A novel antitumor antibiotic, 2a,3,4,5,6,6a,7,11b-octahydro-11-methoxy-12-methyl-3,6-imino-1H-2-oxa-11 c- azanaphth(1,2,3-cd)azulene-5-carboxylic acid monocitrate (quinocarmycin citrate; KW2152) was selected for investigation in a number of experimental tumor systems because of its efficacy against