Combination therapy of radiation and Sizofiran (SPG) on the tumor growth and metastasis on squamous-cell carcinoma NR-S1 in syngeneic C3H/He mice.

The efficacy of Sizofiran(SPG), a highly purified beta-1,3-D-glucan from the culture broth of basidiomycetes Schizophyllum commune Fries, in combination with local irradiation was investigated using squamous-cell carcinoma NR-S1 and syngeneic hosts of C3H/He mice. NR-S1 tumor was implanted sc in the thigh of C3H/He mice. When tumor grew to 4 mm in diameter, the local irradiation of 55 Gy was delivered. SPG was injected im at a dose of 5 mg/kg. When SPG was administered after irradiation, remarkable inhibition of tumor growth was observed in comparison with the radiation alone group. Furthermore, the combination effect of radiation and active immunotherapy using mitomycin C-treated NR-S1 cells as vaccine was examined. When radiotherapy and active immunotherapy were combined with SPG, suppression of tumor growth was observed from an early stage in comparison with the group which was not administered SPG. SPG also inhibited the pulmonary metastasis of NR-S1 tumor after radiotherapy.