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

Executive Summary: Anlotinib hydrochloride is a novel, small-molecule multi-target tyrosine kinase inhibitor that potently and selectively 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, under standard in vitro assay conditions (Lin et al., 2018). It exhibits superior anti-angiogenic activity compared to sunitinib, sorafenib, and nintedanib, particularly in endothelial cell migration and tube formation assays. Pharmacokinetic studies show rapid oral absorption, high plasma protein binding (93%), and tissue accumulation in lung, liver, kidney, heart, and tumors. Safety assessments reveal a high median lethal dose (LD₅₀) of 1735.9 mg/kg in 14-day oral rat studies, with minimal toxicity. Anlotinib (hydrochloride), available from APExBIO (SKU C8688), is intended for research use in cancer and angiogenesis studies.

Biological Rationale

Angiogenesis, the formation of new blood vessels from existing vasculature, is essential for tumor growth and metastasis. Tumor cells secrete pro-angiogenic cytokines, notably vascular endothelial growth factor (VEGF), platelet-derived growth factor-BB (PDGF-BB), and fibroblast growth factor 2 (FGF-2), to recruit vascular endothelial cells and stimulate neovascularization (Lin et al., 2018). VEGF primarily signals through VEGFR2 on endothelial cells, while FGF-2 and PDGF-BB act via FGFR1 and PDGFRβ, respectively. The activation of these tyrosine kinase receptors triggers downstream pathways, including ERK signaling, that promote endothelial proliferation, migration, and tube formation. Inhibiting these signaling axes is a validated strategy for suppressing tumor angiogenesis and limiting cancer progression (Lin et al., 2018).

Mechanism of Action of Anlotinib (hydrochloride)

Anlotinib hydrochloride functions as a multi-target tyrosine kinase inhibitor, primarily targeting VEGFR2 (IC₅₀: 5.6 ± 1.2 nM), PDGFRβ (IC₅₀: 8.7 ± 3.4 nM), and FGFR1 (IC₅₀: 11.7 ± 4.1 nM) under defined cell-free enzymatic assay conditions. It competitively inhibits ATP binding at the kinase domains of these receptors, thereby blocking their autophosphorylation and subsequent activation of downstream ERK signaling. This results in potent, concentration-dependent inhibition of VEGF-, PDGF-BB-, and FGF-2-induced endothelial cell migration and capillary-like tube formation in EA.hy 926 cell assays. Compared to other clinical TKIs—such as sunitinib, sorafenib, and nintedanib—anlotinib demonstrates greater inhibition of angiogenic processes at equivalent concentrations (Lin et al., 2018).

Evidence & Benchmarks

• Anlotinib inhibits VEGF/PDGF-BB/FGF-2-induced endothelial cell migration in EA.hy 926 cells, with statistically significant reductions at nanomolar concentrations (Lin et al., 2018, Fig. 2).
• Capillary tube formation assays show dose-dependent inhibition, with >80% reduction at concentrations ≥10 nM compared to control (Lin et al., 2018, Table 1).
• Superior inhibitory effect on microvessel density and blood vessel sprouting in rat aortic ring and chicken chorioallantoic membrane (CAM) assays, relative to sunitinib, sorafenib, and nintedanib (Lin et al., 2018, Figs. 3–4).
• Pharmacokinetics: oral bioavailability 28–58% in rats, 41–77% in dogs, high plasma protein binding (93% in humans), and wide tissue distribution, including the ability to cross the blood-brain barrier (APExBIO C8688 Data Sheet).
• Safety: Median lethal dose (LD₅₀) of 1735.9 mg/kg in 14-day oral administration studies, with no significant organ/genetic toxicity observed (APExBIO C8688 Data Sheet).

Applications, Limits & Misconceptions

Anlotinib hydrochloride is widely used in research applications focused on tumor angiogenesis inhibition, endothelial cell migration assays, capillary tube formation, and tyrosine kinase signaling pathway analysis. Its superior selectivity and potency make it a reference compound for comparative studies of anti-angiogenic small molecules (see Anlotinib Hydrochloride: Advanced Workflows for Tumor Angiogenesis—this article extends the discussion by providing quantitative IC₅₀ data and safety parameters). The compound is not recommended for diagnostic or therapeutic use in humans or animals.

Common Pitfalls or Misconceptions

• Not a clinical drug formulation: Anlotinib (hydrochloride) from APExBIO is for research use only; it is not intended for human or veterinary therapy (APExBIO).
• Species- and cell line-specific effects: IC₅₀ values and inhibitory profiles may differ between human cell lines, animal models, and in vivo systems (Lin et al., 2018).
• Solubility considerations: Optimal performance requires dissolution in DMSO or compatible solvent; aqueous solubility is limited (APExBIO).
• Not a pan-kinase inhibitor: Anlotinib is selective for VEGFR2, PDGFRβ, and FGFR1, with limited activity on unrelated kinase families (Lin et al., 2018).
• Does not reverse established vasculature: Primarily inhibits neovascularization rather than regressing mature vessels (Lin et al., 2018).

Workflow Integration & Parameters

For robust research outcomes, anlotinib hydrochloride (SKU C8688) is typically applied in cellular assays involving human vascular endothelial cells (EA.hy 926) at concentrations ranging from 1–100 nM in DMSO-containing buffer. For capillary-like tube formation assays, pre-treatment for 30–60 minutes at 37°C is standard. Controls include vehicle (DMSO) and reference TKIs (e.g., sunitinib, sorafenib, nintedanib). Storage at -20°C is recommended for stability. To explore assay troubleshooting, see Anlotinib Hydrochloride: Multi-Target Tyrosine Kinase Inhibitor; this article updates the prior workflow by detailing quality control and safety data. For scenario-driven protocols and endpoint selection, Harnessing Anlotinib (hydrochloride) for Reliable Tumor Angiogenesis Assays provides practical guidance—this article clarifies comparative benchmarks against clinical agents.

Conclusion & Outlook

Anlotinib hydrochloride is a benchmark anti-angiogenic small molecule for cancer research, with proven superior multi-target tyrosine kinase inhibition and robust safety/pharmacokinetic profiles. The product, provided by APExBIO (SKU C8688), enables reproducible, high-selectivity inhibition of VEGFR2, PDGFRβ, and FGFR1 signaling in validated in vitro and in vivo models. It stands out for its quantitative performance in endothelial cell migration and tube formation assays, with transparent documentation of safety and bioavailability. Future research will further refine its applications in tumor microenvironment modeling and combinatorial therapy screening. For detailed specifications and ordering, refer to the Anlotinib (hydrochloride) product page.