Endocrine Abstracts

JOINT1733

Introduction: Pembrolizumab is a monoclonal anti-programmed death receptor-1 (PD-1) antibody that suppresses T-cell function. While it has gained approval for the treatment of numerous cancers, it is crucial to recognize the potential for serious immune-related adverse events, particularly concerning the endocrine system. Few cases of pembrolizumab-induced isolated corticotrope deficiency were reported in the literature. Herein, we report a new case of a late isolated corticotrope deficiency induced by pembrolizumab.

Observation: A 74-year-old woman was referred to the Department of Endocrinology for secondary adrenal deficiency. Her medical history was notable for hypertension, hypertrophic cardiomyopathy, cervical surgery for primary hyperparathyroidism, and lobectomy for non-small-cell lung carcinoma. Following a recurrence of her lung cancer, she underwent three chemotherapy regimens, including Carboplatin, Alimta, and pembrolizumab. Nine months post-initiation of chemotherapy, she presented with asthenia, weight loss, nausea, and vomiting. On physical examination, the patient had a weight of 69 kg, a height of 1.63 m, corresponding to a body mass index of 25.97 kg/m², an orthostatic hypotension, and a diffuse abdominal tenderness. The rest of examination was normal. The diagnosis of corticotrope deficiency was established based on a significantly low cortisol level of 28 nmol/lwith a low ACTH level of 4.9 ng/L. Other pituitary hormone levels were normal, confirming the diagnosis of isolated corticotrope deficiency. Magnetic resonance imaging (MRI) of the pituitary gland appeared normal, showing no tumors. The posterior lobe bright spot was intact, and the pituitary stalk was median and thin. The patient was treated with hydrocortisone and responded positively to the therapy.

Discussion: Corticotrope deficiency represents a potentially life-threatening complication of pembrolizumab treatment. Its clinical presentation can often be non-specific, as reported in this case. Previous reports indicate that the median onset of corticotrope deficiency following pembrolizumab administration is approximately 12 weeks. However, late-onset cases, including those occurring after the discontinuation of the drug, have also been documented. Regular monitoring of adrenal function is therefore essential during treatment and following the last dose of pembrolizumab.