Inclusion Criteria:

- Diagnosis* of neurofibromatosis type 1 (NF1) and extensive plexiform and/or
paraspinal neurofibromasproducing pain (not controlled by use of over-the-counter
medications), progressive neurologic deficit, or significant neurologic
consequenceswith continuous tumor growth

- Extensive paraspinal neurofibroma defined as a neurofibroma that involves
multiple neural roots at ≥ 3 spinal levels with connection between the levels or
extending laterally along the nerves

- Symptomatic neurofibromas at < 3 spinal levels, but surgical treatment is
not possible, allowed

- Meets ≥ 2 diagnostic criteria for NF1, including the following:

- Six or more café-au-lait spots (≥ 1.5 cm in postpubertal patients)

- Freckling in the axilla or groin

- Optic glioma

- Two or more Lisch nodules

- Distinctive bony lesion (dysplasia of the sphenoid bone or dysplasia orthinning
of long-bone cortex)

- First-degree relative with NF1

- Patients with documented mutation in neurofibromin gene with onlysymptomatic
plexiform and/or paraspinal neurofibroma who do not fulfill the above clinical
criteria are eligible

- Measurable disease, defined as ≥ 1 lesion whose longest diameter can beaccurately
measured as 8.0 cm^3 with 3-dimensional (3D) MRI

- Skin lesions are consideredmeasurable (e.g., plexiform neurofibromas), but MRI
imaging still required for 3D measurement

- Patients with symptomatic neurofibroma, in whom surgery is not feasible, who refuse
surgery or are not goodsurgical candidates due to high risk of damage to vital
structures or spinal cordinjury are eligible

- No evidence of progressive optic glioma, malignant glioma, malignant peripheralnerve
sheath tumor, or other cancer requiring treatment with chemotherapy orradiotherapy

- ECOG performance status 0-3

- WBC ≥ 3,000/mm^3

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 8.0 g/dL

- Bilirubin normal (patients with Gilbert's syndrome allowed despite elevated
bilirubin)

- Alkaline phosphatase normal

- AST and ALT ≤ 2.5 times upper limit of normal

- Thyroid-stimulating hormone and free thyroxin normal

- Creatinine normal OR creatinine clearance ≥ 60 mL/min

- Ejection fraction ≥ 50% by echocardiogram

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No other uncontrolled, serious medical condition that would preclude study
participation, including any of the following:

- Cardiac arrhythmia

- Diabetes

- Serious infection

- Significant cardiac, pulmonary, hepatic, or other organ dysfunction

- No psychiatric illness or social situation that would preclude study compliance

- No history of allergic reactions attributed to compounds of similar chemical
orbiologic composition to AZD2171

- No New York Heart Association class III or IV disease

- Class II disease controlled with treatment and increased monitoring allowed

- No systolic blood pressure (BP) > 130 mm Hg and diastolic BP > 90 mm Hg

- No history of familial long QT syndrome

- Mean QTc ≤ 470 msec (with Bazett's correction) by EKG

- QTc prolongation ≤ 500 msec

- No other significant ECG abnormality within the past 14 days

- See Disease Characteristics

- More than 30 days since prior investigational agents

- More than 4 weeks since prior radiotherapy, chemotherapy, hormonal therapy directed
at thetumor, immunotherapy, biologic therapy (e.g., interferon), or majorsurgery

- No concurrent medication that may markedly affect renal function (e.g., vancomycin,
amphotericin, or pentamidine)

- No concurrent CYP interactive medications

- No concurrent combination antiretroviral therapy for HIV-positive patients

- No concurrent enzyme-inducing anticonvulsants (e.g., phenytoin, carbamazepine, or
phenobarbital)

- No concurrent use of drugs or biologics with proarrhythmic potential