Anlotinib (AL3818) dihydrochloride

Anlotinib (AL3818) is a highly potent and selective VEGFR2 inhibitor with IC50 less than 1 nM. It has broad-spectrum antitumor potential in clinical trials. Please use saline solution rather than PBS for dilutions. PBS may cause precipitation.

Anlotinib occupies the ATP-binding pocket of VEGFR2 tyrosine kinase and shows high selectivity and inhibitory potency (IC 50 <1 nmol/L) for VEGFR2 relative to other tyrosine kinases. Anlotinib inhibits VEGFR2 and VEGFR3 with IC50 values of 0.2 and 0.7 nmol/L, respectively. The inhibitory potency of anlotinib against VEGFR1 is lower, with an IC50 value of 26.9 nmol/L. The IC50 values of anlotinib for inhibition of the PDGFR-related kinases c-Kit and PDGFRβ are 14.8 and 115.0 nmol/L, respectively. Anlotinib has little effect on the activity of other kinases, including c-Met, c-Src, EGFR and HER2, even at a concentration of 2000 nmol/L. Anlotinib inhibits VEGF-induced signaling and cell proliferation in HUVEC with picomolar IC50 values. However, micromolar concentrations of anlotinib are required to inhibit tumor cell proliferation directly in vitro. Anlotinib significantly inhibits HUVEC migration and tube formation; it also inhibits microvessel growth from explants of rat aorta in vitro[1].

Anlotinib decreases vascular density in tumor tissue in vivo. Compared with the well-known tyrosine kinase inhibitor sunitinib, once-daily oral dose of anlotinib shows broader and stronger in vivo antitumor efficacy and, in some models, causes tumor regression in nude mice. It is well-tolerated in mice. Anlotinib is efficacious at doses (1.5‐6 mg/kg daily) that are significantly lower than effective doses of other TKI, which require doses of 20‐100 mg/kg to achieve significant inhibition of tumor growth in mice[1]. In vivo, anlotinib has showed broad activity against human tumor xenograft models of the colon (SW-620), ovarian (SK-OV-3), liver (SMMC-7721), renal (Caki-1), glioma (U87MG), and non-small cell lung (Calu-3) during dosing period. In Sprague-Dawley rats and beagle dogs, anlotinib is rapidly absorbed from the gastrointestinal tracks after oral administration. The oral bioavailability is 23-45 % in rats and 47-74 % in dogs. Anlotinib exhibits large volume of distribution in both species. In rats, primary tissues, such as the lung, kidneys, liver, and heart, exhibit significant higher exposure levels to anlotinib compared with that in plasma. The exposure level in the brain is comparable with the corresponding plasma level. In tumor-bearing mice, anlotinib concentrates 2.4-2.6 times in tumor tissue than in plasma. In human, anlotinib exhibits a quite long t1/2 (96 ± 17 h), which appeared to be dose-independent[2]. The terminal half-life of anlotinib in dogs (22.8±11.0 h) is longer than that in rats (5.1±1.6 h). This difference appeares to be mainly associated with an interspecies difference in total plasma clearance (rats, 5.35±1.31 L/h/kg; dogs, 0.40±0.06 L/h/kg). In human plasma, anlotinib is predominantly bound to albumin and lipoproteins, rather than to α1-acid glycoprotein or γ-globulins[3].

[1] Xie C, et al. Cancer Sci. 2018, 109(4):1207-1219. [2] Sun Y, et al. J Hematol Oncol. 2016, 9(1):105. [3] Zhong CC, et al. Acta Pharmacol Sin. 2018, 39(6):1048-1063.