OBJECTIVES: I. Estimate the maximum tolerated dose (MTD) of ecteinascidin-743 (ET-743) when administered as a single intravenous infusion every 21 days in adults with solid tumors not amenable to standard therapy. II. Describe the qualitative and quantitative toxic effects of ET-743, and study the predictability, duration, intensity, onset, reversibility, and dose-relationship of these toxic effects in these patients. III. Propose a safe dose for a phase II study based on the MTD determined on this study. IV. Assess the pharmacokinetics of ET-743 at different dose levels. V. Document any antitumor effects of ET-743 in these patients.