Exatecan Mesylate in Treating Children With Relapsed or Refractory Rhabdomyosarcoma

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