Hexamethylmelamine-induced regression of human lung tumors growing in immune deprived mice.

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.