Temozolomide and O6-benzylguanine in Treating Children With Solid Tumors

DISEASE CHARACTERISTICS:

* Histologically confirmed solid tumor refractory to standard therapy and for which no potentially curative therapy exists, including, but not limited to:

  * Rhabdomyosarcoma and other soft tissue sarcomas
  * Ewing's family of tumors
  * Osteosarcoma
  * Neuroblastoma
  * Wilms' tumor
  * Hepatic tumors
  * Germ cell tumors
  * Primary brain tumor
* Histological confirmation may be waived for brainstem or optic gliomas
* Measurable or evaluable disease
* Evidence of progressive disease on prior chemotherapy or radiotherapy or persistent disease after prior surgery

PATIENT CHARACTERISTICS:

Age:

* 21 and under

Performance status:

* ECOG 0-2

Life expectancy:

* At least 8 weeks

Hematopoietic:

* Absolute granulocyte count greater than 1,500/mm\^3
* Hemoglobin greater than 8 g/dL
* Platelet count greater than 100,000/mm\^3

Hepatic:

* Bilirubin normal
* SGPT less than 2 times upper limit of normal
* No significant hepatic dysfunction

Renal:

* Creatinine normal OR
* Creatinine clearance at least 60 mL/min

Cardiovascular:

* No significant cardiac dysfunction

Pulmonary:

* No significant pulmonary dysfunction

Other:

* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception
* Able to swallow capsules
* No significant unrelated systemic illness that would preclude study (e.g., serious infections or organ dysfunction)
* No prior hypersensitivity to dacarbazine, temozolomide, or polyethylene glycol

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* At least 1 week since prior colony-stimulating factors (e.g., filgrastim \[G- CSF\], sargramostim \[GM-CSF\], or epoetin alfa)
* At least 4 months since prior myeloablative therapy requiring bone marrow or stem cell transplantation
* No concurrent anticancer immunotherapy

Chemotherapy:

* See Disease Characteristics
* At least 3 weeks since prior chemotherapy (4 weeks for nitrosoureas) and recovered
* Prior temozolomide allowed provided not administered within past 3 months, no severe toxicities experienced during prior course, and not given in combination with other agents designed to inactivate alanine-glyoxylate aminotransferase
* No other concurrent investigational or standard anticancer chemotherapy

Endocrine therapy:

* Concurrent corticosteroids for control of brain tumor-associated edema allowed provided on stable or decreasing dose for at least 1 week prior to study

Radiotherapy:

* See Disease Characteristics
* At least 4 weeks since prior limited-field radiotherapy
* At least 4 months since prior craniospinal irradiation, total body irradiation, or radiotherapy to more than half of the pelvis
* Recovered from prior radiotherapy
* No concurrent anticancer radiotherapy

Surgery:

* See Disease Characteristics

Other:

* At least 4 weeks since other prior investigational therapy and recovered
* No other concurrent anticancer investigational agents