Hypoparathyroidism: an uncommon adverse effect of treatment with durvalumab

SUMMARY: Immune checkpoint inhibitors (ICIs) are monoclonal antibodies approved for the treatment of numerous cancer types. Toxicities induced by ICIs may affect any organ system and manifest as endocrinopathy. The main side effects related to treatment are immune-related adverse events (irAEs), especially thyroid dysfunction and hypophysitis. Rare endocrine irAEs are diabetes insipidus, hypoparathyroidism, thyrotoxic crisis and hypogonadism. We report a case of hypoparathyroidism induced by ICI treatment with durvalumab, which has not previously been described. LEARNING POINTS: Treatment with immune checkpoint inhibitors (ICIs) is associated with many endocrine side effects. It is recommended that patients treated with ICIs are observed by an endocrinologist. If side effects are treated accordingly, ICI therapy can continue.