Endocrine Abstracts

JOINT3465

Background: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, but they can cause significant endocrine-related adverse events. Hypophysitis, an inflammation of the pituitary gland, occurs in 5-10% of patients receiving combination CTLA-4/PD-1 blockade. However, recent studies suggest that the incidence may be higher, with rates up to 25% reported in patients treated with ipilimumab plus nivolumab for melanoma. This higher incidence may reflect increased awareness and recognition of this immune-related adverse event in real-world clinical practice.

Case Report: A 41-year-old male with stage IV BRAF wild-type melanoma developed severe neurological symptoms during his fourth cycle of ipilimumab/nivolumab therapy. The patient presented with progressive headache, gait ataxia, and generalized tonic-clonic seizures. Initial assessment revealed profound hyponatremia (119 mmol/l)and altered consciousness (GCS E1V1m³). Endocrine evaluation demonstrated complete anterior pituitary failure, consistent with panhypopituitarism. Pituitary imaging showed radiological evidence of hypophysitis. The patient’s presentation illustrates that rapid-onset panhypopituitarism can manifest without classical visual field defects typically associated with pituitary enlargement. Management included high-dose glucocorticoids (IV methylprednisolone 1mg/kg), hormonal replacement therapy (levothyroxine, hydrocortisone, testosterone), and discontinuation of ICI treatment. This approach aligns with current guidelines for managing ICI-induced hypophysitis.

Conclusion: This case report illuminates several critical insights into ICI-induced hypophysitis. Rapid-onset panhypopituitarism can occur without typical visual field defects, challenging traditional diagnostic expectations. The presentation demonstrated that hyponatremia secondary to adrenal crisis may precede radiographic changes, emphasizing the critical importance of early and comprehensive endocrine evaluation. Moreover, the occurrence of seizure activity represents an uncommon neurological manifestation of acute hypophysitis, highlighting the need for heightened clinical vigilance in patients undergoing immune checkpoint blockade. The case underscores the paramount importance of multidisciplinary collaboration between oncologists and endocrinologists in managing complex immune-related adverse events. Implementing protocolized pituitary axis monitoring for patients receiving dual immune checkpoint blockade is essential. This should include rigorous baseline assessments and frequent follow-up testing to enable early detection and intervention. Ultimately, this case reinforces the critical nature of early recognition and prompt management of ICI-induced hypophysitis. Timely and comprehensive medical intervention can prevent potentially life-threatening complications and ensure optimal patient outcomes in the evolving landscape of immunotherapy.