Anticancer activity of bisphosphonic acids in methylnitrosourea-induced mammary carcinoma of the rat--benefit of combining bisphosphonates with cytostatic agents.

This study primarily describes the cytostatic activity of a bisphosphonate and of an alkylating agent linked bisphosphonate toward mammary carcinomas in vivo. Bisphosphonates had been shown to be therapeutically active in bone metastases. There is no animal tumor model available in which both primary mammary carcinomas and bone metastases can be studied simultaneously. Therefore, the Walker carcinosarcoma model, which was used as a model for bone metastasis in earlier studies, was combined with the M-methyl-N-nitrosourea (MNU) induced mammary carcinoma as a model for the primary tumor. Four-, or six-week treatment of MNU-induced mammary carcinomas in Sprague-Dawley rats with the new aromatic bisphosphonate 4[4-[bis(2-chloroethyl)-amino]-phenyl]-1-hydroxybutane-1, 1-bisphosphonate (BAD) showed higher antitumor activity than treatment with melphalan or with 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) alone. BAD is the APD moiety covalently bound to a molecule derived from melphalan. A combination therapy with 11.75 mg/kg/day APD and 0.6 mg/kg/day melphalan showed the best therapeutic efficacy in this tumor model. In comparison to monotherapy with BAD, APD, or melphalan, a significantly higher rate of complete remissions was achieved. APD, itself, was not genotoxic in 3 employed short term assays. Since bisphosphonates had been shown to be therapeutically active in bone metastases, the antitumor potency of these compounds against experimental primary mammary carcinomas, coupled with the non-genotoxicity of APD and the inhibition of osteolytic bone metastases, might be an important advancement for adjuvant chemotherapy of human mammary carcinomas.

Synthesis, toxicity, and therapeutic efficacy of 4-amino-N-(2'-aminophenyl)-benzamide: a new compound preferentially active in slowly growing tumors.

The present paper describes 4-amino-N-(2'-aminophenyl)benzamide (GOE1734) with regard to synthesis; toxicity in mice, rats, and dogs; and differential therapeutic efficacy in slowly and rapidly proliferating rat tumors. GOE1734, an analog of a group of compounds known for other than antitumor effects with relatively simple N-acyl-O-phenylenediamine structure, is characterized by a low bacterial mutagenic potential after in vitro metabolic activation and DNA-DNA crosslinking activity after in vivo treatment. Maximum tolerated doses in rats and dogs amount to 4 and 1 mg/kg, respectively. High growth-inhibiting efficacy was obtained in intratibially implanted osteosarcoma, in methylnitrosourea-induced primary mammary carcinoma, and in acetoxymethyl-methylnitrosamine-induced colorectal adenocarcinoma. GOE1734 proved to be ineffective in transplanted Yoshida sarcoma and Walker 256 carcinosarcoma when single or multiple doses were administered at dose levels that were moderately toxic or not toxic. Some antitumor effects were observed in L5222 leukemia after ip transplantation, but no effect could be observed after ic implantation or in vitro incubation and subsequent retransplantation of these cells. Since the latter three rat tumors are characterized by relatively short tumor volume doubling times (0.5-2 days), whereas the first three grow slower (tumor volume doubling time, 11-19 days), the remarkable differential antitumor activity of GOE1734 in fast and slowly growing malignancies is striking.