The aim of this study was to investigate whether the newly synthesized bisphosphonic acid-linked N-Lost derivative BAD retains bone-seeking and cytostatic properties. The paper describes experiments on mutagenicity in vitro and on toxicity in vivo. BAD is characterized by very low mutagenic activity toward histidine auxotrophic Salmonella typhimurium strains. Cytotoxic effects were tested in rat osteosarcoma and in Walker carcinosarcoma 256B. The LD50 of i.v. injected BAD was 146 mg/kg. Acute toxicity is probably caused by calcium complexing of the bisphosphonate part of the molecule. Labeling experiments showed moderate accumulation in bone and osteosarcoma, as well as in lung metastases. BAD effected high tumor growth inhibition in osteosarcoma and Walker carcinosarcoma-bearing rats and marked prolongation of survival; histologic and radiographic examination revealed rapid calcification of osteosarcoma and lung metastases. BAD-pretreatment produced protective effects against osteolysis induced by intratibially implanted Walker carcinosarcoma ascites cells. The cytostatic efficacy of equitoxic doses of BAD in rat osteosarcoma is comparable to that of dacarbazine and in Walker carcinosarcoma to that of melphalan.

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