3,4-Dihydroxybenzylamine: a dopamine analog with enhanced antitumor activity against B16 melanoma.

3,4-Dihydroxybenzylamine (DHBA), a dopamine analog, was much less toxic than dopamine when tested against the B16 melanoma in vivo and in vitro. Daily doses of 1,000 mg DHBA/kg were better tolerated than doses of 400 mg dopamine/kg. When tested against the B16 melanoma in (C57BL/6 x DBA/2)F1 mice, DHBA had a significantly improved therapeutic effect as shown by a life-span increased 70% as compared to 48% with dopamine. DHBA shared the catecholamine property of selectively inhibiting thymidine incorporation as compared to leucine or uridine incorporation. Because the inhibitory effects of DHBA on the B16 melanoma cells in vitro were similar to those of dopamine, much of the improved efficacy in vivo might be attributed to decreased toxicity.