A Phase I Trial of Af-001 in Patients With Differentiated Thyroid Cancer

Inclusion Criteria: \<Ia part\> * Patients with differentiated thyroid cancer (papillary carcinoma, follicular carcinoma) after total thyroidectomy. * Patients with radically unresectable, recurrent, metastatic disease who are judged by the principal investigator or sub-investigator (hereinafter, "principal/sub-investigators") to be refractory to or intolerant of standard-of-care therapy. \<Ib part\> * Patients with radically unresectable, recurrent, metastatic disease who are RAI naive * Patients with measurable lesions. \<Ia/Ib part\> * Patients with an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 to 2 and stable general condition. * Patients expected to survive for at least 6 additional months based on clinical symptoms and physical examination findings. Exclusion Criteria: \<Ia/Ib part\> * Patients who need to preserve fertility. * Females who are pregnant or may be pregnant, breastfeeding patients, or patients or their partners who cannot agree to appropriate contraception. * Patients with active multiple cancers (synchronous multiple cancers and ectopic double cancers with a disease-free period of \<=3 years). * Patients with uncontrolled active infections. * Patients who are positive for hepatitis B virus surface (HBs) antigen, hepatitis C virus (HCV) antibodies, or human immunodeficiency virus (HIV) antibodies.