Monoclonal antibodies such as Ipilimumab (against cytotoxic T-lymphocyte-associated antigen 4 [CTLA-4]) and nivolumab (against programmed death protein 1 [PD-1]), block inhibitory regulatory T cell molecules and achieve anti-tumour effect by enhanced T cell activation at the cost of autoimmunity1,2,3,4,5. We report a case of presumed autoimmune hypophysitis and type 1 diabetes after treatment with ipilimumab and nivolumab for metastatic melanoma.
A 54-year-old woman presented with seizures and confusion. Medical history included melanoma with intracranial metastases treated with craniotomy, radiation and a course of ipilimumab nine weeks prior. MRI excluded new cerebral lesions but showed an enlarged pituitary not present previously. Static anterior pituitary function evaluation revealed hypopituitarism involving the pituitary-thyroid and pituitary-gonadal axes (T4 of 6.2 pmol/L with TSH of 1.2 mIU/L; low gonadotrophins of FSH 8 IU/L and LH 1 IU/L). ACTH insufficiency was suspected but could not be established due to concurrent dexamethasone therapy (cortisol < 35 nmol/L, ACTH < 5 ng/L). A clinical diagnosis of ipilimumab-induced hypophysitis (IH) was made.
Despite complications, the patient completed the ipilimumab course and then received nivolumab. Five weeks later, she presented with severe symptomatic hyperglycaemia (serum glucose 21.7 mmol/L) and ketoacidosis (pH 6.91, serum beta-hydroxybutyrate 9.4 mmol/L), requiring an insulin infusion. Abdominal CT showed a normal pancreas with no radiological evidence of pancreatitis or metastasis. The acute presentation with hyperglycaemia, ketoacidosis and low C-peptide levels led to the diagnosis of presumed autoimmune diabetes. Serum autoantibodies (IA2 and GAD65) were negative.
There is little data on nivolumab-induced autoimmune diabetes. It has been reported in one recent study6. This is the first report of ipilimumab-induced hypophysitis followed by apparent nivolumab-induced type 1 diabetes. These are uncommon adverse events of immunotherapy but are expected to rise in incidence as immunotherapy becomes more prevalent.