PURPOSE To evaluate the safety, maximum tolerated dose (MTD), and pharmacokinetics of patupilone administered once every 3 weeks with proactive standardized diarrhea management in patients with resistant or refractory ovarian, fallopian, or peritoneal cancer. PATIENTS AND METHODS Patients received patupilone (6.5 to 11.0 mg/m(2)) every 3 weeks via 20-minute infusion. Adverse events, dose-limiting toxicities (DLT), MTD, and tumor response were determined. The tumor response was measured by Response Evaluation Criteria in Solid Tumors (RECIST) and cancer antigen 125 levels. Results Forty-five patients were enrolled. Adverse events were mild to moderate in intensity, and grade 3 diarrhea (13%) was the most commonly reported serious adverse event. Grade 3 peripheral neuropathy was noted in two patients (4%). Diarrhea, peripheral neuropathy, and fatigue were the most common DLTs; however, these were uncommon in the first cycle and the MTD was therefore not reached in this study. Overall response (OR; complete and partial responses; median cycles, 8) per RECIST in patients with measurable disease (n = 36) was 19.5%. Median duration of disease stabilization (complete and partial responses and stable disease) was 15.8 months. These results appear improved from a previous study in a similar patient population using a weekly schedule (2.5 mg/m(2)/week; N = 53; OR, 5.7%). CONCLUSION Patupilone once every 3 weeks was well-tolerated at doses up to 11.0 mg/m(2). Patupilone demonstrated promising antitumor activity in patients with drug-resistant/refractory disease. An ongoing phase III study in this patient population is testing the 10.0 mg/m(2) dose.