Pembrolizumab-Induced Adrenal Insufficiency in Patients with Untreated Advanced Non-Small Cell Lung Cancer: A Case Series

Abstract Pembrolizumab-induced adrenal insufficiency (AI) is recognized as a rare immune-related adverse event (irAE) that can be fatal if diagnosis is delayed. Clinical features of AI in patients with advanced non-small cell lung cancer (NSCLC) who received pembrolizumab as the first-line treatment were observed. Five out of 49 patients with untreated advanced NSCLC developed AI between April 2017 and February 2021. Of the 5 patients, 4 developed AI with a grade >3 and were hospitalized. The median time of the onset of AI from the start of first-line treatment was 4.63 months. All the patients improved after corticosteroid replacement therapy. The efficacy of treatment was complete response in 1 patient and partial response in 4 patients. Median progression-free survival was 37.7 months, and overall survival had not been reached. This case series revealed the efficacy of immunotherapy in AI as an irAE.