Inclusion Criteria
Diagnosed with neurofibromatosis type 1
Plexiform neurofibroma that is progressive or causing significant morbidity
Measurable disease amenable to volumetric MRI imaging
Central review or MRI required prior to enrollment
Complete resection of plexiform neurofibroma is not feasible or if subject refuses surgery
Fully recovered from acute toxic effects of all prior chemotherapy or radiotherapy
No myelosuppressive chemotherapy within 4 weeks of study entry At least 7 days since completion of hematopoietic growth factors
At least 14 days since completion of biologic agent
At least 4 weeks since receiving any investigational drug
Physiologic or stress doses of steroids allowed in patients with endocrine deficiencies
At least 6 months from radiation therapy to index tumor and at least 6 weeks from radiation to areas outside of index plexiform neurofibroma
At least 2 weeks from surgery AND recovered from any effects of surgery
Adequate bone marrow and organ function
Exclusion Criteria
Active optic glioma or other low-grade glioma requiring treatment with chemotherapy or radiation therapy
Malignant glioma, malignant peripheral nerve sheath tumor, or other malignancy requiring treatment in the last 12 months
Dental braces or prosthesis that interferes with volumetric analysis of the neurofibroma(s)
Unable to swallow tablets
Currently pregnant or breastfeeding
Subjects of reproductive potential who have not agreed to use effective contraception
Subject requires anticoagulants
Concomitant treatment of strong CYP3A4 inducers or inhibitors
A known history of HIV seropositivity or known immunodeficiency
Impairment of gastrointestinal function or gastrointestinal disease that may affect the absorption of cabozantinib
Patients who have an uncontrolled infection
Clinically-significant gastrointestinal bleeding within 6 months before the first dose of study treatment
Any other signs indicative of pulmonary hemorrhage within 3 months before the first dose of study treatment
Radiographic evidence of cavitating pulmonary lesion(s)
Concurrent severe and/or uncontrolled medical disease which could compromise participation in the study (e.g. uncontrolled diabetes, uncontrolled hypertension, severe infection, severe malnutrition, chronic liver or renal disease, active upper GI tract ulceration)
Cardiovascular disorders