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 children who have relapsed or refractory rhabdomyosarcoma.

OBJECTIVES:

• Determine the objective response rate (complete and partial responses) in pediatric patients with relapsed or refractory rhabdomyosarcoma treated with exatecan mesylate.
• Determine the time to tumor progression in patients treated with this drug.
• Determine the median survival and survival at 6 and 12 months in patients treated with this drug.
• Assess pain in patients treated with this drug.
• Evaluate the quantitative and qualitative toxic effects of this drug in these patients.
• Evaluate the pharmacokinetics of this drug in these patients.

OUTLINE: This is an open-label, nonrandomized, multicenter study.

Patients receive exatecan mesylate IV over 30 minutes on days 1-5. Treatment repeats every 3 weeks for up to 12 courses in the absence of disease progression or unacceptable toxicity. Patients who achieve a complete response (CR) receive 6 additional courses beyond CR.

PROJECTED ACCRUAL: A total of 13-27 patients will be accrued for this study within 1 year.

DISEASE CHARACTERISTICS:

• Histologically confirmed recurrent or resistant rhabdomyosarcoma

• Measurable disease

  • The following are not considered measurable disease:

    • Ascites
    • Pleural effusion
    • Lytic bone lesions
• No symptomatic brain metastases

PATIENT CHARACTERISTICS:

Age

• Any age

Performance status

• ECOG 0-2 (over 10 years old)
• Lansky 60-100% (10 years old and under)

Life expectancy

• At least 12 weeks

Hematopoietic

• Absolute neutrophil count at least 750/mm^3
• Platelet count at least 75,000/mm^3
• Hemoglobin at least 8.5 g/dL

Hepatic

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

Renal

• Creatinine no greater than 1.5 times ULN

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No life threatening illness (unrelated to tumor) within the past 6 months
• No other malignancy within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix
• No concurrent active serious infection
• No concurrent uncontrolled infection
• No overt psychosis or other incompetency that would preclude study compliance or giving informed consent
• No other concurrent noncancer-related illness that would preclude study participation or follow-up

PRIOR CONCURRENT THERAPY:

Biologic therapy

• At least 3 months since prior autologous bone marrow or stem cell transplantation
• No concurrent anticancer biologic therapy

Chemotherapy

• Recovered from prior adjuvant or systemic chemotherapy
• Prior topoisomerase I inhibitor therapy allowed
• No other concurrent anticancer chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• More than 4 weeks since prior extensive radiotherapy to the cranial-spinal axis, whole pelvis, or 25% of marrow reserve
• No concurrent anticancer radiotherapy

Surgery

• At least 4 weeks since prior major surgery
• Recovered from prior surgery
• No concurrent anticancer surgery

Other

• At least 28 days since prior investigational drugs (including analgesics or antiemetics)
• No more than 2 prior regimens for rhabdomyosarcoma
• No concurrent grapefruit-containing beverages or foods
• No other concurrent investigational drugs during and for 28 days after final dose of study drug