What is the clinical presentation for ipilimumab-induced hypophysitis (IH)?
The diagnosis of IH is presumptive and based on the presence of new-onset hypopituitarism in medically-treated patients, and without an alternative etiology. It is most commonly observed in older males (mean age 55 years) and after ≈ 3 months (or 3–4 cycles) of treatment. Clinically, patients typically present with headaches (84%), fatigue (66%), and hyponatremia (56%). Biochemically, central hormone deficiencies are commonly observed for the thyroid (93%), gonadal (85%), and adrenal (75%) axes, and less commonly for GH (28%), and prolactin (25%). Conversely, ADH deficiency is very rarely observed (< 1%). The absence of DI is a distinct clinical feature of IH, in contrast to other forms of hypophysitis and metastatic disease of the posterior pituitary gland/stalk. Radiographically, heterogeneous mild pituitary gland enhancement, or stalk thickening are common, although the MRI may also be normal.
On a positive note, the development of IH generally predicts a more effective anticancer response and survival is improved in patients with melanoma treated with ipilimumab who develop IH.