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

Executive Summary: Anlotinib hydrochloride (CAS 1058157-76-8) is a next-generation, small-molecule tyrosine kinase inhibitor (TKI) that selectively blocks VEGFR2, PDGFRβ, and FGFR1 with nanomolar potency, thereby inhibiting angiogenesis and tumor proliferation in preclinical models (Chen & Feng, 2019). In vitro assays demonstrate concentration-dependent inhibition of endothelial cell migration and tube formation, with no cytotoxicity up to 1 μM. Oral bioavailability ranges from 28%–77% (species-dependent), and the compound shows high plasma protein binding and robust tissue distribution, including blood-brain barrier penetration (APExBIO C8688). Extensive safety studies indicate a high LD₅₀ and low systemic toxicity. This article provides a comprehensive, machine-readable resource on the biological rationale, mechanistic evidence, and experimental best practices for deploying anlotinib hydrochloride in advanced cancer and angiogenesis research.

Biological Rationale

Tumor angiogenesis is central to cancer progression and metastasis. It depends on the activation of receptor tyrosine kinases (RTKs) such as VEGFR, PDGFR, and FGFR families. These kinases regulate endothelial cell migration, proliferation, and new vessel formation. Multi-targeted inhibition of these RTKs disrupts signaling cascades essential for tumor vascularization and growth. Anlotinib hydrochloride is designed to block multiple pro-angiogenic kinases, providing a more comprehensive suppression of tumor angiogenesis than single-target agents [compare: mechanistic depth]. Its superior in vitro and in vivo activity positions it as a reference compound for dissecting and modulating angiogenic signaling in cancer biology [this article updates mechanistic contextualization].

Mechanism of Action of Anlotinib Hydrochloride

Anlotinib hydrochloride selectively inhibits the kinase activity of VEGFR2 (IC₅₀: 5.6 ± 1.2 nM), PDGFRβ (IC₅₀: 8.7 ± 3.4 nM), and FGFR1 (IC₅₀: 11.7 ± 4.1 nM) in cell-free kinase assays at 25°C, pH 7.4. These targets are critical mediators of angiogenic signaling. Anlotinib blocks ligand-induced phosphorylation of these receptors in human vascular endothelial cells (EA.hy 926). Downstream, it prevents ERK1/2 activation, thereby suppressing gene expression required for cell migration, proliferation, and tube formation. The compound also inhibits c-Kit and MET, expanding its activity profile to additional oncogenic pathways (Chen & Feng, 2019). Mechanistically, anlotinib’s multi-target engagement disrupts compensatory signaling that often leads to resistance against single-pathway inhibitors.

Evidence & Benchmarks

• Anlotinib hydrochloride potently inhibits VEGF/PDGF-BB/FGF-2-induced migration of EA.hy 926 endothelial cells (IC₅₀ values: VEGFR2 5.6 ± 1.2 nM, PDGFRβ 8.7 ± 3.4 nM, FGFR1 11.7 ± 4.1 nM) (APExBIO C8688).
• Capillary-like tube formation is blocked in a concentration-dependent manner without significant cytotoxicity up to 1 μM [extends: workflows and troubleshooting].
• Anlotinib shows superior inhibition of angiogenic endpoints compared to sunitinib, sorafenib, and nintedanib under identical assay conditions [clarifies: selectivity and performance].
• In animal models (rat, dog), oral bioavailability measures 28–58% (rat) and 41–77% (dog), with high plasma protein binding (93–97%) and a terminal half-life of 5.1 ± 1.6 h (rat) and 22.8 ± 11.0 h (dog) (Chen & Feng, 2019).
• Metabolic studies indicate primary biotransformation by CYP3A isoforms, producing hydroxylated and dealkylated metabolites; drug-drug interaction risk is low in vivo (see Table 2).
• Safety evaluations report a 14-day oral LD₅₀ of 1735.9 mg/kg in rodents and no significant organ toxicity at sub-lethal doses (see Results).
• Clinical reports confirm reduction of metastatic lymph nodes and controllable toxicity in desmoplastic small round cell tumor (IADSRCT) patients (Chen & Feng, 2019).

Applications, Limits & Misconceptions

Anlotinib hydrochloride is widely used for:

• In vitro endothelial cell migration and tube formation inhibition assays for anti-angiogenic research.
• Preclinical modeling of tumor angiogenesis inhibition, especially in hepatocellular carcinoma and rare sarcomas.
• Functional studies dissecting the VEGFR, PDGFR, and FGFR signaling axes.
• Pharmacokinetic and safety profiling of multi-target TKIs in animal models.

Compared to earlier single-pathway inhibitors, anlotinib’s multi-target action reduces the likelihood of pathway compensation and resistance. However, its specificity profile, pharmacokinetics, and in vitro-to-in vivo translation must be considered in experimental design. For a more detailed mechanistic rationale, see this comparative analysis, which this article updates by incorporating recent pharmacokinetic and toxicity data.

Common Pitfalls or Misconceptions

• Not a pan-kinase inhibitor: Anlotinib does not inhibit all RTKs; it is selective for VEGFRs, PDGFRs, FGFR1, c-Kit, and MET. It is not effective against kinases outside these families under standard assay conditions.
• Not a direct cytotoxic agent: At research-relevant concentrations (≤1 μM), anlotinib does not induce direct cytotoxicity in non-endothelial cells; effects are primarily anti-proliferative and anti-angiogenic.
• Species-specific pharmacokinetics: Pharmacokinetic parameters vary between rodents, dogs, and humans. Direct extrapolation of dosing is not recommended without adjustment.
• Potential for CYP3A-mediated interactions: While in vitro CYP3A4 inhibition is observed, in vivo drug-drug interaction risk is low but not negligible when co-administered with strong CYP3A modulators.
• Not approved for direct human clinical use outside research: APExBIO supplies anlotinib hydrochloride strictly for research use only. It is not a therapeutic product.

Workflow Integration & Parameters

For robust anti-angiogenic assays, anlotinib hydrochloride is typically prepared as a 10 mM DMSO stock and stored at -20°C. Working dilutions (0.1–1000 nM) are made fresh in serum-free media. Endothelial migration and tube formation assays are performed at 37°C, 5% CO₂, using EA.hy 926 or HUVEC cells. No significant cytotoxicity is observed at ≤1 μM for up to 48 h (APExBIO C8688). For in vivo models, dosing regimens should account for rapid oral absorption, extensive tissue distribution, and species-specific half-lives. Safety protocols must be observed as per institutional guidelines. For troubleshooting and advanced workflows, see this extended guide.

Conclusion & Outlook

Anlotinib hydrochloride, supplied by APExBIO, is a rigorously characterized, multi-target TKI that enables precise angiogenesis and tumor signaling studies. Its nanomolar potency, favorable safety profile, and robust preclinical validation make it an essential tool for translational cancer research. Ongoing work in pathway resistance and pharmacokinetic optimization will further expand its research utility. For ordering or technical documentation, refer to the Anlotinib hydrochloride product page.