GLPG0187, a broad spectrum integrin receptor antagonist, inhibits αvβ1-integrin (IC50: 1.3 nM).

GLPG0187 is an effective inhibitor of osteoclastic bone resorption and angiogenesis. In a solid-phase assay, GLPG0187 shows selectivity for several RGD integrin receptors (IC50s: 1.3/3.7/2.0/1.4/1.2/7.7 nM, for αvβ1/3/5/6/8 and α5β1). GLPG0187 dose-dependently increases the E-cadherin/vimentin ratio. GLPG0187 dose-dependently reduces the size of the aldehyde dehydrogenase high subpopulation of prostate cancer cells. GLPG0187 causes cell rounding and clumping. GLPG0187 dose-dependently and markedly reduces in tumor cell migration. At all concentrations, GLPG0187 markedly reduces cell proliferation.

GLPG0187 obviously reduces their metastatic tumor growth by blocking αv-integrins. GLPG0187 markedly lows Bone tumor burden and markedly inhibits the number of bone metastases/mouse. The progression of bone metastases and the formation of new bone metastases during the treatment period is significantly inhibited by GLPG0187.

HSP90 competition isothermal calorimetry: Kd values for AT13387 binding to HSP90 are determined with a competition Isothermal Calorimetry (ITC) format. ITC experiments are performed on a Micro Cal VP-ITC at 25 °C in a buffer comprising 25 mM Tris, 100 mM NaCl, 1 mM MgCl2 and 1 mM Tris(2-carboxy- ethyl)phosphine at pH 7.4 in order to maintain the higher affinit

Tumour cell proliferation is determined using the MTS assay. PC3 cells are seeded at 10,000 cells/well in 96 well plates containing either GLPG0187 (0.5, 5, or 50 ng/mL), vehicle or media control, then cultured in 100 μL medium for 24 hr. Cell proliferation is analyzed using 20 μL MTS dye incubated for 3 hr at 37°C in the dark. Absorbance from each well (6/treatment) is quantified at 490 nm and the mean fluorescence calculated. The assay is repeated at 48, 72 and 96 hr, on three independent occasions.

GLPG0187 is prepared in 1:1 dimethyl sulfoxide in PBS.The effect of GLPG0187 on bone loss is evaluated in 3-month-old castrated male mice after 4 weeks of treatment with dosing starting immediately after castration (preventive protocol). Two different modes of administration are used: either subcutaneous twice daily with 10, 30, or 100 mg/kg of GLPG0187, either oral, twice daily with 30, 100, or 300 mg/kg of GLPG0187.