RÉSUMÉ
Background: Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of several solid tumors. The use of ICIs is expected to rise as a growing number of indications are approved for their use by the US Food and Drug Administration and with the increasing number of patients with cancer. Unfortunately, ICIs are associated with the development of immune-mediated adverse reactions (IMARs). About 5% to 10% of patients developing severe toxicities requiring treatment postponement or discontinuation. IMARs can affect any organ, but most frequently the skin and endocrine glands are involved. Case Presentation: We present a case series of IMARs observed at the New Mexico Veterans Affairs Medical Center. First, we present a case of grade 4 myocarditis in an 84-year-old man receiving chemoimmunotherapy for lung adenocarcinoma to demonstrate the rapid progression of this rare condition. Second, we present a case of uveitis in a 70-year-old man with superficial bladder cancer undergoing treatment with pembrolizumab. Finally, we present a case of a 63-year-old man with pleuritis and organizing pneumonia secondary to dual ICI treatment (nivolumab and ipilimumab) for mesothelioma. A discussion regarding the epidemiology of these IMARs, expected course, and optimal management follows each rare toxicity described. Conclusions: Though these toxicities are uncommon, they serve as a reminder to clinicians across specialties that IMARs can drive the acute deterioration of any organ, and consideration of toxicities secondary to ICIs should be considered for any atypical presentation of unclear etiology.