The invention provides methods for treating various types of cancer/tumor by administering the combination of Dll4 antagonists, in particular, Dll4 antibodies and fragments thereof that specifically bind human Dll4, and chemotherapeutic agents. Such combination therapies exhibit synergistic effects compared to the treatment with either agent alone. Thus, the methods of the invention are particularly beneficial for cancer patients who have low tolerance to the side effects caused by high dosages required for the treatment by either agent alone, by being able to reduce effective dosages. Pharmaceutical compositions and kits containing Dll4 antagonists and chemotherapeutic agents are also provided.本發明提供治療多種型態之癌症/腫瘤之方法,其藉由投與Dll4拮抗劑與化學治療劑之組合物,特別是Dll4抗體及其專一性結合人類Dll4之片段。與單獨其中之一劑之治療相較,該合併療法顯示出協同效應,因此,本發明之方法藉由降低有效劑量而特別有利於對單獨一藥劑治療所需高劑量造成的副作用具低耐受性之癌症患者;亦提供含有Dll4拮抗劑與化學治療劑之醫藥組成物及套組。