Compositions and methods for treating subjects with disorders characterized by hyper-proliferating cells such as tumors and cancers are provided. The compositions comprise agents that are combinations of saposin C (or prosaposin-related polypeptides) and phospholips (or inner leaflet components). This anti-tumor agent is administered in the methods of the invention according to a dosing regimen. Administering an agent of the invention results in a positive therapeutic response in a subject with a tumor.