Quantitative biochemical differences between tumor and host as a basis for cancer chemotherapy. V. Niacin and 6-aminonicotinamide.

Abstract

Summary 6-Aminonicotinamide (6-AN), a potent niacin antagonist, was observed to exert strong antitumor activity against the mammary Adenocarcinoma 755 grown in C57BL mice. This effect was completely reversed by the concomitant administration of nicotinamide. Tumor regression occurred with levels of the drug (3.0–4.0 mg/kg) which caused marked weight loss (approximately 20 per cent). With lower doses, a carcinostatic effect was noted with less marked weight loss. The combination of 8-azaguanine with this lower dose of 6-AN resulted in tumor regression without appreciable host weight loss. The addition of testosterone to this double combination further reduced weight loss without changing the degree of tumor regression. Differential biochemical effects with two niacin antagonists, 6-AN and 2-ethylamino-1,3,4-thiadiazole (TD) have been noted. TD increased DPN in various tissues, whereas 6-AN had little or no effect. The antitumor activity of 6-AN suggests that a new class of compounds bears study as potential cancerocidal agents.