RATIONALE: Imatinib mesylate may stop the growth of tumor cells by blocking the enzymes necessary for tumor cell growth.

PURPOSE: This phase II trial is studying how well imatinib mesylate works in treating patients with recurrent Ewing's family of tumors or desmoplastic small round-cell tumor.

OBJECTIVES:

• Determine the effectiveness of imatinib mesylate in patients with recurrent Ewing's family of tumors or desmoplastic small round-cell tumor.
• Determine the toxic effects of this drug in these patients.
• Determine the duration of disease-free and overall survival of patients treated with this drug.

OUTLINE: This is an open-label study.

Patients receive oral imatinib mesylate twice daily on days 1-28. Courses repeat every 28 days.

PROJECTED ACCRUAL: A total of 20-40 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Diagnosis of Ewing's family of tumors OR desmoplastic small round-cell tumor

• Must have immunohistochemical evidence of expression of greater than 2+/4+ for either Kit (CD117) or platelet-derived growth factor receptor -a or -b

• No symptomatic brain metastases

  • Asymptomatic brain metastases are allowed provided patient is not on concurrent anticonvulsants or corticosteroids

PATIENT CHARACTERISTICS:

Age

• Over 16

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• Absolute neutrophil count greater than 1,500/mm^3
• Platelet count greater than 100,000/mm^3
• Hemoglobin greater than 9 g/dL

Hepatic

• Bilirubin less than 1.5 times upper limit of normal (ULN)
• SGOT and SGPT less than 2.5 times ULN
• No chronic active hepatitis
• No cirrhosis
• No other acute or known chronic liver disease

Renal

• Creatinine less than 1.5 times ULN

Cardiovascular

• No concurrent poorly controlled or severe cardiovascular disease

Pulmonary

• No concurrent poorly controlled or severe pulmonary disease

Other

• HIV negative
• No concurrent poorly controlled or severe central nervous system disease
• No other concurrent poorly controlled or severe nonmalignant disease

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• At least 3 weeks since prior chemotherapy

Endocrine therapy

• See Disease Characteristics

Radiotherapy

• At least 3 weeks since prior radiotherapy

Surgery

• More than 2 weeks since prior major surgery

Other

• More than 28 days since prior investigational agents