A model of localized osteolysis induced by the MBT-2 tumor in mice and its responsiveness to etidronate disodium.

A new experimental method to test the effect of drugs on tumor-induced osteolysis using a bladder tumor in mice has been designed. The method consisted of inoculating MBT-2 tumor cells s.c. over the calvaria in mice, resulting in a local tumor causing fragmentation of the bone. This was accompanied by adjacent osteoplastic changes, which were evaluated by X-ray and histological examination. Etidronate disodium (EHDP), a diphosphonate derivative, at a dose of 3 mg/kg to 30 mg/kg s.c. protected the bone by decreasing the extent of osteolysis as judged by the same criteria. Therapy with EHDP prolonged the survival period. This inhibition was obtained with no apparent effect on the growth of the MBT-2 tumor.