Study Comparing Two Doses of Lenvatinib for Treating Radioactive Iodine Resistant Thyroid Cancer

Inclusion Criteria

• Diagnosed with specific types of thyroid cancer, such as papillary, follicular, or Hurthle Cell thyroid cancer.
• The cancer must not be curable by surgery and must meet certain criteria, such as not absorbing radioactive iodine or progressing despite treatment.
• Must have measurable or evaluable cancer.
• No more than one previous treatment with certain targeted therapies for thyroid cancer.
• Cancer must be causing symptoms or progressing on the most recent treatment.
• Must be at least 18 years old.
• Must be in relatively good health with a performance status score of 0 to 2.
• Blood pressure must be below 140/90.
• Must have adequate blood cell counts and organ function.
• Must agree to use effective contraception during the study and for 30 days after the last dose of lenvatinib.
• Must be able to understand and sign a consent form.

Exclusion Criteria

• Have certain types of thyroid cancer, such as anaplastic or medullary thyroid cancer.
• Have previously been treated with lenvatinib.
• Have another type of cancer that could interfere with the study.
• Currently taking other investigational drugs.
• Have untreated brain metastases.
• Have a history of severe allergic reactions to similar drugs.
• Taking medications that affect heart rhythm without a 7-day washout period.
• Have uncontrolled illnesses, such as heart failure or infections.
• Pregnant or breastfeeding.
• Have untreated or uncontrolled HIV, hepatitis B, or hepatitis C infections.
• Have had major surgery within 14 days before starting the study.