Thyroid dysfunction after immune checkpoint inhibitor treatment in a single-center Chinese cohort: a retrospective study

Thyroid dysfunction is a common adverse event after immune checkpoint inhibitor (ICI) therapy. The clinical manifestations of thyroid immune-related adverse events (irAEs) are variable and the underlying mechanisms remain unclear.To identify the clinical and biochemical characteristics of Chinese patients with ICI-related thyroid dysfunction.We retrospectively reviewed patients with carcinoma who received ICI therapy and underwent evaluation of thyroid function during hospitalization at Peking Union Medical College Hospital between January 1, 2017 and December 31, 2020. Clinical and biochemical features were analyzed in patients who developed ICI-related thyroid dysfunction. Survival analyses were performed to determine the effect of thyroid autoantibodies on thyroid abnormalities and the impact of thyroid irAEs on clinical outcomes.The cohort included 270 patients with a median follow-up of 17.7 months; 120 (44%) of these patients developed thyroid dysfunction on immunotherapy. The most common thyroid irAE was overt hypothyroidism (with/without transient thyrotoxicosis), which occurred in 38% of patients (n = 45), followed by subclinical thyrotoxicosis (n = 42), subclinical hypothyroidism (n = 27), and isolated overt thyrotoxicosis (n = 6). The median time to first clinical presentation was 49 days (interquartile range 23, 93) for thyrotoxicosis and 98 days (interquartile range 51, 172) for hypothyroidism. In patients treated with PD-1 inhibitors, hypothyroidism was strongly associated with younger age (odds ratio [OR] 0.44, 95% confidence interval [CI] 0.29-0.67; P < 0.001), previous thyroid disease (OR 4.30, 95% CI 1.54-11.99; P = 0.005), and a higher baseline thyroid-stimulating hormone level (OR 2.76, 95% CI 1.80-4.23; P < 0.001). Thyrotoxicosis was only associated with the baseline thyroid-stimulating hormone (TSH) level (OR 0.59, 95% CI 0.37-0.94; P = 0.025). Thyroid dysfunction after initiation of ICI therapy was associated with better progression-free survival (hazard ratio [HR] 0.61, 95% CI 0.44-0.86; P = 0.005) and overall survival (hazard ratio 0.67, 95% CI 0.45-0.99; P = 0.046). Anti-thyroglobulin antibody positivity increased the risk of thyroid irAEs.The occurrence of thyroid irAEs with diverse phenotypes is common. Distinct clinical and biochemical characteristics suggest heterogeneity among different subgroups of thyroid dysfunction, which requires further research to explore the under mechanism.