Of 91 patients treated with a PD-L1 inhibitor, 19 (21%) developed new onset thyroid dysfunction, of which 14 presented with hypothyroidism and 5 with thyrotoxicosis (3 progressed to hypothyroidism, 2 returned to euthyroidism), and 4 (4%) had worsening of preexisting hypothyroidism.
We found that endocrine side effects after anti-PD-1/PD-L1 therapy are relatively rare, with hypothyroidism (range < 1 to 40%) and hypophysitis (range < 1 to 10%) being the two most common.
A 73-year-old women known for myositis, Crohn's disease, and hypothyroidism and diagnosed with PD-L1 positive stage IV pulmonary adenocarcinoma is treated with Pembrolizumab.