A statistical-heuristic method for selecting drugs for animal screening is developed with molecular structure features as predictors of biological activity. The method is intended to work on large amounts of data over varied structures. A trial of this method on a small data set allows some comparison with more sophisticated pattern recognition methods. Problems connected with interdependence among structure predictors are critical in this method and schemes to eliminate redundancy are reviewed. Alternate sets of structure predictors are considered. The discussion here outlines directions to be taken in the near future.
This paper reports the application of pattern recognition and substructural analysis to the problem of predicting the antineoplastic activity of 24 test compounds in an experimental mouse brain tumor system based on 138 structurally diverse compounds tested in this tumor system. The molecules were represented by three types of substructural fragments, the augmented atom, the heteropath, and the ring fragments. Of the two pattern recognition methods used to predict the activity of the test compounds the nearest neighbor method predicted 83% correctly while the learning machine method predicted 92% correctly. The test structures and the important substructural fragments used in this study are given and the implications of these results are discussed.
The current report presents the data of the Division of Cancer Treatment of the National Cancer Institute (NCI) on the antitumor activity of the anthracycline antibiotic 4'-epidoxorubicin in experimental tumor systems. Direct comparisons are made with doxorubicin in individual experiments, and the data are related to those of earlier studies in the form of a review of experimental activity, in order to assess the relative activity of 4'-epidoxorubicin and doxorubicin. The experimental test models utilized by the NCI for these studies included the leukemias P388 and L1210, B-16 melanoma, Lewis lung carcinoma, the colon tumors 26 and 38, and the mammary tumors CD8F1 and C3H16/C. The human tumors growing in xenograft in athymic mice included the models LX-1 lung tumor, CX-1 colon tumor, and MX-1 mammary tumor. Additional comparisons were made with the tumor models Gross leukemia, sarcoma 180, MSV-induced sarcoma, MS-2 tumor, and a variety of human tumors growing in athymic mice, as well as with in vivo toxicologic and in vitro cytotoxicity models. Although for 4'-epidoxorubicin there is only a minimal alteration of the configuration of the doxorubicin molecule, quantitative comparison of 4'-epidoxorubicin and doxorubicin revealed not only similarities but also differences in biological activity. Both drugs showed activity against a broad spectrum of experimental tumors, with 4'-epidoxorubicin more effective against some tumors and equally effective against others. 4'-Epidoxorubicin evidenced less toxicity than doxorubicin in both acute and chronic toxicity studies with retention of therapeutic effectiveness and showed reduced cardiotoxicity. With 4'-epidoxorubicin there resulted a higher therapeutic index and therapeutic ratio, permitting the use of higher dosage and a greater margin of safety. The preclinical differences in therapeutic and toxicologic manifestations of 4'-epidoxorubicin, reflecting apparent alterations in pharmacologic properties and mode of action in comparison with doxorubicin, support the broad spectrum clinical trials of this already-demonstrated clinically active drug.
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