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Objectives: The use of immune checkpoint inhibitors (ICIs) in cancer treatment is increasing. Literature about endocrinopathies associated with ICIs in children is limited. This study investigates ICIs and thyroid dysfunction in pediatric patients at one institution.

Methods: Retrospective chart review of patients ages 1 to 19 was completed who received any of the following ICIs between January 2000 and November 2023: PD-1 inhibitors (nivolumab or pembrolizumab), PD-L1 inhibitors (durvalumab or atezolizumab), and CTLA-4 inhibitors (ipilimumab or tremelimumab). Patients were excluded if thyroid function tests (TFTs) were not available to review or if patients passed away within 30 days of ICI initiation. TFTs were considered abnormal if they were outside the reference range for age.

Results: Data analysis included nineteen patients. Of these, thirteen patients received nivolumab and three patients received multiple ICIs. Average age at time of ICI initiation was 14.9 years. Baseline TFTs were obtained in fourteen patients at ICI initiation and ten of these patients also had TFTs checked after initiation. Abnormal TFTs were seen in five patients after starting ICI therapy; four of these patients received nivolumab and one received pembrolizumab. Average time to thyroid dysfunction from ICI initiation was 3.3 months. Levothyroxine (LT4) was started in three patients for persistent abnormal TFTs (one patient had central hypothyroidism and two patients had primary hypothyroidism). Average time to LT4 treatment was 4.2 months. Two patients developed hypothyroidism prior to starting ICI therapy. Of these, one patient developed hyperthyroidism 2.9 weeks after ICI initiation. Hyperthyroidism resolved with temporary LT4 discontinuation, followed by restarting LT4. Six patients had baseline abnormal TFTs with ICI initiation of which two patients required levothyroxine.

Conclusions: Thyroid dysfunction can be seen within several months of ICI initiation, particularly PD-1 inhibitors. Hypothyroidism and hyperthyroidism were seen, though hypothyroidism was more common. This study supports monitoring TFTs (both TSH and free T4 levels) at baseline and during therapy with ICI. Limitations to our study include small patient population. Future studies should look at development of other endocrinopathies in children such as diabetes mellitus or adrenal insufficiency.


Endocrinology, Diabetes, and Metabolism | Pediatrics


Presented at the Pediatric Endocrine Society (PES) 2024 Annual Meeting; Chicago, IL; May 2-5, 2024.

Thyroid Dysfunction in Patients Receiving Immune Checkpoint Inhibitors