Synthesis, Evalution of Antiproliferative Activity, and Investigations of the Mechanism of Action of Novel Antitumor Agents

In the course of this project, a large number of novel chemical compounds have been prepared. Out of this series several of the compounds were found to exhibit significant antitumor activity in a special animal model. The aim was to synthesize a novel class of compounds and screen them for anti-proliferative activity. We succeeded in the preparation of about 350 new compounds as described in our project proposal. The majority of these compounds have been screened in tissue culture for antitumor activity. Dose-response curves were established in the following human tumor cell lines: Burkitts lymphoma, CCRF-CEM (lymphoblastoid cells), HeLa (epitheloid cervix carcinoma), HT-29 (colon adenocarcinoma), KB-3-1 (human oral epidermoid carcinoma), the multidrug resistant KB-C1 and the hydroxyurea-resistant KB-HU sublines. Most of the compounds tested turned out to exhibit high antiproliferative activity in the nano-molar (nM) range. In addition, the influence of several of these compounds on the cell cycle and on apoptosis was investigated. Two compounds (EPH 355 and 362) were found to induce apoptosis above average. About 50 of the most active compounds identified in our assay system were submitted to the US National Cancer Institute (NCI), Bethesda, Maryland for additional screening in their in vitro anti-cancer 60 cell line assay. Most of the compounds tested in this assay system were found to be differentially active against colon, melanoma, renal, CNS, cervical, and ovarian cancers. Although most of the compounds turned out to be very cytostatic, the highly selective compounds (~ 20) were further evaluated in the in vivo Hollow Fibre Assay. Five compounds showing positive results in this assay have been selected for xenograft studies in nude mice. The results obtained from our studies as well as from the US-NCI shows that mechanism(s) of action of these compounds is/are different from that of established anticancer agents. Initial investigations have revealed that these compounds inhibit cell growth through the development of radicals. The results from this project have been used as the basis for an Austrian and World Patent applications. Results from an earlier project (P09879-MED) relating to the present one has been published in the International Journal of Cancer. Furthermore, the results presented in said publication was the subject of a discussion from the news agency Reuters.