Hyperthermic photodynamic therapy combined with topical administration of OK-432 in the mouse carcinoma

This study investigated the combined effect of photodynamic therapy (PDT) using high power laser irradiation (HPL), which generates both a hyperthermic and a photodynamic effect, and OK-432 on NR-S1 mouse squamous cell carcinoma. The photosensitizer (haematoporphyrin oligomers 20 mg/kg BW) was injected to the mice intraperitoneally 48 h before laser irradiation. OK-432 was injected into the tumour 3 h prior to laser irradiation. The experimental protocols consisted of HPL-PDT with or without OK-432, low power laser PDT with or without OK-432, HPL alone and OK-432 alone, and a control group. The tumour necrotic area was determined, and tumour sizes were measured 3, 7 and 10 days after each protocol. The anti-tumour effect of HPL-PDT was enhanced by preadministration with OK-432. Treatment with OK-432 alone or hyperthermic HPL irradiation presented little anti-tumour effect. HPL-PDT in combination with OK-432 topically administered 3 h before photo-irradiation is considered to be a promising therapeutic modality.