SAT-239 Combination of Immune Check Point Inhibitors Causing Hypopituitarism

Introduction: Immune Check Point inhibitors (ICI) have been associated with immune related adverse events including a wide array of Endocrinopathies particularly when a combination of ICIs is used. We present a case of Hypopituitarism secondary to CTLA-4 inhibitor Iplimumab and PD-1 inhibitor Pembrulizumab in a patient with Vulvar Melanoma. Case Description: 49-year-old female with past medical history of Type 2 Diabetes and Vulvar Melanoma presented with nausea, vomiting and fatigue. The patient had surgical excision of Vulvular Melanoma and had been on chemotherapy with Pembrolizumab and Ipilimumab for 1 month. She was found to be hypotensive in the ER, but blood pressure improved after fluid resuscitation. Her blood sugar levels were 76 MG/DL. She denied using any insulin in the last 24 hours. AM Cortisol was <1 UG/ML. TSH was 0.205 UIU/ML with free T4 at 0.74 NG/DL. FSH was 2.5 MIU/ML. LH was 0.5 MIU/ML. Prolactin was 90.2 NG/ML. ACTH was less than 9 PG/ML. MRI of the brain showed mildly enlarged pituitary gland with suprasellar extension, measuring 10.5 mm in craniocaudal height and normal homogeneous enhancement. A diagnosis of Hypopituitarism secondary Ipilimumab and Pembrolizumab was made. She was started on steroids and thyroid replacement. The patient’s symptoms resolved, and she was discharged home in a stable condition with outpatient Endocrinology follow up. Discussion: Immune checkpoint inhibitors (ICI) includes PD1(Programmed cell death receptor 1) inhibitors like Pembrolizumab and CTLA-4 (Cytotoxic T Lymphocyte Antigen-4) inhibitors like Ipilimumab. CTLA-4 inhibitors have more frequently been associated with Hypophysitis leading to particularly ACTH and TSH deficiencies and causing secondary adrenal insufficiency and secondary hypothyroidism. Posterior Pituitary involvement is less common. MRI usually shows mild to moderate enlargement of the pituitary gland. ICI therapy usually does not need to be stopped. Patients commonly require long term glucocorticoid and thyroid replacement.