Efficacy of XL184 (Cabozantinib) in Advanced Medullary Thyroid Cancer

Inclusion Criteria: * The subject has a histologically confirmed diagnosis of MTC that cannot be removed by surgery, is locally advanced, or has spread in the body. * The subject is at least 18 years old. * The subject has an ECOG (Eastern Cooperative Oncology Group) performance status ≤ 2. * The subject has documented worsening of disease (progressive disease) at screening compared with a previous CT scan or MRI image done within 14 months of screening. * The subject has recovered from clinically significant adverse events (side effects) due to any other medications that were administered prior to randomization. * The subject has adequate organ and bone marrow function. * Subjects who are sexually active (male and female) must agree to use medically accepted methods of contraception during the course of the study and for 3 months following discontinuation of study treatments. * The subject has no other diagnosis of cancer (unless non-melanoma skin cancer, an early form of cervical cancer, or another cancer diagnosed ≥ 2 years previously) and currently has no evidence of malignancy (unless non-melanoma skin cancer or an early form of cervical cancer). * Female subjects of childbearing potential must have a negative pregnancy test at screening. Exclusion Criteria: * The subject has received prior treatment for their cancer within 4 weeks of randomization (6 weeks for nitrosoureas or mitomycin C). * The subject has received radiation to ≥ 25 % of bone marrow. * The subject h…