Photodynamic therapy with di-l-arginine protoporphyrinate on WiDr human colon adenocarcinoma xenografts in athymic nude mice

Exposure of WiDr tumours in mice to red light (λ = 632 nm, fluence 150 J/cm2, fluence rate 250 mW/cm2) 24 and 72 h after intravenous administration of 10 mg/kg of PP(Arg)2 caused extensive tumour necrosis. Epidermal damage and infiltration of inflammatory cells was seen 24 h after light exposure but not after 72 h.