ANTI-TUMOR AGENT

An object of the present invention is to provide an anti-tumor agent that exhibits a remarkably excellent anti-tumor effect. According to the present invention, there is provided an anti-tumor agent for curing cancer, the anti-tumor agent having a liposome which has an inner water phase and having an aqueous solution which is an outer water phase and disperses the liposome, in which the liposome encompasses topotecan or a salt thereof, a lipid constituting the liposome contains a lipid modified with polyethylene glycol, dihydrosphingomyelin, and cholesterol, the inner water phase contains an ammonium salt, and the topotecan or the salt thereof encompassed in the liposome is administered at a dose rate of 0.1 mg/m2 body surface area to 10 mg/m2 body surface area, in terms of topotecan per administration.