Cohorts of 3-6 patients receive escalating doses of ixabepilone until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 or more of 6 patients experience dose-limiting toxicity. Intrapatient dose escalation to one dose level above the enrollment dose level is allowed in patients who have stable or responding disease or are experiencing other benefits from therapy (e.g., decrease in tumor-related pain symptoms) and who have no grade 2 or greater non-hematologic toxicity and no grade 3 or greater hematologic toxicity. Additional patients are treated at the MTD. Patients treated at the MTD may not undergo intrapatient dose escalation.