Background and Aim Immune checkpoint inhibitors have significantly improved the clinical outcomes of many cancer types, but they induce a range of immune‐related adverse events (irAEs). Although adrenal insufficiency (AI) is a rare irAE, it can lead to serious consequences. This study aimed to determine the clinical features of patients with advanced non‐small‐cell lung cancer (NSCLC) who developed AI following pembrolizumab treatment. Methods We retrospectively reviewed and analyzed the clinical data of all patients with NSCLC treated with pembrolizumab at Juntendo University Hospital from February 2017 to December 2020. The diagnosis of AI was established based on the Endocrine Emergency Guidance for the acute management of endocrine complications of checkpoint inhibitor therapy in the UK and the clinical practice guidelines of the Japan Endocrine Society. Result AI was clinically suspected in 59 out of 186 patients treated with pembrolizumab, and 10 (5.4%) cases were confirmed. The symptoms included hyponatremia (n = 9), fatigue (n = 8), and loss of appetite (n = 6). All patients had low adrenocorticotropic hormone (ACTH) levels, and five patients were diagnosed with isolated ACTH deficiency. All patients completely recovered with corticosteroid replacement. The median time to onset of AI was 8.0 (range 3.8–15.2) months. The median progression‐free survival in these patients was 22.4 (95% confidence interval 11.2–not reached) months. Conclusion The incidence of AI among patients treated with pembrolizumab is more frequent than previously reported. In addition, secondary AI, especially isolated ACTH deficiency, is a major form of AI induced by pembrolizumab.

The coronavirus disease 2019 (COVID-19) is a condition caused by the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) which first emerged in December 2019. Although several papers have reported the presence bradycardia in patients with COVID-19, the pathophysiology behind this remains unclear. Therefore, we investigated the presence of bradycardia in patients with COVID-19. A total of 153 patients with COVID-19 and 90 patients with influenza who were hospitalized in our hospital from January 1, 2020 to December 31, 2021 and from January 1, 2014 to December 31, 2021, respectively, were enrolled. After adjustment, the incidence of bradycardia and steroid use in patients with COVID-19 were significantly higher than those in patients with influenza (P-value = 0.0067 and P-value = 0.0003, respectively). We then compared the detailed characteristics of patients with COVID-19 to evaluate risk factors for bradycardia. Multivariate logistic regression analysis revealed that steroid use was significantly related to bradycardia (P-value = 0.031; odds ratio [OR]: 3.67; 95% confidence interval [CI]: 1.12–11.96). Overall, results showed a higher incidence of bradycardia in patients with COVID-19 who received steroid treatment. To the best of our knowledge, this is the first report to discuss the potential risk of excessive steroid use patients with COVID-19.