Regression of human lung tumor xenografts induced by water-soluble analogs of hexamethylmelamine.
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Biomedical subjects
Publications and source records attributed to S A Clarke.
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Hexamethylmelamine is known to be effective in humans in the treatment of certain malignant tumors, especially bronchial carcinoma. It is, however, quite inactive against a number of animal tumors, making difficult a study of its mechanism of action in experimental systems. In a reexamination of the effects of hexamethylmelamine, two tumors were found to be very sensitive, namely, a mouse plasma cell tumor (PC6) and a human bronchial carcinoma (P246) growing in immune deprived mice. Both tumors undergo a significant and almost complete regression, even when well established, and hence may serve as model systems for the study of the mechanism of action of hexamethylmelamine.
Human lung, ovarian, colonic, and renal carcinomas have been grown in mice artificially deprived of T-lymphocytes. All grew slowly and were shown to have a human karyotype even after several transplant generations. Their responses to chemotherapy were similar to the expected clinical response with the important exception of hexamethylmelamine which caused complete regression of two lung carcinomas (even when weighing up to 2.5 g at the start of treatment) and a renal carcinoma, while completely inhibiting the growth of an ovarian carcinoma and another lung carcinoma. Measurement of plasma carcinoembryonic antigen levels proved to be of value in assessing drug efficacy.