The present invention relates to methods for treating cancer by administering a therapeutically effective amount of compound of formula (I), such as selective NPY5R antagonist MK-0557 (trans-N-[1-(2-fluorophenyl)-3-pyrazolyl]-3-oxospiro[6-azaisobenzofuran-1(3H), 1′-cyclohexane]-4′-carboxamide), or a pharmaceutically acceptable salt thereof, to a subject in need thereof The methods can further comprise administering a chemotherapeutic agent to the subject in need thereof.