Patterns of hormonal changes in hypophysitis by immune checkpoint inhibitor.

Background/aims: Immune checkpoint inhibitors (ICIs) can induce immune-related adverse events, including endocrine dysfunctions, which can have serious consequences on patient health and quality of life. The clinical course and characteristics of immune-related hypophysitis (irH) are not well established. This study aimed to analyze the clinical course and characteristics of irH.

Methods: This single-center, retrospective study analyzed data from electronic medical records of Asan Medical Center, spanning January 2017 through June 2021. It included adult patients with solid tumors who underwent thyroid and adrenal function tests, along with gonadotropin and/or growth hormone evaluations, following the initiation of ICI treatment within the same period. The study explored the clinical characteristics of ICI-treated patients with and without irH, the incidence of irH, the time to irH onset, and the associated hormonal changes.

Results: Twenty-one patients were included in this analysis. Clinical characteristics did not differ significantly between the irH (n = 13) and non-irH (n = 8) groups. Deficiency rates in the irH group were 23.1% for thyroid-stimulating hormone (n = 3), 76.9% for adrenocorticotropic hormone (n = 10), 61.5% for gonadotropin (n = 8), and 15.4% for growth hormone (n = 2). The overall incidence was 0.9 per person-year, with 6-month and 1-year cumulative incidences of 38.8% and 57.1%, respectively. The median time from ICI initiation to irH diagnosis was 7.7 months. Time to levothyroxine replacement was shorter in the irH group.

Conclusion: The findings provide evidence that could facilitate the prediction of ICI-induced irH based on clinical course and characteristics.