Antitumor activity of new anthracycline antibiotics, aclacinomycin-A and its analogs, and their toxicity

New anthracycline antibiotics have been isolated from the culture of Streptomyces galilaeus MA144-M1. Among 14 anthracycline compounds, aclacinomycin-A showed the strongest activity in inhibiting leukemia L-1210 and had lower toxicity than others. Antitumor activity of aclacinomycin-A against leukemia L-1210 and P-388, solid sarcoma-180, and lymphosarcoma 6C3HED was examined in comparison with adriamycin and daunomycin. Aclacinomycin-A showed the same degree of activity against leukemia L-1210 and P-388, when administered intraperitoneally, as daunomycin and somewhat less than adriamycin. In oral administration, aclacinomycin-A also exhibited a significant activity on leukemia L-1210. The degree of inhibition of the growth of sarcoma-180 and 6C3HED lymphosarcoma transplanted subcutaneously by aclacinomycin-A was almost the same as that of adriamycin and daunomycin, although the optimal dose was about twice more than adriamycin. Acute cardiotoxicity of aclacinomycin-A by a test using hamsters was more than 10 times lower than that of adriamycin.