While the anthracycline antitumor antibiotic adriamycin (doxorubicin) retains its premier position in clinical cancer chemotherapy, its toxicity and lack of effectiveness against some of the more common advanced carcinomas continue to emphasize the need for anthracycline analogs with improved therapeutic efficacy. Discounting the conventional view that anthracycline antitumor action is tied mechanistically to drug-DNA binding, we have successfully developed novel DNA-nonbinding adriamycin analogs from concept to clinic; these include N-(trifluoroacetyl)adriamycin-14-valerate (AD 32), which has gone through extensive Phase I-II studies, and N-(trifluoroacetyl)adriamycin-14-0-emiadipate(AD 143), which is expected shortly to enter clinical trials. Recently we have found lipophilic N-alkyladriamycin derivatives with significant therapeutic superiority to adriamycin in experimental system, despite poor DNA-binding; and with mechanistic properties differing from adriamycin and from AD 32/AD 143. In an integrated program of chemical and biological studies, we plan to thoroughly explore the structure-activity relationships among N-alkyl- and corresponding 14-acyl-substituted anthracyclines, including the effect of combining N-alkylation with N-trifluoroacetylation. The synthesis and properties of novel 7-0-(4'-N-alkyl)morpholinylanthracyclinone analogs will be explored. Further studies probing structure-activity correlations among analogs related to AD 32 and AD 143 are proposed; studies will also be directed towards linking AD 143 with tumor-specific monoclonal antibodies. Based on the promise of some recently obtained analogs, a number of anthracyclinone furanoside derivatives, with azido, amino, or desamino functionality in the sugar, will be studied as glycoside ring-contracted variants of parent anthracycline antibiotics. Various aminoglycoside anthracyclines and analogs will be used for conversion to nitrosoureas in a rational attempt to obtain agents with dual chemotherapeutic and/or radiosensitizing properties. As before, chemical studies will be augmented by a range of appropriate biological studies aimed at exploring the therapeutic potential of the semisynthetically-derived target compounds. In vitro studies will include growth-inhibition assays against sensitive and resistant lymphoid-derived cell lines and effects of agents on macro-molecule synthesis. In vivo evaluation will include determination of the antitumor effects of target compounds on various murine solid tumor models, as well as in leukemia systems; nitrosoureas will additionally be studied for possible drug radiation synergy.
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