The objectives of this study are to evaluate safety, efficacy and pharmacokinetics of sorafenib for the treatment of Japanese patients with anaplastic thyroid carcinoma (ATC) or locally advanced or metastatic medullary thyroid carcinoma (MTC).

Inclusion Criteria:

• Japanese patients with ATC (Anaplastic thyroid carcinoma) or locally advanced or metastatic MTC (medullary thyroid carcinoma)
• Not a candidate for surgery or radiotherapy with curative intent
• Histologically or cytologically confirmed ATC or MTC
• Measurable or non-measurable disease (but clinically evaluable) according to RECIST 1.1.
• Age >= 18 years
• Adequate bone marrow, liver and renal function to be conducted within 14 days prior to treatment
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1
• Life expectancy of at least 12 weeks

Exclusion Criteria:

• Histologic subtypes of thyroid cancer other than anaplastic or medullary carcinoma
• Prior anti-cancer treatment with tyrosine kinase inhibitors, monoclonal antibodies (licensed or investigational) that target VEGF or VEGF (vascular endothelial growth factor) receptors or other targeted agents
• Prior chemotherapy for thyroid cancer (only one regimen is allowed)
• Major surgery, open biopsy, or significant traumatic injury within 30 days prior to enrollment in the study.
• Subjects with tracheal, bronchial or esophageal infiltration with significant risk of bleeding but without having received local treatment prior to enrollment in the study