RATIONALE: SU5416 may stop the growth of colorectal cancer by stopping blood flow to the tumor. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die.

PURPOSE: Phase I/II trial to study the effectiveness of combining SU5416 and irinotecan in treating patients who have advanced colorectal cancer.

OBJECTIVES: I. Determine the maximum tolerated dose (MTD) and dose-limiting toxicity of SU5416 in combination with irinotecan in patients with advanced colorectal cancer. II. Determine time to disease progression, objective response rate, and survival time in these patients receiving this regimen at the MTD. III. Evaluate the safety and tolerance of this regimen in these patients.

OUTLINE: This is a dose-escalation study of SU5416. Patients receive irinotecan IV over 90 minutes on day 1 of weeks 1-4 and SU5416 IV over 60 minutes on days 1 and 4 of weeks 1-6. Treatment continues every 6 weeks in the absence of unacceptable toxicity or disease progression. Cohorts of 3-6 patients receive escalating doses of SU5416 until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose preceding that at which 2 of 3 or 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, additional patients are accrued to receive treatment with SU5416 and irinotecan at the recommended phase II dose. Patients are followed every 3 months.

PROJECTED ACCRUAL: A total of 3-24 patients will be accrued for the phase I portion of this study within 12 months. An additional 44 patients will be accrued for the phase II portion of this study within 7 months.

• Drug: irinotecan hydrochloride
• Drug: semaxanib

DISEASE CHARACTERISTICS: Histologically confirmed locally advanced or metastatic adenocarcinoma of the colon or rectum not amenable to potentially curative treatment Measurable or evaluable disease Measurable disease defined as at least 1 bidimensionally measurable lesion at least 1 x 1 cm that is outside field of any prior radiotherapy Must have received a prior chemotherapy regimen containing a fluorinated pyrimidine No more than 2 prior chemotherapy regimens for locally advanced or metastatic disease in phase I and only 1 prior chemotherapy regimen for locally advanced or metastatic disease in phase II If progression while on or within 6 months of adjuvant therapy, the adjuvant regimen is considered treatment for metastatic disease No history of or clinically apparent CNS metastases or leptomeningeal carcinomatosis disease

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 mg/dL SGOT no greater than 3 times upper limit of normal No known Gilbert's disease Renal: Creatinine no greater than 1.5 mg/dL OR Creatinine clearance at least 60 mL/min Cardiovascular: No uncompensated coronary artery disease on electrocardiogram or physical examination No history of myocardial infarction No severe/unstable angina in the past 6 months No deep venous or arterial thrombosis within past 3 months Pulmonary: No pulmonary embolism within past 3 months Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after study History of prior malignancy allowed (phase I only) No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer (phase II) No uncontrolled diabetes mellitus No known allergy to Cremophor or Cremophor-based drug products No active or uncontrolled infection No psychiatric disorders that would preclude study No history of seizures No other severe concurrent disease that would preclude study

PRIOR CONCURRENT THERAPY: Biologic therapy: No prophylactic hematopoietic growth factors (e.g., filgrastim (G-CSF)) No concurrent biologic therapy Chemotherapy: See Disease Characteristics No prior SU5416, irinotecan, or any topoisomerase I inhibitor No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy and recovered No concurrent radiotherapy Surgery: At least 4 weeks since prior major surgery and recovered Other: At least 30 days since other prior investigational drugs No concurrent phenytoin, phenobarbital, or other antiepileptic prophylaxis No concurrent prochlorperazine on day of irinotecan administration No other concurrent anticancer therapy