PD-1 inhibitor-induced thyroiditis and ACTH deficiency

A woman in her 70s on pembrolizumab for non-small cell lung cancer experienced progressive fatigue, intractable nausea and reduced mobility since commencing her cancer treatment. After repeat admissions and prolonged inpatient stay from compounded septicaemia, a diagnosis of programmed cell death 1 (PD-1) inhibitor-induced hypophysitis was confirmed, with remarkable improvement on commencement of cortisol replacement.While this side effect is known to oncologists, the non-specific symptoms and a lack of familiarity with PD-1 inhibitor and programmed cell death ligand 1 inhibitor therapies in other medical fields can result in diagnostic delays if not actively searching for hypophysitis.Intractable nausea, vomiting and weight loss, even in the absence of hyponatraemia or hypoglycaemia, should trigger physicians to consider hypophysitis.