OBJECTIVES: I. Determine the dose-limiting toxic effects and maximum tolerated dose of augmerosen (G3139) administered in combination with irinotecan in patients with unresectable metastatic or recurrent colorectal cancer. II. Determine the quantitative and qualitative toxicity of this drug combination in this patient population. III. Assess the plasma pharmacokinetics of this combination in these patients. IV. Document the antitumor activity of this drug combination in these patients in a phase II study. V. Determine the relevant biologic endpoints of treatment in tumor biopsies prior to and after therapy with G3139 at two dose levels and assess the pharmacokinetic and pharmacodynamic correlations.