Verseon Corporation presented new preclinical data on its anticancer drug candidates at the American Association for Cancer Research (AACR) annual meeting yesterday. Dr. Mohan Sivaraja, Associate Director of Discovery Biology, presented studies showing that Verseon's drug candidates are potent against a range of cancer cell lines, including those that exhibit multidrug resistance. While chemotherapy remains the first line of treatment against most cancers, many tumors develop resistance to chemotherapy agents over time, limiting their efficacy. A common way for cancer cells to render drugs ineffective is by triggering an overproduction of transport proteins (efflux pumps) that expel many chemicals, including chemotherapeutics. In addition, cells can become resistant to tubulin-targeting chemotherapy drugs by overexpression of ß-III tubulin. The preclinical studies presented at the AACR conference demonstrate that Verseon's drug candidates target cancer cells by inhibiting the protein tubulin, which leads to cell cycle arrest. While marketed chemotherapies such as doxorubicin, paclitaxel, and vincristine show up to 2,000-fold reduced potency in cell lines overexpressing the major MDR1, MRP1, and BCRP efflux pumps, Verseon's drug candidates are only weakly affected by these transporters (typically less than 2-fold). The Company's drug candidates also appear unaffected by the overexpression of ß-III tubulin. Dr. Sivaraja also presented pharmacokinetic data for one of Verseon's tubulin inhibitors, which shows good exposure suitable for infusion. The candidate was also well tolerated in a preclinical repeat-dosing study.