acronine and Disease-Models--Animal

Originally isolated from an Australian plant, acronycine is an antitumor alkaloid with poor water solubility and low potency. The modest antitumor activity of this compound was markedly improved by the total synthesis of original analogs resulting in the selection of S23906-1, a diester derivative of 1,2-dihydrobenzo[b]acronycine. S23906-1 is characterized in vitro by a high potency in clonogenic assays and uncommon cell cycle pertubations. In vivo, this compound demonstrated a selectivity for human solid tumors as compared to murine transplantable tumors. The unique pharmacological profile of S23906-1 was particularly defined by a broad antitumor efficacy when administered i.v. or orally on aggressive orthotopic models of human lung, ovarian and colon models with comparable or better activity than clinically used anticancer drugs. The molecular mechanism of action of S23906-1 could involve DNA alkylation, modulation of cyclin E protein levels and inhibition of DNA synthesis leading to apoptosis. Ongoing preclinical toxicological studies will help to define the potential of this novel agent which is already considered as a valuable candidate for clinical studies.

Topics: Acronine; Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Cell Cycle; Disease Models, Animal; Humans; In Vitro Techniques; Mice; Mice, Inbred Strains; Mice, Nude; Neoplasms, Experimental; Survival Rate; Xenograft Model Antitumor Assays

S 23906-1 is a novel acronycine derivative selected on the basis of its potency in vitro. We investigated the antitumor activity of S 23906-1 against several murine transplantable tumors (C38 colon carcinoma, P388 leukemia, B16 melanoma, and Lewis lung carcinoma) and in orthotopic models of human lung (NCI-H460 and A549), ovarian (IGROV1 and NIH:OVCAR-3), and colorectal cancers (HCT116 and HT-29). Against established C38 colon carcinoma, S 23906-1 administered twice i.v. from 1.56-6.25 mg/kg markedly inhibited tumor growth. Treatment at the optimal dose (6.25 mg/kg) induced tumor regression in all of the mice. Acronycine was 16-fold less potent and only moderately active at the maximum tolerated dose, 100 mg/kg. Against other murine tumors of the former National Cancer Institute panel, S 23906-1 was either only moderately active or totally inactive. When evaluated in human orthotopic models, S 23906-1 given p.o. or i.v. demonstrated a marked antitumor activity against human carcinomas. In the two human lung cancer models, S 23906-1 increased the survival of the animals in a dose-dependent manner and induced treated versus control values of 162% (NCI-H460) and 193% (A549). Vinorelbine was less active, with treated versus control values of 119% and 174%, respectively. A significant survival benefit was also observed against the two i.p. ovarian tumors in which S 23906-1 was as active as paclitaxel, inducing 80% long-term survivors in the NIH:OVCAR-3 model. Lastly, S 23906-1 inhibited the growth of primary HT-29 and HCT116 colon tumors grafted onto the cecum as efficiently as irinotecan and eradicated the formation of lymph node, hepatic, and pulmonary metastases in the aggressive HCT116 model. The novel spectrum of activity of S 23906-1 compared with existing anticancer agents warrants further preclinical investigation.

Topics: Acronine; Animals; Antineoplastic Agents; Disease Models, Animal; Female; HT29 Cells; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Inbred DBA; Mice, Nude; Mice, SCID; Neoplasms, Experimental; Survival Analysis; Time Factors; Tumor Cells, Cultured; Xenograft Model Antitumor Assays