PDCD1 and thyroiditis: In this prospective study, we analysed the development of thyroid dysfunction in a large number of patients (n = 209) treated with anti-PD-1 antibodies, and showed that the presence of anti-thyroid antibodies at baseline is a biomarker of the development of destructive thyroiditis and/or hypothyroidism induced by not only nivolumab but also pembrolizumab.