Inclusion Criteria:

* Patients with newly diagnosed diffuse intrinsic pontine gliomas (DIPGs), defined as tumors with a pontine epicenter and diffuse involvement of at least 2/3 of the pons, are eligible without histologic confirmation; patients with brainstem tumors that do not meet these criteria or not considered to be typical intrinsic pontine gliomas will only be eligible if the tumors are biopsied and proven to be an anaplastic astrocytoma, glioblastoma multiforme, gliosarcoma, or anaplastic mixed glioma; patients with juvenile pilocytic astrocytoma, fibrillary astrocytoma, gangliogliomas, or other mixed gliomas without anaplasia are not eligible; patients with disseminated disease are not eligible, and magnetic resonance imaging (MRI) of spine must be performed if disseminated disease is suspected by the treating physician
* Karnofsky >= 50% for patients > 16 years of age and Lansky >= 50 for patients =< 16 years of age; patients who are unable to walk because of paralysis, but who are up in a wheelchair, will be considered ambulatory for the purpose of assessing the performance score
* Patients must not have received any prior treatment except dexamethasone and/or surgery
* Peripheral absolute neutrophil count (ANC) >= 1000/uL
* Platelet count >= 100,000/uL (transfusion independent, defined as not receiving platelet transfusions within a 7 day period prior to enrollment)
* Hemoglobin >= 8.0 g/dL (may receive red blood cell \[RBC\] transfusions)
* Creatinine clearance or radioisotope glomerular filtration rate (GFR) >= 70ml/min/1.73 m\^2 or a serum creatinine based on age/gender as follows:

* 0.8 mg/dL (3 to < 6 years of age)
* 1 mg/dL (6 to < 10 years of age)
* 1.2 mg/dL (10 to < 13 years of age)
* 1.5 mg/dL (male) or 1.4 mg/dL (female) (13 to < 16 years of age)
* 1.7 mg/dL (male) or 1.4 mg/dL (female) (>= 16 years of age)
* Bilirubin (sum of conjugated + unconjugated) =< 1.5 x upper limit of normal (ULN) for age
* Serum glutamate pyruvate transaminase (SGPT) (alanine aminotransferase \[ALT\]) =< 110 U/L; for the purpose of this study, the ULN for SGPT (ALT) is 45 U/L
* Serum albumin >= 2 g/dL
* Patients with seizure disorder may be enrolled if on non-enzyme inducing anticonvulsants (with the exception of valproic acid) and seizures are well controlled
* Patients must be able to swallow capsules or liquids; patients dependent on nasogastric (NG) tube feeding are not permitted to receive protocol therapy
* Enrollment must be no later than 28 days after the date of radiographic diagnosis or surgery, whichever is the later date

Exclusion Criteria:

* Pregnant or breast-feeding women will not be entered on this study; pregnancy tests must be obtained in girls who are post-menarchal; males or females of reproductive potential may not participate unless they have agreed to use an effective contraceptive method
* Growth factors that support platelet or white cell number or function must not have been administered within the 7 days prior to enrollment
* Patients who are currently receiving another investigational drug are not eligible
* Patients who are currently receiving other anti-cancer agents are not eligible
* Patients must not currently be receiving enzyme inducing anticonvulsants
* Patients on valproic acid must discontinue valproic acid for at least 2 weeks before starting protocol therapy
* Patients receiving coumadin, heparin, low-molecular weight heparin, or any other anti-coagulants are not eligible for study entry
* Patients receiving acetylsalicylic acid (ASA) (> 81 mg/day), non-steroidal anti-inflammatory drugs, clopidogrel (Plavix), dipyridamole (Persantine), or any other drug that inhibits platelet function are not eligible for study entry
* Patients who have an uncontrolled infection are not eligible
* Patients who in the opinion of the investigator may not be able to comply with the safety monitoring requirements of the study are not eligible