Rubeomycin A1

Doxorubicin is an essential component of the treatment of aggressive lymphoma, childhood solid tumors, bone and soft tissue sarcomas, and breast cancer and additional indications are emerging. On the other hand, daunorubicin has occupied the central position of interest in the treatment of acute leukemia. Epirubicin has a spectrum very similar to doxorubicin but lesser toxicity. The ability to protect against cardiotoxicity with ICRF-187 further enhances clinical interest in exploiting modifications in doze intensity to therapeutic advantage. Idarubicin has at least equivalent activity to daunorubicin and doxorubicin in leukemia. New areas of research in relation to anthracycline antibiotics include introduction of new the analogs, insight into mechanisms of resistance, the reversal of multidrug resistance in vitro, the protection of cardiac toxicity, and the study of other important biochemical reactions relevant to cytotoxicity. Orally active anthracyclines such as idarubicin and compounds which lack cross-resistance with the parent drugs or have other mechanisms for cytotoxicity are being developed. It is likely that these modifications will lead to an expanding therapeutic spectrum for these already widely useful drugs.

Idarubicin showed the superior activity against Acute Non-Lymphocytic Leukemia (ANLL) in the prospective randomized trials comparing to daunorubicin and it is judged that the analog will become the first choice in the treatment on ANLL. Anthracyclines including SM-5887, KRN-8602, ME-2303 under studies in Japan have shown comparable or superior antitumor activities and lower cardiac toxicities compared to doxorubicin in preclinical studies and therefore the results obtained in clinical trials are expected. Phase II trials of anthrapyrazoles which is an analog of mitoxantrone are in progress. Among three compounds entered it is of note that CI-941 has demonstrated an excellent activity against advanced breast cancer.

The absolute configurations of rubeomycins A and A1 (corresponding to carminomycins II and III) and rubeomycins B and B1 (corresponding to 4-hydroxybaumycinols A1 and A2), except at the C-1" position, were determined by comparison of the optical rotations and other spectral data of rubeomycin derivatives with those of daunomycin and L-(+)-lactic acid.