Inclusion Criteria:

- Age > or equal to 18 months to 21 years

- Diagnosis Patients with NF1 and progressive, symptomatic or life-threatening
plexiform neurofibromas which are not surgically resectable. Patients without
biopsy-proof of plexiform must have at least one other diagnostic criteria for NF1: 6
or more cafe-au-lait spots, freckling in the axilla or groin, optic glioma, 2 or more
Lisch nodules, distinctive bony lesion, first degree relative with NF1.

- Only eligible if complete tumor resection is not feasible, or if a patient with a
surgical option refuses surgery.

- Patients may be treated on this trial without having received prior therapy. If
patients have received prior therapy, they must have recovered from all toxic effects
prior to entering this study.

- Must have life expectancy of at least 12 months and a performance score (Karnofsky or
Lansky) of > or equal to 50.

- Must have adequate liver, kidney and bone marrow function

Exclusion Criteria:

- Clinically significant unrelated systemic illness.

- Received an investigational agent within the past 30 days.

- Evidence of active visual pathway glioma

- History of malignant peripheral nerve sheath tumor or ther cancer other than
surgically cured non-melanoma skin cancer or cervical carcinoma in situ

- Ongoing radiation therapy, chemotherapy, hormonal therapy directed at the tumor, or
immunotherapy.

- Inability to return for follow-up visits or obtain follow-up studies

- Severe cardiovascular disease

- Pre-existing sever psychiatric condition or history of psychiatric disorder requiring
hospitalization or a history of suicidal ideation or attempt.

- Thyroid dysfunction not responsive to therapy.

- Uncontrolled diabetes mellitus

- History of seropositivity for HIV

- Subjects who are pregnant, lactating, or of reproductive potential and not practicing
an effective means of contraception.

- Any medical condition requiring chronic systemic corticosteroids.

- Subjects who are known to be actively abusing alcohol or drugs.