GLPG0187 is a compound that belongs to the class of organic compounds known as naphthyridines, and has been studied as a potential drug in the treatment of solid tumors. GLPG0187 is a broad spectrum integrin receptor antagonist that inhibits αvβ1 integrin. In vitro, this compound was found to diminish the size of the aldehyde dehydrogenase high subpopulation of prostate cancer cells dose-dependently. It also significantly reduced tumor cell migration and cell proliferation. In vivo, it reduced metastatic tumor growth, and inhibited the progression of bone metastases as well as the formation of new bone metastases. Phase I studies have been completed to study safety and drug tolerance of GLPG0187. The drug was well tolerated, but continuous infusion of GLPG0187 did not show signs of monotherapy efficacy.