A Study of Pemetrexed in Children With Recurrent Cancer

Inclusion Criteria:

* Patients must have osteosarcoma, Ewing's sarcoma, medulloblastoma, neuroblastoma, rhabdomyosarcoma, ependymoma or high-grade non-brainstem glioma
* Measurable disease
* Eastern Cooperative Oncology Group (ECOG) performance 0,1,2
* Adequate renal, liver and bone marrow function
* Patient's current disease state must be one with no known curative therapy or therapy proven to prolong survival with an acceptable quality of life

Exclusion Criteria:

* Growth factors that support platelet or white cell number or function must not have been administered within the last 7 days prior to enrollment (14 days if Neulasta)
* Patients with central nervous system (CNS) tumors who have not been on a stable or decreasing dose of dexamethasone or other corticosteroid for 7 days prior to enrollment
* Patients with uncontrolled infection
* Patients who have received pemetrexed previously
* Patients with pleural effusions or ascites