PURPOSE The purpose of this study was to establish the maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and preliminary activity of BMS-188797 administered weekly. EXPERIMENTAL DESIGN Patients with advanced malignancies were treated with escalating doses of BMS-188797 on a weekly schedule as a 1-h i.v. infusion. Plasma sampling was performed to characterize the pharmacokinetics of BMS-188797. RESULTS Eighteen patients with advanced malignancies were enrolled at three dose levels ranging from 35 to 65 mg/m(2). The number of patients evaluated at each dose level was as follows: 35 mg/m(2) (n = 3); 50 mg/m(2) (n = 9); and 65 mg/m(2) (n = 6). At 65 mg/m(2), three of six patients had a DLT (one had grade 4 neutropenia lasting >7 days, and two had grade 3 diarrhea). Expansion of the 50-mg/m(2) dose cohort to nine patients established this dose as the MTD, with one patient experiencing a DLT (grade 4 neutropenia with fever). Two partial responses were observed (lung cancer, 7+ months; ovarian cancer, 6+ months durations), as well as two minor responses (esophageal cancer, 5 months; ovarian cancer, 5 months). Both patients with partial responses had been clinically resistant to paclitaxel. Plasma pharmacokinetic mean values of maximum concentration (C(max)) and area under the curve (AUC(0-48)) increased in a dose-dependent manner within the range of doses used in this study, and in three of four patients, the DLTs correlated with AUC. CONCLUSIONS The MTD and the recommended Phase II dose of weekly BMS-188797 is 50 mg/m(2). The drug demonstrates antitumor activity in taxane-refractory solid tumors and is now being evaluated in combination with carboplatin.