Anticancer agents which contain as the active ingredient heme oxygenase inhibitory metalloporphyrin derivatives which are conjugated with amphipathic or water-soluble polymers (in particular, Zn-protoporphyrin (ZnPP) conjugated with polyethylene glycol). Because of being conjugated to amphipathic or water-soluble polymers, such as polyethylene glycol, the active ingredient can be administered by intravenous injection and can exert a remarkable anticancer effect owing to tumor-selective delivery.
