Evaluating the Safety and Efficacy of Oral Lenvatinib in Medullary and Iodine-131 Refractory, Unresectable Differentiated Thyroid Cancers, Stratified by Histology

Inclusion criteria:

1. Histologically or cytologically confirmed diagnosis of medullary thyroid cancer (MTC) or differentiated thyroid cancer (DTC).
2. Measurable disease meeting the following criterion:

   1. At least one lesion (greater than or equal to 1.5 cm in longest diameter for non-lymph nodes and greater than or equal to 2.0 cm in longest diameter for lymph nodes) which is serially and accurately measurable according to modified response evaluation criteria in solid tumours (RECIST) using either computed tomography (CT) or magnetic resonance imaging (MRI).
   2. Lesions that have had electron beam radiotherapy must show evidence of progressive disease based on modified RECIST to be deemed a target lesion.
3. Evidence of disease progression by RECIST using site assessment of CT/MRI scans within 12 months (+1 month to allow for variances in patient scanning intervals) prior to study entry.
4. DTC must be 131-I refractory/resistant: never demonstrated 131-I uptake, progression despite 131-I uptake, or cumulative dose of 131-I of greater than 600 millicurie (mCi) (last dose given at least 6 months prior to study entry).
5. Well controlled blood pressure prior to study entry.

Exclusion criteria:

1. Anaplastic thyroid carcinoma, thyroid lymphoma, mesenchymal tumors of the thyroid, metastases to the thyroid.
2. Brain or leptomeningeal metastases.
3. Significant cardiovascular impairment (history of congestive heart failure, New York Heart Association \[NYHA\] Class II, unstable angina or myocardial infarction within 6 months of study start, or serious cardiac arrhythmia).
4. Marked baseline prolongation of QT/corrected QT (QTc) interval.
5. Proteinuria greater than 1+ or greater than 30 mg in dipstick testing.
6. Active hemoptysis (bright red blood of at least one-half teaspoon) in the 28 days prior to study entry.