OBJECTIVES: I. Determine the maximum tolerated dose of ICI D1694 (TDX) when given with irinotecan (CPT-11) every 3 weeks in patients with advanced solid malignancies. II. Describe the pharmacokinetics of TDX and CPT-11 when given in combination. III. Investigate the relationship between topoisomerase I expression in peripheral mononuclear cells and myelosuppression and/or gastrointestinal toxicity. IV. Investigate the effect of CPT-11 on thymidylate synthase expression in tumor.