EXAMINER: This phase IV trial is assessing two doses (60mg and 140mg) of an oral drug (cabozantinib) in the treatment of progressive, metastatic Medullary Thyroid Cancer (MTC)A Randomized, Double-blind Study To Evaluate the Efficacy and Safety of Cabozantinib (XL184) at 60 mg/Day Compared to a 140 mg/Day in Progressive, Metastatic Medullary Thyroid Cancer Patients

Exclusion

1. The subject has previously received cabozantinib.
2. Receipt of any type of small molecule kinase inhibitor or hormonal therapy within 28 days or 5 half-lives of the compound or active metabolites, whichever is shorter, before randomization.
3. Receipt of any systemic anti-tumor therapy within 28 days of randomization (42 days for nitrosoureas or/ mitomycin C).
4. Receipt of any other type of investigational agent within 28 days of randomization.
5. Receipt of radiation therapy within 28 days (14 days for radiation for bone metastases) of randomization or radionuclide treatment within 42 days of randomization. Subject is ineligible if there are any clinically relevant ongoing complications from prior radiation therapy.
6. The subject has untreated and/or active (progressing or requiring anticonvulsants or corticosteroids for symptomatic control) central nervous system (CNS) metastasis. Must have completed radiation therapy ≥ 28 days prior to randomization and be stable without corticosteroids or anti-convulsant treatment for ≥ 10 days.
7. Treatment at therapeutic doses with oral anticoagulants or platelet inhibitors (examples are warfarin and clopidogrel).
8. The subject has uncontrolled, significant intercurrent illness including, but not limited to, cardiovascular disorders, gastrointestinal disorders, active infections, non-healing wounds, recent surgery.
9. Corrected QT interval calculated by the Fridericia formula (QTcF) > 500 ms within 28 days before randomization.
10. The subject is unable to swallow multiple tablets or capsules.
11. The subject has a previously identified allergy or hypersensitivity to components of the study treatment formulation.
12. The subject is pregnant or breastfeeding.
13. The subject has had a diagnosis of another malignancy within 2 years before randomization, except for superficial skin cancers, or localized, low-grade tumors deemed cured and not treated with systemic therapy.