OUTLINE: This is a dose escalation, multicenter study. Patients receive oral ILX23-7553 for 5 days. Treatment repeats every 2 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 3-6 patients receive escalating doses of ILX23-7553 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 or 2 of 10 patients experience dose limiting toxicity. Patients are followed monthly for at least 2 months.