Immune checkpoint inhibitors and endocrinopathies in pediatric brain tumor patients.

Objectives: Immune checkpoint inhibitors (ICIs) are emerging treatment options for children with brain tumors, who are already at risk for developing endocrinopathies due to tumor location and treatment. Endocrine ICI-related adverse effects (irAEs) are common in adults but poorly characterized in the pediatric population. The aims of this study were to determine in pediatric brain tumor patients in a single institution (1) if endocrine surveillance took place before and after ICIs were initiated, and (2) the occurrence of endocrine irAEs.

Methods: This is a retrospective chart review of 22 pediatric brain tumor patients treated with ICIs at Children's Hospital Los Angeles between 2010 and 2022. We analyzed endocrine laboratory results, patient demographics, and treatment course.

Results: Most patients (82 %) received surveillance in at least one endocrine system before ICI treatment - all had thyroid function tested (100 %) whereas non-thyroid endocrine functions were seldomly assessed (6-22 %). Only those patients with surveillance prior to treatment had ongoing surveillance after ICI initiation - 100 % for thyroid function and 17-39 % for other endocrine systems. Hypothyroidism was the only endocrine problem diagnosed after ICI initiation, in two patients (9 %). Of note, most patients (68 %) expired during or shortly after ICI treatment.

Conclusions: This is one of the first institutional surveys of pediatric ICIs in a high-volume pediatric brain tumor center. Thyroid surveillance commonly occurred in pediatric patients, revealing diagnoses of hypothyroidism, which is consistent with adult data. However, little information is available for non-thyroid endocrine conditions, reflecting the need for comprehensive and systematic endocrine surveillance.