Inclusion Criteria

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