The incidence of thyroid disorders (painless thyroiditis, hypothyroidism, thyrotoxicosis, or thyroid storm [11]) is about 10% in patients receiving anti–PD–1/PD–L1 alone [8,89,125], but euthyroid Graves’ ophthalmopathy and other rare endocrine diseases have also been reported [82]. Here, PDCD1 is linked to thyrotoxicosis.