor angiogenesis and tyrosine kinase signaling pathways. Offered by APExBIO as the C8688 research kit (Anlotinib (hydrochloride)), it is pivotal for researchers seeking robust, reproducible insights into angiogenesis inhibition. As new data emerge, Anlotinib hydrochloride is expected to remain a cornerstone reagent for translational cancer research and anti-angiogenic workflow optimization.