Acquired angioedema late in the course of nivolumab treatment.

IntroductionAlthough programmed cell death-1 inhibitors have become the mainstay of treatment for many cancers, their use can at times be accompanied by unusual side effects.Case reportWe describe herein a 43-year-old patient with Lynch syndrome and colon cancer who developed facial swelling 18 months after starting nivolumab therapy. Our patient also experienced a grade 1 maculopapular rash due to this agent. Naranjo nomogram assessment showed a probable causality between nivolumab and angioedema (score of 8).Management & outcomeGiven the modest intensity of symptoms and the excellent response of metastatic colon cancer to nivolumab, this agent was continued without interruptions. She was prescribed prednisone 20 mg orally daily as needed to be taken if the swelling progressed, or if respiratory symptoms developed. The patient experienced another two similar episodes over the next months; however, they were self-limiting and did not require steroids. Subsequently, she had no further similar symptoms.DiscussionRare reports of angioedema associated with immune checkpoint inhibitor (ICI) treatment have previously been described. The exact mechanism of these phenomena is unknown, but bradykinin release leading to increased vascular permeability might be involved. Clinicians, pharmacists, and patients should be aware of this rare side effect of ICIs as it can be life-threatening when involving the respiratory tract and causing impending airway obstruction.