A vascular-acting photosensitizer consisting of a water-soluble, palladium-substituted bacteriochlorophyll derivative with potential antineoplastic activity. Upon administration, paldeliporfin is activated locally when the tumor bed is exposed to low-power laser light; reactive oxygen species (ROS) are formed upon activation and ROS-mediated necrosis may occur at the site of interaction between the photosensitizer, light and oxygen. Vascular-targeted photodynamic therapy (VTP) with padeliporfin may allow tumor-site specific cytotoxicity while sparing adjacent normal tissues.