RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die.

PURPOSE: Phase II trial to study the effectiveness of exatecan mesylate in treating patients who have metastatic stomach cancer.

OBJECTIVES:

• Determine the objective response rate of patients with previously untreated metastatic gastric cancer treated with exatecan mesylate (DX-8951f).
• Determine the time to tumor progression in this patient population when treated with this drug.
• Determine the survival at 6 and 12 months in this patient population when treated with this drug.
• Determine the quantitative and qualitative toxic effects of this drug in this patient population.
• Determine the pharmacokinetics of this drug in the plasma of these patients.

OUTLINE: This is a multicenter study.

Patients receive exatecan mesylate (DX-8951f) IV over 30 minutes on days 1-5. Treatment repeats every 21 days for at least 2 courses in the absence of disease progression or unacceptable toxicity.

Patients are followed every 3 months.

PROJECTED ACCRUAL: A total of 12-37 patients will be accrued for this study within 12 months.

DISEASE CHARACTERISTICS:

• Histologically confirmed gastric or gastroesophageal adenocarcinoma

  • Lymph node involvement and/or distant metastasis

• No squamous cell carcinoma, small cell carcinoma, lymphoma, or leiomyosarcoma of the stomach

• Measurable disease with indicator lesions outside the field of prior radiotherapy

  • At least 20 mm by conventional scan OR

  • At least 10 mm by spiral CT scan

  • Nonmeasurable lesions include the following:

    • Primary tumor
    • Bone lesions
    • Leptomeningeal disease
    • Ascites
    • Pleural/pericardial effusion
    • Inflammatory breast disease
    • Lymphangitis cutis/pulmonitis
    • Cystic lesions
    • Abdominal masses not confirmed and followed by imaging techniques

• No prior treatment for locally advanced or metastatic disease

  • Prior adjuvant treatment allowed if disease recurrence noted at least 6 months after completion of adjuvant treatment

• No known brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-2

Life expectancy:

• At least 12 weeks

Hematopoietic:

• Absolute neutrophil count at least 1,500/mm3
• Platelet count at least 100,000/mm3
• Hemoglobin at least 9.0 g/dL

Hepatic:

• Bilirubin no greater than 2.0 mg/dL
• AST or ALT no greater than 2.5 times upper limit of normal (ULN) (5 times ULN if liver metastases present)
• Albumin at least 2.8 g/dL
• PT or INR no greater than 1.5 times ULN (coumadin independent)

Renal:

• Creatinine no greater than 1.5 mg/dL

Cardiovascular:

• No active congestive heart failure
• No uncontrolled angina
• No myocardial infarction within the past 6 months

Other:

• No concurrent serious infection
• No other malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix
• No overt psychosis, mental disability, or incompetence that would preclude informed consent
• No other life-threatening illness
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics

Biologic therapy:

• No concurrent anti-cancer biologic therapy
• No concurrent prophylactic colony stimulating factors during first course of therapy

Chemotherapy:

• Recovered from prior adjuvant chemotherapy
• No other concurrent anti-cancer chemotherapy
• No other concurrent anti-cancer cytotoxic therapy

Endocrine therapy:

• Concurrent megestrol for appetite stimulation allowed

Radiotherapy:

• At least 4 weeks since prior radiotherapy and recovered
• No prior wide-field radiotherapy to more than 25% of bone marrow
• No concurrent anti-cancer radiotherapy

Surgery:

• At least 4 weeks since prior major surgery and recovered
• No concurrent anti-cancer surgery

Other:

• No other investigational drugs (including analgesics or antiemetics) for at least 4 weeks prior to, during, and for 4 weeks after study