PDCD1 and thyroid gland undifferentiated (anaplastic) carcinoma: Spartalizumab is a humanized IgG4 anti-PD-1 (S228P) mAb, which binds to PD-1 and blocks the interaction between the receptor and its ligands, programmed death-ligand 1 (PD-L1), and programmed death-ligand 2 (PD-L2).14 Spartalizumab has shown clinical efficacy in various malignancies, including non-small cell lung cancer (NSCLC),15 melanoma,15 anaplastic thyroid cancer,16 neuroendocrine neoplasms,17 and nasopharyngeal cancer.18