Everolimus (RAD001)

Clin Cancer Res,2009 Mar 1;15(5):1612-22.

mTOR inhibitor RAD001 (everolimus) has antiangiogenic/vascular properties distinct from a VEGFR tyrosine kinase inhibitor.[Pubmed: 19223496]

Comparison of the antiangiogenic/vascular properties of the oral mammalian target of rapamycin (mTOR) inhibitor RAD001 (everolimus) and the vascular endothelial growth factor receptor (VEGFR) inhibitor vatalanib (PTK/ZK).
METHODS AND RESULTS:
Antiproliferative activity against various tumor histotypes and downstream effects on the mTOR pathway were measured in vitro. In vivo, antitumor activity, plasma, and tumor RAD001 levels were measured. Activity in several different angiogenic/vascular assays in vitro and in vivo was assessed and compared with PTK/ZK. RAD001 inhibited proliferation in vitro (IC50 values<1 nmol/L to >1 micromol/L), and in sensitive and insensitive tumor cells, pS6 kinase and 4E-BP1 were inhibited. Activity in vitro did not correlate with activity in vivo and significant responses were seen in tumors with IC50 values>10-fold higher than tumor RAD001 concentrations. In vitro, RAD001 inhibited the proliferation of VEGF-stimulated and fibroblast growth factor-stimulated human endothelial cells but not dermal fibroblasts and impaired VEGF release from both sensitive and insensitive tumor cells but did not inhibit migration of human endothelial cells. In vivo, in tumor models derived from either sensitive or insensitive cells, RAD001 reduced Tie-2 levels, the amount of mature and immature vessels, total plasma, and tumor VEGF. RAD001 did not affect blood vessel leakiness in normal vasculature acutely exposed to VEGF nor did it affect tumor vascular permeability (Ktrans) as measured by dynamic contrast-enhanced magnetic resonance imaging. However, the pan-VEGFR inhibitor PTK/ZK inhibited endothelial cell migration and vascular permeability but had less effect on mature vessels compared with RAD001.
CONCLUSIONS:
VEGFR and mTOR inhibitors show similar but also distinct effects on tumor vascular biology, which has implications for their clinical activity alone or in combination.

Tumour Biol,2012 Oct;33(5):1349-62.

Antitumor effect of the mTOR inhibitor everolimus in combination with trastuzumab on human breast cancer stem cells in vitro and in vivo.[Pubmed: 22492237]

Cell lines:BT474 cell line and the primary breast cancer cells
Concentrations: 0.001-10 μM
Incubation Time: 24 hours
Method:
The 3-(4-5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction assay (MTT assay) is used to compare the effects of Everolimus or trastuzumab on total breast cancer cells and breast CSCs. The total cells and the stem cells from the BT474 cell line and the primary breast cancer cells are respectively seeded into 96-well plates with different concentrations of the drugs, with five wells for each concentration, and the cells are cultured at 37 °C with 5 % CO2 in an incubator for 24 hours. The concentrations of Everolimus are 1 nM, 10 nM, 100 nM, 1 μM and 10 μM, and the concentrations of trastuzumab are 0.5 μg/mL, 1 μg/mL, 10 μg/mL, 50 μg/mL, and 100 μg/mL. The combinatorial inhibitory effect of Everolimus and Trastuzumab on the in vitro growth of breast CSCs is examined by MTT assay as well using 10 μg/mL trastuzumab in combination of increasing concentrations of everolimus (1 nM, 10 nM, 100 nM and 1 μM). After drug treatment for 24 hours, 20 μL MTT [5 mg/mL in phosphate buffered saline (PBS)] is added to each well, and the cells are incubated at 37 °C with 5 % CO2 and saturated humidity for 4 hours. Following the subsequent removal of the supernatant, 150 μL dimethyl sulfoxide (DMSO) is added to each well, and the cells are vortexed for 10 minutes. The light absorbance (OD value) is measured for each well using an ELISA reader. Each experiment is repeated in triplicate, and dose–response curves are plotted. The probit software of the statistical software package SPSS 17.0 for Windows is used to calculate the inhibitory concentration (IC50) of Everolimus.

Tumour Biol,2012 Oct;33(5):1349-62.

Antitumor effect of the mTOR inhibitor everolimus in combination with trastuzumab on human breast cancer stem cells in vitro and in vivo.[Pubmed: 22492237]

Animal Models: Cultured BT474 stem cells are injected beneath the left breast pad of BALB/c nude mice.
Dosages: ≤2 mg/kg
Administration: Administered via p.o.