Vascular‐targeted photodynamic therapy with glucose‐conjugated chlorin e6 for dogs with spontaneously occurring tumours

BACKGROUND: Photodynamic therapy (PDT) using photosensitisers is a minimally invasive treatment for malignant tumours. However, ideal photosensitisers are not yet established. Recently, we developed a new photosensitiser, glucose‐conjugated chlorin e6 (G‐Ce6). OBJECTIVES: To evaluate the clinical efficacy of vascular‐targeted PDT (VTP), a type of PDT utilising a short drug‐light interval, using G‐Ce6 to treat spontaneously occurring tumours in dogs. METHODS: Five dogs with spontaneously occurring tumours (malignant melanoma: three; haemangiopericytoma: two; and squamous cell carcinoma: one) were subjected to VTP. These dogs were intravenously injected with G‐Ce6 at doses of 1–3 mg/kg 5 min before laser irradiation. Tumours were superficially or interstitially irradiated using a 677‐nm diode laser. RESULTS: Repeated VTP decreased tumour size, yielding complete remission in three dogs. Complications such as oedema surrounding normal tissues and fistulae were observed, and the oedema was self‐limiting. The fistula was cured by debriding the necrotic tissues formed after VTP. CONCLUSIONS: Our findings demonstrate that VTP using G‐Ce6 had antitumour effects in dogs with spontaneously occurring tumours.