The effect of DB-67, a lipophilic camptothecin derivative, on topoisomerase I levels in non-small-cell lung cancer cells

Purpose To determine the in vitro drug sensitivity of two non-small-cell lung cancer cell lines after treatment with the novel lipophilic camptothecin derivative, 7-tert-butyldimethylsilyl-10-hydroxycamptothecin (DB-67), to determine if topoisomerase I protein levels decrease after treatment with DB-67, and to assess the duration and extent of topoisomerase I modulation after DB-67 exposure, in order to provide information about drug resistance that may be useful in determining an appropriate dosing schedule for DB-67.