Abstract: Objective To investigate the clinical characteristics and management of endocrine dysfunction induced by sintilimab. Methods One case of gastric cancer who developed isolated adrenocorticotropic hormone deficiency and primary hypothyroidism after sintilimab treatment was reported while related literature was reviewed. Results The endocrine adverse reactions were strongly associated with sintilimab based on clinical manifestations, laboratory findings, and temporal relationship. After discontinuation of sintilimab and initiation of prednisone and levothyroxine replacement therapy, the patient’s symptoms were resolved completely, allowing for immunotherapy resumption. Conclusion Patients receiving sintilimab should be monitored for endocrine adverse reactions (e.g., hyponatremia and fatigue), in case of which lifelong hormone replacement is required. Baseline assessment and regular endocrine function monitoring are crucial to early detection and prevention of serious outcomes.

Key words: Sintilimab, Isolated Adrenocorticotropic Hormone Deficiency, Primary Hypothyroidism, Prednisone, Levothyroxine, Adverse Drug Reactions