Figure 2. Mechanisms of PDT of an experimental tumour.

PS is injected IV followed by a time delay [drug-light interval (DLI)]. Then activating red light is delivered to the tumour cause the production of ROS. The ROS can cause direct tumour cell killing by necrosis or apoptosis, shut-down the tumour blood supply and activate neutrophils (PMN) and dendritic cells (DC) that stimulates an anti-tumour immune response.