Predictors of thyroid adverse events during cancer immunotherapy: a real-life experience at a single center

Background: Thyroid dysfunction is among the most common immune-related adverse events (irAEs) of immune checkpoint inhibitors (ICIs) therapy. Data regarding potential predictors of the development of thyroid irAEs are still limited and sometimes conflicting.

Patients and methods: We assessed potential risk factors and clinical outcomes associated with the onset of thyroid irAEs in a cohort of patients with different types of cancer treated with ICIs at a single center. Clinical and biochemical data, including thyroid function tests and autoantibodies at baseline and during treatment, were collected, and the onset of thyroid irAEs was recorded. Patients with thyroid dysfunction and/or under levothyroxine therapy before starting ICI were excluded.

Results: 110 patients (80 M, 30 F, aged 32-85 years; 56.4% non-small-cell lung cancer, 87% treated with anti-PD-1) with complete information were included in the study. Among them, 32 (29%) developed thyroid irAEs during ICIs therapy. Primary hypothyroidism was the most common irAEs, occurring in 31 patients (28.18% of the whole cohort), including 14 patients who experienced a transient thyrotoxicosis. About 60% of irAEs occurred within the first 8 weeks of therapy. At multivariate analysis, anti-thyroid autoantibodies positivity at baseline (OR 18.471, p = 0.022), a pre-existing (autoimmune and non-autoimmune) thyroid disorder (OR 16.307, p < 0.001), and a family history of thyroid diseases (OR = 9.287, p = 0.002) were independent predictors of the development of thyroid irAEs.

Conclusion: Our data confirm the high frequency of thyroid dysfunctions (mostly hypothyroidism) during ICIs, and provide data on valuable predictors of thyroid toxicities that may help clinicians in identifying patients at risk for developing irAEs.