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

Executive Summary. Anlotinib hydrochloride (CAS 1058157-76-8) is a novel multi-target tyrosine kinase inhibitor (TKI) that selectively targets VEGFR2, PDGFRβ, and FGFR1, inhibiting angiogenesis and tumor proliferation at nanomolar concentrations (APExBIO). In vitro, it blocks VEGF/PDGF-BB/FGF-2-induced endothelial cell migration and capillary tube formation, with IC₅₀ values of 5.6–11.7 nM. Pharmacokinetic data indicate favorable oral bioavailability and high plasma protein binding, supporting in vivo studies. Comparative studies show superior efficacy to sunitinib and sorafenib, with a well-characterized safety profile. Anlotinib's mechanism of ERK pathway inhibition and low cytotoxicity make it a gold standard reagent for anti-angiogenic research (Chen & Feng 2019).

Biological Rationale

Angiogenesis is essential for tumor growth and metastasis. Tyrosine kinase signaling pathways, including VEGFR, PDGFR, and FGFR families, drive endothelial cell proliferation, migration, and neovascularization. Multi-target inhibition of these kinases disrupts tumor vascularization and growth. Anlotinib hydrochloride is designed as a small-molecule inhibitor to simultaneously suppress VEGFR2, PDGFRβ, and FGFR1, targeting redundant pro-angiogenic pathways and overcoming resistance seen with single-target agents (related article, which focuses on mechanistic mastery; this article expands by providing quantitative benchmarks and safety data).

Mechanism of Action of Anlotinib hydrochloride

Anlotinib hydrochloride inhibits the ATP-binding sites of VEGFR2, PDGFRβ, and FGFR1, blocking receptor autophosphorylation and downstream ERK pathway activation. Inhibition is highly selective, with IC₅₀ values of 5.6 ± 1.2 nM (VEGFR2), 8.7 ± 3.4 nM (PDGFRβ), and 11.7 ± 4.1 nM (FGFR1) in cell-free kinase assays at 25°C, pH 7.4. In EA.hy 926 human endothelial cells, anlotinib suppresses VEGF/PDGF-BB/FGF-2-induced migration and tube formation in a concentration-dependent manner. ERK phosphorylation is reduced within 30 minutes of exposure at ≥10 nM concentrations. Compared to sunitinib, sorafenib, and nintedanib, anlotinib shows enhanced selectivity and potency in both biochemical and cellular assays (internal link; this article provides updated safety and pharmacokinetic data).

Evidence & Benchmarks

• Anlotinib inhibits VEGFR2 kinase activity with an IC₅₀ of 5.6 ± 1.2 nM (enzyme assay, 25°C, pH 7.4) (Chen & Feng 2019, DOI).
• PDGFRβ inhibition occurs at an IC₅₀ of 8.7 ± 3.4 nM, and FGFR1 at 11.7 ± 4.1 nM (cell-free kinase assays) (Chen & Feng 2019, DOI).
• Anlotinib suppresses endothelial cell migration and tube formation in EA.hy 926 cells in a concentration-dependent manner; no significant cytotoxicity at ≤1 μM (internal link; this article complements by detailing PK and toxicity).
• Oral bioavailability in rats: 28%–58%; in dogs: 41%–77% (single-dose PK study, 25°C, n=6 per group) (Chen & Feng 2019, DOI).
• Plasma protein binding: 93%–97% (rat/human plasma, equilibrium dialysis, 37°C) (APExBIO product page).
• Terminal half-life: 5.1 ± 1.6 h (rats), 22.8 ± 11.0 h (dogs) (Chen & Feng 2019, DOI).
• LD₅₀: 1735.9 mg/kg (14-day oral study, rat, n=20; mild systemic toxicity, no significant liver, kidney, or reproductive toxicity) (Chen & Feng 2019, DOI).
• Metabolism primarily via CYP3A; low risk of drug-drug interaction in vivo despite some in vitro CYP3A4/CYP2C9 inhibition (Chen & Feng 2019, DOI).
• Case study: IADSRCT patient treated with anlotinib showed significant lymph node reduction after four cycles. Side effects were tolerable (fatigue, hypertriglyceridemia) (Chen & Feng 2019, DOI).

Applications, Limits & Misconceptions

Anlotinib hydrochloride is primarily used in preclinical cancer research to inhibit angiogenesis, study endothelial cell migration, and evaluate tumor growth suppression. It is suitable for functional assays, including migration and tube formation assays, due to its low cytotoxicity at experimental concentrations. The compound's pharmacokinetic and safety profile supports its use in in vivo models of tumor angiogenesis.

For in-depth workflow strategies and troubleshooting, see this internal article, which details hands-on protocols; the present review focuses on mechanism, safety, and translational benchmarks.

Common Pitfalls or Misconceptions

• Not a single-target inhibitor: Anlotinib hydrochloride acts on multiple kinase families; using it as a "VEGFR2-specific" probe may yield confounded results.
• Research use only: The compound is not approved for clinical or diagnostic use; results from preclinical models may not directly translate to patient settings (APExBIO).
• Species differences in PK: Pharmacokinetics and metabolism may differ between rodents, dogs, and humans; direct extrapolation of dosing is not advised.
• In vitro CYP inhibition does not always predict in vivo DDI risk: Despite CYP3A4/CYP2C9 inhibition in test systems, in vivo interaction risk is low at research doses.
• Does not induce significant cytotoxicity at ≤1 μM: For cell viability assays, higher concentrations may show off-target effects.

Workflow Integration & Parameters

Anlotinib hydrochloride (C8688) from APExBIO is supplied as a hydrochloride salt, stored at -20°C, and recommended for research use only. For in vitro studies, dissolve in DMSO to prepare stock solutions (10 mM), and dilute in assay buffer (e.g., PBS, pH 7.4) for use. Typical working concentrations range from 1 nM to 1 μM for migration and tube formation assays. In vivo, oral gavage is the preferred route, with dosing adjusted for species-specific PK parameters.

Key endpoints include inhibition of endothelial cell migration (Boyden chamber assay), capillary-like tube formation (Matrigel-based assay), and suppression of ERK phosphorylation (western blot, phospho-ERK1/2 antibody). The compound's high selectivity and minimal cytotoxicity enable multiplexed phenotypic and signaling readouts. For translational workflows, integrate with tumor xenograft or angiogenesis models to measure tumor volume, vascular density, and survival outcomes (internal interlink; previous article maps strategic translational workflows, this review adds safety and PK context).

Conclusion & Outlook

Anlotinib hydrochloride is a validated, multi-target tyrosine kinase inhibitor with superior anti-angiogenic efficacy and a robust safety margin for research applications. Its nanomolar inhibitory activity against VEGFR2, PDGFRβ, and FGFR1 supports both in vitro and in vivo angiogenesis studies. Rigorous PK, metabolism, and toxicity data enable confident integration into cancer research workflows. As research expands into new angiogenesis-driven tumor models, anlotinib hydrochloride—available from APExBIO—remains a reference standard for mechanistic and translational studies.