Patients receive oral tributyrin every 8 hours for 3 weeks. Treatment continues every 4 weeks for 2 courses in the absence of disease progression or unacceptable toxicity. Patients who achieve stable disease may receive additional courses at the discretion of the protocol chairperson. Cohorts of 3-6 patients receive escalating doses of tributyrin until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 6 patients experience dose-limiting toxicity.