OUTLINE: This is a dose-escalation study to estimate the maximum tolerated dose (MTD) of penclomedine. Cohorts of 3-6 patients are treated at escalating doses until the MTD is reached. Patients receive oral penclomedine for 5 consecutive days every 4 weeks. If tumor progression or unacceptable toxicity is documented during any treatment course, the patient is removed from study. A total of 10 patients will be treated at the dose determined to be the MTD (the recommended phase II dose).